The Early Change in PaCO2 After Extracorporeal Membrane Oxygenation Initiation is Associated with Neurological Complications.

RATIONALE: Large decreases in PaCO2 that occur when initiating extracorporeal membrane oxygenation (ECMO) in patients with respiratory failure may cause cerebral vasoconstriction and compromise brain tissue perfusion. OBJECTIVES: To determine if the magnitude of PaCO2 correction upon ECMO initiation is associated with an increased incidence of neurological complications in patients with respiratory failure. METHODS: We conducted a multicenter international retrospective cohort study using the Extracorporeal Life Support Organization (ELSO) Registry, including adults with respiratory failure on any ECMO mode between 2012 and 2017. The relative change in PaCO2 in the first 24 hours was calculated as (24hPostECMOPaCO2 - PreECMOPaCO2)/PreECMOPaCO2. Our primary outcome was the occurrence of neurological complications, defined as seizures, ischemic stroke, intracranial hemorrhage, or brain death. MEASUREMENTS AND MAIN RESULTS: We included 11,972 patients, 88% of whom were supported with venovenous-ECMO. The median relative change in PaCO2 was -31% (IQR -46 to -12%). Neurological complications were uncommon overall (6.9%) with a low incidence of seizures (1.1%), ischemic stroke (1.9%), intracranial hemorrhage (3.5%), and brain death (1.6%). Patients with a large relative decrease in PaCO2 > 50%) had an increased incidence of neurological complications compared to those with a smaller decrease (9.8% vs. 6.4%; p<0.001). A large relative decrease in PaCO2 was independently associated with neurological complications after controlling for previously described risk factors (OR 1.7; 95% CI 1.3-2.3; p<0.001). CONCLUSIONS: In patients receiving ECMO for respiratory failure, a large relative decrease in PaCO2 in the first 24 hours after ECMO initiation is independently associated with an increased incidence of neurological complications.