Effect of Various Inspired Oxygen Concentrations on Pulmonary and Systemic Hemodynamics and Oxygenation during Resuscitation in a Transitioning Preterm Model

BACKGROUND: The Neonatal Resuscitation Program recommends initial resuscitation of preterm infants with low oxygen (O(2)) followed by titration to target preductal saturations (SpO(2)). We studied the effect of resuscitation with titrated O(2) on gas exchange, pulmonary and systemic hemodynamics. METHODOLOGY: Twenty-nine preterm lambs (127d-gestation) were randomized to resuscitation with 21%O(2) (n=7), 100%O(2) (n=6) or initiation at 21% and titrated to target SpO(2) (n=16). Seven healthy term control lambs were ventilated with 21%O(2). RESULTS: Preductal SpO(2) achieved by titrating O(2) was within the desired range similar to term lambs in 21%O(2). Resuscitation of preterm lambs with 21 and 100%O(2) resulted in SpO(2) below and above the target respectively. Ventilation of preterm lambs with 100%O(2) and term lambs with 21%O(2) effectively decreased pulmonary vascular resistance (PVR). In contrast, preterm lambs with 21%O(2) and titrated O(2) demonstrated significantly higher PVR than term lambs on 21%O(2). CONCLUSION(S): Initial resuscitation with 21%O(2) followed by titration of O(2) led to suboptimal pulmonary vascular transition at birth in preterm lambs. Ventilation with 100%O(2) in preterm lambs caused hyperoxia but reduced PVR similar to term lambs on 21%O(2). Studies evaluating initiation of resuscitation at higher O(2) concentration followed by titration based on SpO(2) in preterm neonates are needed.