Comparative bench study evaluation of a modified snorkeling mask used during COVID-19 pandemic and standard interfaces for non-invasive ventilation

Purpose: The aim of this bench study is to compare the standard NIV and nCPAP devices (Helmet, H; Full face mask, FFM) with a modified full face snorkeling mask used during COVID-19 pandemic. Methods: A mannequin was connected to an active lung simulator. The inspiratory and expiratory variations in airways pressure observed with a high simulated effort, were determined relative to the preset CPAP level. NIV was applied in Pressure Support Mode at two simulated respiratory rates and two cycling-off flow thresholds. During the bench study, we measured the variables defining patient-ventilator interaction and performance. Results: During nCPAP, the tested interfaces did not show significant differences in terms of ∆Pawi and ∆Pawe. During NIV, the snorkeling mask demonstrated a better patient-ventilator interaction compared to FFM, as shown by significantly shorter Pressurization Time and Expiratory Trigger Delay (p < 0.01), but no significant differences were found in terms of Inspiratory Trigger Delay and Time of Synchrony between the interfaces tested. At RR 20sim, the snorkeling mask presented the lower ΔPtrigger (p < 0.01), moreover during all the conditions tested the snorkeling mask showed the longer Pressure Time Product at 200, 300, and 500 ms compared to FFM (p < 0.01). A major limitation of snorkeling mask is that during NIV with this interface it is possible to reach maximum 18 cmH2O of peak inspiratory pressure. Conclusions: The modified snorkeling mask can be used as an acceptable alternative to other interfaces for both nCPAP and NIV in emergencies.