Inspiratory work and airway pressure with continuous positive airway pressure delivery systems

Chest. 1985 Oct;88(4):519-26. doi: 10.1378/chest.88.4.519.


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.

MeSH terms

  • Forced Expiratory Flow Rates
  • Humans
  • Lung Volume Measurements
  • Models, Biological
  • Positive-Pressure Respiration / instrumentation*
  • Respiration*