Cardioplegic solutions are the standard in myocardial protection during cardiac surgery, since they interrupt the electro-mechanical activity of the heart and protect it from ischemia during aortic cross-clamping. Nevertheless, myocardial damage has a strong clinical impact. We tested the hypothesis that the short-acting beta-blocker esmolol, given immediately before cardiopulmonary bypass and as a cardioplegia additive, would provide an extra protection to myocardial tissue during cardiopulmonary bypass by virtually reducing myocardial activity and, therefore, oxygen consumption to zero.
This was a single-centre, double-blind, placebo-controlled, parallel-group phase IV trial. Adult patients undergoing elective valvular and non-valvular cardiac surgery with end diastolic diameter >60 mm and ejection fraction <50% were enrolled. Patients were randomly assigned to receive either esmolol, 1 mg/kg before aortic cross-clamping and 2 mg/kg with Custodiol® crystalloid cardioplegia or equivolume placebo. The primary end-point was peak postoperative troponin T concentration. Troponin was measured at Intensive Care Unit arrival and at 4, 24 and 48 hours. Secondary endpoints included ventricular fibrillation after cardioplegic arrest, need for inotropic support and intensive care unit and hospital stay.
We found a reduction in peak postoperative troponin T, from 1195 ng/l (690–2730) in the placebo group to 640 ng/l (544–1174) in the esmolol group (p=0.029) with no differences in Intensive Care Unit stay [3 days (1-6) in the placebo group and 3 days (2-5) in the esmolol group] and hospital stay [7 days (6–10) in the placebo group and 7 days (6–12) in the esmolol group]. Troponin peak occurred at 24 hours for 12 patients (26%) and at 4 hours for the others (74%). There were no differences in other secondary end-points.
Adding esmolol to the cardioplegia in high-risk patients undergoing elective cardiac surgery reduces peak postoperative troponin levels. Further investigation is necessary to assess esmolol effects on major clinical outcomes.
Myocardial tolerance to ischemia is influenced by age and preoperative cyanosis through unknown mechanisms and significantly affects postoperative outcomes. Cytochrome c oxidase (CcOx), the terminal enzyme of the mitochondrial electron transport chain, may play a role in the susceptibility to ischemic-reperfusion (IR) injury. Our study aimed at investigating changes in human myocardial CcOx activity based on age and preoperative oxygen saturation to understand its role in transition from neonatal to mature myocardium and hypoxic conditions.
The right atrial appendage from patients undergoing first time surgical repair/palliation of congenital heart defects was analyzed for steady state CcOx activity by oxidation of ferrocytochrome c via spectrophotometry and steady state CcOx subunit I protein content by protein immunoblotting. Student’s t-test compared CcOx activity and protein levels between patients with preoperative hypoxia and normoxia. Multiple linear regression analysis was used to assess the effects of age and preoperative arterial oxygen saturations (SaO2) on CcOx protein activity and protein content.
Thirty-two patients with a median (interquartile range) age of 83 days (8-174) and preoperative oxygen saturation 98% (85-100%) were enrolled. Independent of age, preoperative SaO2 <=90% was associated with significantly greater CcOx steady state activity (p=0.004). Additionally, older age itself was associated with increased CcOx steady state activity (p=0.022); the combination of preoperative SaO2 and age account for 33% of the variation in CcOx steady state activity (R2=0.332). There was no increase in the CcOx subunit I protein content with either age or preoperative hypoxia.
In patients with congenital heart disease, an increase in CcOx steady state activity is seen with increasing age. Hypoxia leads to upregulation of CcOx steady state activity without an increase in the amount of enzyme protein itself. Higher CcOx activity in older and cyanotic patients may indicate CcOx-dependent reactive oxygen species as the mechanism for IR injury.
We sought to quantify the location and volume of thrombus in used hollow-fiber membrane oxygenators and correlate the volume of thrombus with patient demographics, flow characteristics and anticoagulation parameters.
Hollow-fiber membrane oxygenators (Quadrox D, Maquet, Rastatt, Germany) were collected after clinical use in ECMO circuits and divided into sections. Each section was digitally imaged and analyzed using ImageJ software. The location and total volume (cm3) of thrombus was calculated for different sections. In an effort to predict thrombus formation, we correlated thrombus volume with possible aggravating and mitigating variables.
We collected 41 oxygenators from 27 patients. Twenty-seven (66%) were configured in the veno-venous mode and 14 (34%) in the veno-arterial mode. The median duration of use was 131 hours (interquartile range 61–214 hours). Eighteen (44%) were removed when the patient recovered, six (15%) were removed after withdrawal of care and seventeen (41%) were exchanged. The median volume of thrombus was 11.4 cm3 (interquartile range 2.2–44.5 cm3).
A multivariable linear regression model suggested that the combination of median flow, configuration of ECMO and visible thrombus partially predicted internal thrombus volume (adjusted R2=0.39).
Years of experience and level of education are two important determinants of a clinician’s expertise. While entry-to-practice criteria for admission to perfusion training in Canada changed from clinical experience-based criteria to education-based criteria in 2006, the effects of these changes have not been studied.
To determine the academic and clinical backgrounds of perfusionists in Canada, ascertain perceptions about the adequacy of training and evaluate the effects of the changes on the composition of the perfusion community of Canada.
An electronic questionnaire was distributed to all practicing perfusionists in Canada, addressing details regarding clinical experience, academic education and perceptions about the adequacy of training.
Two hundred and twenty-eight questionnaires were completed, representing a 72% response rate. Perfusionists admitted under academic-based criteria have significantly higher levels of education (100% degree holders vs 69.1%, p<0.001), but less antecedent clinical training and experience (median, IQR: 0, 0 – 4.5 years vs 2, 2 – 8 years, p<0.0001), are younger (median age range 31-35 years vs 51-55 years, p<0.0001), more likely to be female (58.7% vs 41.3%, p=0.006) and are significantly more likely to enter perfusion because of attraction to the type of work (p=0.045). Many perfusionists (70, 32%) in Canada believe themselves inadequately trained for their clinical assignments outside the OR. In addition, 19% of perfusionists plan to retire over the next 10 years.
The introduction of education-based entry criteria has changed the academic and clinical experience levels of perfusionists in Canada. Strategies designed to better prepare perfusionists for their clinical assignments outside the OR are merited.
We evaluated the influence of intra-aortic balloon size and volume on mesenteric and renal flows.
Thirty healthy swine underwent 120-minute ligation of the left anterior descending coronary artery followed by 6 hours of reperfusion. Then, they were randomly assigned to the following five groups of animals, with six animals in each group: no intra-aortic balloon pump (IABP), a short 35-mL IABP, a short 40-mL IABP, a long 35-mL IABP and a long 40-mL IABP. Superior mesenteric artery (SMA) and renal flows were measured at baseline (t0), at 2-hour ischemia (t1) and every hour thereafter until 6 hours of reperfusion (from tR1 to tR6).
SMA flows increased significantly at tR1 only in the two short IABP groups (p<0.001) and balloon volume did not appear to affect flows which, at any experimental time-point, were comparable using 35 mL or 40 mL balloons (p>0.05). Renal flows appeared to be influenced by balloon length, but not by volume. Indeed, flows in the renal arteries rose during IABP treatment; the increase was significantly higher in the short balloon groups and throughout the whole reperfusion (all, p<0.001).
Changes in visceral perfusion during IABP assistance were significantly related to balloon length, but not to its volume. This could be relevant for the evolution of balloon engineering design in order to reduce the incidence of mesenteric ischemia following IABP. Further research is necessary to confirm these findings.
Current blood pumps used for cardiopulmonary bypass generally fall into two different pump design categories; non-occlusive centrifugal pumps and occlusive, positive-displacement roller pumps. The amount of foreign surface area of extracorporeal circuits correlates with post-operative morbidity due to systemic inflammation, leading to a push for technology that reduces the amount of foreign surfaces. Current roller pumps are bulky and the tubing forms an arc in the pumping chamber (raceway), positioning the inlet 360 degrees from the outlet, making it very difficult to place the pump closer to the patient and to efficiently reduce tubing length. These challenges put existing roller pumps at a disadvantage for use in a compact cardiopulmonary bypass circuit. Centrifugal blood pumps are easier to incorporate into miniature circuit designs. However, the prime volumes of current centrifugal pump designs are large, especially for pediatric extracorporeal circuits where the prime volumes are too great to be of clinical value.
We describe a preliminary report on a novel, occlusive, linear, single-helix, positive-displacement blood pump which allows for decreased prime volume and surface area of the extracorporeal circuit. This new experimental pump design was used to perfuse a 6 kilogram piglet with a pediatric cardiopulmonary bypass circuit for two hours of continuous use. Blood samples were obtained every thirty minutes and assayed for plasma free hemolysis generation.
The results from this initial experiment showed low plasma free hemoglobin generation and encourages the authors to further develop this concept.
The aim was to evaluate the association between perioperative inflammatory biomarkers and atrial fibrillation (AF) in cardiac surgical patients.
Forty-two patients undergoing cardiac surgery were divided into three groups according to the occurrence of AF: Group A (n = 22) – patients with no AF, Group B (n = 11) – patients with new onset AF postoperatively and Group C (n = 9) – patients with preoperative history of atrial fibrillation. The serum levels of PTX3, CRP, TLR2, IL-8, IL-18, sFas, MMP-7 and MMP-8 were measured at the following time points: before surgery, immediately and 6 h after surgery and on the 1st, 3rd and 7th postoperative days (POD).
Serum levels of PTX3 showed a significant difference between Groups A and C on the 3rd POD (p<0.05) and on the 7th POD (p<0.0001). IL-8 levels were different between Groups A and C immediately after surgery (p<0.05), 6 hours after surgery (p<0.05) and on the 3rd POD (p<0.05). There was a difference between Groups B and C on the 1st POD in IL-8 levels (p<0.05). The sFas levels differed between Groups A and C on the 3rd POD (p<0.01) and the 7th POD (p<0.05). There was also a difference on the 7th POD (p<0.05) between the Groups B and C. No significant differences between the groups was seen for other biomarkers.
This study demonstrates significantly different dynamics of PTX3, IL-8 and sFas levels after cardiac surgery in relation to AF.
Myocardial damage is an independent predictor of adverse outcome following cardiac surgery and myocardial protection is one of the key factors to achieve successful outcomes. Cardioplegia with Custodiol is currently the most used cardioplegia during minimally invasive cardiac surgery (MICS). Different randomized controlled trials compared blood and Custodiol cardioplegia in the context of traditional cardiac surgery. No data are available for MICS.
The aim of this study was to compare the efficacy of cold blood versus Custodiol cardioplegia during MICS.
We retrospectively evaluated 90 patients undergoing MICS through a right mini-thoracotomy in a three-year period. Myocardial protection was performed using cold blood (44 patients, CBC group) or Custodiol (46 patients, Custodiol group) cardioplegia, based on surgeon preference and complexity of surgery.
The primary outcomes were post-operative cardiac troponin I (cTnI) and creatine kinase MB (CKMB) serum release and the incidence of Low Cardiac Output Syndrome (LCOS). Aortic cross-clamp and cardiopulmonary bypass times were higher in the Custodiol group. No difference was observed in myocardial injury enzyme release (peak cTnI value was 18±46 ng/ml in CBC and 21±37 ng/ml in Custodiol; p=0.245). No differences were observed for mortality, LCOS, atrial or ventricular arrhythmias onset, transfusions, mechanical ventilation time duration, intensive care unit and total hospital stay.
Custodiol and cold blood cardioplegic solutions seem to assure similar myocardial protection in patients undergoing cardiac surgery through a right mini-thoracotomy approach.
Unfractionated heparin is the preferred anticoagulant in extracorporeal membrane oxygenation (ECMO) patients. However, there is a lack of consensus on its titration and monitoring. The objective of this study was to describe the efficacy and safety of a pharmacy managed heparin protocol utilizing activated partial thromboplastin time (aPTT) in comparison to our standard physician-managed activated clotting time (ACT)-based anticoagulation in ECMO patients.
Patients administered a heparin drip while on ECMO were included in the study. The primary endpoints were the incidence of hemorrhagic and thrombotic complications.
A total of 122 adult patients were identified who were on ECMO with heparin anticoagulation; sixty-one patients were managed with each of the physician-managed ACT and pharmacy managed aPTT protocols. No statistically significant difference was observed between the physician ACT and the pharmacy aPTT groups in overall hemorrhagic (69% vs 80%, p=0.145) or thrombotic complications (41% vs 39%, p=0.853).
There was a similar rate of thrombotic and bleeding events between the two study groups. A pharmacy managed heparin protocol utilizing aPTT monitoring appears to be a safe and effective method of providing anticoagulation in adult ECMO patients.
To assess the in vitro effects of drug sequestration in extracorporeal membrane oxygenation (ECMO) on -aminocaproic acid (EACA) concentrations.
This in vitro study will determine changes in EACA concentration over time in ECMO circuits. A pediatric dose of 2,500 mg was administered to whole expired blood in the simulated pediatric ECMO circuit. Blood samples were collected at 0, 30, 60, 360 and 1440-minute intervals after initial administration equilibration from three different sites of the circuit: pre-oxygenator (PRE), post-oxygenator (POST) and PVC tubing (PVC) to determine the predominant site of drug loss. The circuit was maintained for two consecutive days with a re-dose at 24 hours to establish a comparison between unsaturated (New) and saturated (Old) oxygenator membranes. Comparisons between sample sites, sample times and New versus Old membranes were statistically analyzed by a linear mixed-effects model with significance defined as a p-value <0.05.
There were no significant differences in EACA concentration with respect to sample site, with PRE and POST samples demonstrating respective mean differences of 0.30 mg/ml and 0.34 mg/ml as compared to PVC, resulting in non-significant p-values of 0.373 [95% CI (-0.37, 0.98)] and 0.324 [95% CI (-0.34, 1.01)], respectively. The comparison of New vs. Old ECMO circuits resulted in non-significant changes from baseline, with a mean difference of 0.50 mg/ml, 95% CI (-0.65, 1.65), p=0.315.
The findings of this study did not show any significant changes in drug concentration that can be attributed to sequestration within the ECMO circuit. Mean concentrations between ECMO circuit sample sites did not differ significantly. Comparison between New and Old circuits also did not differ significantly in the change from baseline concentration over time. Sequestration within ECMO circuits appears not to be a considerable factor for EACA administration.
Patients undergoing hybrid aortic arch reconstruction require careful protection of vital organs. We believe that whole body perfusion with tailored dual circuitry may help to achieve optimal patient outcomes.
Our circuit has evolved from a secondary circuit utilizing a cardioplegia delivery device for lower body perfusion to a dual-oxygenator circuit. This allows individually controlled regional perfusion with ease of switching from secondary to primary circuit for total body flow. The re-design allows for separate flow and temperature regulation with two oxygenators in parallel. All patients underwent a single-stage operation for simultaneous treatment of arch and descending aortic pathology via a sternotomy, using a hybrid frozen elephant trunk technique.
We report six consecutive patients undergoing hybrid arch and frozen elephant trunk reconstruction using a dual-oxygenator circuit. Five patients underwent elective surgery and one was emergent. One patient had an acute dissection while three underwent concomitant procedures, including a Ross procedure and two valve-sparing root reconstructions. Three cases were redo sternotomies. The mean pump time was 358 ± 131 min, the aortic cross clamp time 243 ± 135 min, the cardioplegia volume of 33,208 ml ± 16,173, cerebral ischemia 0 min, lower body ischemia 76 ± 34 min and the average lower body perfusion time was 142 min. Two patients did not require any donor blood products. The median intensive care unit (ICU) and hospital lengths of stay (LOS) were two days and 10 days, respectively. The average peak serum lactate on CPB was 7.47 mmol/L and, at admission to the ICU, it was 3.37 mmol/L. Renal and respiratory failure developed in the salvage acute type A dissection patient. No other complications occurred in this series.
Whole body perfusion as delivered through individually controlled dual-oxygenator circuitry allows maximum flexibility for hybrid aortic arch reconstruction. A modified circuit perfusion strategy may help to limit intra-operative metabolic derangements, providing improved clinical outcomes.
Extracorporeal membrane oxygenation (ECMO) is an established tool for respiratory and circulatory support. In computed tomography, altered hemodynamics in ECMO patients requires special considerations and handling in contrast injection and its timing. In this article, we demonstrate changes in hemodynamics in ECMO patients captured on contrast-enhanced CT examinations and pitfalls in strategies for contrast injection in relation to the ECMO flow, cardiac function and the placement of ECMO cannulas. Contrast-enhanced CT of patients with ECMO requires prior knowledge of the ECMO cannulas, central venous lines, changes of hemodynamics induced by low cardiac output and the influence of adjustment of ECMO on blood flow in order to optimize injection of the contrast material and timing of the scan. Special considerations include temporary reduction of the ECMO flow, selection of the injection site and increasing volume or flow rate of the contrast material.
Since the introduction of CO2 insufflation during open heart surgery in our hospital, we incidentally observed thrombus formation in the dissected heart, in the pericardium and in the cardiotomy reservoir of the cardiopulmonary bypass system. Furthermore, we measured very high levels of pCO2, causing severe acidosis, in stagnant blood in the pericardium and cardiotomy reservoir.
In this in vitro study, we assessed the influence of acidosis and hypothermia on heparin potency and thrombin formation.
We assessed heparin potency in function of pH (pH 5.0-7.4) and temperature (24-37°C) by comparing the activated partial thromboplastin time in platelet-poor plasma between samples with and without unfractionated heparin. We measured thrombin formation in platelet-poor plasma by means of fluorescent, calibrated, automated thrombography in function of pH (pH 5.0-7.4) and temperature (24-37°C). The parameters of interest were the endogenous thrombin potential and the peak amount of thrombin generation.
The major finding of this study is the significant decrease in the efficiency of unfractionated heparin in delaying thrombus formation at acidotic (pH 5.0-7.0) conditions (p=0.034-0.05). Furthermore, we found that thrombin formation is significantly increased at hypothermic (24-34°C) conditions (p=<0.001-0.01).
Based on the results of our in-vitro study, we conclude that acidosis may lead to a decreased heparin potency. Acidosis, as induced by CO2 insufflation, may predispose patients to incidental thrombus formation in stagnant blood in the open thorax and in the cardiotomy reservoir. Hypothermia might further increase this risk. Therefore, we recommend reconsidering the potential advantages and disadvantages of using CO2 insufflation during cardiopulmonary bypass.
We aimed to investigate the compliance of plasma apelin-12 levels to show angiographic properties and hospital MACE in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI).
The association of apelin-12 levels with the N/L ratio on admission was assessed in 170 consecutive patients with primary STEMI undergoing primary PCI. All patient SYNTAX scores and thrombolysis in myocardial infarction (TIMI) flow grades were also assessed. Patients were divided into two groups according to their TIMI flow grade. Patients with a TIMI 0-2 flow and TIMI 3 flow with grade 0/1 myocardial blush grade (MBG) score were defined as the no-reflow group and patients with TIMI grade 3 flow with >=2 MBG were considered as the normal flow group.
Baseline apelin-12 levels were significantly lower in the no-reflow group than in the normal flow group (3.3±1.81 vs 6.2±1.74, p<0.001). In-hospital events, including death, myocardial infarction (MI) and re-infarction were significantly higher in patients in the no-reflow group than normal flow group (23% vs 7%, p<0.001). Apelin-12 level was negative correlated with the N/L ratio (r= -0.352, p<0.001), Hs-Crp (r=-0.272, p=0.01) and SYNTAX score (r= -0.246, p=0.029). In the multivariate regression analysis, apelin-12, presence of no-reflow and the SYNTAX score were independent predictors of in-hospital MACE (odds ratio [OR] 1.41, 95% confidence interval (CI) [1.27 to 1.67], p=0.001 for apelin-12, OR 1.085, [0.981 to 1.203], p<0.001 for no-reflow and OR 0.201, 95% CI [0.05 to 0.47], p= 0.004 for SYNTAX score).
We have shown that lower apelin-12 level on admission is associated with higher SYNTAX scores and no-reflow phenomenon and may be used as a prognostic marker for hospital MACE in patients with STEMI.
Intestinal fatty acid-binding protein (I-FABP) is increasingly employed as a highly specific marker of intestinal necrosis. However, the value of this marker associated with cardiovascular surgery with hypothermic circulatory arrest is unclear. The aim of this study was to measure serum I-FABP levels and provide the transition of I-FABP levels with hypothermic circulatory arrest to help in the management of intestinal perfusion.
From August 2011 to September 2013, 33 consecutive patients who had aortic arch surgery with hypothermic circulatory arrest or heart valve surgery performed were enrolled in the study. Twenty patients had aortic surgery with hypothermic (23-29°C) circulatory arrest and 13 patients had heart valve surgery with cardiopulmonary bypass (33°C).
I-FABP levels increased, both in patients undergoing aortic surgery with hypothermic circulatory arrest and heart valve surgery with cardiopulmonary bypass, reaching peak levels shortly after the administration of protamine. I-FABP levels in patients with aortic surgery were significantly higher with circulatory arrest. They reached peak levels immediately after recirculation and there was a significant drop at the end of surgery (p<0.001). I-FABP levels in heart valve surgery were gradually increased, with the highest at the administration of protamine; they gradually decreased. Peak I-FABP levels were significantly higher in patients undergoing aortic surgery with hypothermic circulatory arrest than in patients with heart valve surgery. However, no postoperative reperfusion injury occurred in the intestinal tract due to the use of hypothermic organ protection.
Plasma I-FABP monitoring could be a valuable method for finding an intestinal ischemia in patients with cardiovascular surgery.
Muscle tissue saturation (StO2) measured with near-infrared spectroscopy has generally been considered a measurement of the tissue microcirculatory condition. However, we hypothesized that StO2 could be more regarded as a fast and reliable measure of global than of regional circulatory adequacy and tested this with muscle, intestinal and brain metabolomics at normal and two levels of low cardiopulmonary bypass blood flow rates in a porcine model.
Twelve 80 kg pigs were connected to normothermic cardiopulmonary bypass with a blood flow of 60 mL/kg/min for one hour, reduced randomly to 47.5 mL/kg/min (Group I) or 35 mL/kg/min (Group II) for one hour followed by one hour of 60 mL/kg/min in both groups. Regional StO2 was measured continuously above the musculus gracilis (non-cannulated leg). Metabolomics were obtained by brain tissue oxygen monitoring system (Licox) measurements of the brain and microdialysis perfusate from the muscle, intestinal mucosa and brain. A non-parametric statistical method was used.
The systemic parameters showed profound systemic ischaemia during low CPB blood flow. StO2 did not change markedly in Group I, but in Group II, StO2 decreased immediately when blood flow was reduced and, furthermore, was not restored despite blood flow being normalized. Changes in the metabolomics from the muscle, colon and brain followed the changes in StO2.
We found, in this experimental cardiopulmonary bypass model, that StO2 reacted rapidly when the systemic circulation became inadequate and, furthermore, reliably indicate insufficient global tissue perfusion even when the systemic circulation was restored after a period of systemic hypoperfusion.
The purpose of this study is to describe the sedative and analgesic requirements identifying factors associated with medication escalation in neonates and children supported on ECMO.
Observational retrospective cohort study in a tertiary pediatric intensive care unit from June 2009 to June 2013.
One hundred and sixty patients were included in the study. Fentanyl and midazolam were the first line agents used while on ECMO. Higher opiate requirements were associated with younger age (p=0.01), thoracic cannulation (p=0.002), the use of dexmedetomidine (p=0.007) and prolonged use of muscle relaxants (p=0.03). Higher benzodiazepine requirements were associated with younger age (p=0.01), respiratory failure (p=0.02) and the use of second line agents (p=0.002). One third of the patients required second line agents as adjuvants for comfort without a decrease in opiate and/or benzodiazepine requirements.
Providing comfort to subpopulations of pediatric ECMO patients seems to be more challenging. The use of second line agents did not improve comfort in our cohort. Prospective studies are required to optimize analgesia and sedation management in children on ECMO.
Status asthmaticus is a life-threatening condition characterized by progressive respiratory failure due to asthma that is unresponsive to standard therapeutic measures. We used extracorporeal membrane oxygenation (ECMO) to treat patients with near-fatal status asthamticus who did not respond to aggressive medical therapies and mechanical ventilation under controlled permissive hypercapnia.
Between January 2011 and October 2015, we treated 16 adult patients with status asthmaticus (8 women, 8 men, mean age: 50.5±10.6years) with veno-venous ECMO (13 patients) or veno-arterial (3 patients). Patients failed to respond to conventional therapies despite receiving the most aggressive therapies, including maximal medical treatments, mechanical ventilation under controlled permissive hypercapnia and general anesthetics.
Mean time spent on ECMO was 300±11.8 hours (range 36–384 hours). PaO2, PaCO2 and pH showed significant improvement promptly after ECMO initiation p=0.014, 0.001 and <0.001, respectively, and such values remained significantly improved after ECMO, p=0.004 and 0.001 and <0.001, respectively. The mean time of ventilation after decannulation until extubation was 175±145.66 hours and the median time to intensive care unit discharge after decannulation was 234±110.30 hours. All 16 patients survived without neurological sequelae.
ECMO could provide adjunctive pulmonary support for intubated asthmatic patients who remain severely acidotic and hypercarbic despite aggressive conventional therapy. ECMO should be considered as an early treatment in patients with status asthmaticus whose gas exchange cannot be satisfactorily maintained by conventional therapy for providing adequate gas change and preventing lung injury from the ventilation.
Modified ultrafiltration (MUF) is a technique which is commonly used immediately post-cardiopulmonary bypass (CPB) for open heart surgery in children. There are many advantages of MUF, but there are also a number of less reported disadvantages. At our institution, after considering all of the available data, a decision was made to no longer perform MUF. The primary motivation being the simplified and miniaturized CPB circuit would reduce hemodilution, decrease our likelihood of reaching our transfusion trigger during CPB and, potentially, improve safety. This study reports the before and after data from this practice change. A total of 160 patients less than 8kg were studied over 38 months and divided into neonatal and pediatric cohorts. Parameters reported in this study include: demographics, hematocrit, blood product transfusion, hemostasis, hemodynamics and outcomes. Although retrospective, our analysis supports an advantage of preventing hemodilution (via circuit miniaturization) versus reversing hemodilution (via MUF) at our institution with the patient population we examined.
There is no acceptable method of testing oxygen transfer performance in membrane oxygenators quickly and easily during cardiopulmonary bypass. Pre-clinical testing of oxygenators is performed under controlled situations in the laboratory, correlating oxygen transfer to blood flow using 100% oxygen. This laboratory method cannot be used clinically as oxygen transfer values vary significantly at each blood flow and the FiO2 is not kept at 1. Therefore, a formula was developed which corrects the existing FiO2 to attain a PaO2 of 150 mmHg: the corrected FiO2 at 150 mmHg. In graph form, this corrected FiO2 (x-axis) is correlated to the patient’s oxygen consumption levels (y-axis), which determines the membrane oxygenator oxygen transfer performance.
Blood gas and hemodynamic parameters taken during cardiopulmonary bypass using the Medtronic Fusion were used to calculate the oxygen consumption (inlet conditions to the oxygenator) and the corrected FiO2 for a PaO2 of 150 mmHg. Validation of the formula "FiO2-PaO2/(Pb–pH2O)+0.21" was carried out by plotting the calculated values on a graph using PaO2 values between 145 to 155 mmHg and then, using the corrected FiO2 for PaO2s outside of this range.
All trend-lines correlated significantly to confirm that the Medtronic Fusion had an extrapolated oxygen transfer of 419 milliliters O2/min at an FiO2 of 1 to achieve a PaO2 of 150 mmHg.
Use of the corrected FiO2 correlated to the oxygen transfer conditions of the membrane oxygenator can easily be used on a routine basis, providing valuable information clinically. When used by the manufacturer under laboratory conditions, further clinically relevant data is provided in terms of FiO2 and resultant PaO2s instead of the present limitations using blood flow. In this way, a clinically justifiable method has been developed to finally establish a standard in testing membrane oxygenator performance.
Cardiac surgery is known to trigger a systemic inflammatory response. While the use of conventional cardiopulmonary bypass (CPB) results in profound inflammation, modified mini-CPB is considered less harmful. We evaluated the impact of cardiac surgery on the expression of CD162, CD166, CD195 molecules and their association with the type of CPB used.
Twenty-four patients were enrolled in our study. Twelve of them were operated using conventional CPB while the other twelve patients underwent surgery with mini-CPB. Blood samples were analysed by flow cytometry. We observed a significant increase in median fluorescence intensity of CD162 and CD195 that peaked instantly after surgery and normalized to the baseline value on the 1st day post surgery, whereas CD166 was initially down-regulated and its median fluorescence intensity (MFI) value increased to the baseline in the next few days.
We observed immediate changes in the expression of CD162, CD166, and CD195 molecules on the neutrophils after surgery in both study groups of patients. The intensity of the observed changes was significantly greater in the group of patients who underwent conventional CPB compared to patients who underwent mini-CPB cardiac surgery.
Pediatric patients with hemophagocytic lymphohistiocytosis (HLH) may develop refractory respiratory or cardiac failure that warrants consideration for extracorporeal membrane oxygenation (ECMO) support. The purposes of this study were to describe the use and outcomes of ECMO in pediatric HLH patients, to identify risk factors for hospital mortality and to compare their ECMO use and outcomes to the ECMO population as a whole.
Pediatric patients (<= 18 years) with a diagnosis of HLH in the Extracorporeal Life Support Organization (ELSO) Registry were included.
Between 1983 and 2014, data for 30 children with HLH were available in the ELSO registry and all were included in this study. All cases occurred in the last decade. Of the 30 HLH patients, 24 (80%) had a respiratory indication for ECMO and six (20%) had a cardiac indication (of which 4 were E-CPR and 2 cardiac failure). Of the 24 respiratory ECMO patients, 63% were placed on VA ECMO. Compared with all pediatric patients in the ELSO registry during the study period (n=17,007), HLH patients had worse hospital survival (non-HLH 59% vs HLH 30%, p=0.001). In pediatric HLH patients, no pre-ECMO risk factors for mortality were identified. The development of a hemorrhagic complication on ECMO was associated with decreased mortality (p=0.01). Comparing HLH patients with respiratory failure to patients with other immune compromised conditions, the overall survival rate is similar (HLH 38% vs. non-HLH immune compromised 31%, p=0.64).
HLH is an uncommon indication for ECMO and these patients have increased mortality compared to the overall pediatric ECMO population. These data should be factored into decision-making when considering ECMO for pediatric HLH patients.
HemoSep® is a commercial ultrafiltration and haemoconcentration device for the concentration of residual bypass blood following surgery. This technology is capable of reducing blood loss in cardiac and other types of "clean site" procedures, including paediatric surgery. Clinical feedback suggested that the device would be enhanced by including a sensor technology capable of discerning the concentration level of the processed blood product. We sought to develop a novel sensor that can, using light absorption, give an accurate estimate of packed cell volume (PCV).
A sensor-housing unit was 3D printed and the factors influencing the sensor’s effectiveness – supply voltage, sensitivity and emitter intensity - were optimised. We developed a smart system, using comparator circuitry capable of visually informing the user when adequate PCV levels (>=35%) are attained by HemoSep® blood processing, which ultimately indicates that the blood is ready for autotransfusion.
Our data demonstrated that the device was capable of identifying blood concentration at and beyond the 35% PCV level. The device was found to be 100% accurate at identifying concentration levels of 35% from a starting level of 20%.
The sensory capability was integrated into HemoSep’s® current device and is designed to enhance the user’s clinical experience and to optimise the benefits of HemoSep® therapy. The present study focused on laboratory studies using bovine blood. Further studies are now planned in the clinical setting to confirm the efficacy of the device.
Gaseous microemboli (GME) may originate from the extracorporeal circuit and enter the arterial circulation of the patient. GME are thought to contribute to cerebral deficit and to adverse outcome after cardiac surgery. The arterial filter is a specially designed component for removing both gaseous and solid microemboli. Integration of an arterial filter with an oxygenator is a contemporary concept, reducing both prime volume and foreign surface area. This study aims to determine the air-handling properties of four contemporary oxygenator devices with an integrated arterial filter. Two oxygenator devices, the Capiox FX25 and the Fusion, showed significant increased volume of GME reduction rates (95.03 ± 3.13% and 95.74 ± 2.69%, respectively) compared with both the Quadrox-IF (85.23 ± 5.84%) and the Inspire 6F M (84.41 ± 12.93%). Notably, both the Quadrox-IF and the Inspire 6F M as well as the Capiox FX 25 and the Fusion showed very similar characteristics in volume and number reduction rates and in detailed distribution properties. The Capiox FX25 and the Fusion devices showed significantly increased number and volume reduction rates compared with the Quadrox-IF and the Inspire 6F M devices. Despite the large differences in design of all four devices, our study results suggest that the oxygenator devices can be subdivided into two groups based on their fibre design, which results in screen filter (Quadrox-IF and Inspire 6F M) and depth filter (Capiox FX25 and Fusion) properties. Depth filter properties, as present in the Capiox FX25 and Fusion devices, reduced fractionation of air and may ameliorate GME removal.
The purpose of this study is to report our experience with del Nido cardioplegia (DNC) in the setting of minimally invasive aortic valve surgery. Forty-six consecutive patients underwent minimally invasive aortic valve replacement (AVR) through a "J" ministernotomy: twenty-five patients received the DNC (Group 1) and 21 patients received standard blood cardioplegia (SBC) (Group 2). The rate of ventricular fibrillation at unclamping was significantly lower in the DNC group (12% vs 52%, p=0.004), as well as postoperative creatinine kinase-MB (CK-MB) values (11.4±5.2 vs 17.7±6.9 µg/L, p=0.004). There were no deaths, myocardial infarctions or major complications in either group. Less postoperative use of intravenous insulin (28% vs 81%, p<0.001) was registered in the DNC group. In conclusion, the DNC is easy to use and safe during minimally invasive AVR, providing a myocardial protection at least equivalent to our SBC, improved surgical efficiency, minimal cost and less blood glucose perturbations.
To establish the diagnostic accuracy of a ‘focused vascular lower limb arterial duplex scan (F-VLAD)’ developed to facilitate rapid decision-making for acute limb ischaemia (ALI).
Ten cases of ALI were identified from our patient database; clinical details, history and examination findings were extracted from the clinical notes. Original ‘full’ duplex ultrasound (DUS) pictorial reports were ‘re-formatted’ to include only anatomical segments included in the ‘F-VLAD’ scan. The series of 10 reports were emailed to 1741 vascular surgeons. Each recipient received a random mixture of full and F-VLAD scans. Participants were asked regarding next step in management and confidence in decision-making (Likert scale; 1 strongly disagree, 5 strongly agree). The cases were again sent out to the same database and respondents were asked as to the cause of ischaemia (embolic or thrombosis).
Eighty-one participants responded to the first survey and 43 participants to the second survey. Participants felt more confident making decisions regarding management using the full duplex report compared to the F-VLAD report (4 (3-4) vs 3 (2-4), median (IQR); p<0.001). However, there was no significant difference in diagnostic accuracy (differentiating embolus from thrombosis) when comparing the F-VLAD and full DUS reports (85.4% vs 88.3%; p=0.461). F-VLAD and ‘full’ DUS reports had comparable sensitivity (85.1% vs 86.8%), specificity (85.6% vs 89.2%),positive predictive value (PPV) (80.4% vs 81.9%) and negative predictive value (NPV) (89.2% vs 92.2%), respectively.
The F-VLAD scan has comparable accuracy to a traditional full DUS in diagnosing the underlying aetiology of ALI. This may facilitate surgeon-performed point-of-care DUS.
Single-dose del Nido cardioplegia has been used in the pediatric population for many years. Only a small amount of data exists about its use in adult cardiac surgery. We sought to compare the outcomes of all patients undergoing coronary artery bypass, using our 4:1 blood cardioplegia versus single-dose 1:4 del Nido cardioplegia, at our institution.
Data were retrospectively reviewed from all patients during 2 consecutive years (2013-2014). We switched our cardioplegia protocol from 4:1 blood cardioplegia to exclusively 1:4 single-dose del Nido cardioplegia in early 2014. A total of 408 patients were evaluated. Two hundred and forty-nine consecutive patients underwent coronary artery bypass using blood cardioplegia and 159 using del Nido Cardioplegia.
Cardiopulmonary bypass time, cross-clamp time, in-hospital mortality and length of stay were similar (p>0.05): 63 ± 23 vs. 65 ± 21 min, 50 ± 20 vs. 52 ± 20 min, 0.8% vs. 0.6% and 6.4 ± 3 vs. 5.8 ± 3 days, respectively. For secondary outcomes: patients requiring defibrillation was 105/249 (42%) vs. 13/159 (8%) (p<0.0001), blood transfusion was required in 96/249 (38%) vs. 48/159 (30%) (p<0.085), total volume administered was 1139mL vs. 813 mL per case (p<0.0001), hematocrit change was 11.6% vs. 10.9% (p<0.04) and the mean cost per dose was $157.54 vs $5.74.
Single-dose del Nido cardioplegia is an effective and economic cardioplegia and can be used with good outcomes in coronary surgery. Most patients have spontaneous return of sinus rhythm and there is a trend towards decreased transfusion rate.
Acute anemia is associated with both cerebral dysfunction and acute kidney injury and is often treated with red blood cell transfusion. We sought to determine if blood transfusion changed the cerebral oximetry entropy, a measure of the complexity or irregularity of the oximetry values, and if this change was associated with subsequent acute kidney injury.
This was a retrospective, case-control study of patients undergoing cardiac surgery with cardiopulmonary bypass at a tertiary care hospital, comparing those who received a red blood cell transfusion to those who did not. Acute kidney injury was defined as a perioperative increase in serum creatinine by >=26.4 μmol/L or by >=50% increase. Entropy was measured using approximate entropy, sample entropy, forbidden word entropy and basescale4 entropy in 500-point sets.
Forty-four transfused patients were matched to 88 randomly selected non-transfused patients. All measures of entropy had small changes in the transfused group, but increased in the non-transfused group (p<0.05, for all comparisons). Thirty-five of 132 patients (27%) suffered acute kidney injury. Based on preoperative factors, patients who suffered kidney injury were similar to those who did not, including baseline cerebral oximetry levels. After analysis with hierarchical logistic regression, the change in basescale4 entropy (odds ratio = 1.609, 95% confidence interval = 1.057–2.450, p = 0.027) and the interaction between basescale entropy and transfusion were significantly associated with subsequent development of acute kidney injury.
The transfusion of red blood cells was associated with a smaller rise in entropy values compared to non-transfused patients, suggesting a change in the regulation of cerebral oxygenation, and these changes in cerebral oxygenation are also associated with acute kidney injury.
Minimally invasive coronary artery bypass surgery performed through a left thoracotomy has potential benefits over conventional sternotomy, including reduced surgical trauma, faster recovery and potential improvement in quality of life. This study is a prospective assessment of quality of life in patients undergoing off-pump coronary bypass by median sternotomy and left anterior thoracotomy.
Quality of life was assessed by the EuroQoL questionnaire, with additional questions on dyspnoea, angina, wound pain and scar aesthetics. Outcomes were compared across the data sets at pre-operation, three weeks and three months post-operation.
Sixty-six (17 minimally invasive and 49 off-pump) patients (mean age 65±12, 7 females and 59 males) were included. Significant differences in mean EuroQol outcomes were observed for activities, F(1,64) = 5.86, (p<0.05), pain scores, F(1,64) = 4.658 (p=0.035) and scar aesthetics, F(1,64) = 16.83 (p<0.05). There was an additional significant interaction, F(1.898, 121.49) = 3.282, (p<0.05), between time and group for activity levels; exploring this further indicated no significant difference at baseline, but significantly greater improvement observed in the minimally invasive group over time.
At 3 weeks, 50% of minimally invasive patients compared to 82% of sternotomy patients (p<0.001) required oral analgesia. At 3 months, 8% of minimally invasive patients and 21% of sternotomy patients (p<0.001) required oral analgesia.
Off-pump coronary artery bypass performed with a minimally invasive approach through a left thoracotomy appears to result in earlier improvement in quality of life outcomes compared to conventional sternotomy. These results are important when counselling patients regarding the benefits and difference between a left anterior thoractomy MIDCABG and conventional OPCAB and can be used as pilot data for a larger trial examining differences in the MIDCABG and conventional full sternotomy OPCAB procedures.
The iLA-activve® Novalung is a new extracorporeal device specifically designed for lung support in patients with hypercapnic and/or hypoxemic respiratory failure. To date, only low-flow applications for decompensated hypercapnic chronic obstructive pulmonary disease have been reported in the literature. Here, we briefly report three cases of iLA-activve use in patients with hypercapnic-hypoxemic acute lung failure assisted with mid-flow (up to 2.4 L/min) and different single/double venous cannulation. The main findings of our small case series were: firstly, extracorporeal blood flows over 2.0 L/min across the membrane provided clinically satisfying decarboxylation and improved oxygenation; secondly, the ratio between blood flow through the membrane and the patient’s cardiac output (CO) was a major determinant for the oxygen increase. The latter could, therefore, be a useful indicator for understanding performance in the complex and multifactorial evaluation of patients with extracorporeal veno-venous lung support.
The role of elevated whole blood viscosity (WBV) in the pathogenesis of atherosclerosis is well known. We sought to investigate the gender differences in the association between WBV, coronary blood flow and tissue oxygen delivery index (TODI) in cardiac syndrome X (CSX).
Forty-six CSX patients and 14 healthy volunteers were enrolled. The coronary flow parameters were obtained with transthoracic Doppler echocardiography and WBV was measured (at high-shear and low-shear rates of 300s-1 and 5s-1, respectively) using a scanning capillary tube viscometer. TODI was determined from the ratio of hematocrit to WBV measured at a low-shear rate of 5s-1.
In male patients, the mean diastolic coronary flow velocity (CFV) and diastolic velocity time integral (VTI) were significantly decreased compared to control group (all p<0.05) and the WBV showed significant negative correlation with peak systolic CFV (r = –0.559 at 300s-1, r = –0.438 at 5s-1), mean systolic CFV (r = –0.577 at 300s-1, r = –0.488 at 5s-1), systolic VTI (r = –0.576 at 300s-1, r = –0.530 at 5s-1) and diastolic VTI (r = –0.553 at 300s-1, r = –0.551 at 5s-1) (all p<0.01). Meanwhile, although female patients showed no significant relationships between WBV and coronary flow parameters, TODI were significantly decreased compared to the control group (3.64 ± 0.34 vs. 4.07 ± 0.38%/centipoises (cP), respectively, p=0.008).
Our study suggests that there are gender-related differences in the pathogenesis of microvascular angina and gender-specific approaches for CSX patients might be needed.
Low-flow extracorporeal life support can be used for cardiopulmonary support of paediatric and neonatal patients and is also emerging as a therapy for patients suffering from exacerbation of chronic obstructive pulmonary disease. However, pump heating and haemolysis have proven to negatively affect the system and outcome. This in vitro study aimed at gaining insight into blood warming, pump heating and haemolysis related to the performance of a new low-flow centrifugal pump. Pump performance in the 400-1,500 ml/min flow range was modulated using small-sized dual-lumen catheters and freshly donated human blood. Measurements included plasma free haemoglobin, blood temperature, pump speed, pump pressure, blood flow and thermographic imaging. Blood warming (Tmax=0.5°C) had no relationship with pump performance or haemolysis (R2max=0.05). Pump performance-related parameters revealed no relevant relationships with haemolysis (R2max=0.36). Thermography showed no relevant heat zones in the pump (Tmax=36°C). Concerning blood warming, pump heating and haemolysis, we deem the centrifugal pump applicable for low-flow extracorporeal circulation.
The effect of obesity on allogeneic intraoperative blood product transfusion in patients undergoing coronary artery bypass graft surgery (CABG) is poorly understood. We analyzed the influence of obesity on the risk of intraoperative red blood cell (RBC) transfusion among 45,200 consecutive non-reoperative CABG procedures from a multi-institutional perfusion database. A body mass index (BMI) in obese I category was associated with a 9.9% decrease in transfusion risk (p<0.05). Compared to patients with a normal BMI, obese I and obese III patients do not have any change in the relative risk of RBC transfusion. Overweight and mild obesity have a protective role in reducing intraoperative blood transfusion during cardiopulmonary bypass (CPB) surgery. However, logistic regression analysis showed that much of the observed reduction in transfusion rates for obese patients can be accounted for by other known confounds. The lack of a linear effect of increasing BMI on blood transfusion risk is a novel finding and warrants further investigation.
The coronary slow-flow phenomenon (CSFP) is a multifactorial angiographic finding with no established pathogenesis.
To investigate the role of clinical profile and laboratory findings in patients with CSFP.
We prospectively recruited 69 patients with angiographically diagnosed CSFP and compared them with 88 patients with normal coronary flow. Demographic information, comorbidities and laboratory analysis, including complete blood count with differential, lipid profile and serum biochemical analysis, were documented and compared in univariate and multivariate analyses.
Patients with CSFP were more likely to be male and active smokers. Total cholesterol, triglyceride, hemoglobin and hematocrit, platelet count, mean platelet volume, platelet distribution width and red cell distribution width (RDW) were all higher in patients with CSFP. In multivariate regression analysis, including smoking, total cholesterol, hematocrit, fasting blood glucose and red cell distribution width, except fasting blood glucose, all variables were independently associated with CSFP. Receiver operating characteristic curve analysis revealed a cut-off point of 13.05% for RDW with a sensitivity of 74.6% and a specificity of 77.3% (p<0.001, AUC = 0.802) A cut-off value of 11.35% for PDW had a 89.9% sensitivity and 98.9% specificity for the prediction of CSFP (p<0.001, AUC = 0.970)
The changes of circulating blood cell components in patients with CSFP may be indicative of underlying inflammation and endothelial dysfunction that should be investigated in experimental studies.
Blood transfusions could have serious consequences for patients. A reduction in the transfusion rate could be accomplished by an optimized blood management. Clear guidelines and awareness among all employees at a single institution have resulted in a reduction in transfusion rates in recent years. Identification of the group of patients who still received a blood transfusion in recent years could result in a further reduction. This study enrolled 4022 patients undergoing cardiothoracic surgery between 2008 and 2013. Patients were divided into three groups: "no blood transfusion", "transfusion of packed red cells only" and "any other combinations of blood transfusion". In total, 16 variables were tested for their association with the administration of homologous blood. The variables associated with blood transfusion were included in a stepwise multinomial logistic regression analysis to find the variables with the strongest association.
For the transfusion of packed red cells only and any other combinations of blood transfusion, the following predictors are found: gender, age, weight, type of surgery, reoperation, unstable angina pectoris, endocarditis, recent myocardial infarction, preoperative creatinine level, preoperative hemoglobin level and preoperative platelet count. The best predictor for the transfusion of packed red cells is preoperative hemoglobin level (4.1 to 7.8 mmol/l). For other blood products, the strongest association was found with type of surgery (aortic surgery, ventricular septal rupture and intracardiac tumour).
A computational fluid dynamics model of a bicuspid aortic valve has been developed using idealised three-dimensional geometry. The aim was to compare how the orifice area and leaflet orientation affect the hemodynamics of a pure bicuspid valve. By applying physiologic material properties and boundary conditions, blood flow shear stresses were predicted during peak systole. A reduced orifice area altered blood velocity, the pressure drop across the valve and the wall shear stress through the valve. Bicuspid models predicted impaired blood flow similar to a stenotic valve, but the flow patterns were specific to leaflet orientation. Flow patterns developed in bicuspid aortic valves, such as helical flow, were sensitive to cusp orientation. In conclusion, the reduced opening area of a bicuspid aortic valve amplifies any impaired hemodynamics, but cusp orientation determines subsequent flow patterns which may determine the specific regions downstream from the valve most at risk of clinical complications.
With an increase in the number of patients who are on antiplatelet medications until the day of surgery, we undertook a prospective observational study to assess the ability of thromboelastography, thromboelastography platelet mapping and aggregometry via multiplate to detect platelet dysfunction and predict blood loss following coronary artery bypass grafting (CABG) surgery.
Platelet function was evaluated pre- and post-cardiopulmonary bypass via thromboelastography, thromboelastography platelet mapping and aggregometry via multiplate in 52 patients undergoing coronary artery bypass grafting surgery. The median chest tube drainage of all patients in the study was ascertained to stratify patients into two groups: patients with and those without evidence of excessive blood loss after cardiac surgery.
Although all modalities could detect a decrease in platelet function following cardiopulmonary bypass, univariate and multivariate regression analysis identified preoperative arachidonic acid and adenosine diphosphate testing via multiplate as independent predictors of bleeding after cardiac surgery. Receiver operating curves on these multiplate parameters showed an area under the curve of 0.68 (p=0.03) and 0.66 (p=0.01) for arachidonic acid and adenosine diphosphate assays, respectively.
This pilot study shows that preoperative multiplate testing may be a better predictor of platelet dysfunction and the resultant blood loss following cardiac surgery.
In this experimental study, we primarily aimed to show the hemodynamic effects and superiority of this newly designed cannula for perfusion compared to standard subclavian cannulation. The new cannula (Figure 1) allows bidirectional axial flow and it directly fits in the brachiocephalic trunk (innominate artery).
We used a cardiopulmonary bypass roller pump, reservoir, 3/8- 1/2- 1/4-inch Y-connectors and tubing set. Lines were set as seen in Figures 2, 3, 4 and 5. The anatomy of the aorta (ascending, arch, branches, descending) was mimicked, using tubing sets with different sizes and the connectors yielding similar angles and configurations. In this experimental vascular system, systemic vascular resistance was created with partial clamping of the common tubing set. The cannulation sites were created in the subclavian artery and the innominate artery. Perfusion was established with the same pump rate and the same occlusion pressures (systemic vascular resistance). The pressure readings were obtained in the right carotid artery, the left carotid artery and the left subclavian artery.
These experimental models of vasculature allowed us to measure pressures in the carotid system for different cannulation set-ups, using both our newly designed double-outflow cannula, which was introduced via the innominate artery, and the standard arterial cannula, which was introduced via the subclavian artery. Higher pressure recordings were obtained in the carotid system with the new cannula introduced through innominate artery.
Higher cerebral perfusion readings were obtained with our newly designed bidirectional cannula introduced via the innominate artery compared to standard cannulation through the right subclavian artery.
Recent advances in blood pump technology have led to an increased use of centrifugal pumps for prolonged extracorporeal membrane oxygenation (ECMO). Data from the Extracorporeal Life Support Organization confirms that many institutions have converted to centrifugal pumps after prior experience with roller pump technology. Centrifugal pump technology is more compact and may generate less heat and hemolysis than a conventional roller pump. Based on the potential advantages of centrifugal pumps, a decision was made institution-wide to convert to centrifugal pump technology in pediatric implementation of ECMO. Based on limited prior experience with centrifugal pumps, a multidisciplinary approach was used to implement this new technology. The new centrifugal pump (Sorin Revolution, Arvada, CO) was intended for ECMO support in the cardiac intensive care unit (CICU), the pediatric intensive care unit (PICU) and the neonatal intensive care unit (NICU).
The perfusion team used their knowledge and expertise with centrifugal pumps to create the necessary teaching tools and interactive training sessions for the technical specialists who consisted primarily of registered nurses and respiratory therapists. The first phase consisted of educating all personnel involved in the care of the ECMO patient, followed by patient implementation in the CICU, followed by the PICU and NICU.
The institution-wide conversion took several months to complete and was well received among all disciplines in the CICU and PICU. The NICU personnel did use the centrifugal pump circuit, but decided to revert back to using the roller pump technology. A systematic transition from roller pump to centrifugal pump technology with a multidisciplinary team can ensure a safe and successful implementation.
Near-infrared spectroscopy (NIRS) is a non-invasive method that reflects real-time cerebral oxygenation (rSO2) by the use of two adhesive optodes placed on the forehead of the patient. Frontal sinuses vary anatomically and a large frontal sinus might compromise the NIRS signal since the NIRS optodes are placed at the skin surface superficial to the underlying frontal sinus. The aim of this case-series was to elucidate whether there is a difference in the obligate changes in rSO2 during cardiac surgery between patients with a small as opposed to a large anterior-posterior distance of the frontal sinus based on magnetic resonance imaging. Two matched groups with small (n = 5) vs. large (n = 5) frontal sinus (3.2 vs. 18.1 millimeters) in this case-series showed no difference in obligate changes of rSO2 (p = 0.54).
Veno-arterial extracorporeal membrane oxygenation (V-A ECMO) is a life-saving procedure in patients with both respiratory and cardiac failure. Bleeding complications are common since patients must be maintained on anticoagulation. Massive hemoptysis is a rare complication of ECMO; however, it may result in death if not managed thoughtfully and expeditiously.
A retrospective chart review was performed of consecutive ECMO patients from 7/2010-8/2014 to identify episodes of massive hemoptysis. The management of and the outcomes in these patients were studied. Massive hemoptysis was defined as an inability to control bleeding (>300 mL/day) from the endotracheal tube with conventional maneuvers, such as bronchoscopy with cold saline lavage, diluted epinephrine lavage and selective lung isolation. All of these episodes necessitated disconnecting the ventilator tubing and clamping the endotracheal tube, causing full airway tamponade.
During the period of review, we identified 118 patients on ECMO and 3 (2.5%) patients had the complication of massive hemoptysis. One case was directly related to pulmonary catheter migration and the other two were spontaneous bleeding events that were propagated by antiplatelet agents. All three patients underwent bronchial artery embolization in the interventional radiology suite. Anticoagulation was held during the period of massive hemoptysis without any embolic complications. There was no recurrent bleed after appropriate intervention. All three patients were successfully separated from ECMO.
Bleeding complications remain a major issue in patients on ECMO. Disconnection of the ventilator and clamping the endotracheal tube with full respiratory and cardiac support by V-A ECMO is safe. Early involvement of interventional radiology to embolize any potential sources of the bleed can prevent re-hemoptysis and enable continued cardiac and respiratory recovery.
Vacuum-assisted venous drainage (VAVD) is widely used to enhance venous blood return from patients undergoing cardiopulmonary bypass (CPB). This vacuum can accidentally reach the oxygenator of the heart-lung machine and draw gas bubbles into the blood. This is known as bubble transgression (BT) and may cause air emboli in the arterial blood line. In order to avoid BT and minimize the risk of patient injury, knowledge of oxygenator tolerance to vacuum load is critical. Thus, the main aim of this thesis was to investigate how much vacuum a membrane oxygenator can withstand before BT appears.
We investigated four different adult oxygenators: Quadrox-i, Affinity Fusion, Capiox RX25 and Inspire 6M. They were tested in an in vitro setup where VAVD vacuum was allowed to reach the oxygenator through a non-occlusive roller pump. An ultrasonic clinical bubble counter, Gampt BCC 200, was used to count bubbles on the arterial line when the arterial pump was restarted.
We observed a significant increase in bubble count for two of the oxygenators, caused by -30 mmHg of VAVD vacuum in the blood reservoir (Affinity Fusion and Inspire 6M). Massive air ingress was shown in two of the oxygenators, caused by -30 mmHg of VAVD vacuum in the reservoir (Capiox RX25) and -40 mmHg of VAVD vacuum in the reservoir (Affinity Fusion).
VAVD vacuum may cause bubble transgression in an oxygenator. This was shown for all the oxygenators in this test. VAVD vacuum may cause visible massive air ingress in an oxygenator. This was shown for two of the oxygenators in this test (Capiox RX25 and Affinity Fusion). An alarm triggering on negative pressure in the oxygenator or a pressure relief valve might improve safety when using VAVD.
Supposedly, minimized extracorporeal circulation or off-pump revascularization as alternatives to conventional extracorporeal circulation (ONCAB) reduce inflammation and coagulation disturbances.
One hundred and twenty coronary artery bypass graft (CABG) patients were prospectively randomized for three surgical techniques. Coagulation and inflammation markers were measured up to 72 hours postoperatively.
Coagulation factors I, II, V, X, antithrombin III and C-reactive protein did not differ perioperatively between the groups and increased, as did several other markers, 12 to 72 hours postoperatively. Compared to its alternatives, ONCAB showed the most obvious transient increase in thrombin-antithrombin complexes (p<0.0001), D-dimers (p=0.0059), tissue factor pathway inhibitor (p=0.0005), factor VIII (p=0.0041) and tumor necrosis factor α (p=0.0300) during the operation and up to 12 hours postoperatively. Furthermore, ONCAB generated lower leukocyte and platelet counts and higher values of soluble P-selectin and soluble intercellular adhesion molecule 1 at some time points.
With similarity in pivot coagulation factors, a specific detrimental influence of ONCAB on common coagulation pathways was excluded. Higher perioperative concentrations of products from the coagulation cascade most likely indicate activation of pericardial blood – recirculated only in ONCAB. Furthermore, with only temporary differences in markers of inflammation, the alternatives to ONCAB altogether were without advantage at 72 hours postoperatively. In the general answer to surgical trauma, the part of modern extracorporeal circulation is possibly overestimated.
The study is registered at the German Clinical Trial Registry. Registration number DRKS00007580. URL: https://drks-neu.uniklinik-freiburg.de/drks_web/ URL:
Re-transfusion of lipid particles and activated leucocytes with shed mediastinal blood (SMB) can aggravate cardiopulmonary bypass-associated inflammation and increase the embolic load. This study evaluated the fat and leucocyte removal capacity of the RemoweLL cardiotomy reservoir.
Forty-five patients undergoing elective on-pump cardiac surgery were randomly allocated to filtration of SMB using the RemoweLL or the Admiral cardiotomy reservoir. The primary outcome was a drop in leucocytes and lipid particles obtained with the two filters. The effect of the filters on other blood cells and inflammatory mediators, such as myeloperoxidase (MPO), was also assessed.
The RemoweLL cardiotomy filter removed 16.5% of the leucocytes (p<0.001) while no significant removal of leucocytes was observed with the Admiral (p=0.48). The percentage reductions in lipid particles were similar in the two groups (26% vs 23%, p=0.2). Both filters similarly affected the level of MPO (p=0.71).
The RemoweLL filter more effectively removed leucocytes from SMB than the Admiral. It offered no advantage in terms of lipid particle clearance.
We aimed to characterize the coagulation disturbances which may increase the risk of bleeding, thrombosis or death shortly after implantation of an extracorporeal membrane oxygenation (ECMO) or ventricular assist (VAD) device.
Antithrombotic treatment was started in 23 VAD and 24 ECMO patients according to the hospital protocol. Additionally, conventional laboratory testing, rotational thromboelastometry (ROTEM®) and platelet function analysis (Multiplate®) were performed at predetermined intervals.
Four out of twenty-four (16.7%) of ECMO patients and 6/23 (26.1%) of VAD patients had severe bleeding after the procedure. When all the patients were analyzed together, low maximum clot firmness (MCF) in ExTEM and FibTEM analyses was associated with severe bleeding (p<0.05) and low MCF in FibTEM with 30-day mortality. Low platelet count and hematocrit levels were also associated with severe bleeding. When VAD and ECMO patients were separated into different groups, the association between ROTEM® parameters, bleeding and survival was found only in limited time points.
Four patients with VAD had cerebral ischemia indicative of thromboembolism. However, this had no significant correlation with ROTEM® or Multiplate® parameters.
Hypocoagulation shown by ROTEM® was associated with bleeding complications in patients with mechanical circulatory support. In contrast, hypercoagulation did not correlate with clinical thrombosis.
Use of extracorporeal life support (ECLS) has significantly increased in critically ill patients refractory to medical management. ECLS requires systemic anticoagulation to avoid thromboembolic complications and superimposed coagulopathies are common. Transesophageal echocardiography (TEE) is frequently employed to assess cannula position and cardiac function during extracorporeal therapy. The goal of this study was to assess whether TEE probe insertion and removal in systemically anticoagulated ECLS patients was safe compared to patients without ECLS and normal coagulation studies.
Eighty-seven separate TEE examinations in 53 adult ECLS patients were analyzed. Detailed complication profiles were logged for each patient from initiation through discontinuation of ECLS. Routine coagulation testing was recorded within two hours prior to the TEE exams. Controls consisted of age- and gender-matched patients undergoing perioperative TEE without ECLS and normal coagulation (N=87).
Overall TEE-associated morbidity in ECLS patients was 2.3% and consisted of minor oropharyngeal bleeding (2/87 TEE exams) exclusively. The patients presenting with oropharyngeal bleeding received heparin for anticoagulation and had two or more abnormal coagulation studies at the time of TEE. Seventy-nine percent of ECLS patients received intravenous heparin infusions, 6.8% argatroban and 3.4% epoprostenol. Ten-point-eight percent of patients were not anticoagulated at the time of TEE because of pre-existing bleeding complications and/or deranged plasmatic coagulation profiles. No major complications (e.g., esophageal perforation, gastrointestinal bleeding, accidental extubation) were recorded in either group.
TEE remained safe in critically ill patients under ECLS, despite systemic anticoagulation, during probe insertion, manipulation and removal. TEE-related complications pertained solely to oropharyngeal bleeding amenable to conservative management.
To investigate whether human serum albumin coating before cardiopulmonary bypass (CPB) could improve platelet function and hemostasis and mitigate the inflammatory response among patients receiving aortic arch replacement with deep hypothermic circulatory arrest (DHCA).
Sixty patients were included and randomized into two groups: the Control Group (CG, receiving 40 g human albumin 5 minutes after the initiation of CPB) and the Study Group (SG, circulating the prime with 40 g albumin for 5 minutes before CPB). Rapid thromboelastography, complete blood count, coagulation tests and cytokines (IL-1, IL-6, IL-10, TNF-α and PAF) were measured at two intervals: after anesthesia induction and before CPB (T1) and 10 minutes after heparin reversal before any blood product transfusion (T2).
Compared with T1, the fibrinogen and MA levels in both groups reduced significantly after heparin reversal and fell within the normal range for most patients. The platelet count reduction (PLT) in the Study Group was significantly less than in the Control Group (p=0.031). Despite the inflammatory factor levels increasing after CPB (p<0.001), no differences were found between the Control Group and the Study Group. Fewer red blood cells were given in the Study Group, but this was not significant (p=0.05).
Most patients receiving aortic arch replacement with DHCA have normal platelet function and fibrinogen levels after heparin reversal. Albumin coating before CPB may mitigate the platelet count reduction, but not platelet dysfunction. There is a trend that the patients treated with albumin coating received less red blood cell transfusions.
To evaluate late outcomes after posterior mitral valve (MV) annulus double-suture annuloplasty for degenerative (non-ischaemic) MV insufficiency.
Between 2005 and 2011, 138 patients underwent MV repair using posterior MV double-suture annuloplasty and an additional 105 patients underwent tricuspid valve repair. The study protocol included operative mortality, reoperation rate and reasons, as well as echocardiographic parameters at pre- and postoperative and follow-up periods (2-9 years).
In-hospital mortality was 2/138 (1.45%). Early post operation, no regurgitation was noted in 74/136 (54.4%) patients, Io regurgitation was observed in 55/136 (40.4%), IIo was observed in 6/136 (4.4%) and IIIo was observed in 1/136 (0.7%); during late follow-up (from 2 to 9 years), no regurgitation was observed in 21.6% patients, Io was observed in 58%, IIo was observed in 17% and IIIo was observed in 3.4%. The mean preoperative anterolateral diameter of the MV annulus was 39.02±4.97 mm and, at late follow-up, it was 27.66±3.94 mm (p=0.000); at these same time points, left ventricular end-diastolic diameter (LVEDD) was 55.74±7.29 mm and 49.17±6.01 mm (p=0.000), respectively, and the left ventricular ejection fraction (LVEF) was 53.08±8.93% and 50.92±6.78%, respectively (p=0.007).
This study demonstrates suture annuloplasty to be an effective treatment up to 9 years for degenerative mitral valve disease. This technique enables preservation of the posterior mitral valve annulus diameter with stable long-term (up to 9 years) reduction, a competent (no regurgitation/<=IIo regurgitation) MV in 96.6% of cases and positive left ventricular (LV) remodelling.
Veno-venous extracorporeal membrane oxygenation (VV-ECMO) is a treatment option to correct blood oxygenation in cases of severe respiratory failure. However, it is time-limited and, in cases of no- recovery, it is a bridge-to-lung transplant therapy. We report our experience of two patients waiting for emergency lung transplantation under VV-ECMO using the Avalon® cannula. Both presented signs of ECMO failure after prolonged support, i.e. increased hemolysis, decreased blood flow rate and increased negative pressure of the venous inflow line, leading to an inadequate systemic oxygenation. The addition of a second venous inflow line, by the insertion of another venous femoral cannula, significantly increased blood flow rate, decreasing both centrifugal pump rotation speed and negative pressure (suction) of the venous inflow line. These hemodynamic improvements, together with reduced blood consumption, were maintained during an additional week of ECMO support. Ultimately, both patients died from multi-organ failure due to the absence of available donor organs. Few cases having been described up until now, but the addition of a second venous drainage cannula to the Avalon® system could potentially improve hemodynamic parameters and, therefore, stabilize hypoxemic patients. This may be an option to gain time in long-lasting VV-ECMO support as a potential life-saving attempt.
Current trends in pediatric cardiac surgery and anesthesiology include goal-directed allogeneic blood transfusion, but few studies address the transfusion of platelets and cryoprecipitate. We report a quality improvement initiative to reduce the transfusion of platelets and cryoprecipitate in infants having cardiac surgery with cardiopulmonary bypass (CPB).
Data from 50 consecutive patients weighing four to ten kilograms having cardiac surgery with CPB were prospectively collected after the institution of a policy to obtain each patient’s platelet and fibrinogen levels during the rewarming phase of CPB. Data from 48 consecutive patients weighing four to ten kilograms having cardiac surgery with CPB prior to the implementation of the policy change were retrospectively collected. Demographics, laboratory values and blood product transfusion data were compared between the groups, using the Chi-square/Fisher’s exact test or the T-Test/Wilcoxon Rank-Sum test, as appropriate.
The results showed more total blood product exposures in the control group during the time from bypass through the first twenty-four post-operative hours (median of 2 units versus 1 unit in study group, p=0.012). During the time period from CPB separation through the first post-operative day, 67% of patients in the control group received cryoprecipitate compared to 32% in the study group (p=0.0006). There was no difference in platelet exposures between the groups.
Checking laboratory results during the rewarming phase of CPB reduced cryoprecipitate transfusion by 50%. This reproducible strategy avoids empiric and potentially unnecessary transfusion in this vulnerable population.
Several factors have been historically advocated to explain the coagulative and inflammatory disorders following cardiopulmonary bypass (CPB). In this paper, we describe the presence of circulating non-hematological cells, introduced within the bloodstream during CPB. We defined the origin of the cells and tested their impact on coagulation.
We collected peripheral arterial blood samples in twenty consecutive coronary artery bypass graft cases at four different surgical moments and assessed the presence and nature of circulating cells with the use of the CELLSEARCH® Test, immunocytochemistry and immunofluorescence, evaluating the expression of cytokeratin and calretinin. The effect of the circulating non-hematological cells on coagulation was tested in vitro, using the ROTEM assay.
A mean of 263.85 ± 57.5 (median 258.5) cells were present in the samples following the suction of blood from the surgical field while all the other samples were negative (zero cells) (p<0.00001). Immunologic tests confirmed the mesothelial origin of the cells. The ROTEM® assay of the blood samples contaminated by the mesothelial cells presented longer clotting times (53.4 ± 8.2 secs 48.3 ± 8.9 sec, p=0.05), longer clot formation times (137.1 ± 31.5 sec vs 111.9 ± 25.2 sec, p=0.009), smaller alfa angle amplitudes (66.7 ± 9.1° vs 71.1 ± 5.1°, p=0.04) and maximum clot firmness times (59.0 ± 5.4 sec vs 61.9 ±4.6 sec, p=0.004) than the controls.
The presence of circulating non-hematological cells during CPB with a mesothelial immunophenotype alters in vitro coagulation assays. This finding can help to further understand the pathophysiology of CPB.
This study examines the efficacy of hypobaric oxygenation as it relates to the elimination of gaseous microemboli (GME) at designated flow, pressure and temperature combinations.
Hypobaric oxygenation was employed for experimental trials (n=60), but not for control trials (n=60), while circuit design, data measurements and testing conditions were maintained for both settings. Hypobaric oxygenation conditions were created by applying 100% oxygen at sub-atmospheric sweep gas pressures of 0.67 atmospheres to the gas phase of an integrated hollow-fiber microporous membrane oxygenator. GME were quantified using an Emboli Detection and Classification system (EDAC), while a continuous air infusion, at a rate of 100 ml/min, was applied to the circuit. Trials were conducted at 37°C, 28°C, and 18°C and at two flow and line pressure combinations of: 3.5 L/min & 150 mmHg and 5 L/min & 200 mmHg.
Sub-atmospheric sweep gas pressures allowed adequate oxygenation independent of carbon dioxide removal while significantly reducing the potential entrance of nitrogen into the blood. GME was reduced significantly across all temperatures and flows when compared to control trials; GME counts were reduced by 99.7% post-oxygenator and 99.99% at the arterial cannula.
Correlation between the use of hypobaric oxygenation and GME counts suggests hypobaric oxygenation could play a significant role in the reduction of GME.
This observational study aimed to investigate the relationship between renal injury, endothelial function and oxidative stress in claudicants undergoing maximal treadmill exercise. Twenty patients with claudication were identified in whom the urinary N-acetyl-β-D-glucosaminidase (β-NAG)/creatinine ratio, plasma oxidative state and endothelial function were tested pre- and post-maximal treadmill walking exercise. Of the 20 participants in this study, the urinary NAG/creatinine (Cr) rose from a pre-exercise level of 8.9, 6.7 to 14.3 (μmol/L/mmol Cr; median, IQR) to 12.9, 9.1 to 17.7 post exercise (p = 0.0003, Mann Whitney U test). Of the 20 participants, eight participants had a rise of the NAG/Cr ratio post exercise whereas 12 did not. Participants with a rise in the NAG/Cr ratio post exercise had a greater ability to increase endothelial reactivity (%; median, IQR; 2.56, 0.1 to 3.7) cf. (0.1, –4.8 to 0.9, p = 0.03); they also walked further (metres; median, IQR; 415, 208 to 908) cf. (170, 100 to 315, p = 0.04), had a lower pre-exercise H2O2 (median, IQR; 1.9, 1.4 to 2.3 cf. 2.7, 2.1 to 3.3; p = 0.04) and a greater rise in H2O2 post exercise (18.8, –1.5 to 129.7 cf., –7.7, –13.9 to –2.0, p = 0.04). The mechanism by which the phenotypically distinct sub-group of patients with intermittent claudication who experience a NAG/Cr rise involves complex interactions between systemic oxidative stress and endothelial function. Implications on cardiovascular risk in this group requires further investigation.
We explored the relationship between activated clotting time (ACT) and activated partial thromboplastin time (aPTT) when used to monitor anticoagulation in patients undergoing extracorporeal membrane oxygenation (ECMO) support.
Data obtained in patients undergoing ECMO support between October 2012 and August 2013 in a single centre were reviewed. Clinical data were extracted from our Clinical Information System and ECMO database. ACT and aPTT values were paired when taken from the same patient, with the ACT preceding the aPTT and the heparin infusion rate was kept constant between samples. The aPTT and ACT were normalized by dividing by the mean of their respective reference ranges and are referred to as APR and N-ACT, respectively. Bivariate analysis and Bland-Altman plots were used to assess correlation and agreement. Mixed effects regression was used to model the effects of variables, including platelet count, creatinine and urea levels, plasma free haemoglobin, white cell count and ECMO flow rate on concordance between APR and N-ACT measurements.
The Pearson product-moment correlation coefficient in 15 patients was calculated as r=0.55. The Bland-Altman plot shows a mean difference between the APR and the N-ACT of –0.08. The 95% limits of agreement were –0.67 to 0.51. Results from mixed effects regression analysis on data from the 15 patients identified platelet count (and thrombocytopenia) and urea as significant independent predictors of concordance between APR and N-ACT.
We report a moderate degree of positive correlation between APR and N-ACT. We conclude that there is poor agreement between the ACT and aPTT for the heparin concentrations in patients supported with ECMO. Our results indicate that platelet count and urea are significant independent variables affecting concordance between ACT and aPTT measurements.
Postoperative hepatic dysfunction may occur in an otherwise uncomplicated open heart surgery. One of the reasons is malpositioning of the inferior vena cava (IVC) cannula in the hepatic vein (HV) or beyond. A straight cannula is considered more likely to be malpositioned compared to the angled cannula and a malpositioned cannula can lead to hepatic dysfunction.
In this prospective study, forty adult patients undergoing atrial septal defect repair were randomized into two groups as: straight cannula group (n=20) and angled cannula group (n=20). The cannula position was assessed by transesophageal echocardiography (TEE) (hepatic vein view). Alanine aminotransferase levels (ALT) and bilirubin levels were measured immediately, at 6 hours and on day 1, day 2 and day 7 after surgery as a marker of hepatic injury.
TEE localization of the IVC cannula was achieved in all patients except one. Visualization was good in 85% of patients. A cannula in the HV or beyond the HV in the IVC was considered malpositioned. The number of cases of cannula malposition was 10 (50%) and 4 (20%) in the straight and angled cannula groups, respectively. The pattern of change in serum bilirubin and liver enzymes levels in the postoperative period was similar in both the groups (p>0.05). The mean distance between the right atrium (RA) - inferior vena cava (IVC) junction to the hepatic vein was 1.94±0.56 cm and the mean diameters of the IVC and HV were 1.95±0.5 and 1.31±0.33 cm, respectively.
TEE can be used to monitor IVC cannula position. A higher frequency of cannula malposition was observed with the straight cannula compared to the angled cannula, but was not found to be associated with hepatic dysfunction.
The intention of the present study was to evaluate possible cardioprotective properties of inhalation anesthesia with sevoflurane.
A porcine, open-chest model of right ventricular ischemia was used in 7 pigs receiving inhalation anesthesia with sevoflurane. The model was earlier developed and published by our group, using pigs receiving intravenous anesthesia with propofol. They served as controls. The animals were observed for three hours after the induction of right ventricular ischemia by ligation of the main branches supplying the right ventricular free wall.
In the sevoflurane group, the cardiac output recovered 2 hours after the induction of ischemia and intact right ventricular stroke work was observed. In the propofol group, no such recovery occurred. The release of troponin T was significantly lower than in the sevoflurane group.
Inhalation anesthesia with sevoflurane seems superior to intravenous anesthesia with propofol in acute right ventricular ischemic dysfunction.
Current guidelines for the treatment of hypothermic cardiocirculatory arrest recommend extracorporeal life support and rewarming, using cardiopulmonary bypass or extracorporeal membrane oxygenation circuits. Both have design-related shortcomings which may result in prolonged reperfusion time or insufficient oxygen delivery to vital organs. This article describes clear advantages of minimally invasive extracorporeal circulation systems during emergency extracorporeal life support in hypothermic arrest. The technique of minimally invasive extracorporeal circulation for reperfusion and rewarming is represented by the case of a 59-year-old patient in hypothermic cardiocirculatory arrest at 25.3°C core temperature, with multiple trauma. With femoro-femoral cannulation performed under sonographic and echocardiographic guidance, extracorporeal life support was initiated using a minimally invasive extracorporeal circulation system. Perfusing rhythm was restored at 28°C. During rewarming on the mobile circuit, trauma surveys were completed and the treatment initiated. Normothermic weaning was successful on the first attempt, trauma surgery was completed and the patient survived neurologically intact. For extracorporeal resuscitation from hypothermic arrest, minimally invasive extracorporeal circulation offers all the advantages of conventional cardiopulmonary bypass and extracorporeal membrane oxygenation systems without their shortcomings.
Cardiopulmonary bypass (CPB) may cause platelet dysfunction, contributing to bleeding. There are no investigations of how CPB affects platelet mitochondrial respiration and what correlation this has with platelet aggregation and bleeding.
We studied platelet mitochondrial respiration and aggregation in eighteen adult cardiac surgery patients having CPB. The relationships between respiration, aggregation and postoperative bleeding were analyzed.
Platelet respiration, reflected by the respiratory control ratio (RCR), was unchanged after CPB (mean difference in RCR= –0.02 (95% CI=–1.45 to 1.42), p=0.98). Further, there were no significant relationships between indexed adenosine diphosphate (ADP) or thrombin receptor-activating peptide (TRAP)-induced aggregation and the RCR (p=0.12 and p=0.41). Only post-CPB ADP - induced aggregation correlated with 24-hr chest tube output (p=0.04), but indexing for platelet count attenuated the effect (p=0.07).
Platelet mitochondrial respiration is preserved after CPB and is not correlated with aggregation or bleeding. Only post-CPB, ADP-induced aggregation correlates with postoperative bleeding.
The aim of our study was to investigate the effects of pulsatile cardiopulmonary bypass (CPB) on renal function and the need for haemofiltration in patients with preoperative renal impairment undergoing cardiac surgery.
Clinical data were collected prospectively for patients undergoing cardiac surgery with pulsatile CPB (Group A, n=66) and compared to matched patients with standard non-pulsatile CPB (Group B, n=66). Patients included in the study had mild renal impairment and at least moderate risk from surgery as defined by logistic EuroSCORE. Emergency operations were excluded.
Patients in Groups A and B had similar age (71 ± 10 versus 70 ± 10 years), sex distribution, mean preoperative renal function (creatinine clearance 63.9 ± 28 versus 67.7 ± 27.3 ml/min) and overall risk profile as predicted by the logistic EuroSCORE (8 ± 8.3 versus 11.05±13.3, p=0.122). Intraoperative variables were comparable with respect to bypass and cross-clamp times (96 ± 37 minutes and 64 ± 28 minutes versus 103 ± 40 minutes and 70 ± 33 minutes in Groups A and B, respectively). A smaller proportion of patients in Group A (4.5% versus 15%, p=0.076) required haemofiltration in the postoperative period. Postoperative mortality was low in both groups (Group A 1.54% versus Group B 3.03%, p=1.00).
Within the limitations imposed by retrospective analyses, our study demonstrates that pulsatile CPB may confer a reno-protective effect in higher-risk patients with pre-existing mild renal dysfunction undergoing cardiac surgery.
We sought to reveal whether the severity of angina pectoris affects sleep quality after elective coronary artery bypass grafting.
Patients scheduled to undergo isolated coronary artery bypass grafting were divided into two groups, having a recent myocardial infarction (Group 1, n=22, mean age 59.40±7.79 years) or not having a recent myocardial infarction (Group 2, n=30, mean age 59.73±7.72 years). The assessment included the Canadian Cardiovascular Society Angina Score, the visual analogue scale for postoperative pain and the Pittsburgh Sleep Quality Index (PSQI).
The two groups were similar in regard to baseline characteristics. Cross-clamp time was significantly higher (p=0.007) and the use of inotropes was significantly more common (p=0.01) in those patients with recent myocardial infarction compared to those without. Mean Canadian Cardiovascular Society scores were also higher in patients with recent myocardial infarction (p=0.02). Total Pittsburgh Sleep Quality Index score was significantly higher in patients with recent myocardial infarction (8.45±3.50 vs. 5.03±2.32, respectively, p<0.001). In multivariate analysis, higher angina score (OR: 3.27, 95% CI, 1.20-8.90, p=0.02) and longer time of intensive care unit stay (OR: 6.15, 95% CI, 1.49-25.35, p=0.01) were found to be independent predictors of poor sleep quality. The Canadian Cardiovascular Society angina score showed a significant positive correlation with poor sleep duration score (<0.001), sleep disturbance score (p=0.02), day dysfunction due to sleepiness score (p=0.001), sleep efficiency score (p=0.003), overall sleep quality score (0.03) and total PSQI score (p=0.004).
The severity of angina pectoris in the preoperative period is independently associated with worse sleep quality after elective isolated coronary artery bypass surgery.
Cardiac surgery with cardiopulmonary bypass may be necessary in patients with pre-existing, continuous-flow, left ventricular assist devices. Heart transplantation or exchange of a malfunctioning left ventricular assist device are the most common scenarios. However, reoperation may also be needed for acquired valvular disease or device malposition. In these cases, operative strategies that enable safe conduct of cardiopulmonary bypass and, if needed, cardioplegic arrest while the left ventricular assist device remains in situ, are essential. Such strategies would avoid unnecessary replacement of working components of the left ventricular assist device and, importantly, avoid damage to them during the period of cardiopulmonary bypass. Adequate anticoagulation, avoidance of regurgitant flow into the device, prevention of blood stagnation in the hardware and careful deairing after periods of pump stoppage are key principles. We present a stepwise algorithm for the management of the HeartMate II device during such cases.
Previously, we reported that the oxyhemoglobin dissociation curve is shifted leftward in patients who receive autologous umbilical cord blood (UCB) during neonatal open heart surgery. In this study, we assessed whether allowing the pCO2 to rise during hypothermic cardiopulmonary perfusion would shift the curve back to the right and improve tissue oxygenation.
The study population included prenatally diagnosed patients with transposition of the great arteries. The study cohort was divided into two groups and consisted of early patients originally managed with lower pCO2 levels (Group I, n=42, 2009-12) and later patients subsequently managed with higher pCO2 levels (Group II, n=38, 2012-14).
Patients received similar volumes of collected autologous UCB (Group I, 80 ml; Group II, 75ml, p=0.207) with a similar mean level of HbF during CPB (Group I, 90±8%; Group II, 87±9%, p=0.310). Higher levels of pCO2 during CPB (Group I, 31 mmHg; Group II, 37 mmHg, p=0.011) resulted in a rightward shift of the oxyhemoglobin dissociation curve (increased p50O2) (Group I, 19.5±3.4 mmHg; Group II, 22.5±2.2 mmHg, p=0.011). The use of a higher pCO2 strategy was associated with decreased serum lactate during CPB (Group I, 4.7±2 mmol/l; Group II, 2.8±1.4 mmol/l, p=0.001), decreased duration of mechanical ventilation (Group I, 46h; Group II, 22h, p<0.001) and decreased of length of intensive care unit (ICU) stay (Group I, 7.6±2.6, Group II, 5.6±2.2, p=0.003)
A higher pCO2 during CPB in neonates who underwent open heart surgery using UCB resulted in a rightward shift of the oxyhemoglobin dissociation curve and was associated with improved serum lactate levels.
Predicting the post-dilution hematocrit is an important tool to avoid preventable anemia or unnecessary transfusion. Simplified empirical formulas currently used for such a prediction may lead to large errors. We aimed to improve the accuracy of these formulas by a better estimation of the dilution volume and the patient circulatory blood volume.
We compared the estimation accuracy of two formulas, using fixed (formula A) versus estimated (formula D) dilution volume and patient circulatory blood volume for 100 cardiac interventions. The difference between predicted and measured HctT1 was considered as "good" if less than 0.5%, "moderate" between 0.5 and 2% and "poor" if higher than 2%. The influence of the body mass index (BMI) on patient blood volume estimation was explored by categorized groups’ comparison.
The mean difference between predicted and measured HctT1 differed significantly between formulas A and D. Formula A didn’t differ from HctT1 (p=0.19, IC95% [-0.89-0.18]), but a significant and higher underestimation was observed in the BMI<=25 group compared to the other BMI groups (p<0.001). Formula D overestimated HctT1 (p<0.001, IC95% [1.01-1.93]) without a difference between the BMI groups. No difference was observed in their overall proportions of good (11 vs 10%), moderate (44 vs 46%) and poor predictions (47 vs 44%) (p=0.117).
Formulas used for post-dilution hematocrit prediction lead to major estimation errors and a risk of inadequate transfusion practices. Estimations performed by experienced clinicians could not minimize these biases in all clinical cases as significant errors remain, with potential clinical impact. No estimation formula should be used as a hard tool for transfusing patients, but rather as a guide to predicting the probability of transfusion requirement.
To compare the emboli filtration efficiency of five integrated or non-integrated oxygenator-filter combinations in cardiopulmonary bypass circuits.
Fifty-one adult patients underwent surgery using a circuit with an integrated filtration oxygenator or non-integrated oxygenator with a separate 20 µm arterial line filter (Sorin Dideco Avant D903 + Pall AL20 (n=12), Sorin Inspire 6 M + Pall AL20 (n=10), Sorin Inspire 6M F (n=9), Terumo FX25 (n=10), Medtronic Fusion (n=10)). The Emboli Detection and Classification quantifier was used to count emboli upstream and downstream of the primary filter throughout cardiopulmonary bypass. The primary outcome measure was to compare the devices in respect of the median proportion of emboli removed.
One device (Sorin Inspire 6 M + Pall AL20) exhibited a significantly greater median percentage reduction (96.77%, IQR=95.48 – 98.45) in total emboli counts compared to all other devices tested (p=0.0062 – 0.0002). In comparisons between the other units, they all removed a greater percentage of emboli than one device (Medtronic Fusion), but there were no other significant differences.
The new generation Sorin Inspire 6 M, with a stand-alone 20 µm arterial filter, appeared most efficient at removing incoming emboli from the circuit. No firm conclusions can be drawn about the relative efficacy of emboli removal by units categorised by class (integrated vs non-integrated); however, the stand-alone 20 µm arterial filter presently sets a contemporary standard against which other configurations of equipment can be judged.
Despite the clinical success and growth in the utilization of continuous flow ventricular assist devices (cfVADs) for the treatment of advanced heart failure, hemolysis and thrombosis remain major limitations. Inadequate and/or ineffective anticoagulation regimens, combined with high pump speed and non-physiological flow patterns, can result in hemolysis which often is accompanied by pump thrombosis. An unexpected increase in cfVADs thrombosis was reported by multiple major VAD implanting centers in 2014, highlighting the association of hemolysis and a rise in lactate dehydrogenase (LDH) presaging thrombotic events. It is well established that thrombotic complications arise from the abnormal shear stresses generated by cfVADs. What remains unknown is the link between cfVAD-associated hemolysis and pump thrombosis. Can hemolysis of red blood cells (RBCs) contribute to platelet aggregation, thereby, facilitating prothrombotic complications in cfVADs? Herein, we examine the effect of RBC-hemolysate and selected major constituents, i.e., lactate dehydrogenase (LDH) and plasma free hemoglobin (pHb) on platelet aggregation, utilizing electrical resistance aggregometry. Our hypothesis is that elements of RBCs, released as a result of shear-mediated hemolysis, will contribute to platelet aggregation. We show that RBC hemolysate and pHb, but not LDH, are direct contributors to platelet aggregation, posing an additional risk mechanism for cfVAD thrombosis.
Minimally invasive direct coronary artery bypass (MIDCAB) and totally endoscopic coronary artery bypass (TECAB) techniques may improve recovery and reduce hospital stay following coronary artery bypass surgery (CABG). However, working in a limited space with indirect visualisation would greatly benefit from a simple, high-quality and reproducible automated distal anastomotic method. Several devices have been developed; however, their uptake has been limited due to uncertainty around their impact on patient outcomes.
A systematic review of the literature identified six studies, incorporating 139 subjects undergoing MIDCAB or TECAB surgery using a distal anastomotic device.
The overall 30-day mortality was 0.7% (1/137). No cardiac specific mortality was observed. For each outcome of perioperative myocardial infarction (MI), postoperative stroke and haemorrhage, only a single event was observed for each (n=1/136, 1/138 and 1/136, respectively). The overall device failure rates were low, with the use of additional sutures only reported in a single case with the Magnetic Vascular Port (MVP) device. Anastomotic time ranged from a mean of 3.32 minutes with the MVP device to 20 minutes with the C-Port device.
These results demonstrate the overall acceptable early outcomes of distal anastomotic devices for use in minimally invasive coronary bypass surgery. Future research should focus on designing adequately powered, comparative, randomised trials, focusing on major adverse cardiac and cerebrovascular events (MACCE) outcomes in both the short and long-term, with clear case-by-case reasons for device failure and a comparison of anastomotic times. In this way, we may determine whether such devices will facilitate the minimal access and robotic coronary procedures of the future.
Dabigatran etexilate is a direct thrombin inhibitor approved for use in patients with non-valvular atrial fibrillation. There is no currently available pharmacological therapy to reverse this renally cleared anticoagulant. Dabigatran has a low level of plasma protein binding and has been considered dialyzable. We used a pig model with renal artery ligation to exclude intrinsic drug excretion to examine the efficacy of ultrafiltration (UF) during cardiopulmonary bypass (CPB) for dabigatran removal.
Dabigatran was intravenously infused (20 mg) in Yorkshire pigs (male, n=7, 70±1 kg) following renal artery ligation. CPB with UF was initiated after heparinization and continued until a total volume of 6 liters of UF effluent was removed. Serial labs, including dabigatran concentration, activated coagulation times (ACT), hematocrit and creatinine were drawn at intervals before the start of CPB and then incrementally during UF (0, 2, 4 and 6 L removed). Hemodialysis (HD) was performed on one animal following UF.
Dabigatran concentration (ng/mL) rose from undetectable levels at baseline to 296±70 (p<0.05) at the conclusion of infusion, but dropped significantly upon administration of heparin (178±40, p<0.05). A further decrement in dabigatran concentration was observed from the administration of heparin to the start of CPB (to 135±28, p<0.05). Once on CPB, dabigatran remained stable, with the end UF (eUF) dabigatran concentration being 133±34. Dabigatran concentration in the UF effluent was measured in one animal and was 98.8, with 6 L of effluent having been removed. The total recovery of dabigatran was calculated to be less than 5%. Dabigatran concentrations also did not decrease appreciably with HD on CPB following UF.
UF in conjunction with CPB was ineffective at removing dabigatran. Heparin demonstrated a dabigatran-lowering effect, suggesting a possible drug interaction or assay impairment. Based on these findings, emergent cardiac surgery with UF on cardiopulmonary bypass to remove dabigatran is not advisable. Alternative forms of drug removal or reversal must be identified.
We measured and compared changes in the percentage of cells expressing CD80, CD86, CD40, HLA-DR and the expression of these molecules on B cells and monocytes of patients who underwent either on-pump, mini on-pump or off-pump cardiac surgery.
Blood samples from patients who underwent either on-pump, mini on-pump or off-pump cardiac surgery were collected before surgery, instantly after surgery and on the 1st, 3rd and 7th days after surgery. Surface expression of CD80, CD86, CD40 and HLA-DR molecules was determined by flow cytometry.
Our results show that all three surgical techniques altered the expression of these molecules, as well as the percentage relative number of specific cell populations. We identified statistically significant differences when comparing different surgical techniques. On-pump surgery revealed a more pronounced impact on the phenotype of immune system cells than the other techniques. Therefore, it is likely that the function of immune cells is changed the most by on-pump surgery. We found a lower decrease in the number of CD80+ monocytes and a lower drop in the CD40 expression on monocytes in off-pump patients in comparison with on-pump patients.
All the types of cardiac surgical techniques, off-pump, on-pump and modified mini-invasive on-pump, are associated with changes in CD80, CD86, CD40 and HLA-DR expression. We found several significant differences in the expression of the selected molecules when we compared all three groups of patients.
Does additional postoperative collection and processing of mediastinal shed blood with a cell salvage device reduce the number of allogeneic blood transfusions compared to intraoperative cell salvage alone?
A single-centre cohort study in which adult patients with coronary artery bypass grafting or aortic valve replacement were allocated to either a C.A.T.S® group with intraoperative blood processing only or a CardioPat® group with both intra- and postoperative blood processing. The primary endpoint was the number of allogeneic blood transfusions during hospital admission.
The study included 99 patients; 50 in the C.A.T.S® and 49 in the CardioPat® group.
There was no difference in the number of red blood cells (RBC) (C.A.T.S® group 43 units versus CardioPat® 50 units, p=0.74), fresh frozen plasma (C.A.T.S® 8 units versus CardioPat® 8 units, p=1.00) or platelets (C.A.T.S® 5 units versus CardioPat® 4 units, p=1.00) transfused during the hospital stay.
Cardiac creatinine kinase (CK-MB) and troponin levels did not differ between the groups although a significant time effect (p<0.001) was present. Creatinine kinase (CK) levels were not different between the groups three hours after arrival in the intensive care unit (ICU) (CardioPat® group versus C.A.T.S® group, p=0.17). But, compared to the C.A.T.S® group on the first (350 [232-469] IU/L) and second postoperative days (325 [201-480] IU/L), the increase in CK levels was more in the CardioPat® group on the first (431 [286-642] IU/L, p=0.02) and second postoperative days (406 [239-760] IU/L, p=0.05), resulting in a difference between the groups (p=0.04)
Postoperative cell salvage does not reduce transfusion requirements compared to intraoperative cell salvage alone, but results in elevated total CK levels that suggest haemolysis.
The inflammatory process has been reported to be associated with aortic dissection (AD) from the development to the prognosis. The aim of the study was to investigate a relationship between the neutrophil to lymphocyte ratio (NLR) and in-hospital outcomes in patients with acute aortic dissection (AAD) who underwent surgical repair.
One hundred and eighty-four patients who were admitted with the diagnosis of type A AAD who underwent surgical repair at two large tertiary hospitals. According to their NLR, 91 patients had high NLR (>6.0) and 93 patients had low NLR (<=6.0).
The frequency of major bleeding, hospital-related infection, multi-organ dysfunction and mortality in hospital were higher in the high NLR group compared to the low NLR group. NLR, WBC count and operation duration were found to be independent predictors for in-hospital mortality.
The novel inflammatory marker NLR may be used to predict worse outcomes and hospital mortality in patients with AAD treated by surgical repair.
Veno-arterial (V-A) extracorporeal membrane oxygenation (ECMO) is increasingly being used for patients with refractory cardiopulmonary failure. This study evaluates the short-term (to discharge) and longer-term (1 year) survival among older (>=65 years) versus younger (<65 years) adults, adjusted for comorbidities, in a diverse cohort of V-A ECMO patients.
This was a retrospective cohort analysis of 131 adult patients (28% >=65 years old) who received V-A ECMO at an academic medical center from 2004-2013. Demographics, comorbidities and surgical characteristics were abstracted from the medical records and verified. Mortality status at discharge and at one year post-ECMO were determined by the hospital clinical information system, updated monthly with Social Security Death Index data. Cox proportional hazard analyses were conducted to evaluate associations between age strata and mortality at discharge and at one year post ECMO initiation, adjusted for covariates.
The survival rate following V-A ECMO was 48% (n=68/131) to discharge and 44% (n=58/131) to one year. Age >=65 versus <65 was significantly associated with increased mortality during hospitalization (HR:2.03; 95%CI=1.23-3.33) and at one year (HR:1.81; 95% CI=1.12-2.93); these associations were attenuated and did not retain statistical significance after adjustment for comorbidities (HR:1.61; 95%CI=0.90-2.88 and HR:1.42; 95% CI=0.81-2.50, respectively). Statistically significant predictors of mortality at discharge and one year included history of coronary artery bypass graft, peripheral vascular disease and renal failure/dialysis (p<0.05).
Older age was not independently associated with short-term or longer-term survival among V-A ECMO patients, but may reflect greater comorbidity, suggesting that age alone may not disqualify patients from V-A ECMO therapy.
Experimental circuits for biomaterial surface testing are frequently limited by the tested blood volume, composition of the circuit, flow conditions and the use of animal blood. This report describes an ex vivo set-up for simulated cardiopulmonary bypass with human blood perfusion. We investigated the clinical generalizability of the observed effects on hematological and metabolic parameters and the hemocompatibility of the system.
The simulated cardiopulmonary bypass circuit consisted of a heparin-coated tubing system connected to an oxygenator and a venous reservoir. Normothermic flow of blood obtained from healthy donors was maintained at 2.4 L/min/m2 by a roller pump. Heparin was dosed to obtain a target activated clotting time (ACT) >=500 s. Blood was drawn at baseline and 0, 10, 60 and 120 minutes following the initiation of blood flow to determine hematological and metabolic parameters and the hemocompatibility of the extracorporeal system. Data were analyzed using repeated measures ANOVA.
Two hours of blood perfusion resulted in a small, but clinically unimportant reduction in hematocrit, whereas hemoglobin levels and red blood cell, platelet and leukocyte counts remained stable. There was a significant increase in ACT throughout the experiment. While pO2 levels and the pH remained unaltered during the experiment, pCO2 values decreased from 51 ± 6 mmHg at T0 to 41 ± 3 mmHg at T120 (p<0.001). Simulated cardiopulmonary bypass induced a two-fold increase in C3a (p=0.001) while tissue factor was decreased from 44 ± 14 pg/mL at T0 to 38 ± 13 pg/mL at T120 (p=0.009). Levels of CD40L, prothrombin fragment 1+2, β-thromboglobulin and factor VIIa remained stable over time.
The ex vivo set-up for simulated cardiopulmonary bypass mimicked the clinical cardiosurgical setting. Exposure of fresh donor blood to the extracorporeal circuit showed a good hemocompatibility, indicated by maintained hematological parameters and a mild immune response.
Extracorporeal circulation and its systems have been known to increase the inflammatory response and cause protein absorption in coronary bypass surgery. In this study, we aimed to compare the affinities of phosphorylcholine-coated and uncoated oxygenators on the cellular inflammatory response and protein absorption.
Twenty patients undergoing elective coronary bypass were randomly allocated into two groups: Phosphorylcholine-coated oxygenators were used in 10 patients (Group 1) and uncoated oxygenators were used in the other 10 patients (Group 2) during surgery. Samples were obtained from blood and oxygenators at the induction of anesthesia, the beginning and end of cardiopulmonary bypass (CPB) and postoperative 1st day. Parameters related with white blood cells were studied with flow cytometry and electron microscopy in these samples.
White blood cell and neutrophil counts were increased while platelet counts were significantly decreased in both groups postoperatively. CD3+ T cell levels were significantly decreased at the end of CPB and on postoperative day 1. CD3+ CD25+ T cell levels were found to be significantly lower in Group 2 on the 1st postoperative day. Electron microscopic evaluation demonstrated that phosphorylcholine-coated fibers were less likely to absorb blood components and proteins.
Results of the current study have shown that phosphorylcholine-coated oxygenators were more likely to trigger a cellular immune response compared to the uncoated oxygenators.
Although fresh frozen plasma (FFP) is one of the most commonly used hemostatic agents in clinical specialties today, there is little evidence available supporting its administration. Our present study observed the effects of a priming strategy without FFP during cardiopulmonary bypass (CPB) on postoperative coagulation and clinical recovery in pediatric patients, aiming to supply new evidence for evidence-based use of FFP.
Eighty pediatric patients with congenital heart disease undergoing cardiac surgery with CPB were randomized to receive either 10-20 ml/kg 4% succinylated gelatin (Gelofusine, GEL group, n = 40) or 1-2 units FFP (FFP group, n = 40) in the pump prime. Rapid-thromboelastography (r-TEG) and functional fibrinogen level were measured before skin incision and 15 minutes after heparin reversal. We recorded the volume of chest tube drainage, transfusion requirements and the dosage of pharmacological agents. The ventilation time, ICU length of stay and hospitalization time after surgery were also collected.
After heparin neutralization, there were significantly elevated levels of fibrinogen in the FFP group, which were manifested by r-TEG parameters MAf and FLEV. No significant differences were observed between the two groups in postoperative bleeding, transfusion requirements and the usage of pharmacological agents. Recovery time was also comparable between the two groups.
In conclusion, prophylactic use of FFP in the priming solution does not provide clinical benefits as presumed. Artificial colloids, such as Gelofusine, can be used safely and effectively as a substitute for FFP in the pump prime. TEG is an effective assessment tool to evaluate postoperative coagulation function in pediatric patients.
During parental development, the umbilical cord is physiologically and genetically part of the fetus and, in humans, normally contains a pair of arteries and a vein. The umbilical vein (UV) supplies the fetus with oxygenated, nutrient-rich blood from the placenta. In contrast, the fetal heart pumps deoxygenated, nutrient-depleted blood through the umbilical arteries (UA) back to the placenta. Although the extreme importance of the mechanical properties of the UA and UV, such as linear elasticity and non-linear hyperelasticity, is fully recognized, detailed viscoelastic, time-dependent, mechanical behavior of umbilical cord components is still lacking. A deep investigation on the quasilinear, viscoelastic (QLV), time-dependent, mechanical behavior of the UV could help to understand its long-term patency for the treatment of coronary artery disease (CAD) as a coronary artery bypass graft (CABG).
In the present study, the mechanical properties during tension of the human umbilical artery and umbilical vein were evaluated using a QLV approach. A ramp of stress-relaxation tests were performed on UA and UV samples extracted from term Caesarian deliveries, after uncomplicated pregnancies, from eight female umbilical cords. The QLV coefficients were calculated by fitting the experimental stress-relaxation data to the material model.
The results revealed that the peak stress in UA samples is significantly higher than that of UV samples. In addition, the equilibrium stress was reached in about 50 seconds for both the UAs and UVs in tension.
The findings of this study could have implications, not only for understanding the viscoelastic, time-dependent, mechanical behavior of UAs and UVs, but also for interventions and surgeries, including balloon-angioplasty, bypass and stenting.
Patients with apical ballooning syndrome may develop dynamic left ventricular outflow obstruction due to systolic anterior motion of the mitral valve leaflet and secondary functional mitral regurgitation, causing decreased cardiac output and hypotension. If suspected, bedside echocardiography will quickly confirm this complication. Positive inotropic/chronotropic agents should be avoided as they may exacerbate outflow tract obstruction, resulting in further hemodynamic compromise.
Excessive hemodilution during cardiopulmonary bypass (CPB) is associated with an increased rate of red blood cell (RBC) transfusion and acute kidney injury (AKI). Minimization of the oxygenator priming volume is a measure to contain hemodilution. In this study, we evaluated the new oxygenator, Sorin Inspire 6™, with respect to its ability to limit hemodilution, RBC transfusion rate and postoperative AKI rate.
A retrospective study on a consecutive series of 1,724 adult patients receiving heart surgery with CPB. Patients treated with the Inspire 6™ were assigned to the low priming volume oxygenator (LPVO) group (N=383) and patients treated with conventional oxygenators to the conventional group (N=1,341). Dynamic priming volume, time course of the hematocrit, RBC transfusions and AKI rate were compared between the groups.
Priming volume was significantly (p=0.001) lower in the LPVO group (624±113 mL) vs. the conventional group (775±150 mL), with higher values of hematocrit during and after CPB. After correction for other confounders, patients in the LPVO group had a significantly lower RBC transfusion rate (odds ratio 0.68, 95% confidence interval 0.52-0.90, p=0.006) and AKI rate (odds ratio 0.55, 95% confidence interval 0.32-0.93, p=0.032).
The Inspire 6™ oxygenator allows a significant containment of hemodilution during CPB, reducing the risk of RBC transfusions and postoperative AKI.
To develop a standardized simulation-based curriculum to teach medical knowledge and technical, communication and critical thinking skills necessary to initiate and wean from cardiopulmonary bypass (CPB) to junior cardiac trainees (CTs) in France. Performance on post-curricular tests was compared between CTs who participated in the new curriculum to those who did not.
The simulation-based curriculum was developed by content and education experts. Simulations sequentially taught the skills necessary for initiating and weaning from CPB as well as managing crises by adding fidelity and complexity to scenarios. Nine CTs were randomly assigned to the new curriculum (n=5) or the traditional curriculum (n=4). Skills were assessed using tests of medical knowledge and technical, communication (GRS) and critical thinking (SCT) skills. A two-sample Wilcoxon rank-sum test compared average scores between the two groups. Alpha of 0.05 was set to indicate statistically significant differences.
The resutls revealed that CTs in the new curriculum significantly outperformed CTs in the traditional curriculum on technical (18.2 vs 14.8, p=0.05) and communication (3.5 vs 2.2, p=0.013) skills. There was no significant difference between CTs in the new curriculum in the Script Concordance Test (16.5 vs 14.8, p=0.141) and knowledge tests (26.9 vs 24.6, p=0.14) compared to CTs in the traditional curriculum.
Our new curriculum teaches communication and technical skills necessary for CPB. The results of this pilot study are encouraging and relevant. They give grounds for future research with a larger panel of trainees. Based on the current distribution of scores, a sample size of 12 CTs per group should yield significant results for all tests.
The worldwide demand for ECMO support has grown. Its provision remains limited due to several factors (high cost, complicated technology, lack of expertise) that increase healthcare cost. Our goal was to assess if an intensive care unit (ICU)-run ECMO model without continuous bedside perfusionists would decrease costs while maintaining patient safety and outcomes.
A new ECMO program was implemented in 2010, consisting of dedicated ICU multidisciplinary providers (ICU-registered nurses, mid-level providers and intensivists). In year one, we introduced an education platform, new technology and dedicated space. In year two, continuous bedside monitoring by perfusionists was removed and new management algorithms designating multidisciplinary providers as first responders were established. The patient safety and cost benefit from the removal of the continuous bedside monitoring of the perfusionists of this new ECMO program was retrospectively reviewed and compared.
During the study period, 74 patients (28 patients in year 1 and 46 patients in year 2) were placed on ECMO (mean days: 8 ± 5.7). The total annual hospital expenditure for the ECMO program was significantly reduced in the new model ($234,000 in year 2 vs. $600,264 in year 1), showing a 61% decrease in cost. This cost decrease was attributed to a decreased utilization of perfusion services and the introduction of longer lasting and more efficient ECMO technology. We did not find any significant changes in registered nurse ratios or any differences in outcomes related to ICU safety events.
We demonstrated that the ICU-run ECMO model managed to lower hospital cost by reducing the cost of continuous bedside perfusion support without a change in outcomes.
Acute mesenteric ischemia (AMI) is an infrequent, but complicated, life-threatening condition. Given this poor outcome, an estimation of mortality would aid in decision making for physicians, patients and their families. Red cell distribution width (RDW) is reflective of systemic inflammation. RDW is a remarkable prognostic marker for determining the risk of mortality in a wide range of clinical manifestations. The objective of this study was to investigate the association between RDW and mortality in patients with AMI.
The medical records of patients who underwent laparotomy with a preoperative diagnosis of AMI were reviewed retrospectively. Primary outcome variable was the hospital mortality rate.
Estimating the receiver operating characteristic area under the curve showed that RDW has good discriminative power for mortality (area under the curve = 0.713; 95% confidence interval, 0.584–0.841). With a cut-off value of 14.85 for RDW, mortality could be correctly predicted in approximately 70% of cases.
Increased RDW at admission was a predictor of the extent of necrosis and mortality in AMI patients. Further prospective studies are necessary to more accurately assess the importance of RDW in these patients.
Currently there are no medications that can be administered to help deliver more oxygen to the myocardial region experiencing abnormal perfusion. The purpose of this study was to look at the nanoparticle dodecafluoropentane in an emulsion as an oxygen carrier. Using nanoparticles as an oxygen carrier is advantageous because they are able to carry oxygen past blockages that are obstructing red blood cells (6-8 µm) due to their smaller size (250 nm). With the reintroduction of oxygen to the ischemic muscle tissue, a reduced infarct size should be seen.
Male C57BL/6J mice underwent left anterior descending artery (LAD) ligation using 8-0 monofilament nylon suture. Immediately after ligation of the LAD, the control group received a 200-µl intravenous injection of phosphate buffered saline (PBS). The treated group received a dose of 0.6 ml/kg of dodecafluoropentane diluted to a total volume of 200 µl in PBS. The mice were then allowed to recover from anesthesia and were sacrificed 24 hours after the time of ligation. After the mice were sacrificed, the heart was excised and placed at -20°C for 20 minutes. The heart was then sliced into 1-mm sections and stained with tetrazolium red to identify the infarcted area. The area of infarct and ventricle were then analyzed using ImageJ software.
The average area of infarct in comparison to the ventricle for the control mice was 29.3±0.04% compared to 11.7±0.02% for the dodecafluoropentane-treated mice.
The use of dodecafluoropentane in this murine model of myocardial infarction showed a 60% reduction in infarct size (p<0.01). The possibility of using nanoparticles to deliver oxygen to hypoxic tissues has interesting implications and justifies further study.
We describe a single-centre experience of extracorporeal life support (ELS) for patients with severe and refractory cardiogenic shock, refractory cardiac arrest and severe respiratory failure.
Between September 2007 and September 2012, 56 intra-hospital and 10 inter-hospital adult patients were supported.
The median ELS duration was 3 (0.9 - 6) days in venoarterial and 9.2 (7.4 - 24.4) days in venovenous supported patients. At hospital discharge and follow-up (12 and 40 months), survival among the respiratory (venovenous) patients and cardiac (venoarterial) patients was 84% and 38%, respectively. Survival in severe refractory cardiogenic shock patients was related to early initiation of ELS (<8 hours of onset of failure). A delay in initiating venoarterial ELS (>8 hours) and increased pre-ELS pH and lactate levels were associated with death in all cardiomyopathy patients, independent of infarct size.
Our results exemplify the benefits of ELS as a bridge to initial stabilization of critically ill patients. Potentially, the early application of ELS technology can lower mortality and morbidity in patients with a regressive pathology.
Microplegia (whole blood cardioplegia with reduced volume) retains all the advantages of blood cardioplegia (such as superior oxygen-carrying capacity, better osmotic properties and antioxidant capability, etc.) without the potential disadvantages of hemodilution (such as myocardial edema). We sought to perform a systematic review and meta-analysis to compare microplegia and standard blood cardioplegia on the cardioprotective effects for patients undergoing coronary artery bypass grafting (CABG).
MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials were searched for relevant controlled trials published in English, from their inception up to May 15th, 2013. Data on low output syndrome, spontaneous return to sinus rhythm, volume of cardioplegia and perioperative myocardial infarction were analyzed.
Five studies, totaling 296 patients, were included out of 77 retrieved citations. The microplegia group used less volume of cardioplegia (WMD, -514.79 ml, 95%CI: -705.37 ml to -324.21 ml) when compared with the standard blood cardioplegia group. There were no statistical differences in the incidence of low output syndrome (RR, 0.95, 95%CI: 0.55 to 1.62), spontaneous return to sinus rhythm (RR, 1.64, 95%CI: 0.61 to 4.41) and perioperative myocardial infarction (RR, 0.62, 95%CI: 0.19 to 2.08).
Microplegia was associated with less volume of cardioplegia, whereas the incidence of spontaneous return to sinus rhythm and perioperative myocardial infarction were similar, but large controlled randomized trials are still needed to confirm this.
Extracorporeal membrane oxygenation (ECMO) in patients with severe pulmonary failure is able to keep patients alive until organ regeneration, until shunting out for further diagnostic and therapeutic options or until transportation to specialized centers. Nonetheless, extracorporeal techniques require a high degree of expertise, so that a confinement to specialized centers is meaningful. Following from this requirement, the need for inter-hospital transfer of patients with severely compromised pulmonary function is rising.
We report about our experience with a portable ECMO system during inter-hospital air or ground transfer of patients with cardiopulmonary failure.
The portable ECMO system was used for transportation to the center and in-hospital treatment in 36 patients with an average age of 53 years suffering from respiratory failure. Accordingly, the ECMO system was implanted as a veno-venous extracorporeal system. Pre-ECMO ventilation time was 5.2 (2-9) days. Twelve patients were transported to our institution by ground and 24 patients by air ambulance over a median distance of 46 km. With the assistance of the ECMO device, prompt stabilization of cardiopulmonary function could be achieved in all patients without any technical complications. Post-ECMO ventilation was 9.8 days. Weaning from the ECMO system was successful in 61% of all patients after a median device working period of 12.7 days; median ICU stay was 34 days and a survival rate of 64% of patients was achieved. Technical (8%) and device-associated bleeding (11%)/thromboembolic (8%) complication rates showed very acceptable levels.
Our experience demonstrates that miniaturized, portable ECMO therapy allows location-independent, out-of-center stabilization of pulmonary compromised patients with consecutive inter-hospital transfer and further in-house treatment, so that sophisticated ECMO therapy can be offered to every patient, even in hospitals with primary healthcare.
Ischaemia-reperfusion (IR) injury is partly caused by the release of reactive oxygen species and cytokines and may result in remote organ injury. Surgical patients are exposed to surgical stress and anaesthesia, both of which can influence the IR response. An IR model without these interfering factors of surgery is, therefore, useful to test the potential of antioxidant and cytokine-modulatory treatments.
The aim of this study was to characterize a human ischaemia-reperfusion model with respect to oxidative and inflammatory biomarkers.
Ten male volunteers were exposed to 20 minutes of lower limb ischaemia. Muscle biopsies and blood samples were taken at baseline and 5, 15, 30, 60 and 90 minutes after tourniquet release and analysed for malondialdehyde (MDA), ascorbic acid, dehydroascorbic acid, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-1 receptor antagonist (IL-1Ra), IL-6, IL-10, TNF-receptor (TNF-R)I, TNF-RII and YKL-40.
We found no significant increase in MDA in the muscle biopsies after reperfusion. Plasma levels of oxidative and pro- and anti-inflammatory parameters showed no significant differences between baseline and after reperfusion at any sampling time.
Twenty minutes of lower limb ischaemia does not result in an ischaemia-reperfusion injury in healthy volunteers, measurable by oxidative and pro- and anti-inflammatory biomarkers in muscle biopsies and in the systemic circulation.
Coronary artery perforation (CAP) is an infrequent and life-threatening complication of percutaneous coronary intervention (PCI), requiring prompt intervention. There is insufficient data about the prognosis and management of CAP in patients with acute coronary syndrome (ACS). The aim of this study was to investigate the management of CAP in patients with ACS.
The results of 25 patients with CAP were retrospectively analyzed.
Of the 25 patients, 14 patients (56%) had ACS. According to the Ellis classification, the grade of perforation was type-I in 8 (32%) patients, type-II in 6 (24%) patients and type-III in 11 (44%) patients. Prolonged balloon inflation was performed to 20 (80%) cases of CAP. It successfully sealed the perforation in three cases of type-I, five cases of type-II CAP and in seven cases of type-III CAP. Seven patients underwent covered stent implantation. Emergent CABG was required in two patients with type-III CAP. In-hospital mortality was not observed in the patients.
The outcomes of CAP in patients with ACS were similar to patients with stable coronary disease. The continuation of anti-platelet agents after the successful management of CAP may be encouraged in these patients.
The aim of present study was to assess whether vitamin D, with proven beneficial effects on the cardiovascular system, has any effect on angina and exercise-induced ischemia in patients with cardiac syndrome X and low serum vitamin D.
Patients with cardiac syndrome X and low serum vitamin D3 were studied before and after treatment with an intramuscular injection of vitamin D3 (300,000 units, every other week for 2 months). We determined the angina episode (per day) and several indices of exercise capacity.
At the end of the treatment course (75±6 day), a significant increase of serum vitamin D3 occurred and was within the normal range (45±8 ng/ml) and the frequency of angina improved significantly (p=0.003). Exercise duration and maximal work capacity increased significantly (p<0.001). Maximal ST-segment depression (mm) decreased significantly (p=0.001). The calculated Duck treadmill score improved significantly (p=0.001).
Our findings show that vitamin D replacement therapy in patients with cardiac syndrome X and vitamin D deficiency dramatically improves symptoms and signs of ischemia.
Choroid, which is the vascular tissue responsible for blood supply to the outer parts of the retina, might be affected by hemodynamic events. We aimed to reveal choroidal thickness and ocular pulse amplitude changes after cardiopulmonary bypass in which gross hemodynamic alterations occur.
Forty-two eyes of 42 patients who underwent heart surgery with cardiopulmonary bypass were examined in this prospective, cross-sectional case series. The spectral domain optical coherence tomography (Spectralis, Heidelberg, Germany) was used to analyze sub-foveal choroidal thickness. The ocular pulse amplitude, the surrogate of gross choroidal blood flow, was measured with the Pascal dynamic contour tonometer (Pascal DCT, Swiss Microtechnology AG, Port, Switzerland).. The intraocular pressure was also measured with this tonometer. The examinations were performed pre-operatively and post-operatively at the first week and first month.
The mean age of the patients was 58.8 ± 12.4 years. The mean sub-foveal choroidal thickness and ocular pulse amplitude values did not change statistically significantly after the operations at the follow-up visits (p>0.05). Also, there were no important correlations between cardiopulmonary bypass time and mean sub-foveal choroidal thickness and ocular pulse amplitude changes at the post-operative first week (p>0.05). The intraocular pressure values were decreased markedly at the control visits (p<0.05).
Sub-foveal choroidal thickness and ocular pulse amplitude are unchanged, while intraocular pressure decreases one week and one month after cardiopulmonary bypass.
We evaluated a pattern for connecting a hemofiltration apparatus after the ECMO oxygenator and observed the effects on the levels of inflammatory cytokines. All animals were anesthetized and ventilated, were randomly divided into 3 groups and observed for 24 h: S group (n = 6) received cannulation and heparin infusion; E group (n = 6) received venovenous (VV)-ECMO and heparin infusion; E+H group (n = 6) received hemofiltration with VV-ECMO placed after the oxygenator and heparin infusion. Hemodynamics, gas exchange parameters and plasma cytokine levels were measured simultaneously. After VV-ECMO, oxygenation was maintained in the E and E+H groups. In the E group, the levels of TNF-α, IL-1β, IL-6 and IL-8 increased markedly in the first 2–6 h and then remained stable from 12–24 h. Concentrations of TNF-α, IL-1β, IL-6 and IL-8 in the E+H group were lower than those in the E group. We concluded that the manner of connecting the hemofiltration apparatus after the oxygenator helped maintain adequate oxygenation and was easy to perform. Connecting hemofiltration to ECMO minimized the ECMO-associated effects of pro-inflammatory cytokines.
The adequacy of cerebral blood flow and the level of regional oxygen saturation during CPR and early post-resuscitation phases assuring favorable neurological outcome are not known. We demonstrate the feasibility of cerebral blood flow and oxygenation monitoring by a continuous transcranial Doppler combined with cerebral oximetry in a patient with refractory cardiac arrest treated by extracorporeal life support.
Human albumin is the conventional cardiopulmonary bypass circuit primer. However, it has high manufacturing costs. Crystalloid and colloid solutions have been developed as alternatives, including a new generation of non-ionic hydroxyethyl starch (HES). The efficacy of hydroxyethyl starch with a 130 molecular weight and substitution degree of 0.4 (hydroxyethyl starch 130/0.4) was compared with human albumin for use in cardiopulmonary bypass surgery in American Society of Anesthesiologists’ grade I-II pediatric congenital heart disease patients. Efficacy was evaluated by comparing perioperative hemodynamic parameters, including plasma colloid osmotic pressure, renal function, blood loss, allogeneic blood volumes and plasma volume substitution. The hydroxyethyl starch group exhibited significantly higher preoperative colloid osmotic pressure (p<0.01) and significantly lower operative renal function and postoperative allogeneic blood volumes than the human albumin group. No significant differences were observed in serum creatinine, glucose, hematocrit or lactic acid levels (p>0.05). Our results indicate that hydroxyethyl starch may be a viable alternative to human albumin in pediatric patients undergoing relatively simple cardiopulmonary bypass surgeries.
We hypothesized that the optimization of renal haemodynamics by maintaining a high level of mean arterial blood pressure (MAP) during cardiopulmonary bypass (CPB) could reduce the rate of acute kidney injury (AKI) in high-risk patients.
In this randomized, controlled study, we enrolled 300 patients scheduled for elective cardiac surgery under cardiopulmonary bypass. All had known risk factors of AKI: serum creatinine clearance between 30 and 60 ml/min for 1.73m2 or two factors among the following: age >60 years, diabetes mellitus, diffuse atherosclerosis. After a standardized fluid loading, the MAP was maintained between 75-85 mmHg during CPB with norepinephrine (High Pressure, n=147) versus 50-60 mmHg in the Control (n=145). AKI was defined by a 30% increased of serum creatinine (sCr). We further tested others definitions for AKI: RIFLE classification, 50% rise of sCr and the need for haemodialysis.
The pressure endpoints were achieved in both the High Pressure (79 ± 6 mmHg) and the Control groups (60 ± 6 mmHg; p<0.001). The rate of AKI did not differ by group (17% vs. 17%; p=1), whatever the criteria used for AKI. The length of stay in hospital (9.5 days [7.9-11.2] vs. 8.2 [7.1-9.4]) and the rate of death at day 28 (2.1% vs. 3.4%) and at six months (3.4% vs. 4.8%) did not differ between the groups.
Maintaining a high level of MAP (on average) during normothermic CPB does not reduce the risk of postoperative AKI. It does not alter the length of hospital stay or the mortality rate.
The current goal of treatment after acute ischemic stroke is the increase of cerebral blood flow (CBF) in ischemic brain tissue. Intra-aortic balloon pump (IABP) counterpulsation in the setting of cardiogenic shock is able to reduce left ventricular afterload and increase coronary blood flow. The effects of an IABP on CBF have not been sufficiently examined. We hypothesize that the use of an IABP especially enhances cerebral blood flow in patients with pre-existing heart failure.
In this pilot study, 36 subjects were examined to investigate the effect of an IABP on middle cerebral artery (MCA) transcranial Doppler (TCD) flow velocity change and relative CBF augmentation by determining velocity time integral changes (VTI) in a constant caliber of the MCA compared to a baseline measurement without an IABP. Subjects were divided into two groups according to their left ventricular ejection fraction (LVEF): Group 1 LVEF >30% and Group 2 LVEF ≤30%.
Both groups showed an increase in CBF using an IABP. Patients with a LVEF ≤30% showed a significantly higher increase of VTI in the MCA under IABP augmentation compared to patients with a LVEF >30% (20.9% ± 3.9% Group 2 vs.10.5% ± 2.2% Group 1, p<0,05). The mean arterial pressure (MAP) increased only marginally in both groups under IABP augmentation.
IABP improves cerebral blood flow, particularly in patients with pre-existing heart failure and highly impaired LVEF. Hence, an IABP might be a treatment option to improve cerebral perfusion in selected patients with cerebral misperfusion and simultaneously existing severe heart failure.
The use of cardioplegia solution has substantially increased the safety of cardiac surgery. It protects the myocardium by inducing a rapid and complete diastolic arrest, minimizing myocardial energy requirements, preventing ischaemic damage during the arrest phase and minimizing or preventing reperfusion injury once coronary blood flow is restored.
This article is a summary of important information that has accumulated in the literature about cardioplegia and describes how our understanding of cardioplegia has evolved. The basic principles of myocardial ischaemia and reperfusion injury and how they relate to myocardial protection are described. Blood and crystalloid cardioplegia are compared with respect to biochemical and physiological differences.
Recent patient demographic changes, with surgeons operating on older, more complex patients who have more severe and diffuse disease, are discussed. This cohort of patients potentially requires prolonged elective ischaemia; hence, improved myocardial protection would be of benefit. We highlight areas of study that have demonstrated a new concept of myocardial protection, known as polarized arrest. Many pharmacological agents have been shown (in experimental studies) to have the ability to induce a polarized arrest and to provide improved protection.
Transmembrane pressure drop reflects the resistance of an artificial lung system to blood transit. Decreased resistance (low transmembrane pressure drop) enhances blood flow through the oxygenator, thereby, enhancing gas exchange efficiency. This study is part of a previous one where we observed the behaviour and the modulation of blood pressure drop during the passage of blood through artificial lung membranes.
Before and after the induction of multi-organ dysfunction, the animals were instrumented and analysed for venous-venous extracorporeal membrane oxygenation, using a pre-defined sequence of blood flows.
Blood flow and revolutions per minute (RPM) of the centrifugal pump varied in a linear fashion. At a blood flow of 5.5 L/min, pre- and post-pump blood pressures reached -120 and 450 mmHg, respectively. Transmembrane pressures showed a significant spread, particularly at blood flows above 2 L/min; over the entire range of blood flow rates, there was a positive association of pressure drop with blood flow (0.005 mmHg/mL/minute of blood flow ) and a negative association of pressure drop with temperature (-4.828 mmHg/oCelsius). These associations were similar when blood flows of below and above 2000 mL/minute were examined.
During its passage through the extracorporeal system, blood is exposed to pressure variations from -120 to 450 mmHg. At high blood flows (above 2 L/min), the drop in transmembrane pressure becomes unpredictable and highly variable. Over the entire range of blood flows investigated (0 – 5500 mL/min), the drop in transmembrane pressure was positively associated with blood flow and negatively associated with body temperature.
Historically, the activated clotting time (ACT) has been the preferred monitoring test of the heparin effect in extracorporeal membrane oxygenation (ECMO) patients. However, few adult studies have evaluated its correlation to the heparin dose or other monitoring tests, such as the activated partial thromboplastin time (aPTT). This retrospective study sought to evaluate the correlation between the heparin dose and these monitoring tests.
Patients administered a heparin drip during ECMO were included in this study. The primary endpoints were the correlation between heparin dose and ACT or aPTT and the relationship between paired ACT and aPTT samples.
Forty-six patients met the criteria for study inclusion. A better correlation was observed for heparin dose and aPTT (Pearson product-moment correlation coefficient (r) = 0.43 – 0.54) versus ACT (r = 0.11 – 0.14). Among the paired sample data, ACT values did not differ significantly between Groups two (aPTT 60 – 75 seconds) and three (aPTT >75 seconds).
The heparin dose correlated better with aPTT relative to ACT and, thus, may be considered a more effective tool for the dosing of heparin in adult ECMO patients. Paired ACT and aPTT sample data suggested a poor relationship between these two anticoagulant monitoring tests.
Cerebral embolization during pediatric cardiac surgery may be an underappreciated source of subsequent neurodevelopmental impairment. Transcranial Doppler ultrasound is a neuromonitoring tool that can provide intraoperative surveillance for cerebral embolization. We hypothesized that increased cerebral embolic signals detected during infant cardiac surgery would be associated with worse neurodevelopmental outcomes at follow-up. A study group of 24 children who underwent infant cardiac surgery with transcranial Doppler detection of cerebral embolic signals returned at intermediate follow-up for standardized neurodevelopmental assessment. The children were evaluated using two neurocognitive tests and the parents completed two questionnaires regarding observed behavior. Statistical analysis assessed for correlation between the number of cerebral embolic signals at surgery and the results of the neurodevelopmental assessment. Of the 67 test parameters analyzed, five showed a significant association with the number of embolic signals, yet, all in the contrary direction of the clinical hypothesis, likely representing a Type I error. Thus, in this small cohort of patients, the number of cerebral embolic signals detected during infant cardiac surgery was not shown to be associated with worse neurodevelopmental outcomes at intermediate follow-up. A larger study is probably necessary to ascertain the potential influence of cerebral embolic signals on eventual neurologic outcomes in children. The clinical relevance of cerebral embolic signals during pediatric cardiac surgery remains undetermined and deserves further investigation.
In the presence of nitric oxide synthase (NOS) inhibitors, the contribution of residual NO to endothelium-dependent relaxation induced by chemical agonists acetylcholine and bradykinin has been documented in resistance vessels. However, the contribution of residual NO to the vasodilatation in response to pressure and fluid shear stress is not well understood. In this study, to demonstrate the activity of residual NO, we applied a NO scavenger, hydroxocobalamin (HCX), on the phenylephrine-induced increase in perfusion pressure in the presence of NOS inhibitors, N-nitro-L-arginine (L-NA) or N-nitro-L-arginine methyl ester (L-NAME) in the rat perfused mesenteric bed. The perfusion pressure was increased by phenylephrine (1-2 µM), an α1-adrenoceptor agonist. This increase was augmented by the addition of L-NA or L-NAME. In the presence of any NOS inhibitors, the application of hydroxocobalamin (100 µM) further increased the perfusion pressure. The removal of endothelium by saponin (50 mg/L) and the use of a non-selective protein kinase inhibitor, staurosporine (5 nM), and a tyrosine kinase inhibitor, erbstatin A (30 µM), but not a calmodulin inhibitor, calmidazolium (0.5 µM), inhibited the additional pressor responses induced by L-NA or L-NAME and a combination of either of them with hydroxocobalamine. These findings show that there could be a NOS inhibitor-resistant residual NO production in response to pressure in the rat mesenteric vascular bed. This residual NO production may be associated with the activation of tyrosine kinase and protein kinases, but not calmodulin. Finally, this pressure-induced residual NO exerts a modulatory role against vasoconstriction induced by phenylephrine.
The Impella Recover LP 5.0® is an aortic transvalvular microaxial pump designed to unload the left ventricle and to ensure a systemic flow in severe left ventricular dysfunction.
We propose a new suggestion for the Impella 5.0 as a temporary right ventricular assist device after the surgical treatment of a posterior post-infarction ventricular septal defect.
The aim of this study was to determine the relationship between oxidative stress markers and the duration of ischemia in rat mesenteric and peripheral ischemia models.
Forty rats were divided into five equal groups, as follows: rats in Group I (control group) were sacrificed to determine the baseline characteristics of the serum markers; the superior mesenteric artery was clamped via a simple laparotomy to induce mesenteric ischemia in Groups II and III; the right common femoral artery was clamped to induce peripheral ischemia in Groups IV and V. Blood samples were taken at 2 (Groups II and IV) and 6 (Groups III and V) hours after these procedures. The serum total oxidative status (TOS), total antioxidant capacity (TAC), oxidative stress index (OSI) and paraoxonase-1 (PON-1) enzyme activities were evaluated in the samples obtained from each group.
The OSI level of the control group was 91.00±5.46 (mean ± SD). The OSI levels taken 2 hours after the induction of mesenteric ischemia and peripheral ischemia were significantly higher (194.50±11.16 and 301.75±19.98, respectively (p<0.05)). However, these levels decreased to 151.88±17.02 (mesenteric ischemia) and 108.88±9.46 (peripheral ischemia) after 6 hours. The PON-1 levels of Group III (mesenteric ischemia at 6 hours) (99.75±7.26), Group IV (peripheral ischemia at 2 hours) (96.88±4.09), and Group V (peripheral ischemia at 6 hours) (111.25±10.33) were slightly elevated over that of the control group (87.38±5.31). However, the PON-1 level of Group II (mesenteric ischemia at 2 hours) (42.88±3.14) was lower than that of the other groups (p<0.05).
Despite the increment of oxidative markers in early periods of ischemia (2nd hour), which was a hypoxic response of ischemic cells, they have decreased markedly in prolonged ischemia. This might have been caused by the opening of some collateral circulation or the destruction of the ischemic cells.
Phonocardiography, the digital recording of heart sounds, is becoming increasingly popular as a primary detection system for diagnosing heart disorders and is relatively inexpensive. The electrocardiogram (ECG) is often used when recording the phonocardiogram in order to help identify the systolic and diastolic components. In this study, a heart sound segmentation algorithm has been developed which automatically separates the heart sound signal into these component parts.
100 patients with normal and abnormal heart sounds were studied. The algorithm uses homomorphic filtering to produce time-domain intensity envelopes of the heart sounds and separates the sounds into four overlapping parts: the first heart sound, the systolic period, the second heart sound and the diastolic period.
The performance of the algorithm was evaluated using 14,000 cardiac periods from 100 digital phonocardiographic recordings, including normal and abnormal heart sounds. In tests, the algorithm was over 93 percent correct in detecting the first and second heart sounds.
The automatic segmentation algorithm presented uses wavelet decomposition and reconstruction to select a suitable frequency band for envelope calculations and has been found to be effective in segmenting phonocardiogram signals into four component parts without using an ECG reference.
Previous studies showed the association between the major adverse cardiovascular outcomes and both higher neutrophil and lower lymphocyte counts. We aimed to investigate whether there is an association between the neutrophil-lymphocyte ratio (NLR) value and the development of coronary collateral circulation (CCC) in patients with coronary chronic total occlusion (CTO).
A total of 274 patients with CTO were included in this study. Patients were then classified according to their Rentrop collateral grades as either poor (Rentrop grades 0-1) or good (Rentrop grades 2-3). Clinical information and analyses of blood samples were obtained from a review of the patients’ charts.
Although there was no difference between the two groups with regard to cardiovascular risk profiles, the NLR values were significantly higher in the patients who had poorly developed CCC (2.6 ± 0.5 vs 2.2 ± 0.4, p<0.001). NLR, high-sensitivity C-reactive protein (hs-CRP), white blood cell count (WBC), age, diabetes, fasting glucose levels and body mass index were found to have univariate association with poorly developed CCC (p<0.1). In a multivariate logistic regression model, NLR (odds ratio 1.88, 95% confidence interval (CI) 1.37–2.74; p<0.001), high-sensitivity C-reactive protein and WBC were found to be the independent predictors of poor CCC. In receiver operator characteristic curve analysis, the optimal cut-off value of NLR to predict poor CCC was found as 2.17, with 77% sensitivity and 65% specificity.
NLR, as a novel cardiovascular risk marker, is an important, simple and inexpensive method which can be used by the cardiologist as a screening inflammation tool to estimate the development of CCC in patients with CTO.
Brain tissue is a very soft tissue in which the mechanical properties depend on the loading direction. While few studies have characterized these biomechanical properties, it is worth knowing that accurate characterization of the mechanical properties of brain tissue at different loading directions is a key asset for neuronavigation and surgery simulation through haptic devices. In this study, the hyperelastic mechanical properties of rat brain tissue were measured experimentally and computationally. Prepared cylindrical samples were excised from the parietal lobes of rats’ brains and experimentally tested by a tensile testing machine. The effects of loading direction on the mechanical properties of brain tissue were measured by applying load on both longitudinal and circumferential directions. The general prediction ability of the proposed hyperelastic model was verified using finite element (FE) simulations of brain tissue tension experiments. The uniaxial experimental results compared well with those predicted by the FE models. The results revealed the influence of loading direction on the mechanical properties of brain tissue. The Ogden hyperelastic material model was suitably represented by the non-linear behavior of the brain tissue, which can be used in future biomechanical simulations. The hyperelastic properties of brain tissue provided here have interest to the medical research community as there are several applications where accurate characterization of these properties are crucial for an accurate outcome, such as neurosurgery, robotic surgery, haptic device design or car manufacturing to evaluate possible trauma due to an impact.
Computational simulations have the potential to aid understanding of cardiovascular hemodynamics under physiological conditions, including exercise. Therefore, blood hemodynamic parameters during different heart rates, rest and exercise have been investigated, using a numerical method. A model was developed for a healthy subject. Using geometrical data acquired by echo-Doppler, a two-dimensional model of the chamber of aortic sinus valsalva and aortic root was created. Systolic ventricular and aortic pressures were applied as boundary conditions computationally. These pressures were the initial physical conditions applied to the model to predict valve deformation and changes in hemodynamics. They were the clinically measured brachial pressures plus differences between brachial, central and left ventricular pressures. Echocardiographic imaging was also used to acquire different ejection times, necessary for pressure waveform equations of blood flow during exercise. A fluid-structure interaction simulation was performed, using an arbitrary Lagrangian-Eulerian mesh. During exercise, peak vorticity increased by 14.8%, peak shear rate by 15.8%, peak cell Reynolds number by 20%, peak leaflet tip velocity increased by 47% and the blood velocity increased by 3% through the leaflets, whereas full opening time decreased by 11%. Our results show that numerical methods can be combined with clinical measurements to provide good estimates of patient-specific hemodynamics at different heart rates.
The introduction of new and more advanced technology in healthcare occurs with an increasing speed. Therefore, more attention is needed for safety evaluation of new devices or techniques from an end-user perspective, especially when (inter-) national perfusion safety standards are lacking.
A recently increased awareness of the safety risks as a consequence of technical or human error has provoked interest in optimisation of perfusion methodology and devices.
To prevent or reduce the severity or likelihood of failures of new technology, ‘failure mode effect analysis’ is a proven proactive technique. When it is used as a qualitative analysis for possible hazards in patient treatment associated with the use of medical devices, it’s called healthcare failure mode effect analysis (hFMEA).
To evaluate the safety of the Extra Corporeal Circulation Optimized (ECCO, Sorin Group, Mirandola, Italy) miniaturized bypass circuit, hFMEA was used. A multi disciplinary team that consisted of two clinical perfusionists, a clinical physicist, a clinical physicist trainee and a technician has performed this analysis.
The hFMEA demonstrated that failure of the bubble sensor for the electric remote clamping system on the arterial line (Figure 1), activated by air passing the venous bubble trap, had the highest risk score of all failure modes. This has led to the implementation of an extra low-level sensor in the system to prevent air passing through into the centrifugal pump. The hFMEA has also indicated that extra individual simulation training is needed for handling critical failures during the use of the miniature bypass system.
Early identification of possible technology failures in any process or device can avoid adverse patient outcomes. The technique of hFMEA is a valuable tool in evaluating the use of high-risk apparatus, such as an extracorporeal bypass system, in patient treatment in order to increase patient safety.
One challenge in providing extracorporeal circulation is to supply optimal flow while minimising adverse affects, such as haemolysis. To determine if the recent generation constrained vortex pumps with their inherent design improvements would lead to reduced red cell trauma, we undertook a study comparing three devices. Utilizing a simulated short-term ventricular assist circuit primed with whole human blood, we examined changes in plasma free haemoglobin values over a six-day period. The three pumps investigated were the Maquet Rotaflow, the Levitronix PediVAS and the Medos Deltastream DP3.This study demonstrated that all three pumps produced low levels of haemolysis and are suitable for use in a clinical environment. The Levitronix PediVAS was significantly less haemolytic than either the Rotaflow (p<0.05) or the DP3 (p<0.05). There was no significant difference in plasma free haemoglobin between the Rotaflow and the DP3 (p=0.71).
Selective inhibition of inward rectifier K+ channels could abolish the protection mediated by ischemic preconditioning, but the roles of these channels in ischemic postconditioning have not been well characterized. Our study aims to evaluate the effect of inward rectifier K+ channels on the protection induced by ischemic postconditioning.
Langendorff-perfused rat hearts (n=8 per group) were split into four groups: postconditioning hearts (IPO group); ischemic postconditioning with BaCl2 hearts (PB group); ischemic postconditioning with zacopride hearts (PZ group); and without ischemic postconditioning (CON group). After suffering 30 minutes of global ischemia, groups IPO, PB and PZ went through 10 seconds of ischemic postconditioning with three different perfusates: respectively, Krebs–Henseleit buffer (IPO group); 20 μmol/L BaCl2 (antagonist of the channel, PB group); 1 μmol/L zacopride (agonist of the channel, PZ group).
At the end of reperfusion, the myocardial performance was better preserved in the PZ group than the other three groups. The PB group showed no significant differences from the CON group.
Our study has shown that the IK1 channel agonist zacopride is associated with the enhancement of ischemic postconditioning.
Cardiac surgery on neonates for the correction of congenital heart defects is usually associated with the transfusion of packed red blood cells (PRBCs) into the cardiopulmonary bypass (CPB) circuit. We hypothesised that such transfusions of stored PRBCs directly into the arterial system may increase postoperative morbidity when compared to intravenous transfusion.
In this retrospective cohort study, data from 122 consecutive neonates who received transfusions of PRBCs in the course of corrective surgery for congenital heart defects were analysed. Group assignment was according to the timing of the first transfusion: during CPB (On-CPB) or after weaning from CPB (Post-CPB). Chi Square and rank sum tests were applied to compare clinical characteristics. Times until extubation and release from the intensive care unit were analysed by Kaplan-Meier curves and by multivariate Cox regression.
Transfusion of PRBCs during CPB was associated with greater 48 hour blood loss (mean±standard deviation, 86±125 versus 32±16 mL/kg, p<0.001), longer duration of mechanical ventilation (214±268 versus 99±75 h, p<0.001) and longer stay on the intensive care unit (10.9±12.1 versus 5.3±3.5 days, p<0.001). However, the groups also differed in many characteristics, such as bodyweight, complexity of surgery or preoperative haemoglobin concentration, which may also affect outcome. Yet, multivariate analyses confirmed an independent association of transfusion On-CPB with an adverse clinical outcome.
Our results are consistent with the hypothesis that the transfusion of PRBCs during CPB may increase postoperative morbidity. However, due to the limitations of this retrospective analysis, further studies are needed to confirm a causal relationship between the timing of the transfusion and the clinical outcome and to elucidate putative mechanisms of such an association.
Cardiopulmonary bypass can result in hemodilution due to the crystalloid prime, increasing the need for blood transfusion. Alternative perfusion techniques have the potential to decrease this hemodilution. The objective of this study was to determine whether a protocol of retrograde autologous prime (RAP) and venous antegrade prime (VAP) reduces the need for blood transfusion and increases the hematocrit following cardiac surgery.
We performed a retrospective review of 140 consecutive non-randomized patients who underwent cardiac surgery with cardiopulmonary bypass between November 2011 and September 2012. RAP and VAP techniques were used in 70 patients while the other 70 were managed with conventional perfusion strategies. The primary outcome measure was a composite outcome of any blood transfusion or a discharge hematocrit less than 27%.
Baseline demographics and patient characteristics were similar between the two groups, with the exception of the RAP/VAP group having a lower baseline creatinine. There was a trend toward decreased perioperative blood transfusions in the RAP/VAP group (13/70, 19%) compared with the non-RAP/VAP group (23/70, 33%, p=0.053). RAP/VAP patients had a significantly higher hematocrit at hospital discharge (30.0 ± 4.3% vs. 28.3 ± 4.1%, p=0.012). The number of patients receiving a transfusion or being discharged with an hematocrit less than 27% was significantly less in the RAP/VAP group (21 vs. 41, p=0.001). This effect persisted on multivariable analysis.
RAP and VAP perfusion techniques may reduce hemodilution, potentially resulting in less blood transfusions and higher postoperative hematocrits. These techniques should be considered in all patients undergoing cardiac surgery with cardiopulmonary bypass.
During coronary artery bypass grafting (CABG), one of the most important complications related to the internal mammary artery (IMA) is perioperative spasm. Nebivolol causes endothelium-dependent vascular relaxation by increasing nitric oxide (NO) release and prevents endothelial dysfunction in long-term use. In our study, we measured the effect of a third generation beta blocker, nebivolol, on the flow dynamics of IMA grafts.
We recruited 90 hypertensive patients undergoing isolated CABG operation, who were divided into three groups and each group included 30 patients: Group 1 patients were under antihypertensive treatment other than beta-blockers (angiontensin-converting enzyme [ACE] inhibitors, calcium channel blockers or diuretics; monotherapy or combination therapy), Group 2 received metoprolol (50 mg/day) and Group 3 received nebivolol (5 mg/day). These antihypertensive therapies were given for at least one week before the operation and continued thereafter. IMA blood flow volume was measured for one minute just before cardiopulmonary bypass (measurement A) and before left internal mammary artery (LIMA)-left anterior descending (LAD) artery anastomosis (measurement B) in the three groups. Cardiac output measurements were also achieved simultaneously.
The measurement A results were 56.3 ± 36.2, 54.6 ± 28.1 and 66.8 ± 34.2 mL/min in Groups 1, 2 and 3, respectively (p<0.05). The measurement B results were 78.3 ± 29.6, 80 ± 28.8 and 91.1 ± 40.8 mL/min in Groups 1, 2 and 3 (p<0.05), respectively. There were no differences in cardiac outputs among the groups; 5.2 ± 1.4, 5.0 ± 1.6 and 5.3 ± 1.1 L/min (p>0.05). While the cardiac outputs were similar within the three groups, the IMA free flow volume was higher in the nebivolol group after local papaverine use.
Nebivolol might represent a good choice in hypertensive patients undergoing cardiac surgery by preventing perioperative myocardial hypoperfusion which increases early morbidity and mortality.
This study aimed to evaluate the effects of pulmonary artery perfusion with a urinary trypsin inhibitor (UTI) as a lung protective strategy in order to provide an experimental basis for immature lung clinical protective strategies on deep hypothermia with low-flow (DHLF) cardiopulmonary bypass (CPB)-induced pulmonary injury in an infant piglet model.
The piglets (n=15), aged 18.7±0.3 days, weight 4.48±0.21kg, were randomly divided into 3 groups, with 5 piglets in each group: the control group, the pulmonary artery perfusion without UTI group (Group P) and the pulmonary artery perfusion with UTI group (Group U). The levels of the cytokines tumour necrosis factor-α, myeloperoxidase, malondialdehyde and interleukin-10 (TNF-α, MPO, MDA and IL-10) in pulmonary venous serum and lung tissue and the activity of NF-kappa B in lung tissue were measured by enzyme-linked immunosorbent assay (ELISA) and electrophoresis mobility shift assay (EMSA), respectively.
After DHLF-CPB, all of the piglets demonstrated a state of lung injury as a deterioration of lung function indices, lung injury scores, pulmonary ultrastructure changes, expression of TNF-α, MPO, MDA and IL-10 and the activities of nuclear factor-kappa B (NF-B), while pulmonary artery perfusion with UTI significantly ameliorated lung function and histopathological changes, with greatly decreased serum levels of TNF-α and MPO compared to the other two groups. Also, we found an increase in the level of IL-10 in Group U lungs compared with that in Group P lungs, which correlated with a strong inhibition in the activity of NF-B.
Pulmonary artery perfusion with UTI ameliorated the DHLF-induced immature pulmonary injury in the lungs via a reduction of pro-inflammatory cytokine expression and up-regulated levels of IL-10 by inhibiting the activity of NF-B.
Narrowed true lumen and patent false lumen through to the terminal aorta is a high-risk condition for malperfusion syndromes (MS) in acute type-A aortic dissection. It is important to ascertain how the true and false lumens behave after surgery.
We retrospectively investigated 45 patients with this pathology. The true lumen sizes at the narrowest levels above and below the superior mesenteric artery were followed by computed tomography after surgery (0-36 months).
Thirty-seven MS were seen in 23 patients. Hospital mortality was 8.9%. The narrowed true lumen was not enlarged in the first 6 months with a patent false lumen. The elephant trunk procedure did not improve the true lumen size. An extremely narrowed (≤3mm) true lumen was associated with a significantly high incidence of MS and mortality.
High incidences of MS were observed in this particular pathology. An extremely narrowed true lumen was accompanied by a high incidence of MS and mortality.
This study examined the effect of coronary artery revascularization on left ventricular function and the results of strain imaging for the detection of ischemia before and after coronary artery bypass graft (CABG) surgery.
Sixty-eight patients with a history of coronary artery disease (CAD) were included, prospectively. Conventional echocardiography and color tissue Doppler-derived strain-strain rate echocardiographic imaging were performed 24 hours before and 3 months after CABG surgery.
While strain rate values of the basal septum, middle segment of the lateral wall, middle segment of the inferior wall, and middle and basal segments of the anterior wall were significantly increased, other segments did not change after the operation. The mean systolic strain rate value was significantly increased after the operation. Left ventricle strain values in the middle segment of the septum, middle and basal segments of the inferior wall, and middle and basal segments of the anterior wall were significantly increased after the operation. No significant difference was noted in the basal septum or the middle and basal segments of the lateral wall after the operation. The mean systolic strain value was significantly increased after the operation.
The results of this study suggest that strain and strain rate echocardiography can provide an accurate evaluation of regional contractile function after CABG, even in the segments that are apparently normal.
Medically refractory hemorrhage in patients on ECMO (extracorporeal membrane oxygenation) support can have catastrophic complications. Recombinant-Activated Factor VII (rFVIIa; NovoSeven®) may provide lifesaving hemostasis; however, there are reports of catastrophic thrombosis related to its administration.
This review attempts to add safety and efficacy data to existing literature regarding the use of rFVIIa for refractory hemorrhage in pediatric patients on ECMO support.
A retrospective chart review was performed for all pediatric patients on ECMO who received rFVIIa for refractory hemorrhage from 2004 to 2009. Data was extracted for each refractory bleeding event, including patient blood loss and transfused blood products in the 6 hours before the first dose, between rFVIIa doses and in the 6 hours after the final dose. For purposes of data collection, a hemorrhagic event was defined as new onset hemorrhage or a hemorrhage occurring at least 12 hours after the most recent dose of rFVIIa.
In total, seven patients aged 1 month to 15 years received rFVIIa for 14 different hemorrhagic events. There was no significant difference in blood loss or blood product transfusion associated with rFVIIa administration. There was one patient-related and one ECMO-related complication temporally associated with rFVIIa administration: decreased ECMO circuit oxygenator efficiency and the development of an intra-gastric clot requiring surgical evacuation.
These data suggest limited efficacy for rFVIIa use for refractory hemorrhage in pediatric patients on ECMO support. There were two non-catastrophic complications temporally associated with its administration.
During cardiopulmonary bypass (CPB), perfusion at tepid temperatures (33-35°C) is recommended to avoid high temperature cerebral hyperthermia during and after the operation. However, the ideal temperature for uncomplicated adult cardiac surgery is an unsettled question. Typically, the heat exchanger maximum temperature is monitored between 40-42°C to prevent denaturation of plasma proteins, but studies have not been performed to make these conclusions. Therefore, our hypothesis was to determine the temperature in which blood plasma protein degradation occurs after 2 hours of heat exposure. As a result, blood plasma proteins were exposed to heat in the 37-50°C range for 2 hours. Plasma protein samples were loaded onto an 8-12% gradient gel for SDS-PAGE and low molecular weight plasma protein degradation was detected with graded heat exposure. Protein degradation was first detected between 43-45°C of heat exposure. This study supports the practice of monitoring the heat exchanger between 40-42°C to prevent denaturation of plasma proteins.
To review our experience of extracorporeal membrane oxygenation in airway management during tracheal surgery.
A retrospective, observational study was conducted to evaluate the effectiveness of extracorporeal membrane oxygenation in tracheal surgery in Shanghai Chest Hospital between 2008 and 2012.
In all 91 tracheal surgeries, 7 high-risk cases used extracorporeal membrane oxygenation. The duration of extracorporeal membrane oxygenation support ranged from 10 min to 31 min. All extracorporeal membrane oxygenation patients underwent surgical procedures safely and there was no hospital mortality.
Although various advanced anesthesia techniques can ensure a safe airway in tracheal surgery in most cases, extracorporeal circulation plays an important role in high-risk cases.
Sickle cell anemia and thalassemia are hemoglobinopathies rarely encountered in the United States. Compounded with congenital heart disease, patients with sickle cell disease (SCD) requiring cardiopulmonary bypass and open-heart surgery represent the proverbial "needle in the haystack". As such, there is some trepidation on the part of clinicians when these patients present for complex cardiac surgery.
SCD is an autosomal, recessive condition that results from a single nucleotide polymorphism in the β-globin gene. Hemoglobin SS molecules (HgbSS) with this point mutation can polymerize under the right conditions, stiffening the erythrocyte membrane and distorting the cellular structure to the characteristic sickle shape. This shape change alters cellular transit through the microvasculature. As a result, circumstances such as hypoxia, hypothermia, acidosis or diminished blood flow can lead to aggregation, vascular occlusion and thrombosis. Chronically, SCD can give rise to multiorgan damage secondary to hemolysis and vascular obstruction.
This review and case study details an 11-year-old African-American male with known SCD who presented to the cardiothoracic surgical service with congenital heart disease consisting of an anomalous, intramural right coronary artery arising from the left coronary sinus for surgical consultation and subsequent surgical correction. This case report will include a review of the pathophysiology and current literature regarding preoperative, intraoperative and postoperative management of SCD patients.
The circle of Willis (CoW) is a key asset in brain performance as it supports adequate blood supply to the brain. The lumped method (electrical equivalent circuits) is a useful model to simulate the process of the human cardiovascular system. In this study, the whole cardiovascular system is modeled, using an equivalent electrical circuit to investigate an aneurysm in an artery. The cerebrovascular system consists of 29 compartments, which includes the CoW. Each vessel is modeled by a resistor, a capacitor and an inductor. Using MATLAB Simulink, the left and right ventricles are modeled by controlled voltage sources and diodes. The effects of the left internal carotid artery aneurysm (Fusiform) on the pressure of the efferent arteries in the circle of Willis are studied. The modeling results are entirely in agreement with the available clinical observations. The results of the present study may have clinical implications for modeling different cardiovascular diseases, such as arterial stiffness and atherosclerosis.
Extracorporeal membrane oxygenation (ECMO) is increasingly used in ARDS patients with hypoxemia and/or severe hypercapnia refractory to conventional treatment strategies. However, it is associated with severe intracranial complications, e.g. ischemic or hemorrhagic stroke. The arterial carbon dioxide partial pressure (PaCO2) is one of the main determinants influencing cerebral blood flow and oxygenation. Since CO2 removal is highly effective during ECMO, reduction of CO2 may lead to alterations in cerebral perfusion. We report on the variations of cerebral oxygenation during the initiation period of ECMO treatment in a patient with hypercapnic ARDS, which may partly explain the findings of ischemic and/or hemorrhagic complications in conjunction with ECMO.
Sudden cardiac arrest is one of the leading causes of death. Conventional CPR techniques after cardiac arrest provide circulation with reduced and varying blood flow and pressure. We hypothesize that using pressure- and flow-controlled reperfusion of the whole body improves neurological recovery and survival after 15 min of normothermic cardiac arrest.
Pigs were randomized in two experimental groups and exposed to 15 min of ventricular fibrillation (VF). After this period, the animals in the control group received conventional CPR with open chest compression (n=6), while circulation in the treatment group (n=6) was established with an extracorporeal life support system (ECLS) to control blood pressure and flow. Follow-up included the assessment of neurological recovery and magnetic resonance imaging (MRI) for up to 7 days.
Five of the six animals in the control group died, one animal was resuscitated successfully. In the treatment group, 1/6 could not be separated from ECLS. Five out of the six pigs survived and were transferred to the animal facility. One animal was unable to walk and had to be sacrificed 30 hours after ECLS. The remaining 4 animals of the treatment group and the surviving pig from the control group showed complete neurological recovery. Brain MRI revealed no pathological changes.
We were able to demonstrate a significant improvement in survival after 15 minutes of normothermic cardiac arrest. These results support our hypothesis that using an ECLS for pressure- and flow-controlled circulation after circulatory arrest is superior to conventional CPR.
The aim of study was to assess the effects of an intraoperative external head-cooling technique on cognitive dysfunction in the early postoperative period (at the 10th day) in patients after coronary artery bypass graft (CABG) surgery. Patients in Group H (n=25) were cooled with CPB and the intraoperative, external head-cooling technique, patients in Group C (n=25) were cooled only with cardiopulmonary bypass (CPB) to achieve mild hypothermia (33 – 34°C). Cognitive function was analyzed before the operation and after the surgery using the Mini Mental State Examination (MMSE), the Modified Visual Reproduction Test from the Wechsler Memory Scale, Trail Making (A/B), WAIS - Digit Span (WDS) and WAIS Digit Symbol Substitution Test (WDSST). The incidence of cognitive impairment at the 10th day after the surgery was 36% (n=9) in Group H and 64% (n=16) in Group C (p=0.048). The temperature during the aortic cross-clamp period was associated with a lower rate of cognitive dysfunction (p=0.05, r2=0.09). The intraoperative, external head-cooling technique during the aortic cross-clamp period has a neuroprotective effect and leads to less short-term cognitive function impairment after CABG surgery.
Clinician rounding on bedside extracorporeal membrane oxygenation (ECMO) is a common coverage practice at many centers across the USA. Occasionally, clinical issues or concerns may go unnoticed for a considerable period of time during the intervals of clinician rounds. We report a case utilizing the LiveVue (Spectrum Medical, Fort Mill, SC) remote monitoring for care of a patient on ECMO.
A patient was placed on veno-arterial (VA) ECMO in our intensive care unit, using a Rotaflow centrifugal pump and a Quadrox D polymethylpentene (PMP) fiber oxygenator (both Maquet, Fairfield, NJ). Following ECMO initiation and stabilization, a two-hour rounding schedule was established for the covering perfusionist. On day two, shortly after the perfusionist had rounded, the ECMO flow began fluctuating between 0.1 and 2.1 L/min. A compliance alert (i.e. red flashing notification) was recognized by the perfusion team on a large screen monitor installed in the perfusion pump room. Immediate response from the perfusion team identified venous inflow obstruction due to cannula malposition. The pump revolutions per minute (rpm) and, thus, the resulting flow were temporarily reduced to prevent vessel intimal damage and the surgical team was summoned to reposition the venous cannula. Later in that ECMO run, a steady rise in pre-oxygenator pressure was noted by the perfusionist. This increasingly concerning event was able to be trended and monitored with the LiveVue from a remote location. After a few hours, a compliance alert was noticed again on the LiveVue screen in the pump room. The pre-oxygenator pressure increased by 150 mmHg and the circuit flow decreased by half. Again, the perfusionist response was immediate and an oxygenator change-out ensued. Once more, a potentially dangerous clinical scenario was avoided with continuous critical parameter remote monitoring using the LiveVue system.
Extracorporeal membrane oxygenation (ECMO) is an extracorporeal technique of providing both cardiac and respiratory support to patients whose heart and lungs are so severely diseased or damaged that they can no longer serve their function. Neonatal and pediatric ECMO was accepted as practice in the early 1990s and according to the Extracorporeal Life Support Organization, ELSO; of the >50,000 patients registered, 73% have survived extracorporeal life support (ECLS). It is not uncommon to find initial cannulation of a patient receiving ECMO performed by a surgeon and then the maintenance of the patient being left in the hands of various others deemed as the "ECMO Specialists". The specialist has a broad base of professionals, including: nurses, respiratory therapists, perfusionists and physicians. Each institution, having its own unique training for these individuals, has provided a milieu for education, but does not share an established standard of care. From 2009, after the surge of the H1N1 epidemic, adult ECMO has been increasing; n=53 in 2010 to n=110 in 2012 at our institution. The perfusionist has been the "specialist" for ECMO at our institution since the early 1990s and remained at bedside during ECMO. We have now developed a safe circuit and fiscally responsible staffing model that utilizes a perfusionist and a telemetry-based electronic record keeper, permitting the perfusionist to leave the bedside and interact with the circuit when necessary. This has permitted an expansive growth of ECMO in our intensive care units at our facility incorporating a multidisciplinary collaboration system wide.
Mechanical circulatory support emerged for the pediatric population in the late 1980s as a bridge to cardiac transplantation. The Total Artificial Heart (TAH-t) (SynCardia Systems Inc., Tuscon, AZ) has been approved for compassionate use by the Food and Drug Administration for patients with end-stage biventricular heart failure as a bridge to heart transplantation since 1985 and has had FDA approval since 2004. However, of the 1,061 patients placed on the TAH-t, only 21 (2%) were under the age 18. SynCardia Systems, Inc. recommends a minimum patient body surface area (BSA) of 1.7 m2, thus, limiting pediatric application of this device.
This unique case report shares this pediatric institution’s first experience with the TAH-t. A 14-year-old male was admitted with dilated cardiomyopathy and severe biventricular heart failure. The patient rapidly decompensated, requiring extracorporeal life support. An echocardiogram revealed severe biventricular dysfunction and diffuse clot formation in the left ventricle and outflow tract. The decision was made to transition to biventricular assist device. The biventricular failure and clot formation helped guide the team to the TAH-t, in spite of a BSA (1.5 m2) below the recommendation of 1.7m2. A computed tomography (CT) scan of the thorax, in conjunction with a novel three-dimensional (3D) modeling system and team, assisted in determining appropriate fit. Chest CT and 3D modeling following implantation were utilized to determine all major vascular structures were unobstructed and the bronchi were open. The virtual 3D model confirmed appropriate device fit with no evidence of compression to the left pulmonary veins. The postoperative course was complicated by a left lung opacification. The left lung anomalies proved to be atelectasis and improved with aggressive recruitment maneuvers. The patient was supported for 11 days prior to transplantation. Chest CT and 3D modeling were crucial in assessing whether the device would fit, as well as postoperative complications in this smaller pediatric patient.
Successful cardiac surgery is highly dependent upon effective and efficient teamwork. Practical training and development will further enhance the team ability to react to a series of low-frequency occurring adverse events during cardiopulmonary bypass (CPB). One of our specialized educational programs focuses on training the whole team. This training is based on an original animal simulation model. The objective of this pilot study was to assess our method of training and learning in an attempt to optimize and improve team management and functioning.
Four members of the same cardiac surgery team joined our program. They performed a common procedure, with a cardiopulmonary bypass (CPB) circuit set up to produce several adverse incidents. Events management was analyzed and debriefed in technical and non-technical perspectives.
Management of the adverse events was significantly improved. Discussion and debriefing time was fundamental in identifying the most appropriate management for each event. Rescue procedures were assimilated and team training was found to be effective, with the time reduced by up to 50% for 3 events and by up to 70% for air embolism.
Our pilot program is an innovative, low-cost tool for the improvement of the management of adverse events occurring during CPB. It includes the different components of surgical education and training. Such an educational tool might be relevant for training. To confirm those encouraging results, it should be assessed in a larger surgical team panel. Further investigations are required for assessing efficiency in real conditions.
A 50-year-old man was admitted to the intensive care unit with respiratory failure and shock after suffering a massive overdose of amlodipine, lisinopril and hydrochlorothiazide. Despite mechanical ventilation, vasopressors, calcium gluconate, hyperinsulinemia-euglycemia therapy, methylene blue and intravenous fat emulsion, the patient’s respiratory and hemodynamic status deteriorated. Venoarterial extracorporeal membrane oxygenation (ECMO) was initiated to provide cardiopulmonary support in the setting of profound respiratory failure and refractory shock. The patient was placed on ECMO 19 hours after arrival to the hospital, after which vasopressor and ventilatory requirements decreased significantly. The patient was decannulated from ECMO after 8 days and was discharged home after a 56-day hospitalization. Early institution of ECMO should be considered for the management of respiratory failure and refractory shock in the setting of calcium channel blocker overdose when medical therapies are insufficient.
During continuous venoveno haemofiltration (CVVH), extracorporeal drug clearance is dependant on blood flow, ultrafiltration rate, albumin binding, and the drug’s molecular weight and volume of distribution. Drug doses are adjusted assuming reduced drug clearance by the renal system and CVVH. High volume haemofiltration, pre-dilution and different filter membranes can greatly alter drug clearance. Consequently, assessing the adequacy of cephalosporin dosing during CVVH is complex; under- or overdosing may occur. We studied the pharmacokinetic properties of ceftriaxone during CVVH in vitro. Renaflow filters were used to model 6, 20 and 50 kg patients. Each circuit and reservoir was prepared with a known volume of Hartmann’s solution, human albumin solution 4.5% or blood. Pump speed and exchange rate were standardised for weight. Haemosol BO was used as the replacement fluid with 70% pre-dilution. Following paired sampling from the circuit and ultrafiltrate fluid, ceftriaxone was injected into the circuit. Paired samples were taken up to 720 minutes. Ceftraxione concentrations were determined using high performance liquid chromatography (HPLC). Maximum circuit concentrations (Cmax) at 2 minutes for albumin were 3.5, 2.65 and 4.85 mg/l, for blood were 4.5, 6.5 and 5.55 mg/l and for Hartmann’s were 1.65, 2.95 and 3.65 mg/l for 6kg, 20kg and 50kg models. The sieving coefficients (Sc) from blood (ratio of mean concentrations in the ultrafiltrate/circuits samples) were 0.31 and 0.51 with T1/2 (the half life) 62 and 20 minutes in the 6kg and the 20kg circuits, respectively. The data suggest in an in vitro model of ceftriaxone is rapidly cleared during CVVH. Albumin circuits had the lowest Sc and longest terminal T1/2, reflecting protein binding of the drug and suggest ceftriaxone clearance may be more rapid in hypoalbuminaemic patients. The Cmax was lower in the Hartmann circuits, possibly reflecting precipitation of the drug with calcium in this solution.
We retrospectively performed a comparative analysis of temperature measurement sites during surgical repair of the thoracic aorta.
Between January 2004 and May 2006, 22 patients (mean age: 63±12 years) underwent operations on the thoracic aorta with arterial cannulation of the aortic arch concavity and selective antegrade cerebral perfusion (ACP) during deep hypothermic circulatory arrest (HCA). Indications for surgical intervention were acute type A dissection in 14 (64%) patients, degenerative aneurysm in 6 (27%), aortic infiltration of thymic carcinoma in 1 (4.5%) and intra-aortic stent refixation in 1 (4.5%). Rectal, tympanic and bladder temperatures were evaluated to identify the best reference to arterial blood temperature during HCA and ACP.
There were no operative deaths and the 30-day mortality rate was 13% (three patients). Permanent neurological deficits were not observed and transient changes occurred in two patients (9%). During re-warming, there was strong correlation between tympanic and arterial blood temperatures (r= 0.9541, p<0.001), in contrast to the rectal and bladder temperature (r=0.7654, p= n.s; r=0.7939, p= n.s., respectively).
We conclude that tympanic temperature measurements correlate with arterial blood temperature monitoring during aortic surgery with HCA and ACP and, therefore, should replace bladder and rectal measurements.
Legionella is a common cause of community-acquired pneumonia (CAP) and is second only to Pneumococcal pneumonia as a cause of severe CAP that requires treatment in an intensive care unit. We report a case series of patients with severe Legionella pneumonia who developed the acute respiratory distress syndrome (ARDS), failed to improve with mechanical ventilation alone and required extracorporeal life support (ECLS).
We performed a retrospective study of all patients treated with ECLS at our institution for severe ARDS as a result of Legionella pneumonia from 1994 to 2006.
A total of twelve patients with a diagnosis of Legionella pneumonia were treated with veno-venous (VV) ECLS over this time period. Nine of these twelve (75%) were successfully treated and weaned off ECLS and 8 patients (67%) survived to hospital discharge. Two (13%) died of multisystem organ failure, one patient (8%) died from global hypoxic encephalopathy and one (8%) was weaned from ECLS, but ultimately died of liver failure. Renal failure requiring some form of continuous dialysis occurred in seven patients (58%) and the survival for this sub-set of patients was 43%.
Extracorporeal life support for severe ARDS associated with Legionella pneumonia is an effective treatment option when mechanical ventilation fails, especially when introduced early in the course.
The deep hypothermic circulatory arrest (DHCA) technique has been used in aortic arch and isthmus hypoplasia for many years. However, with the demonstration of the deleterious effects of prolonged DHCA, selective cerebral perfusion (SCP) has started to be used in aortic arch repair. For SCP, perfusion via the innominate artery route is generally preferred (either direct innominate artery cannulation or re-routing of the cannula in the aorta is used). Herein, we describe our technique and the result of arch reconstruction in combination with selective cerebral and myocardial perfusion (SCMP) and short-term total circulatory arrest (TCA) (5-10 min) through ascending aortic cannulation.
Thirty-seven cases with aortic arch and isthmus hypoplasia accompanying cardiac defects were operated on with SCMP and short TCA in Baskent University Istanbul Research and Training Hospital between January 2007 and Sep 2012. There were 17 cases with ventricular septal defect (VSD)-coarctation with aortic arch hypoplasia (CoAAH), 4 cases of transposition of the great arteries-VSD-CoAAH, 4 cases of Taussing Bing Anomaly-CoAAH, 2 cases complete atrioventricular canal defect-CoAAH, 3 cases single ventricle-CoAAH, 3 cases of type A interruption-VSD, 2 subvalvular aortic stenosis-CoAAH and 2 cases of isolated CoAAH. The aorta was cannulated in the middle of the ascending aorta in all cases. The cross-clamp was applied to the aortic arch distal to either the innominate artery or the left carotid artery. In addition, a side-biting clamp was applied to the descending aorta. The aorta between these two clamps was reconstructed with gluteraldehyde-treated autogeneous pericardium, using SCMP. The proximal arch and distal ascending aorta reconstructions were carried out under short TCA.
The mean age of the patients was 2.5±2 months. The mean cardiopulmonary bypass and cross-clamp times were 144±58 and 43±27 minutes, respectively. The mean SCMP and descending aorta ischemia times were 22.6±4.8 and 27±6.3 minutes, respectively. Mean TCA time was 7.6±2.1 minutes (min: 4, max 10 min). The mean in-hospital stay time was 8.6±1.9 days. None of the cases operated with this technique had neurological defects. The mortality rate was 2.7% (1 patient).
SCMP with aortic cannulation and short TCA (under 10 minutes) in aortic reconstruction is safe and practical in this high-risk patient group.
An effective animal model was needed for research on the pathophysiology of cardiopulmonary bypass (CPB). Rat models were considered suitable for research into CPB, recently. The aim of the article is to establish a simple and safe CPB model without blood priming in rats, containing the advantages of controlling temperature precisely, being similar to the clinical process and laying the foundation for the further study of a deep hypothermic circulatory arrest (DHCA) model.
Ten Sprague-Dawley rats, divided into a CPB group (n=7) and a sham group (n=3), received sevoflurane inhalation anesthesia and were maintained in an anesthesia state by intubation. The entire CPB circuit consisted of a reservoir, a membrane oxygenator, a roller pump, a heat exchanger and a heat cooler, all of which were connected via silicon tubes. The volume of the priming solution, composed of 6% HES130/0.4 and 125 IU heparin, was less than 12 ml. In the CPB group, a 22G catheter was placed in the left femoral artery for monitoring arterial blood pressure, a 20G catheter was placed in a tail artery for arterial inflow and a homemade, multiorificed catheter was inserted into a right jugular vein for venous drainage. After 90 minutes, the CPB process was terminated when vital signs were stable. In the sham group, the same surgical process was conducted except for the venous drainage. Post-oxygenator blood gas and hemodynamic parameters were measured at each time point before CPB, during CPB and after CPB.
All CPB processes were successfully achieved. Blood gas analysis and hemodynamic parameters of each time point were in accordance with normal ranges. The vital signs of all rats were stable.
The establishment of CPB without blood priming in rats can be achieved successfully. The rat model could be used to study short-term or long-term organ injury mechanisms caused by CPB. Furthermore, on the basis of the precise control of temperature and the depth of anesthesia, the DHCA model in rats could be developed further to study pathophysiological changes of neurological and other organ functions in the future.
Extracorporeal carbon dioxide removal (ECCO2R) may be indicated for refractory status asthmaticus when severe dynamic hyperinflation or life-threatening respiratory acidosis persists despite optimal medical and ventilator management. Most prior reports describe the application of ECCO2R to rapid-onset asthma exacerbation, requiring a short duration of extracorporeal support. We report two patients with refractory status asthmaticus managed with ECCO2R, emphasizing the use of modern extracorporeal technology, cannulation technique and management protocols, which may improve the risk-to-benefit profile of this strategy. This report highlights the challenges in managing patients with distinct asthma exacerbation phenotypes. The potential need for prolonged device support may alter provider expectations and offers a new perspective of the role of ECCO2R for status asthmaticus.
The case report describes a novel technique of pre-emptive plasma "reconstitution" prior to disengagement from cardiopulmonary bypass (CPB) to minimize RV volume overload. The concomitant use of hemoconcentration facilitates volume and blood product management in cardiac transplant after previous left ventricular assist device implant surgery.
Extracorporeal membrane oxygenation (ECMO) provides temporary life-saving support for patients with severe cardiac failure, but is associated with significant morbidity and mortality. While ECMO enables oxygen delivery (DO2), little is known about oxygen consumption (VO2), largely due to technical difficulties. We aimed to introduce the adaptation of respiratory mass spectrometry to measure VO2 in patients during ECMO and to use this unique model to determine the pathological dependency of VO2 on DO2 in humans.
Respiratory mass spectrometry remains the ‘state-of-the-art’ method, allowing the highly sensitive and rapid measurement of VO2 in critically ill patients. The principle and design of the respiratory mass spectrometer are described, together with the setting up of this machine with the ECMO oxygenator and the native lungs of the patients. In two patients with severe dilated cardiomyopathy and little cardiac contraction, the decrease in pump flow and, hence, DO2 by 20% was associated with a decrease in VO2 by 5% and 8%, respectively, whereas the increase in pump flow was not associated with any significant change in VO2.
The direct measurement of VO2 by respiratory mass spectrometry in ECMO patients provides a unique technique for clinical research on the metabolism and VO2-DO2 relationship in this special group of critically ill patients. Our pilot study is the first to demonstrate a pathological dependency of VO2 on DO2 in humans. Further studies are warranted with this technique to examine the changes and the factors affecting systemic oxygen transport in patients during ECMO.
State-of-the-art cardiopulmonary resuscitation (CPR) restores circulation with inconsistent blood-flow and pressure. Extracorporeal life support (ECLS) following CPR opens the opportunity for "controlled reperfusion". In animal experiments investigating CPR with ECLS, systemic anticoagulation before induced cardiac arrest is normal, but a major point of dispute, since preliminary heparinization in patients undergoing unwitnessed cardiac arrest is impossible. In this study, we investigated options for ECLS after an experimental 15 minutes normothermic cardiac arrest, without preceding anticoagulation, in pigs. Neurological recovery was assessed by a scoring system, electroencephalography and brain magnetic resonance imaging. Additionally, brain histology was performed on day seven after cardiac arrest. We demonstrated that preliminary heparin administration was not necessary for survival or neurological recovery in this setting. Heparin flushing of the cannulae seemed sufficient to avoid thrombus formation. These findings may ease the way to using ECLS in patients with sudden cardiac arrest.
A low haematocrit during cardiopulmonary bypass (CPB) is associated with adverse outcomes and often results in homologous blood transfusions. Oxygenators with improved venous reservoir designs aid in reducing the priming volume. Recently, we changed our small adult oxygenator model from the D905 EOS oxygenator (Dideco, Mirandola, Italy) to the Capiox FX1540 (Terumo Corporation, Tokyo, Japan). We conducted a retrospective study of 42 patents to evaluate the impact of the Capiox FX 1540 on blood transfusion requirements in small patients (body surface area (BSA) up to 1.8 m2). The D905 EOS group had a lower minimum intraoperative haematocrit than the FX1540 group (20 ± 3 v 22 ± 4, p = 0.029) with 73% of the patients receiving intraoperative blood transfusions compared with 30% in the FX 1540 group (p = 0.012). Patients in the D905 EOS group received one blood transfusion more during CPB than the FX 1540 patients (p = 0.002). The haematocrits at the end of CPB and in the early postoperative period were identical in both groups. The postoperative ventilation time, length of stay in the intensive care unit and postoperative chest drain bleeding were similar in both groups. In conclusion, the Capiox FX1540 was effective in reducing intraoperative packed red cell transfusions.
Synthetic starches have been positioned as an equivalent substitute for human albumin in extracorporeal prime, with both providing osmotic and oncotic pressure. Another effect of albumin is its ability to coat the synthetic surfaces of an extracorporeal circuit with a biopassivating protein monolayer. Whether this protein biopassivation has any benefit to the patient, assessed by platelet count, platelet function and 24-hour bleeding rate, is considered.
Patients presenting for coronary artery bypass at a Canadian tertiary care hospital were randomized into two groups until a final study size of 20 patients was obtained. The Study Group received 2.5 g of human albumin in the extracorporeal prime and the Control Group remained protein free. Both groups included Voluven 6% as a synthetic starch. Blood samples were obtained at three intervals; Pre-bypass, During bypass (30 minutes after initiation of bypass), and Post-bypass. These samples were assayed for platelet function, platelet count and hemoglobin. Chest tube drainage over a 24-hour period was monitored.
Platelet count was significantly higher in the During sample in the Study Group (196 ± 56.5 x 109/ml versus 160 ± 18.5 x 109/ml, p<0.05), however, this difference was no longer significant with the Post-bypass sample (135 ±36.0 x 109/mL versus 127 ±19 x 109/mL). Platelet function assays (PFA) showed no significant differences. Chest tube drainage after 24 hours was significantly lower in the Study Group (586 ± 131.8 ml/24 h versus 741 ± 272.5 ml/24 h, p<0.05).
Human albumin can passivate the synthetic surfaces of the extracorporeal circuit, which is supported by observations of preserved platelet count and reduced chest tube drainage. Although some statistically significant benefits were observed, the practical benefits of passivating an extracorporeal circuit with human albumin may be minimal.
Retrograde autologous priming (RAP) of the cardiopulmonary bypass (CPB) circuit could reduce the degree of haemodilution associated with priming with acellular solutions. However, there is no strong evidence to prove that the practice of RAP reduced intraoperative packed red cell (PRC) or blood product transfusion.
To evaluate the effect of RAP on intraoperative PRC usage in coronary artery bypass grafting (CABG).
This study is a prospective, observational study on patients who underwent first-time, isolated CABG using CPB between April 2012 and July 2012. Two groups of patients were identified: 1. Non-RAP group (n=128) and 2. RAP group (n=73). The primary outcome for the study was the amount of PRC and blood product usage between the induction of anaesthesia and the cessation of CPB.
Use of PRC and blood products in the operating room was comparable in both groups. Univariate logistic regression showed that RAP was not an independent predictor of PRC or blood product transfusion (p=0.43). Multivariate logistic regression showed that CPB time, preoperative haemoglobin (Hb) levels and creatinine clearance were independent predictors of blood product transfusion.
Practising RAP with mean volumes of 300 ml does not necessarily reduce PRC and other blood product transfusion requirements during CABG. In our practice, RAP was performed, aiming at displacing CPB circuit prime volume with which the perfusionist felt comfortable and dictated by haemodynamic parameters prior to commencing CPB. We presume this is the case in many units around the world. This practice, in our opinion, is not enough to achieve the benefits of RAP, if any, in the form of a reduction of packed red cell transfusion requirements. The true advantages of RAP in cardiac surgery need to be studied in a prospective, randomized, controlled trial.
The choice of the prime solution for cardiopulmonary bypass can play an important role in limiting the effect on blood coagulation, but it is still unclear what the effect of colloids on blood coagulation is. The aim of this study was to investigate the effect of synthetic colloids on blood loss and blood coagulation in patients after on-pump coronary artery bypass graft (CABG) procedures.
Sixty elective, on-pump CABG patients were randomly assigned to receive the prime solutions lactated Ringer’s solution combined with hydroxyethyl starch 130/0.4 (HES, 6% Volulyte, Fresenius Kabi Nederland BV, Zeist, the Netherlands) (HES group) or gelatin (Gelofusin®, B Braun Melsung AG, Melsungen, Germany) (Gelo group). Blood loss was assessed using post-operative chest tube output; secondary endpoints were number of blood component transfusions, routine coagulation test values and rotation thromboelastometry values (Rotem® delta, Pentapharm GmbH, Munich, Germany).
Total post-operative chest tube output was 500 ± 420 ml in the HES group versus 465 ± 390 ml in the Gelo group (p = 0.48). No significant differences were observed in any of the routine coagulation tests values, thromboelastometry parameters or number of blood component transfusions between the groups.
In this randomized, controlled trial of adults after on-pump CABG procedures, there was no significant difference in blood loss or blood coagulation between the HES group and the Gelo group.
Anemia is an independent predictor of acute kidney injury (AKI) following cardiopulmonary bypass (CPB), possibly due to inadequate renal oxygen delivery. The objective of this study was to investigate the effects of CPB and anemia on tissue oxygen tension (pO2) and blood flow in the renal cortex and medulla.
Rats (n=6/group) underwent 1hr of normothermic cardiopulmonary bypass (CPB), with target hemoglobin concentrations (Hb) of 10g/dL (CPB) or 6.5g/dL (anemia-CPB). Renal blood flow (RBF) and tissue PO2 were measured before, during and after 1hr of CPB. To confirm the observed differences in renal cortical and medullary PO2, HIF-1α (ODD) luciferase mice were exposed to 8% O2 (hypoxia) and HIF-1α dependent luminescence was measured in the renal cortex and medulla (n=5).
Renal tissue PO2 values decreased initially and returned towards baseline, however, values at the end of CPB. Anemia-CPB resulted in a significant increase in both renal cortical and medullary blood flow, PO2 remained significantly reduced throughout anemia-CPB. Renal medullary HIF-1α-dependent luminescence confirmed a greater degree of hypoxia in the renal medulla.
During CPB, renal O2 delivery was transiently jeopardized, but recovered after 1hr. Anemia-CPB resulted in a dramatic and sustained reduction in renal cortical and medullary PO2, which suggests an increased risk of renal hypoxic injury with anemia.
The clear difference in the degree of hypoxia in the renal cortex and medulla may be useful in understanding the progress of medullary hypoxia during CPB with anemia and the potential development of AKI. Further studies should aim at identifying early markers of medullary hypoxia and potential agents that may decrease the work and O2 consumption in the renal medulla to reduce the risk of hypoxic damage during CPB and anemia.
Small-caliber expanded polytetrafluoroethylene (ePTFE) grafts cannot be used widely in the clinical situation because of early thrombosis and occlusion. This unsolved and under-recognized problem warrants further investigation.
Grafts of uncoated ePTFE (n = 6) and anti-CD34-coated ePTFE (n = 6) were implanted unilaterally into the carotid artery in 12 domestic pigs. Ultrasonography was used to test the proximal and distal anastomotic stoma morphology, diameters and blood velocities. A thrombosis instrument was used to examine the blood coagulation state. After seven days, the pigs were sacrificed and the implanted grafts were excised for general and histological analysis. Computational fluid dynamics was used to investigate the blood flow fields of the implanted grafts and to calculate parameters that might be indicative of thrombosis.
Thrombosis was detected in 10 of 12 (83.3%) implanted ePTFE grafts, 5 in uncoated grafts and 5 in anti-CD34-coated grafts. Endothelial cell coverage was observed in both uncoated and anti-CD34-coated grafts. No obvious abnormalities in anastomotic stoma or blood coagulation state were observed. Computer-based local hemodynamic simulation showed the low flexibility of synthetic ePTFE grafts caused obvious coarctation. Local wall pressure, velocity and wall shear stress were much higher than in the contralateral normal vessel.
The patency of small-caliber ePTFE grafts for clinical use is impaired by early thrombosis due to mixed causes. Local hemodynamic disturbance was the most powerful predictor of early thrombosis. Decreasing local hemodynamic disturbance, improving the quality of anastomotic stoma, selecting reasonable anticoagulation strategies and promoting rapid endothelialization may increase the long-term patency of small-caliber vascular grafts.
Myocardial protection during cardiac surgery can be accomplished by different cardioplegic solutions. The aim of this study was to assess myocardial damage after heart valve surgery performed with myocardial protection of a single dose of Celsior cardioplegia or with repeated cold blood cardioplegia. After the stratification of 139 valvular patients by means of matching according to cross-clamp and cardiopulmonary bypass time, 32 patients were retained for comparison (16 patients received Celsior and 16 patients received cold blood cardioplegia). Creatine kinase-MB (CK-MB) and cardiac troponin I (cTnI) release were evaluated until six days after the operation. Pre-operative characteristics were similar in both groups. In the Celsior group, CK-MB and cTnI values were significantly higher from the first up to the sixth post-operative day. Peak cTnI values were 19.4±13.4 and 9.7±7 ng/mL (p=0.01) in the Celsior and the Cold Blood group, respectively. Peak CK-MB values were 79.6±58.8 and 45.9±20.6 U/L (p=0.07) in the Celsior and the Cold Blood group, respectively. Cold blood cardioplegia reduces perioperative myocardial damage compared to the Celsior solution in elective cardiac valve operations.
Using a rodent model of middle cerebral artery occlusion (MCAO), we investigated the effect of remote ischemic preconditioning (RIPC) on spatial learning and memory ability after focal cerebral ischemia-reperfusion (I/R).
Thirty-six male Sprague-Dawley rats were randomly allocated into 3 groups (n=12, each): sham group, rats were subjected to sham operations without MCAO and RIPC; I/R group, rats were subjected to 1h of MCAO followed by 3 days of reperfusion; I/R+RIPC group, rats were subjected to RIPC and 1h MCAO followed by 3 days of reperfusion. The spatial learning and memory ability of the rats was measured by the Morris water maze task.The activity of cholineacetyltransferase (ChAT) in the hippocampus CA1 region was observed by an immunohistochemistry method.
In the Morris water maze task, MCAO elicited a significant decrease of the ability of spatial learning and memory in contrast to the sham group. Meanwhile, RIPC induced a significantly shorter prolongation of the escape latency (p<0.05); greater number passing through the platform (p<0.05) and less time for exploring the target quadrant (p<0.05) as compared with values for the I/R group. Furthermore, the number of ChAT positive cells in the CA1 region in the I/R+RIPC group was strikingly more than those of the I/R group (p<0.05).
RIPC could improve the ability of spatial learning and memory after focal cerebral ischemia-reperfusion probably due to its protection of the cholinergic neurons in the hippocampal CA1 region.
Monitoring the blood pump and the oxygen gas flow meter are important maneuvers at the initiation of cardiopulmonary bypass (CPB). We present a novel system, designed to improve safety in the heart-lung machine by linking the control of blood flow and the oxygen gas flow meter. This system uses a mass flow controller to provide and control oxygen flow based on the ventilation-perfusion (V/Q) ratio, using the electronic signal of the blood flow. We tested the system, in vitro and in vivo, and examined the resulting level of blood oxygenation. When extracorporeal circulation was initiated, the oxygen flow was instantly linked to the circulating blood flow, providing an adequate V/Q ratio; the partial pressure of oxygen in the blood was maintained at a normal level. Although we have yet to confirm the safety of this system in clinical trials, the new safety assist device can automatically supply oxygen to the oxygenator at the beginning of CPB.
Previous reports have described the use of extracorporeal membrane oxygenation (ECMO) for acute chest syndrome of sickle cell disease (SCD). However, there have been no reports of venoarterial (VA) ECMO for cardiac dysfunction in patients with SCD. We describe a patient with SCD and life-threatening cardiogenic shock who was successfully treated with VA ECMO. Furthermore, SCD patients have unique comorbidities that warrant particular consideration when utilizing ECMO. We discuss these considerations and review the documented experience with ECMO for pediatric SCD patients from the Extracorporeal Life Support Organization (ELSO) registry. From 1990 until 2012, 52% of the 65 pediatric patients with SCD placed on ECMO survived, with 85% of those receiving venovenous (VV) ECMO surviving and 43% of those receiving VA ECMO surviving. However, significant complications, such as bleeding, neurological injury and kidney injury, also occurred with both VV and VA ECMO. Ten percent of SCD patients receiving VA ECMO experienced either a cerebral infarct or hemorrhage; our patient suffered a cerebrovascular accident while on ECMO, though she survived with good neurologic outcome. To our knowledge, this is the first report of a pediatric patient with SCD and cardiogenic shock successfully managed with VA ECMO. In conjunction with the ELSO registry review, this case report suggests that, while VA ECMO can be successfully used in patients with SCD and severe cardiovascular dysfunction, clinicians should also be aware of the potential for serious complications in this high-risk population.
Biocompatible circuits (BCC) are intended to decrease the activation of blood to the artificial cardiopulmonary bypass (CPB) surface. Typically, the coatings are made of various inert substances or molecules physiologically similar to endothelium.
Thromboelastography (TEG) graphically represents clot formation, strength of clotting and fibrinolysis. TEG analysis was undertaken to determine if coagulation could be preserved by the BCC.
Five different BCC were studied in clinical applications. These five coated circuits were then compared to an identical circuit where only the oxygenator was coated. A pre- and post-bypass TEG was done for comparison. Six well-studied parameters of TEG analysis were compared: R time, Angle, K, Maximum Amplitude (MA), LY30% and Clot Index (CI). Postoperative bleeding and transfusion requirements were compared to TEG results for comparison.
All postoperative TEG results were significantly different from preoperative parameters except LY30%. No BCC circuit was able to prevent the significant disruption of the observed TEG coagulation parameters R, K, angle, MA and CI. Of note, the postoperative TEG parameters resulting from the Control and Trillium™ groups – which had the same type of oxygenator – were practically identical. The oxygenator, which represents the largest surface area in the CPB circuit, is the single most important factor influencing coagulation.
While not harmful, BCC are ineffective in preserving TEG coagulation parameters post CPB. Clinical findings support laboratory TEG results in that there were no differences in bleeding or transfusion requirements between groups.
This randomized prospective study was initiated to clarify whether individualized heparin and protamine dosing has immediate effects on hemostatic activation and platelet function in adult cardiac surgery.
Sixty adults undergoing elective coronary artery bypass grafting (CABG) were assigned to receive individualized heparin and protamine (HMS group, n= 29) or a standard dose (ACT group, n=24). Measures of thrombin generation and Multiplate® (Verum Diagnostica, Munich, Germany) platelet function tests were performed before and after cardiopulmonary bypass (CPB).
HMS patients received higher heparin (p = 0.006) and lower protamine (p<0.001) doses. Post-CPB, HMS managed patients showed significantly lower thrombin generation (thrombin-antithrombin (TAT) p<0.02) than the ACT group. Moreover, HMS managed patients had a better preservation of platelet function (COL p = 0.013; ADP p = 0.04; TRAP p = 0.04).
An individualized and stable heparin concentration and appropriate dosing of protamine can reduce thrombin generation and preserve platelet function, even in short-time CPB.
In this case presentation, the transcatheter aortic valve implantation (TAVI) intervention successfully performed on a 76-year-old male patient with severe degenerative aortic stenosis and diagnosed with myelodysplastic syndrome (MDS) is discussed. This case presentation represents the first case on the treatment of severe aortic stenosis on a patient with myelodysplastic syndrome through the use of the TAVI method and may form an alternative to surgery in patients with severe aortic stenosis who have a known haematological disease. For a successful procedure, the patient must be evaluated in cooperation with the haematology clinic and all necessary precautions regarding bleeding and infection complications of the patient must be taken prior to the procedure.
The aim of this study was to investigate whether normothermic bypass is superior to mild hypothermia in patients with poor left ventricular function. This was achieved by studying defibrillation rates, postoperative requirements of cardiac pacing or other morbidity issues and mortality in patients with left ventricular dysfunction operated upon for elective coronary revascularization.
Data were collected retrospectively from 252 consecutive patients with left ventricular dysfunction (ejection fraction ≤35%) undergoing coronary revascularization between January 2005 and January 2011. Patients operated upon under mild hypothermia (32ºC) were placed in Group 1 and under normothermia (≥35ºC) were placed in Group 2. Comorbidities and postoperative complications were recorded.
There were 128 patients in Group 1 and 124 patients in Group 2. Plasma concentrations of CK-MB and troponin T peaked at 6 hours postoperatively, with no significant difference between the groups. Despite longer aortic cross-clamp time and total bypass time in Group 2, significantly less defibrillation requirement rates after aortic declamping was observed. Hospital mortality occured in 16 patients; 8 patients in each group.
Normothermia enables less requirement for defibrillation after aortic declamping and postoperative cardiac pacing in patients with left ventricular dysfunction, which may be interpreted as better myocardial protection under normothermic bypass. However, maintaining normothermia had no effect on postoperative stroke, postoperative atrial fibrillation, renal failure development and mortality.
Background: It is well documented that transient acidosis during reperfusion is protective. The aim of this study was to evaluate the cardioprotection of acidic buffer or plus cyclosporine A in isolated rat hearts after cardioplegic arrest.
Methods: Langendorff-perfused Sprague–Dawley rat hearts were perfused for 20 min with Krebs–Henseleit (K-H) buffer followed by 30 min of crystalloid cardioplegia and 60 min of reperfusion. Control hearts were perfused with Krebs–Henseleit buffer. Acidic buffer post-conditioning hearts were perfused with acidic K-H buffer (pH 6.8) for the first 3 min of reperfusion. Acidic buffer plus cyclosporine A hearts were perfused with K-H acidic buffer (pH 6.8) containing cyclosporine A (0.2 μmol/L) for the first 3 min of reperfusion.
Results: Compared with the control group, acidic buffer or plus cyclosporine A post-conditioning significantly improved myocardial performance, decreased cytochrome C release into the cytosol, increased Bcl-2 expression and decreased Bax expression, decreased sensitivity of mPTP-opening to [Ca2+] and the rate of apoptosis after reperfusion.
Conclusion: These findings suggested that acidic buffer or plus cyclosporine A post-conditioning prevented apoptosis-related mitochondrial permeabilization and provided the myocardial protection after cardioplegic arrest.