485 - Randomized Trial of 21%, 50% Versus 100% Inspired Oxygen During Chest Compressions in Neonatal Resuscitation: Goldilocks Principle?

Poster Number: 485
Publication Number: 485.231

Clariss Blanco, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Buffalo, NY, United States; Mausma Bawa, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Buffalo, NY, United States; Arun Prasath, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Williamsville, NY, United States; Andreina Mari, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Depew, NY, United States; Sylvia Gugino, SUNY at Buffalo, Buffalo, NY, United States; Justin Helman, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Bufalo, NY, United States; Nicole Bradley, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Buffalo, NY, United States; Jayasree Nair, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Buffalo, NY, United States; Satyan Lakshminrusimha, University of California Davis Children's Hospital, Sacramento, CA, United States; Praveen Chandrasekharan, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Buffalo, NY, United States; Munmun Rawat, University at Buffalo, Buffalo, NY, United States

Background: Birth asphyxia is associated with high mortality and neurological morbidity due to anoxic brain injury that typically follows a severe ischemia and reperfusion insult. Neonatal Resuscitation Program (NRP) guidelines currently recommend ventilation with 100% oxygen (O2) during chest compressions (CC). Insufficient oxygen delivery can worsen cerebral anoxia while excessive oxygen delivery aggravates oxygen free radical formation and can reduce cerebral blood flow. Optimizing cerebral blood flow and oxygen delivery to the brain during CC may potentially improve outcomes.

Objective: The objective of this study is to evaluate whether an intermediate level of inspired O2 (~50%) during CC will increase the incidence and hasten return of spontaneous circulation (ROSC), and result in optimal oxygen delivery to the brain in an ovine model of perinatal asphyxia.

Design/Methods: This blinded randomized study used 12 near-term fetal lambs that were randomized into 3 groups prior to asphyxiation: 21%, 50% and 100%. Two minutes after cardiac arrest, positive pressure ventilation (PPV) with 21% O2 was initiated as per NRP guidelines. CC were then carried out 30 seconds after the onset of PPV, and inspired O2 was either continued at 21% (n=4) or increased to either 50% (n=4) or 100% (n=4). The lambs were continuously monitored for evidence of ROSC and were ventilated for 20 minutes after ROSC. Oxygenation, ventilation and hemodynamics were monitored. The ventilator parameters and FiO2 were titrated to achieve normocapnia on the blood gases and to meet the NRP preductal O2 saturation targets.

Results: All lambs in the 50% group achieved ROSC, while 75% and 50% of the lambs achieved ROSC in the 21% and 100% group, respectively (Table 1). The lambs in the 21% group had the lowest pulmonary artery blood flow while the 100% oxygen group had the highest total cumulative O2 exposure at ROSC. The lambs in the 50% group had the lowest total cumulative O2 exposure after ROSC. The oxygen delivery to the brain throughout the post-ROSC period was significantly higher in the 50% group (p < 0.05) compared to the 21% and 100% groups, as was the mean carotid artery blood flow (Figure 1).Conclusion(s): Use of 50% inspired oxygen during CC for cardiac arrest yielded the highest ROSC rates, higher mean carotid artery blood flow and oxygen delivery to the brain, yet lower total cumulative oxygen exposure after ROSC, compared to 21% and 100% oxygen.
blanco, cla cvblanco, cla cv 2022-01 (2).pdf
Figure 1. Oxygenation and hemodynamic parameters after achieving return of spontaneous circulation in lambs ventilated with 21%, 50% and 100% inspired oxygen during chest compressions.Changes in total cumulative oxygen exposure (A), oxygen delivery to the brain (B), mean pulmonary artery blood flow (C) and mean carotid artery blood flow (D) over 20 minutes post-return of spontaneous circulation. (A) Lambs randomized to the 50% group (black circles) had significantly lower total cumulative oxygen exposure compared to those randomized to the 21% group (P = < 0.0001) (blue squares) and 100% group (P = < 0.0001) (red triangles). (B) In spite of this, oxygen delivery to the brain was higher in the lambs in the 50% group compared with those in the 21% group (P = < 0.0001) and 100% group (P = 0.0244). (C) Mean pulmonary artery blood flow was higher in lambs ventilated with 50% inspired oxygen compared with those ventilated with 21% inspired oxygen (P = < 0.0001). Lambs ventilated with 100% inspired oxygen also had higher mean pulmonary artery blood flow compared with those ventilated with 21% inspired oxygen (P = 0.0002). (D) Carotid artery blood flow was also higher in the lambs in the 50% group compared with those in the 21% group (P = < 0.0001) and 100% group (P = 0.0027); the same was true for lambs in the 100% group compared with those in the 21% group (0.0253). * Significantly different from the 21% group. ‡ Significantly different from the 100% group.