Inspiratory work and airway pressure with continuous positive airway pressure delivery systems.
To determine work-of breathing with continuous positive airway pressure (CPAP) delivery systems, we used a lung model to simulate spontaneous breathing. "Additional work" during tidal breathing was derived by comparing change in airway pressure with change in tidal volume. Seven demand-flow CPAP delivery systems were compared with one continuous-flow, 5-L reservoir-bag system (flow of 60 L/min to maintain positive airway pressure). It was concluded that demand-flow CPAP delivery systems vary widely in the amount of additional work required of a patient. When a lung model is used, some demand-flow systems perform as well as, or better than, a continuous-flow reservoir-bag system.
D005540:Forced Expiratory Flow Rates; D006801:Humans; D008176:Lung Volume Measurements; D008954:Models, Biological; D011175:Positive-Pressure Respiration / Q000295:instrumentation*; D012119:Respiration