Evaluating the efficacy of endotracheal and intranasal epinephrine administration in severely asphyxic bradycardic newborn lambs: a randomised preclinical study.

Objective: Intravenous epinephrine administration is preferred during neonatal resuscitation, but may not always be rapidly administered due to lack of equipment or trained staff. We aimed to compare the time to return of spontaneous circulation (ROSC) and post-ROSC haemodynamics between intravenous, endotracheal (ET) and intranasal (IN) epinephrine in severely asphyxic, bradycardic newborn lambs.

Methods: After instrumentation, severe asphyxia (heart rate <60 bpm, blood pressure ~10 mm Hg) was induced by clamping the cord in near-term lambs. Resuscitation was initiated with ventilation followed by chest compressions. Lambs were randomly assigned to receive intravenous (0.02 mg/kg), ET (0.1 mg/kg) or IN (0.1 mg/kg) epinephrine. If ROSC was not achieved after three allocated treatment doses, rescue intravenous epinephrine was administered. After ROSC, lambs were ventilated for 60 min.

Results: ROSC in response to allocated treatment occurred in 8/8 (100%) intravenous lambs, 4/7 (57%) ET lambs and 5/7 (71%) IN lambs. Mean (SD) time to ROSC was 173 (32) seconds in the intravenous group, 360 (211) seconds in the ET group and 401 (175) seconds in the IN group (p<0.05 intravenous vs IN). Blood pressure and cerebral oxygen delivery were highest in the intravenous group immediately post-ROSC (p<0.05), whereas the ET group sustained the highest blood pressure over the 60-min observation (p<0.05).

Conclusion: Our study supports neonatal resuscitation guidelines, highlighting intravenous administration as the most effective route for epinephrine. ET and IN epinephrine should only be considered when intravenous access is delayed or not feasible.