Portions of two representative reports, a, c and e) one during noninvasive ventilation through a helmet and b, d and f) the other through mask. Portions of two representative reports, a, c and e) one during noninvasive ventilation through a helmet and b, d and f) the other through mask. Tracings of a and b) airway pressure (Paw), c and d) flow and e and f) diaphragm electrical activity (EAdi) are shown. In a, c and e, two ineffective efforts are depicted, while two double-triggerings are depicted in b, d and f. Federico Longhini et al. ERJ Open Res 2017;3:00075-2017 ©2017 by European Respiratory Society