Randomized trial of oxygen weaning strategies following chest compressions during neonatal resuscitation

BACKGROUND: The Neonatal Resuscitation Program (NRP) recommends using 100% O-2 during chest compressions and adjusting FiO(2) based on SpO(2) after return of spontaneous circulation (ROSC). The optimal strategy for adjusting FiO(2) is not known. METHODS: Twenty-five near-term lambs asphyxiated by umbilical cord occlusion to cardiac arrest were resuscitated per NRP. Following ROSC, lambs were randomized to gradual decrease versus abrupt wean to 21% O-2 followed by FiO(2) titration to achieve NRP SpO(2) targets. Carotid blood flow and blood gases were monitored. RESULTS: Three minutes after ROSC, PaO2 was 229 +/- 32 mmHg in gradual wean group compared to 57 +/- 13 following abrupt wean to 21% O-2 (p < 0.001). PaO2 remained high in the gradual wean group at 10 min after ROSC (110 +/- 10 vs. 67 +/- 12, p < 0.01) despite similar FiO(2) (similar to 0.3) in both groups. Cerebral O-2 delivery (C-DO2) was higher above physiological range following ROSC with gradual wean (p < 0.05). Lower blood oxidized/reduced glutathione ratio (suggesting less oxidative stress) was observed with abrupt wean. CONCLUSION: Weaning FiO(2) abruptly to 0.21 with adjustment based on SpO(2) prevents surge in PaO2 and C-DO2 and minimizes oxidative stress compared to gradual weaning from 100% O-2 following ROSC. Clinical trials with neurodevelopmental outcomes comparing post-ROSC FiO(2) weaning strategies are warranted. IMPACT: In a lamb model of perinatal asphyxial cardiac arrest, abrupt weaning of inspired oxygen to 21% prevents excessive oxygen delivery to the brain and oxidative stress compared to gradual weaning from 100% oxygen following return of spontaneous circulation. Clinical studies assessing neurodevelopmental outcomes comparing abrupt and gradual weaning of inspired oxygen after recovery from neonatal asphyxial arrest are warranted.