The Early Change in Pa _{CO ₂} after Extracorporeal Membrane Oxygenation Initiation Is Associated with Neurological Complications

Abstract

<b>Rationale</b>: Large decreases in Pa_CO₂ that occur when initiating extracorporeal membrane oxygenation (ECMO) in patients with respiratory failure may cause cerebral vasoconstriction and compromise brain tissue perfusion.<b>Objectives</b>: To determine if the magnitude of Pa_CO₂ correction upon ECMO initiation is associated with an increased incidence of neurological complications in patients with respiratory failure.<b>Methods</b>: We conducted a multicenter, international, retrospective cohort study using the Extracorporeal Life Support Organization Registry, including adults with respiratory failure receiving ECMO via any mode between 2012 and 2017. The relative change in Pa_CO₂ in the first 24 hours was calculated as (24-h post-ECMO Pa_CO₂ - pre-ECMO Pa_CO₂)/pre-ECMO Pa_CO₂. The primary outcome was the occurrence of neurological complications, defined as seizures, ischemic stroke, intracranial hemorrhage, or brain death.<b>Measurements and Main Results</b>: We included 11,972 patients, 88% of whom were supported with venovenous ECMO. The median relative change in Pa_CO₂ was -31% (interquartile range, -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 Pa_CO₂ (>50%) had an increased incidence of neurological complications compared with those with a smaller decrease (9.8% vs. 6.4%; <i>P</i> < 0.001). A large relative decrease in Pa_CO₂ was independently associated with neurological complications after controlling for previously described risk factors (odds ratio, 1.7; 95% confidence interval, 1.3 to 2.3; <i>P</i> < 0.001).<b>Conclusions</b>: In patients receiving ECMO for respiratory failure, a large relative decrease in Pa_CO₂ in the first 24 hours after ECMO initiation is independently associated with an increased incidence of neurological complications.