Continuous Chest Compressions during Sustained Inflations in a Perinatal Asphyxial Cardiac Arrest Lamb Model

Abstract

Objective

Continuous chest compressions (CCCs) are more effective during resuscitation in adults. Sustained inflation (SI) rapidly establishes functional residual capacity in fluid-filled lungs at birth. We sought to compare the hemodynamics and success in achieving return of spontaneous circulation (ROSC) in an asphyxial cardiac arrest lamb model with transitioning fetal circulation and fluid-filled lungs between subjects receiving CCCs during SI and those receiving conventional 3:1 compression-to-ventilation resuscitation.

Design

Prospective, randomized, animal model study.

Setting

An experimental laboratory.

Subjects

Fourteen newborn term gestation lambs.

Interventions

Lambs were randomized into two groups: 3:1 compression-to-ventilation (control) and CCCs during SI (SI+CCCs). The umbilical cord was occluded to induce asphyxia and asystole. The control group was resuscitated per NRP guidelines. In the SI+CCCs group, SI at 35cm H ₂O was provided for 30 seconds with 1-second interruptions before another SI was provided. 120 chest compressions/min started after the initial SI. The first dose of IV epinephrine was given at 6 minutes if ROSC was not achieved, and then every 3 minutes until ROSC or for a total of four doses.

Measurement and Results

All lambs achieved ROSC in a comparable median time (interquartile range) of 390 (225–405) and 345 (204–465) seconds in the SI+CCCs and control groups, respectively. 4/7 (SI+CCCs) and 3/6 (control) lambs required epinephrine to achieve ROSC. Diastolic blood pressures were lower in the SI+CCCs (4 ± 2 mmHg) compared to the control group (7 ± 2 mmHg); P<0.05. PaCO ₂, PaO ₂, and lactate were similar between the groups during the study period.

Conclusion

In this perinatal cardiac arrest lamb model with transitioning fetal circulation and fluid-filled lungs, SI+CCC is as effective as 3:1 C:V resuscitation in achieving ROSC. Half the lambs achieved ROSC without epinephrine. CCCs during SI reduced diastolic pressures but did not alter gas exchange or carotid blood flow compared to 3:1 C:V resuscitation.