Improving Neonatal Cardiopulmonary Resuscitation Hemodynamics

Abstract

Editorial 2468C hest compressions are rarely needed in newly born infants, with an estimated occurrence of 0.08% for near-term and term deliveries; however, the consequences of a hypoperfused state on the brain and other organ systems can be devastating.1 Newborns that require prolonged cardiac compressions with no signs of life beyond 10 minutes are at risk for exceptionally poor outcomes, with up to 83% mortality and 77% severe disability noted in survivors.2 Although initiation of therapeutic hypothermia appears to have some advantage for cardiopulmonary resuscitation (CPR) recipients who survive the delivery room, 3 optimization of the hemodynamics of neonatal cardiac compressions during CPR remains critical. Article see p 2495The infrequent use of cardiac compressions for newborns in the delivery room has impeded the design and completion of rigorous investigations to determine the most effective neonatal cardiac compression methodologies. 4 The unique physiology of the newborn with initially fluid-filled alveoli, the need to transition from fetal to newborn circulation, the open ductus arteriosus, and the frequent presence of severe asphyxia as the cause of cardiovascular collapse add dimensions that cannot be accurately tested in adult or even pediatric patients or models. Adults most frequently receive CPR for cardiac events, such as ventricular fibrillation. Immediately after cardiac arrest, the aortic oxygen and carbon dioxide concentrations are close to the pre-arrest state.5 With initiation of CPR, the blood perfusing the coronaries has adequate oxygenation and pH. Thus, the problem in cardiac arrest is primarily the lack of blood flow rather than the content of the blood. For this reason, resuscitation algorithms for cardiac arrest focus predominantly on providing continuous, uninterrupted compressions with much less emphasis on ventilation. Adequate oxygenation and ventilation can continue without rescue breathing for several minutes because of chest compression-induced gas exchange and spontaneous gasping during compressions in victims of sudden cardiac arrest. [5][6][7] This is quite different from resuscitation after asphyxia-induced arrest. Animal models of asphyxia clearly demonstrate that a combination of chest compressions and ventilations generates better outcomes and survival than resuscitation with ventilations or compressions alone, 8,9 particularly during prolonged resuscitation. 10 During asphyxia, blood continues to flow but with ever-increasing hypoxemia, hypercarbia, and acidemia until the heart runs out of energy substrate and becomes severely bradycardic and eventually asystolic. Thus, it is not surprising that ventilation is essential to reversing asphyxial arrest.The recent work by Schmölzer et al 11 appearing in this issue of Circulation uses a neonatal model of hypoxia/asphyxia to investigate new ways of enhancing blood flow during neonatal CPR while maintaining adequate ventilation. Although not a perfect model given that the animals already had posttransitional physiology, t...

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

“…Once return of spontaneous circulation (ROSC) is established, pulsed oxyhemoglobin saturation (SpO 2 ) can be measured by pulse oximetry and guide supplemental oxygen administration. The infrequent use of chest compressions [7] has impeded the design and completion of rigorous studies to determine the optimal concentration of inspired oxygen during chest compressions in neonatal resuscitation. The previous studies evaluating optimal oxygen concentration during chest compressions were conducted in 1–3 day old piglet models and did not analyze PaO 2 , oxygen content of arterial blood (CaO 2 ), or oxygen delivery to the brain during chest compressions [8].…”

Chest Compression in Neonatal Cardiac Arrest: Cerebral Blood Flow Measurements in Experimental Models

“…The infrequent occurrence of neonatal cardiopulmonary resuscitation (CPR) with CC has impeded large randomized controlled clinical trials to identify approaches that optimize cerebral as well as systemic hemodynamics [4]. Thus, recommendations are based on mainly indirect evidence from adults, older children and animals, as well as expert opinion.…”