Lactate as a Predictor of Mortality in ECMO CPR Patients: Insights from a Large Single Center Cohort

Background
In adult patients who fail to achieve spontaneous circulation after traditional cardiopulmonary resuscitation, extracorporeal membrane oxygenation is being offered in some centers as a rescue strategy. It is however still difficult to ascertain which patient population benefits from such technology. We sought to identify if lactic acid is a predictor of adverse outcome in patients that undergo resuscitation with extracorporeal membrane oxygenation (ECMO) following in-hospital cardiac arrest.

Methods
This is a retrospective cohort study of patients who underwent E-CPR in the setting of in-hospital cardiac arrest between May 2012-December 2017. One hundred and fifty-seven patients met inclusion criteria and serum lactate levels and mortality data was obtained. The primary outcome of interest was in-hospital mortality. Lactic acid levels were measured and analyzed during the first, second and third days after the cannulation. Multivariate analysis was done to exclude any confounders.

Results
Out of 157 patients undergone ECPR, 44 patients (28%) have survived. Serum lactate was found to be statistically significant between the survivors and non-survivors (mean 9 vs 13.9 mmol/L, P-value 0.013). The highest level of Lactic acid during cannulation also carried significant importance in the prediction of mortality in ECPR patients (mean 9.3 vs 14.3 mmol/L, P-value 0.014). SAVE (Survival after Veno-Arterial ECMO) score didn’t reach statistical significance in our cohort of patients. (mean -8.18 vs -8.75, P-value 0.738).

Conclusions
Lactic acid is a powerful predictor of mortality in ECPR patients. In addition, SAVE score was not discriminatory in this cohort of patients. As the use of ECMO has rapidly grown in the past decade, we need to better understand the utility of this rescue strategy in ECPR patients and develop prediction tools that offer more insight.