Figure 3.
Original tracing of helmet and airway (lung) flow and pressure during HF-BiPAP, BIVENT, and PSV. Compliance was 90 ml/cm H2O, resistance was 3 cm H2O/l/s, at high inspiratory effort, respiratory rate was 30 breaths per minute and delta pressure was 15 cmH2O. Note: During HF-BiPAP inspiratory flow to the helmet was constantly high at about 60 l/minute. Expiratory flow did not become zero due to the high constant free flow. BiVent = time-cycled pressure controlled switching between two continuous positive airway pressure levels; HF-BiPAP = high flow biphasic positive airway pressure; PSV = pressure support ventilation.