Tissue hypoperfusion and hypoxia markers predict mortality in critically ill patients. This study evaluates the ability of serum lactate, central venous oxygen saturation (Scvo ₂), and venous-arterial carbon dioxide difference (GapCo ₂) to predict mortality in patients with postcardiac arrest (post-CA) syndrome.

A prospective observational study of patients with post-CA in a tertiary teaching hospital. Serial assessments of lactate, lactate clearance (Clac), GapCo ₂, and Scvo ₂ in the first 72 hours post-CA were analyzed. Adults (≥18 years) patients resuscitated from CA were included. The primary end point was 28-day mortality and secondary end points were 24- and 72-hour mortality.

A total of 54 patients were recruited, 33 (61,1%) of 54 were men, with a 28-day mortality of 75.9%. Cardiac arrest occurred in-hospital in 84.6% of survivors and 97.5% of nonsurvivors. Lactate and Clac were significantly associated with mortality at 28 days, yielding an area under the receiver–operating characteristic curve of 0.797 (lactate 6 hours) and 0.717 (Clac 6 hours) with a positive predictive value of 96% for lactate 6 hours (> 2.5 mmol/L) and 89.5% for Clac 6 hours (<50%). Survival analysis confirmed the difference between the groups from the 24th hour post-CA. Considering mortality at 24 hours, lactate, Clac, and Scvo ₂ (immediately post-CA, 6 and 18 hours) were different between the groups. In mortality at 72 hours, lactate, Clac, Scvo ₂ (48 hours), and GapCo ₂ (36 and 48 hours) were associated with mortality.

In post-CA syndrome, serum lactate and Clac were consistently able to predict mortality.