Ventilation in Cardiac Arrest

Over the last decades, research in cardiopulmonary resuscitation was primarily focused on uninterrupted chest compressions to restore sufficient circulation. Ventilation during ongoing chest compressions was regarded as potentially deleterious and thus not given any major scientific focus. Current guidelines advise that ventilation be monitored by end-tidal CO2 and emphasize that hyperventilation be avoided. Recent findings from arterial blood gas analyses showed high levels of arterial pCO2, resulting in a frequent occurrence of hypercapnic acidosis, which may be caused by iatrogenic hypoventilation. Ventilation during ongoing chest compressions can be hard to achieve, as nearly every breath may be terminated by simultaneous chest compressions. In case of bag ventilation the applied tidal volumes have not yet been measured und mechanical ventilators so far were not able to ventilate during chest compressions, because pressure limit settings induced termination of inspiration. The aim of this study is to provide patients with the best possible ventilation, even under ongoing chest compressions. Patients are ventilated with a new turbine-driven ventilator (Monnal T60, Air Liquide, France), which can deliver adequate tidal volumes within a very short inspiratory phase due to the inspiratory flow of \> 200l/min. Thus, in deviation from the current recommendations, the ventilation rate can be doubled to 20/min, so that inspiration coincides with cardiac massage less often. The study compares effective ventilation volumes applied by two regimes, 10 breaths/min and 20/min.