Effects of Non-REM sleep on ventilation and respiratory mechanics in adults with cystic fibrosis

To determine the effects of sleep upon respiratory function, five adult patients with cystic fibrosis (CF) were monitored during sleep in a horizontal body plethysmograph. Tidal volume (VT) decreased during non-rapid-eye-movement (NREM) sleep, resulting in a NREM sleep-associated decrement in minute ventilation (VI = 11.10 +/- 0.67, 9.32 +/- 0.91, and 9.17 +/- 1.42 L during wakefulness, stage 2, and stages 3-4, respectively, p < 0.05). There were no NREM sleep-associated changes in respiratory frequency (f) or inspiratory time (TI), but respiratory neuromuscular output was reduced during NREM sleep P-0.1 = 3.33 +/- 0.57, 1.79 rt 0.23, and 1.99 +/- 0.21 cm H2O during wakefulness, stage 2, and stages 3-4, respectively, p = 0.005). Upper airway resistance (Rua), lower airway resistance (Rla), and lung volume did not change in association with NREM sleep. Functional residual capacity (FRC) measurements made using helium dilution indicated large volumes of trapped gas, likely a result of peripheral airways that were closed at FRC. We conclude that in adult patients with CF, NREM sleep is associated with a decrement in VT and VI, NREM sleep does not alter airflow resistance or lung volume, and the observed reductions in VT and VI apparently result from a NREM sleep-associated decrease in respiratory neuromuscular output.