Supplementary Material for: Continuous Chest Compressions with Asynchronous Ventilation in Asphyxiated Preterm Lambs with Asystole

Background: Gas exchange and perfusion are impaired during neonatal cardiopulmonary resuscitation. Continuous chest compressions with asynchronous ventilation (CCCaV) improve oxygenation and hemodynamics in term animal models compared to synchronized 3:1 compressions-to-ventilation (C:V). We hypothesized that CCCaV improves gas exchange and hemodynamics in preterm lambs.
Design: Sixteen extremely preterm (124-126 days gestation) lambs were asphyxiated to cardiac arrest by umbilical cord occlusion. Lambs were randomized to 3:1 C:V following the International Liaison Committee on Resuscitation algorithm, or CCCaV (120 compressions and 40 asynchronized ventilations per minute). Epinephrine was given three minutes into resuscitation and repeated every three minutes until return of spontaneous circulation (ROSC).
Results: All lambs achieved ROSC with no difference in time to ROSC. There was no difference in cerebral oxygen delivery (cDO2) in lambs resuscitated with CCCaV vs. 3:1 C:V (0.05 [0.041] vs. 0.03 mL [0.031] mL O2/kg/min, respectively) during chest compressions. CCCaV yielded higher arterial oxygen content (CaO2 2.07 [1.00] vs. 1.07 [0.69] ml O2/dL), mean arterial pressure (14.2 [2.6] vs 13.2 [2.3] mmHg) and diastolic pressure (8.1 [1.8] vs 7.1 [1.4] mmHg) during chest compressions compared to 3:1 C:V. There was no difference in plasma reduced to oxidized glutathione [GSH/GSSG ratio] between groups at 10 minutes post-ROSC.
Conclusion: CCCaV in asystolic preterm lambs did not alter cerebral oxygen delivery, frequency, or time to ROSC compared to standard 3:1 C:V resuscitation but increased CaO2, mean and diastolic arterial pressure compared to 3:1 C:V without increasing plasma oxidative stress markers.