The Link between Early Serum Lactate Level Peak and Mortality in Postcardiotomy Patients with Extracorporeal Life Support

Objective: Veno-arterial extra-corporeal membrane oxygenation (va-ECMO) is used to support patients with refractory post-cardiotomy failure. Serum lactate level is a marker for tissue hypoxia and associated with higher mortality in critically ill patients. We analyzed the association between the peak lactate in the first 24h of va-ECMO therapy and early morbidity and mortality.

Methods: We retrospectively evaluated 133 patients (pts) between 01/07 and 07/16 requiring va-ECMO support due to postcardiotomy cardiogenic shock. We observed the lactate peak level in the first 24h after initiation of vaECMO and examined possible correlations with survival and predictability of weaning from va-ECMO. The patients were categorized in two groups regarding in hospital mortality as Survivals (33 Patients, 24.8%) and Non-Survivals (100 Patients, 75.2%). Receiver Operator Characteristic (ROC) curves are used to assess the prognostic value of each performance assessment.

Results: Age, gender, preoperative EuroSCORE II and procedures performed did not differ among groups. A total of 56.4% of patients were successfully weaned from va-ECMO. Overall in-hospital mortality was 75.2%. Univariate und multivariate analyses indicated that maximum lactate level during the first 24 hours after va-ECMO initiation (OR) was a reliable predictor of in-hospital mortality (F(1,123) = 5.386, p = 0.022). The maximal lactate concentration in the first 24h did not predict successful weaning from ECMO (F [1,123] = 3.260, p = 0.073) nor lower limb malperfusion or cerebral ischemia during ECMO support (p = ns). Measured AUC for lactate peak in 24 hours as a mortality predictor was 0.749 (p < 0.05), and as a cut off value we found lactate peak in 24 hours > 8 mmol/L with 45% sensitivity and 79% specificity.

Conclusion: Va-ECMO in postcardiotomy patients with cardiogenic shock still carries high intrahospital mortality. Serum lactate levels during the first 24hrs after va-ECMO initiation is highly associated with in-hospital mortality.

No conflict of interest has been declared by the author(s).