Oxygenation and Hemodynamics during Chest Compressions in a Lamb Model of Perinatal Asphyxia Induced Cardiac Arrest.

Munmun Rawat,Carmon Koenigsknecht,Sara Berkelhamer,Payam Vali,Sylvia Gugino,Mahdi Alsaleem,Bobby Mathew,Jayasree Nair,Justin Helman,Satyan Lakshminrusimha,Praveen Chandrasekharan

doi:10.3390/children6040052

Abstract

The current guidelines recommend the use of 100% O2 during resuscitation of a neonate requiring chest compressions (CC). Studies comparing 21% and 100% O2 during CC were conducted in postnatal models and have not shown a difference in incidence or timing of return of spontaneous circulation (ROSC). The objective of this study is to evaluate systemic oxygenation and oxygen delivery to the brain during CC in an ovine model of perinatal asphyxial arrest induced by umbilical cord occlusion. Pulseless cardiac arrest was induced by umbilical cord occlusion in 22 lambs. After 5 min of asystole, lambs were resuscitated with 21% O2 as per Neonatal Resuscitation Program (NRP) guidelines. At the onset of CC, inspired O2 was either increased to 100% O2 (n = 25) or continued at 21% (n = 9). Lambs were ventilated for 30 min post ROSC and FiO2 was gradually titrated to achieve preductal SpO2 of 85–95%. All lambs achieved ROSC. During CC, PaO2 was 21.6 ± 1.6 mm Hg with 21% and 23.9 ± 6.8 mm Hg with 100% O2 (p = 0.16). Carotid flow was significantly lower during CC (1.2 ± 1.6 mL/kg/min in 21% and 3.2 ± 3.4 mL/kg/min in 100% oxygen) compared to baseline fetal levels (27 ± 9 mL/kg/min). Oxygen delivery to the brain was 0.05 ± 0.06 mL/kg/min in the 21% group and 0.11 ± 0.09 mL/kg/min in the 100% group and was significantly lower than fetal levels (2.1 ± 0.3 mL/kg/min). Immediately after ROSC, lambs ventilated with 100% O2 had higher PaO2 and pulmonary flow. It was concluded that carotid blood flow, systemic PaO2, and oxygen delivery to the brain are very low during chest compressions for cardiac arrest irrespective of 21% or 100% inspired oxygen use during resuscitation.

Highlights

The majority of newborn infants require limited or no assistance to undergo successful physiologic transition and stabilization at birth
Twenty-two lambs were asphyxiated to cardiac arrest by umbilical cord occlusion and all lambs achieved return of spontaneous circulation (ROSC)
Lambs ventilated with 21% O2 required 1.4 ± 0.8 doses of epinephrine and those ventilated with 100% O2 during chest compressions (CC) required 1.3 ± 0.8 doses

Summary

Introduction

The majority of newborn infants require limited or no assistance to undergo successful physiologic transition and stabilization at birth. Studies suggest that approximately 10% of infants require some intervention to establish regular respirations at birth with less than 1% needing extensive resuscitative measures such as chest compressions [1]. Newborns who fail to respond to optimized ventilation and chest compressions have a high incidence of mortality and if they survive are at high risk of suffering long-term neurological deficits [2,3]. Initiation of resuscitation with 21% oxygen in term infants is associated with several benefits including earlier time to first cry and reduced mortality [4]. Children 2019, 6, 52 the optimal inspired oxygen concentration during chest compressions in neonatal bradycardia and cardiac arrest is controversial.

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