THEOPHYLLINE IMPROVES GAS-EXCHANGE DURING REST, EXERCISE, AND SLEEP IN SEVERE CHRONIC OBSTRUCTIVE PULMONARY-DISEASE

The effects of theophylline on pulmonary function and gas exchange dur ing rest, sleep, and exercise were assessed in 10 patients with severe but stable chronic obstructive pulmonary disease (COPD; median FEV1, 31% of predicted). The study was randomized, double blind, placebo con trolled, and crossover in design, with each study period lasting 3 wk, and all other usual bronchodilator therapy was continued unchanged. A ll patients had detailed pulmonary function tests, in addition to exer cise testing and overnight sleep studies by standard polysomnography. Theophylline significantly improved gas exchange during rest, exercise , and sleep. Awake resting arterial blood gases showed a higher Pa(O2) on theophylline (78 [53 to 93] mm Hg, median [range]) than placebo (7 2 [47 to 83] mm Hg; p < 0.01 by ANOVA), and Pa(CO2) was lower on theop hylline (42 [38 to 54]) compared with placebo (45 [40 to 51], p < 0.05 by ANOVA). Arterial oxygen saturation (Sa(O2)) was significantly high er on theophylline than placebo during exercise and sleep (p < 0.01), and transcutaneous CO2 was lower during sleep (p < 0.05). Theophylline also resulted in significantly improved pulmonary function and reduce d trapped gas volume (p < 0.05). Exercise performance was no different during theophylline or placebo phases of the study. Sleep quality, ho wever, was significantly impaired on theophylline. We conclude that th eophylline has clinically significant benefits in patients with severe COPD.