Passive continuous positive airway pressure ventilation during cardiopulmonary resuscitation: a randomized cross-over manikin simulation study

While controlled ventilation is most frequently used during cardiopulmonary resuscitation (CPR), the application of continuous positive airway pressure (CPAP) and passive ventilation of the lung synchronously with chest compressions and decompressions might represent a promising alternative approach. One benefit of CPAP during CPR is the reduction of peak airway pressures and therefore a potential enhancement in haemodynamics. We therefore evaluated the tidal volumes and airway pressures achieved during CPAP–CPR. During CPR with the LUCAS? 2 compression device, a manikin model was passively ventilated at CPAP levels of 5, 10, 20 and 30 hPa with the Boussignac tracheal tube and the ventilators Evita^® V500, Medumat^® Transport, Oxylator^® EMX, Oxylog^® 2000, Oxylog^® 3000, Primus^® and Servo^®-i as well as the Wenoll^® diver rescue system. Tidal volumes and airway pressures during CPAP–CPR were recorded and analyzed. Tidal volumes during CPAP–CPR were higher than during compression-only CPR without positive airway pressure. The passively generated tidal volumes increased with increasing CPAP levels and were significantly influenced by the ventilators used. During ventilation at 20 hPa CPAP via a tracheal tube, the mean tidal volumes ranged from 125 ml (Medumat^®) to 309 ml (Wenoll^®) and the peak airway pressures from 23 hPa (Primus^®) to 49 hPa (Oxylog^® 3000). Transport ventilators generated lower tidal volumes than intensive care ventilators or closed-circuit systems. Peak airway pressures during CPAP–CPR were lower than those during controlled ventilation CPR reported in literature. High peak airway pressures are known to limit the applicability of ventilation via facemask or via supraglottic airway devices and may adversely affect haemodynamics. Hence, the application of ventilators generating high tidal volumes with low peak airway pressures appears desirable during CPAP–CPR. The limited CPAP–CPR capabilities of transport ventilators in our study might be prerequisite for future developments of transport ventilators.