Single versus continuous sustained inflations during chest compressions and physiological-based cord clamping in asystolic lambs

Abstract

BackgroundThe feasibility and benefits of continuous sustained inflations (SIs) during chest compressions (CCs) during delayed cord clamping (physiological-based cord clamping; PBCC) are not known. We aimed to determine whether continuous SIs during CCs would reduce the time to return of spontaneous circulation (ROSC) and improve post-asphyxial blood pressures and flows in asystolic newborn lambs.MethodsFetal sheep were surgically instrumented immediately prior to delivery at ~139 days’ gestation and asphyxia induced until lambs reached asystole. Lambs were randomised to either immediate cord clamping (ICC) or PBCC. Lambs then received a single SI (SIsing; 30 s at 30 cmH2O) followed by intermittent positive pressure ventilation, or continuous SIs (SIcont: 30 s duration with 1 s break). We thus examined 4 groups: ICC +SIsing, ICC +SIcont, PBCC +SIsing, and PBCC +SIcont. Chest compressions and epinephrine administration followed international guidelines. PBCC lambs underwent cord clamping 10 min after ROSC. Physiological and oxygenation variables were measured throughout.ResultsThe time taken to achieve ROSC was not different between groups (mean (SD) 4.3±2.9 min). Mean and diastolic blood pressure was higher during chest compressions in PBCC lambs compared with ICC lambs, but no effect of SIs was observed. SIcont significantly reduced pulmonary blood flow, diastolic blood pressure and oxygenation after ROSC compared with SIsing.ConclusionWe found no significant benefit of SIcont over SIsing during CPR on the time to ROSC or on post-ROSC haemodynamics, but did demonstrate the feasibility of continuous SIs during advanced CPR on an intact umbilical cord. Longer-term studies are recommended before this technique is used routinely in clinical practice.

Chest compressions superimposed with sustained inflation during neonatal cardiopulmonary resuscitation: are we ready for a clinical trial?

“…Several post-transitional piglet studies demonstrated reduced time to ROSC (between 60% and 75%) and improved mortality in asphyxiated piglets with CC+SI compared with 3:1 C:V 22 25 26. These findings were not replicated, however, in neonatal lamb models 27 28. The differences in the models, most notably the shape of the chest and the method of providing CC in lambs (ie, compression of side of chest or abdominal compressions), have played a significant role in why CC+SI did not show respiratory or haemodynamic benefits over 3:1 C:V in the newborn lamb model 29 30.…”

Sustained inflation and chest compression versus 3:1 chest compression to ventilation ratio during cardiopulmonary resuscitation of asphyxiated newborns (SURV1VE): A cluster randomised controlled trial

“…Neonatal resuscitation guidelines recommend a 3:1 compression:ventilation (C:V) ratio based on expert opinion, consensus and extrapolation from animal data, rather than strong scientific evidence from clinical studies 1 4. Animal studies have compared C:V ratios (eg, 2:1, 4:1, 9:3 or 15:2) or continuous CC with asynchronised ventilation5–12; however, neither resulted in shorter time to return of spontaneous circulation (ROSC) or reduced mortality. Over the last decade, we have examined continuous CC superimposed by a high distending pressure (termed sustained inflation, SI).…”