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) followed by titration to target preductal saturations (SpO). We studied the effect of resuscitation with titrated O on gas exchange, pulmonary, and systemic hemodynamics.

Methodology: Twenty-nine preterm lambs (127 d gestation) were randomized to resuscitation with 21% O (n = 7), 100% O (n = 6), or initiation at 21% and titrated to target SpO (n = 16). Seven healthy term control lambs were ventilated with 21% O.

Results: Preductal SpO achieved by titrating O was within the desired range similar to term lambs in 21% O. Resuscitation of preterm lambs with 21% and 100% O resulted in SpO below and above the target, respectively. Ventilation of preterm lambs with 100% O and term lambs with 21% O effectively decreased pulmonary vascular resistance (PVR). In contrast, preterm lambs with 21% O and titrated O demonstrated significantly higher PVR than term lambs on 21% O.

Conclusion(s): Initial resuscitation with 21% O followed by titration of O led to suboptimal pulmonary vascular transition at birth in preterm lambs. Ventilation with 100% O in preterm lambs caused hyperoxia but reduced PVR similar to term lambs on 21% O. Studies evaluating the initiation of resuscitation at a higher O concentration followed by titration based on SpO in preterm neonates are needed.