A Randomized, Controlled Animal Study: 21% or 100% Oxygen during Cardiopulmonary Resuscitation in Asphyxiated Infant Piglets

Background: During pediatric cardiopulmonary resuscitation (CPR), resuscitation guidelines recommend 100% oxygen (O-2); however, the most effective O-2 concentration for infants unknown. Aim: We aimed to determine if 21% O-2 during CPR with either chest compression (CC) during sustained inflation (SI) (CC + SI) or continuous chest compression with asynchronized ventilation (CCaV) will reduce time to return of spontaneous circulation (ROSC) compared to 100% O-2 in infant piglets with asphyxia-induced cardiac arrest. Methods: Piglets (20-23 days of age, weighing 6.2-10.2 kg) were anesthetized, intubated, instrumented, and exposed to asphyxia. Cardiac arrest was defined as mean arterial blood pressure < 25 mmHg with bradycardia. After cardiac arrest, piglets were randomized to CC + SI or CCaV with either 21% or 100% O-2 or the sham. Heart rate, arterial blood pressure, carotid blood flow, and respiratory parameters were continuously recorded. Main results: Baseline parameters, duration, and degree of asphyxiation were not different. Median (interquartile range) time to ROSC was 107 (90-440) and 140 (105-200) s with CC + SI 21% and 100% O-2, and 600 (50-600) and 600 (95-600) s with CCaV 21% and 100% O-2 (p = 0.27). Overall, six (86%) and six (86%) piglets with CC + SI 21% and 100% O-2, and three (43%) and three (43%) piglets achieved ROSC with CCaV 21% and 100% O-2 (p = 0.13). Conclusions: In infant piglets resuscitated with CC + SI, time to ROSC reduced and survival improved compared to CCaV. The use of 21% O-2 had similar time to ROSC, short-term survival, and hemodynamic recovery compared to 100% oxygen. Clinical studies comparing 21% with 100% O-2 during infant CPR are warranted.

Automated summary

This study aimed to compare the time to return of spontaneous circulation in infant piglets receiving 21% oxygen and 100% oxygen during cardiac arrest, finding that 21% oxygen had similar efficacy to 100% oxygen. Clinical studies comparing the two oxygen concentrations during infant CPR are recommended.