Assessment of optimal chest compression depth during neonatal cardiopulmonary resuscitation: a randomised controlled animal trial.

AIM: The study aimed to examine the optimal anterior-posterior depth which will reduce the time to return of spontaneous circulation and improve survival during chest compressions. Asphyxiated neonatal piglets receiving chest compression resuscitated with a 40% anterior-posterior chest depth compared with 33%, 25% or 12.5% will have reduced time to return of spontaneous circulation and improved survival.

METHODS: Newborn piglets (n=8 per group) were anaesthetised, intubated, instrumented and exposed to 45 min normocapnic hypoxia followed by asphyxia and cardiac arrest. Piglets were randomly allocated to four intervention groups ('anterior-posterior 12.5% depth', 'anterior-posterior 25% depth', 'anterior-posterior 33% depth' or 'anterior-posterior 40% depth'). Chest compressions were performed using an automated chest compression machine with a rate of 90 per minute. Haemodynamic and respiratory parameters, applied compression force, and chest compression depth were continuously measured.

RESULTS: The median (IQR) time to return of spontaneous circulation was 600 (600-600) s, 135 (90-589) s, 85 (71-158)* s and 116 (63-173)* s for the 12.5%, 25%, 33% and 40% depth groups, respectively (*p<0.001 vs 12.5%). The number of piglets that achieved return of spontaneous circulation was 0 (0%), 6 (75%), 7 (88%) and 7 (88%) in the 12.5%, 25%, 33% and 40% anterior-posterior depth groups, respectively. Arterial blood pressure, central venous pressure, carotid blood flow, applied compression force, tidal volume and minute ventilation increased with greater anterior-posterior chest depth during chest compression.

CONCLUSIONS: Time to return of spontaneous circulation and survival were similar between 25%, 33% and 40% anterior-posterior depths, while 12.5% anterior-posterior depth did not result in return of spontaneous circulation or survival. Haemodynamic and respiratory parameters improved with increasing anterior-posterior depth, suggesting improved organ perfusion and oxygen delivery with 33%-40% anterior-posterior depth.

TRIAL REGISTRATION NUMBER: PTCE0000193.