Effects of supplemental oxygen during activity in patients with advanced COPD without severe resting hypoxemia

Study objectives: To assess oxygen desaturation during activities and to ev aluate the short-term effects of supplemental O-2 use in patients with seve re COPD who do not qualify for long-term O-2 therapy. Design: A double-blind, randomized, placebo-controlled trial. Setting: Outpatients from the pulmonary diseases division of a tertiary-car e university hospital. Patients: Twenty patients with stable COPD with FEV1 /FVC ratios of < 50%, FEV1 levels < 55% of the predicted normal value, and Pao(2) levels of > 60 mm Hg when resting. Interventions: Patients were initially, evaluated with pulmonary function t ests, blood gas analysis, and Doppler echocardiography, and they underwent the following three 6-min walking tests (WTs) in a random sequence: basal W T (BWT); WT while breathing compressed air (CAWT); and WT while breathing O -2 (O2WT). Measurements and results: The distance walked was recorded in meters. Dyspn ea was measured by Borg scale measurement before and after the tests, and a rterial oxygen saturation measured by pulse oximetry (SPo2) was continuousl y monitored. Results were analyzed by grouping patients in the following ma nner: desaturators (DSs) (ie, patients with a drop in SPo2 of at least 5% a nd < 90% during the WT) vs nondesaturators (NDSs); and O-2 responders (ie, patients with an increase of at least 10% in the distance walked and/or a d ecrease of at least 3 points in Borg index score) vs nonresponders. During the BWT, 11 of 20 patients (55%) were defined as desaturators. During the O 2WT, the SPo2 remained at > 90% in every patient. The distance walked incre ased by 22% (p < 0.02), and dyspnea decreased 36% (p < 0.01) in DS patients . In INDS patients, O-2 administration reduced dyspnea by 47% (p < 0.001), but the distance walked did not improve. Responses were markedly different from one patient to another. No significant differences were noticed betwee n the results of the BWT and CAWT in any of the groups. Thirteen O-2 respon ders did not differ from 7 nonresponders either in basal data or in desatur ation measure during the BWT, except that all walking responders (five pati ents) were above the median of basal left ventricle performance. Conclusions: Most of the studied COPD patients desaturated during the BWT. O-2 administration avoided desaturation and could increase the distance wal ked and reduce dyspnea, but these effects were not related to walking desat uration in individual cases. Improvements were not a placebo effect. The th erapeutic role of O-2 dining activities in some patients with severe COPD n eeds to be individually assessed.