RESUMO
This study compares the performance characteristics and clinical effectiveness of the BiPAP-S/T (Respironics, USA) and VPAP-S/T (ResMed, Australia) pressure support ventilator during two weeks of nasal ventilation in 15 patients with stable chronic respiratory insufficiency. All patients were previously stabilised using nasal BiPAP ventilation for at least three months. Subjects had a maximum inspiratory pressure of 20 cm H2O and highest breathing rate of 24 per minute. VPAP is lighter and quieter than BiPAP-S/T (31 vs. 43 dB for IPAP:EPAP = 15:5 cm H2O and breathing frequency = 15 breaths per minute). Both machines demonstrate comparable and reliable triggering at low flow rates for zero and up to 30 l/min mask leak. Clinical evaluation in the S/T mode showed the two ventilators to be equally effective in supporting gas exchange during sleep. Sleep quality and number of respiratory arousals were very similar at the end of the two weeks' test period with BiPAP-S/T and VPAP-S/T. Synchronisation of VPAP-S/T during REM was probably better than with BiPAP-S/T, because in the presence of mouth leak BiPAP-S/T occasionally jammed in IPAP, but VPAP-S/T did not. In conclusion, in the tested settings VPAP-S/T is as effective as BiPAP-S/T in maintaining ventilation and controlling blood gases during sleep in patients with stable respiratory insufficiency.
