Average volume-assured pressure support in obesity hypoventilation: A randomized crossover trial.

BACKGROUND: Average volume-assured pressure support (AVAPS) has been introduced as a new additional mode for a bilevel pressure ventilation (BPV) device (BiPAP; Respironics; Murrysville, PA), but studies on the physiologic and clinical effects have not yet been performed. There is a particular need to better define the most efficient ventilatory treatment modality for patients with obesity hypoventilation syndrome (OHS).

METHODS: In OHS patients who did not respond to therapy with continuous positive airway pressure, the effects of BPV with the spontaneous/timed (S/T) ventilation mode with and without AVAPS over 6 weeks on ventilation pattern, gas exchange, sleep quality, and health-related quality of life (HRQL) assessed by the severe respiratory insufficiency questionnaire (SRI) were prospectively investigated in a randomized crossover trial.

RESULTS: Ten patients (mean [+/- SD] age, 53.5 +/- 11.7 years; mean body mass index, 41.6 +/- 12.1 kg/m2; mean FEV1/FVC ratio, 79.4 +/- 6.5%; mean transcutaneous P(CO2) [PtcCO2], 58 +/- 12 mm Hg) were studied. PtcCO2 nonsignificantly decreased during nocturnal BPV-S/T by -5.6 +/- 11.8 mm Hg (95% confidence interval [CI], -14.7 to 3.4 mm Hg; p = 0.188), but significantly decreased during BPV-S/T-AVAPS by -12.6 +/- 12.2 mm Hg (95% CI, -22.0 to -3.2 mm Hg; p = 0.015). Pneumotachographic measurements revealed a higher individual variance of peak inspiratory pressure (p < 0.001) and a trend for lower leak volumes but also for higher tidal volumes during BPV-S/T-AVAPS. The SRI summary scale score improved from 63 +/- 15 to 78 +/- 14 during BPV-S/T (p = 0.004) and to 76 +/- 16 during BPV-S/T-AVAPS (p = 0.014). Sleep quality and oxygen saturation also comparably improved following BPV-S/T and BPV-S/T-AVAPS.

CONCLUSION: BPV-S/T substantially improved oxygenation, sleep quality, and HRQL in patients with OHS. AVAPS provided additional benefits on ventilation quality, thus resulting in a more efficient decrease of PtcCO2. However, this did not provide further clinical benefits regarding sleep quality and HRQL.