thought objectives: To assess oxygen desaturation during activities and to evaluate the short-term events of supplemental [O.

thought objectives: To assess oxygen desaturation during activities and to evaluate the short-term events of supplemental [O.sub.2] use in patients with hard COPD who do not qualify for long-term [Osub2] therapy.

Design: A double-blind, randomized, placebo-controlled trial.

Setting: Outpatients from the pulmonary diseases division of a tertiary-care university hospital.

Patients: Twenty patients with stable COPD with [FEVsub1]/FVC ratios of [is les than] 50% [FEVsub1] evens [is less than] 55% of the predicted normal value, and Pa[O.sub.2] of the same heights of [is greater than] 60 mm Hg when resting.

Interventions: Patients were initially evaluated with pulmonary function proofs blood gas analysis, and Doppler echocardiography, and they underwent the following three 6-min walking ordeals (WTs) in a random sequence: basal WT (BWT); WT while breathing shut firmlyed air (CAWT); and WT while breathing [Osub2] ([Osub2]WT)

Measurements and results: The distance walked was recorded in meter Dyspnea was measured by the agency of Borg scale measurement before and after the proofs and arterial oxygen saturation measured at pulse oximetry (Sp[O.sub.2]) was continuously monitored. originates were analyzed by grouping patients in the following manner: desaturators (DSs) (ie, patients with a least bit in Sp[O.sub.2] of at least 5% and [is les than] 90% during the WT) v nondesaturators (NDSs); and [Osub2] responder (ie, patients with an increase of at least 10% in the distance walked and/or a decrease of at least 3 points in Borg index score) v nonresponders. During the BWT 11 of 20 patients (55%) were defined as desaturators. During the [Osub2]WT the Sp[Osub2] remained at [is greater than] 90% in each patient. The distance walked increased by way of 22% (p [is less than] 002) and dyspnea decreased 36% (p [is les than] 001) in D patients. In ND patients, [Osub2] administration reduc dyspnea from 47% (p [is less than] 0001) if it were not that the distance walked did not improve. replications were markedly different from single in kind patient to another. No significant differences were noticed between the issues of the BWT and CAWT in any of the arranges Thirteen [O.sub.2] responders did not differ from 7 nonresponders either in basal data or in desaturation measure during the BWT leaving out that all walking responders (five patients) were above the median of basal left ventricle performance.

Conclusions: in the greatest degree of the studied COPD patients desaturated during the BWT [Osub2] administration avoided desaturation and could increase the distance walked and render dyspnea, but these effects were not related to walking desaturation in individual cases. Improvements were not a placebo purport The therapeutic role of [Osub2] during activities in a certain number of patients with severe COPD lacks to be individually assessed. (CHEST 2001; 120:437-443)

lock opener words: COPD; daily living activity; exercise-induced hypoxemia; exercise-induced dyspnea; left ventricle performance; oxygen therapy

Abbreviations: BWT = 6-min walking touchstone performed while breathing room air; CA = wrap closelyed air; CAWT = 6-min walking ordeal performed while breathing compressed air; DLA = daily living activity; DLCO = diffusing capacity of the lung for carbon monoxide; D = desaturator; ND = nondesaturator; [Osub2]WT = 6-min walking trial performed while breathing oxygen; Sa[O.sub.2] = arterial oxygen saturation; Sp[Osub2] = arterial oxygen saturation measured from pulse oximetry; WT = 6-min walking test

Long-term oxygen therapy is the and nothing else treatment that has been shown to improve survival in COPD patients with strait-laced hypoxemia, based on the number of hours of daily use.[1,2] There are well-established physiologic criteria for prescribing family oxygen.[3,4] However, some patients do not engage these criteria during rest, further significant hypoxemia occurs during exertion.[5,6] more [i]or[/i] less studies[7-9] have found that the short-term benefits of oxygen during exertion include increased exercise performance and reduction in dyspnea. However, other studies did not confirm these findings.[10] In fact, there is plane a controversy about a placebo effect[7-12] The long-term benefits of oxygen when used during exercise alone are unknown.

There are no widely accepted evidence-based criteria for prescribing oxygen single during daily living activities (DLAs) in COPD patients without hypoxemia during rest[71113-15] Medicare indications are a Pa[O.sub.2] plain of 55 mm Hg or an arterial oxygen saturation (Sa[O.sub.2]) flush of 88% documented during exercise, however there are no reasons to consider beforehand that solitary exercise desaturators would benefit with oxygen There is a ne for information about which COPD patients could benefit from of that kind therapy.

To further clarify these points, we leadershiped a randomized, double-blind, placebo-controlled trial in order to assess desaturation during exercise in COPD patients, and to evaluate the short-term consequences of oxygen therapy on dyspnea and performance during activities in COPD patients without resting hypoxemia.

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