Effect of various inspired oxygen concentrations on pulmonary and systemic hemodynamics and oxygenation during resuscitation in a transitioning preterm model

Abstract

Background The Neonatal Resuscitation Program recommends initial resuscitation of preterm infants with low oxygen (O2) followed by titration to target preductal saturations (SpO2). We studied the effect of resuscitation with titrated O2 on gas exchange, pulmonary and systemic hemodynamics. Methodology Twenty-nine preterm lambs (127d-gestation) were randomized to resuscitation with 21%O2 (n=7), 100%O2 (n=6) or initiation at 21% and titrated to target SpO2 (n=16). Seven healthy term control lambs were ventilated with 21%O2. Results Preductal SpO2 achieved by titrating O2 was within the desired range similar to term lambs in 21%O2. Resuscitation of preterm lambs with 21 and 100%O2 resulted in SpO2 below and above the target respectively. Ventilation of preterm lambs with 100%O2 and term lambs with 21%O2 effectively decreased pulmonary vascular resistance (PVR). In contrast, preterm lambs with 21%O2 and titrated O2 demonstrated significantly higher PVR than term lambs on 21%O2. Conclusion(s) Initial resuscitation with 21%O2 followed by titration of O2 led to suboptimal pulmonary vascular transition at birth in preterm lambs. Ventilation with 100%O2 in preterm lambs caused hyperoxia but reduced PVR similar to term lambs on 21%O2. Studies evaluating initiation of resuscitation at higher O2 concentration followed by titration based on SpO2 in preterm neonates are needed.

Excess cerebral oxygen delivery follows return of spontaneous circulation in near-term asphyxiated lambs

“…Consideration should also be given to the systemic effects of using different concentrations of oxygen. In particular, supplemental oxygen has an additive effect to lung aeration for reducing pulmonary vascular resistance after birth and is commonly necessary to achieve transition in preterm infants 53,54 . However, most full-term infants with perinatal asphyxia have compliant lungs at birth.…”

How Do We Monitor Oxygenation during the Management of PPHN? Alveolar, Arterial, Mixed Venous Oxygen Tension or Peripheral Saturation?

“…In our lab, in a meconium aspiration model and a preterm RDS model, a PVO 2 demonstrated a change point of 25 and 32 mmHg respectively [ 40 , 41 ] ( Figure 4 ). The utility of PVO 2 from the UVC during the management of PPHN requires further exploration.…”

Oxygen therapy of the newborn from molecular understanding to clinical practice

“…Experimental data as well as large RCTs have contributed greatly to this knowledge, but there is increasing awareness that more data are needed. The amount of oxygen given to newborn infants has been substantially reduced over the last two decades, but whether this is best for survival and long-term outcomes is unclear, especially for preterm infants, who may need some amount of oxygen to decrease pulmonary arterial pressure 119 and to stimulate the respiratory center to open their glottis and to initiate breathing or to remove the hypoxic inhibition of breathing. 120 Until we solve this problem, the oxygen dilemma remains.…”