[Comparison of CPAP and BiPAP equipment with reference to work of breathing, pressure and flow constancy].

We have investigated mask pressure curves and nasal flow during nasal C- and BiPAP ventilation in the recumbent position. Nasal spontaneous breathing, C- and BiPAP-applications of 10 and 10/7 cmH2O have been investigated in 7 patients and 4 controls. With aid of an automatic computerised analysis each in- and expiratory phase has been normalized by time and plotted as pressure-volume-loop from pooled data. The ventilators showed significant intra- and inter-machine differences. The investigations are considered as approach to real assessment of patient's work of breathing on home ventilators. They clearly show that ventilators have individual patterns, which should be considered carefully, long term machine-according effects are not yet known.