Bench comparative evaluation of a new generation and standard helmet for delivering non-invasive ventilation

To evaluate the performance of a new helmet (NH) recently introduced into clinical use relative to that of the standard helmet (SH) in terms of delivering non-invasive continuous positive airway pressure (nCPAP) and pressure support ventilation (nPSV). This was a bench study using a mannequin connected to an active lung simulator. The SH was fastened to the mannequin by armpit braces, which are not needed to secure the NH. The inspiratory and expiratory variations in nCPAP delivered with two different simulated efforts (Pmus), were determined relative to the preset CPAP level. nPSV was applied at two simulated respiratory rates (RR) and two cycling-off flow thresholds. We measured inspiratory trigger delay (Delay(trinsp)), expiratory trigger delay (Delay(trexp)), time of synchrony (Time(sync)), trigger pressure drop (Delta P (trigger)), airway pressure-time product during the triggering phase (PTPt), the initial 200 ms from the onset of the ventilator pressurization (PTP200), and the initial 300 and 500 ms from the onset of the simulated effort; this two latter parameters were expressed as the percentage of the area of ideal pressurization (PTP300-index and PTP500-index, respectively). In nCPAP, at both Pmus, the differences between the two interfaces at both Pmus were small and clinically irrelevant. In nPSV, regardless of the setting, NH resulted in significantly smaller trigger delays, Delta P (trigger), and PTPt. Time(sync), PTP200, PTP300-index, and PTP500-index were also significantly higher with the NH compared to the SH, irrespective of the setting. Compared to the SH, the NH is equally effective in delivering nCPAP and more effective in delivering nPSV, and it is used to avoid the need for armpit braces.