Respiratory function during sleep in patients with chronic obstructive lung disease.

Hypoventilation of normal persons during sleep causes the arterial carbon dioxide tension to rise (1-9). Hypoventilation during sleep is accentu-ated when the respiratory center is further de-pressed by opiates (10); it might be suspected that carbon dioxide retention during sleep would be similarly accentuated in patients with chronic hypercapnia. Indeed, available evidence suggests that such patients with chronic obstructive pulmo-nary disease demonstrate even more marked hypo-ventilation while asleep than that seen in normal persons (11, 12). This study was undertaken to determine the extent of hypoventilation in sleep-ing patients with chronic obstructive pulmonary disease. The study also presented the opportunity to determine the mechanisms responsible for the hypoxia sometimes seen in such patients (13) and to determine the ventilatory pattern during sleep. Methods The only criteria for selection of subjects were avail-ability and the presence of severe chronic airway ob-struction. The first 11 patients were studied during the evening hours. These patients were brought to the lab-oratory shortly before their accustomed hour of sleep (8 to 11 p.m.). The next 8 patients were studied in the early afternoon after a light lunch (1 to 3 p.m.). No * Submitted for publication May 26, 1965; accepted