PURPOSE: Noninvasive bilevel positive airway pressure (PAP) therapy can improve minute ventilation (VE) in patients with chronic respiratory insufficiency (CRI); however, such therapy is fixed and may not adapt to the varying needs of a patient. We hypothesized that in patients with chronic respiratory insufficiency despite receiving bilevel PAP therapy, VE will decrease with deeper stages of sleep and during supine position when compared to wakefulness and lateral decubitus position, respectively. We also hypothesized that VE during averaged volume assured pressure support (AVAPS) is less susceptible to the influences of sleep-wakefulness state and body position than during bilevel PAP therapy.
METHODS: Three consecutive sleep studies were performed in each of 28 patients –prescription validation night, AVAPS or bilevel PAP therapy, and crossover to AVAPS or bilevel PAP therapy. Tidal volume output from device was validated in a separate bench study.
RESULTS: Minute ventilation was lower during deeper stages of sleep than wakefulness (P<0.0001); was lower during bilevel PAP than AVAPS therapy (P=0.029); tended to be lower with greater body mass index (P=0.07), but was not influenced by body position.Changes in minute ventilation were primarily due to changes in tidal volume rather than respiratory rate. These decrements in minute ventilation were associated with a statistically significant, but clinically minor, decrease in oxygenation (P=0.038).
CONCLUSION: In patients with CRI, minute ventilation was determined by sleepwakefulness state, body mass index, and mode of therapy, but not by body position.
CLINICAL IMPLICATIONS: Novel modes of therapy may guarantee adequate ventilation in this patient population.
DISCLOSURE: Cristina Ambrogio, University grant monies None; Grant monies (from sources other than industry) American Lung Association, Veterans Affairs, American Sleep Medicine Foundation for peer-reviewed research grants; Grant monies (from industry related sources) Research grant from Respironics, Inc (Study sponsor) $200,000; Shareholder None; Employee None; Fiduciary position (of any organization, association, society, etc, other than ACCP None; Consultant fee, speaker bureau, advisory committee, etc. Takeda Pharmaceuticals ($7,500); Other None; Product/procedure/technique that is considered research and is NOT yet approved for any purpose. Averaged volume assured pressure support (AVAPS) is not yet approved in the US.