Veno arterial membrane oxygenation (VA ECMO) is increasingly used for cardiogenic failure. However, hemodynamic targets for adequate resuscitation remain a challenge. The PCO2 gap and the ratio between PCO2 gap and the arteriovenous difference in oxygen (PCO2 gap/Da–vO2) are marker of peripheral hypoperfusion. We hypothesized that the PCO2 gap and the PCO2 gap/Da–vO2 ratio might be useful parameters in VA ECMO patients.
Patients and 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 two groups of patients: patients who died of any cause under VA ECMO or in the 72 h following VA ECMO weaning (early death group)—and patients who survived VA ECMO weaning more than 72 h (surviving group). Blood samples were drawn from arterial and venous VA ECMO cannulas at H0, H6, and H24. The ability of PCO2 gap and PCO2 gap/Da–vO2 to discriminate between early mortality and surviving was studied using receiver operating characteristic curves analysis.
We included 20 patients in surviving group and 29 in early death group. The PCO2 gap was higher in the early death group at H6 (7.4 mm Hg [5.7–10.1] vs. 5.9 mm Hg [3.8–9.2], P < 0.01). AUC for PCO2 gap at H6 was 0.76 (0.61–0.92), with a cutoff of 6.2 mm Hg. The PCO2 gap/Da–vO2 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 PCO2 gap/Da–vO2 at H0 and H6 were 0.79 and 0.73 respectively; the cut-off value was 1.4.
Early PCO2 gap and PCO2 gap/Da–vO2 ratio are higher in the early death group in patients under VA ECMO.