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 (127 d 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 the initiation of resuscitation at a higher O-2 concentration followed by titration based on SpO(2) in preterm neonates are needed.