Early veno arterial PCO2 difference is associated with outcome in peripheral veno arterial extracorporeal membrane oxygenation

Abstract

Background: Veno arterial membrane oxygenation (VA ECMO) is increasingly used for cardiogenic failure. However, hemodynamic targets for adequate resuscitation remain a challenge. The PCO 2 gap and the ratio between PCO 2 gap and the arteriovenous difference in oxygen (PCO 2 gap/Da–vO 2 ) are marker of peripheral hypoperfusion. We hypothesized that the PCO 2 gap and the PCO 2 gap/Da–vO 2 ratio might be useful parameters in VA ECMO patients. Methods: We conducted an observational prospective study between September 2015 and February 2017. All consecutive patients >18 years of age who had been treated with peripheral VA ECMO for cardiac failure were included. We compared 2 groups of patients: patients who died of any cause under VA ECMO or in the 72h following VA ECMO weaning (early death group) - and patients who survived VA ECMO weaning more than 72h (surviving group). Blood samples were drawn from arterial and venous VA ECMO cannulas at H0 and H6. The ability of PCO 2 gap and PCO 2 gap/Da–vO 2 to discriminate between early mortality and surviving was studied using ROC curves analysis. Results: We included 20 patients in surviving group and 29 in early death group. The PCO 2 gap was higher in the early death group at H6 (7.4 [5.7–10.1] vs. 5.9 [3.8–9.2], p < 0.01). AUC for PCO 2 gap at H6 was 0.76 (0.61–0.92), with a cut-off of 6.2 mmHg. The PCO 2 gap/Da–vO 2 was higher in the early death group at H0 (2.1 [1.5–2.6] vs. 1.2 [0.9–2.4], p < 0.01) and at H6 (2.1 [1.3–2.6] vs. 1.0 [0.8–1.7], p < 0.01). AUC for PCO 2 gap/Da–vO 2 at H0 and H6 were 0.79 and 0.73 respectively; the cut-off value was 1.4. Conclusions: The PCO 2 gap and the PCO 2 gap/Da–vO2 ratio are associated with early death in patients who undergo VA ECMO.