Continuous Chest Compressions with Asynchronous Ventilation in Asphyxiated Preterm Lambs with Asystole

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.

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 3 min into resuscitation and repeated every 3 min until return of spontaneous circulation (ROSC).

All lambs achieved ROSC with no difference in time to ROSC. There was no difference in cerebral oxygen delivery (C-DO₂) in lambs resuscitated with CCCaV versus 3:1 C:V (0.05 [0.041] vs. 0.03 [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] mm Hg), and diastolic pressure (8.1 [1.8] vs. 7.1 [1.4] mm Hg) 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 min post-ROSC.

CCCaV in asystolic preterm lambs did not alter C-DO₂, 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.