Association between PaCO₂ and outcomes in patients who underwent extracorporeal cardiopulmonary resuscitation for out-of-hospital cardiac arrest

Aim: The optimal arterial partial pressure of carbon dioxide (PaCO₂) for patients undergoing extracorporeal cardiopulmonary resuscitation (ECPR) remains unknown. We aimed to investigate the association between post-resuscitation PaCO₂ and neurological outcomes.

Methods: This retrospective cohort study analyzed data from the Study of Advanced Life Support for Ventricular Fibrillation with Extracorporeal Circulation in Japan, a multicenter registry study across 36 hospitals in Japan, including patients with out-of-hospital cardiac arrest (OHCA) admitted to intensive care units (ICU) after ECPR between 2013 and 2018. Good PaCO₂ management status was defined as a PaCO₂ value of 35-45 mmHg. We classified patients into four groups (poor-poor, poor-good, good-poor, and good-good) according to their PaCO₂ management status upon admission at the ICU and the following day. The primary outcome was a favorable neurological outcome, defined as cerebral performance category 1 or 2, 30 days after cardiac arrest. The secondary outcome was survival 30 days after cardiac arrest.

Results: We classified 885 eligible patients into poor-poor (n = 361), poor-good (n = 231), good-poor (n = 155), and good-good (n = 138) groups. No significant association was observed between PaCO₂ management and favorable 30-day neurological outcomes. Compared with the poor-poor group, the poor-good, good-poor, and good-good groups had adjusted odds ratios of 0.87 (95% confidence interval, 0.52-1.44), 1.17 (0.65-2.05), and 0.95 (0.51-1.73), respectively. The 30-day survival rates among the four groups did not differ significantly.

Conclusion: PaCO₂ values were not significantly associated with 30-day neurological outcomes or survival of patients with OHCA after ECPR.