203: Optimal Early ECMO Sweep Flow and Cerebral Autoregulation in Swine ECPR

Background: In the immediate peri-cannulation period of ECPR, clinicians may increase sweep to correct acidosis and hypercapnia. Given CO2 is a potent vasodilator and cerebral autoregulation regulator, we hypothesized that rapid CO2 removal with high sweep could impair cerebral autoregulation. Methods: In our ECPR swine model, animals were assigned to rapid sweep (200%), slow sweep (25%), or control sweep (100%) flow. Bilateral femoral access was obtained for ECPR. An intracranial pressure (ICP) monitor was placed via burr-hole craniotomy and fibrillatory arrest was induced. To avoid confounding, vasoactive medications and chest compression were not given. At 15 minutes post-arrest, ECMO flow was initiated at 50-60 mL/kg/minute. After five minutes of ECMO, defibrillation was performed. ECMO was maintained for five minutes post-ROSC. ABG data was collected at baseline (T0), after ECMO initiation (T1), after ROSC (T2), and before euthanasia (T3). ICP and MAP data were collected continuously and used to calculate the pressure reactivity index (PRx) at T0 and T3. Results: Six animals were included, with two in each treatment group. ABG data did not differ between groups at T0 or T1. Rapid sweep yielded a higher pH and lower PaCO2 at T2 and T3. PRx at T0 was negative in all groups at T0 and positive in the rapid sweep group at T3, but the correlation index was close to zero, indicating intact autoregulation. Conclusion: In this hyperacute swine ECPR model, rapid sweep flow did not alter cerebral autoregulation function. Further research with a structural brain assessment is necessary.