RESUMO
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.
Assuntos
Respiração com Pressão Positiva/instrumentação , Respiração , Fluxo Expiratório Forçado , Humanos , Medidas de Volume Pulmonar , Modelos BiológicosRESUMO
Pipeline systems are used in most hospitals today to deliver medical oxygen to patient care areas. Intermittent reports have appeared concerning serious problems and failure with these systems. Mandated reserve systems have not provided the necessary backup at times. This article describes an auxiliary system to supply oxygen in a zonal fashion to wall outlets. The system will function during most failure situations; a hazard is inherent in the knowledge of this technique and will be examined.