The effects of an automatic, low pressure and constant flow ventilation device versus manual ventilation during cardiovascular resuscitation in a porcine model of cardiac arrest

Abstract

BackgroundCardiac arrest is an important cause of mortality. Cardiopulmonary resuscitation (CPR) improves survival, however, delivery of effective CPR can be challenging and combining effective chest compressions with ventilation, while avoiding over-ventilation is difficult. We hypothesized that ventilation with a pneumatically powered, automatic ventilator (Oxylator®) can provide adequate ventilation in a model of cardiac arrest and improve the consistency of ventilations during CPR. Methods/resultsTwelve pigs (∼40kg, either sex) underwent 3 episodes each of cardiac arrest and resuscitation consisting of 30s of untreated ventricular fibrillation, followed by 5min of CPR, defibrillation, and ∼30min of recovery. During CPR in each episode, pigs were ventilated in 1 of 3 ways in random balanced order: manual ventilation using AMBU bag (12breaths/min), low pressure Oxylator® (maximum airway pressure 15cmH2O with 20L/min constant flow in automatic mode [Ox15/20]), or high pressure Oxylator® (maximum airway pressure 20cmH2O with 30L/min constant flow in automatic mode [Ox20/30]). During CPR, both Ox15/20 and Ox20/30 resulted in higher levels of positive end expiratory pressure than manual ventilation. Ox15/20 ventilation also resulted in higher arterial pCO2 than manual ventilation. Ox20/30 ventilation yielded higher arterial pO2 and a lower arterial–alveolar gradient than manual ventilation. All pigs were successfully defibrillated, and no measured haemodynamic variables were different between the groups. ConclusionVentilation with an automatic ventilation device during CPR is feasible and provides adequate ventilation and comparable haemodynamics when compared to manual bag ventilation.