EXERTIONAL OXYGEN OF LIMITED BENEFIT IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY-DISEASE AND MILD HYPOXEMIA

It is unclear whether short-term benefits from supplemental oxygen tra nslate into improved quality of life in patients with severe COPD. In a 12 wk double-blind randomized crossover study, we assessed the effec ts of supplemental air and oxygen on exercise performance (step tests and 6 min walking distance [6MWD]) initially and after two 6 wk period s at home using exertional cylinder air or oxygen. We measured quality of life at baseline and after the two 6 wk domiciliary periods. The 2 6 patients (24 males) had a mean age of 73 +/- 6 yr. mean FEV(1), 0.9 +/- 0.4 L; mean DL(CO), 10.6 +/- 2.4 ml/min/mm Hg; mean resting P-O2, 69 +/- 8.5 (range 58 to 82) mm Hg; mean PCO2, 41 +/- 3.3 mm Hg; and me an resting Sa(O2), 94 +/- 2.1 (mean +/- SD). Laboratory tests were per formed breathing intranasal air or oxygen at 4 L/min, and measurements were made of Sa(O2) and Borg dysnea scores. Supplemental oxygen incre ased 6MWD and steps by small, statistically significant increments acu tely at baseline and after 6 and 12 wk, without corresponding falls in Borg score. Degree of desaturation at baseline did not correlate with increase in 6MWD or steps achieved at baseline or at 6 or 12 wk, nor with the domiciliary gas used. There was no difference in 6MWD or step s achieved while breathing supplemental oxygen after 6 wk of domicilia ry oxygen compared with domiciliary air. Small improvements in quality of life indices were found after domiciliary oxygen, and mastery also improved after domiciliary air. There were no differences in quality of life, however, when domiciliary oxygen was compared with domiciliar y air. Although oxygen supplementation induced small acute increments in laboratory exercise performance, such improvements had little impac t on the patients' daily lives.