Comparative evaluation of three interfaces for non-invasive ventilation: a randomized cross-over design physiologic study on healthy volunteers

INTRODUCTION: Interface choice is crucial for non-invasive ventilation (NIV) success. We compared a new interface, the helmet next (H(N)), with the facial mask (FM) and the standard helmet (H(S)) in twelve healthy volunteers. METHODS: In this study, five NIV trials were randomly applied, preceded and followed by a trial of unassisted spontaneous breathing (SB). Baseline settings, for example, 5 cmH(2)O of both inspiratory pressure support (PS) and positive end-expiratory pressure (PEEP), were applied through FM, H(S) and H(N), while increased settings (PS and PEEP of 8 cmH(2)O) were only applied through H(S) and H(N). We measured flow, airway, esophageal and gastric pressures, and calculated inspiratory effort indexes and trigger delays. Comfort was assessed with a visual-analog-scale. RESULTS: We found that FM, H(S) and H(N) at baseline settings were not significantly different with respect to inspiratory effort indexes and comfort. Inspiratory trigger delay and time of synchrony (TI,synchrony) were significantly improved by FM compared to both helmets, whereas expiratory trigger delay was shorter with FM, as opposed to H(S) only. H(N) at increased settings performed better than FM in decreasing inspiratory effort measured by pressure-time product of transdiaphragmatic pressure (PTPdi)/breath (10.7 ± 9.9 versus 17.0 ± 11.0 cmH(2)O*s), and PTPdi/min (128 ± 96 versus 204 ± 81 cmH(2)O*s/min), and PTPdi/L (12.6 ± 9.9 versus 30.2 ± 16.8 cmH(2)O*s/L). TI, synchrony was inferior between H(N) and H(S) at increased settings and FM. CONCLUSIONS: H(N) might hold some advantages with respect to interaction and synchrony between subject and ventilator, but studies on patients are needed to confirm these findings. TRIAL REGISTRATION: ClinicalTrials.gov NCT01610960