INFLUENCE OF SLEEP ON RESPIRATORY-FUNCTION IN EMPHYSEMA

To assess the influence of sleep on respiratory function, five patient s with chronic obstructive pulmonary disease (COPD) with laboratory ev idence of emphysema were monitored during sleep in a horizontal body p lethysmograph. Neither lung volume nor lower airway resistance (Rla) c hanged in association with sleep. Upper airway resistance (Rua) increa sed during sleep and was highest during rapid eye movement (REM) sleep (Rua = 5.9 +/- 1.1, 9.6 +/- 2.1, 11.2 +/- 1.5, and 15.6 +/- 4.1 cm H2 O/L/s during wakefulness, Stages 2, 3-4, and REM, respectively, p < 0. 05). Tidal volume (VT) decreased during sleep, resulting in a sleep-as sociated decrement in minute ventilation (VI = 8.69 +/- 0.46, 7.64 +/- 0.65, 7.08 +/- 0.70, and 5.62 +/- 0.47 L during wakefulness, Stages 2 , 3-4, and REM, respectively, p < 0.05). Respiratory neuromuscular out put was also reduced during sleep (esophageal occlusion pressure [P-0. 1] = 2.69 +/- 0.39, 2.02 +/- 0.27, 1.90 +/- 0.27, and 1.63 +/- 0.25 cm H2O during wakefulness, Stages 2, 3-4, and REM, respectively, p = 0.0 05). We conclude that in patients with emphysema (1) sleep does not al ter lung volume or increase lower airway resistance, (2) sleep is asso ciated with a decrease in VT and VI, and (3) sleep is associated with an increase in Rua and a reduction in P-0.1 that may contribute to the sleep-associated decrease in VI.