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

Background

Cardiac 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/results

Twelve pigs (∼40 kg, either sex) underwent 3 episodes each of cardiac arrest and resuscitation consisting of 30 s of untreated ventricular fibrillation, followed by 5 min of CPR, defibrillation, and ∼30 min of recovery. During CPR in each episode, pigs were ventilated in 1 of 3 ways in random balanced order: manual ventilation using AMBU bag (12 breaths/min), low pressure Oxylator^® (maximum airway pressure 15 cmH₂O with 20 L/min constant flow in automatic mode [Ox15/20]), or high pressure Oxylator^® (maximum airway pressure 20 cmH₂O with 30 L/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.

Conclusion

Ventilation with an automatic ventilation device during CPR is feasible and provides adequate ventilation and comparable haemodynamics when compared to manual bag ventilation.