Initial arterial pco2 and its course in the first hours of extracorporeal cardiopulmonary resuscitation show no association with recovery of consciousness in humans: A single‐centre retrospective study

Background: Cardiac arrest is a severe condition with high mortality rates, especially in the case of prolonged low‐flow durations resulting in severe ischaemia and reperfusion injury. Changes in partial carbon dioxide concentration (pCO2) may aggravate this injury. Extracorporeal cardiopulmonary resuscitation (ECPR) shortens the low‐flow duration and enables close regulation of pCO2. We examined whether pCO2 is associated with recovery of consciousness. Methods: We retrospectively analysed ECPR patients ≥ 16 years old treated between 2010 and 2019. We evaluated initial arterial pCO2 and the course of pCO2 ≤ 6 h after initiation of ECPR. The primary outcome was the rate of recovery of consciousness, defined as Glasgow coma scale motor score of six. Results: Out of 99 ECPR patients, 84 patients were eligible for this study. The mean age was 47 years, 63% were male, 93% had a witnessed arrest, 45% had an out‐of‐hospital cardiac arrest, and 38% had a recovery of consciousness. Neither initial pCO2 (Odds Ratio (OR) 0.93, 95% confidence interval 95% (CI) 0.78–1.08) nor maximum decrease of pCO2 (OR 1.03, 95% CI 0.95–1.13) was associated with the recovery of consciousness. Conclusion: Initial arterial pCO2 and the course of pCO2 in the first six hours after initiation of ECPR were not associated with the recovery of consciousness.