Chest
Volume 138, Issue 1, July 2010, Pages 179-187
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RECENT ADVANCES IN CHEST MEDICINE
Oxygen Therapy for Patients With COPD: Current Evidence and the Long-Term Oxygen Treatment Trial

https://doi.org/10.1378/chest.09-2555Get rights and content

Long-term use of supplemental oxygen improves survival in patients with COPD and severe resting hypoxemia. However, the role of oxygen in symptomatic patients with COPD and more moderate hypoxemia at rest and desaturation with activity is unclear. The few long-term reports of supplemental oxygen in this group have been of small size and insufficient to demonstrate a survival benefit. Short-term trials have suggested beneficial effects other than survival in patients with COPD and moderate hypoxemia at rest. In addition, supplemental oxygen appeared to improve exercise performance in small short-term investigations of patients with COPD and moderate hypoxemia at rest and desaturation with exercise, but long-term trials evaluating patient-reported outcomes are lacking. This article reviews the evidence for long-term use of supplemental oxygen therapy and provides a rationale for the National Heart, Lung, and Blood Institute Long-term Oxygen Treatment Trial. The trial plans to enroll subjects with COPD with moderate hypoxemia at rest or desaturation with exercise and compare tailored oxygen therapy to no oxygen therapy.

Section snippets

Survival

Supplemental oxygen is a well-established therapy with clear evidence for benefit in patients with COPD and severe resting hypoxemia, which is defined as a room air Pao2 ≤ 55 mm Hg or ≤ 59 mm Hg with signs of right-sided heart strain or polycythemia. Oxygen was the first treatment shown to prolong life in people with COPD.3, 4 Current recommendations for prescribing LTOT (Table 1) are based on results from two randomized trials in patients with COPD published almost 30 years ago: the Nocturnal

Mortality

In contrast with the results of the MRC study and NOTT, supplemental oxygen has not been shown to improve survival in patients with COPD and moderate hypoxemia.7, 8 Górecka et al7 randomly assigned 135 patients with a resting room air Pao2 of 56 to 65 mm Hg to receive supplemental oxygen for > 17 h/d (to raise Pao2 to ≥ 65 mm Hg) or no supplemental oxygen. Over a mean observation of 40.9 months, cumulative survival in the treatment and control groups did not differ significantly. Furthermore,

Definition

Important challenges in ascertaining the effectiveness of supplemental oxygen during activity in patients with COPD are the lack of uniform criteria for defining exertional desaturation and standardized exercise protocols. Threshold values for oxygen desaturation range from 88% to 90%, and relative declines vary from 2% to 5% in published investigations. Some studies require maintenance of the oxygen saturation by pulse oximetry (Spo2) below a threshold value for a specified interval (usually

Definition

Nocturnal oxygen desaturation (NOD) has been reported in patients with COPD with an awake Pao2 > 60 mm Hg.39, 40, 41, 42, 43, 44, 45 The most significant episodes of NOD occur during rapid eye movement sleep, with a reported prevalence of 27%.46 However, there are no accepted standards for the level or duration of desaturation that define NOD in patients with COPD45, 46, 47 (Table 3).

Mortality

Although retrospective data suggest a decreased survival in patients with NOD,49 only a few studies examined the

The LOTT

Based on the evidence and unanswered questions summarized herein and the research needs identified by the Sixth Oxygen Consensus Conference2 and a workshop report on LTOT,1 the National Heart, Lung, and Blood Institute and Centers for Medicare & Medicaid Services are sponsoring the LOTT. The LOTT is a multicenter, randomized clinical trial of tailored oxygen therapy (ie, continuous oxygen therapy [24 h/d] for subjects with moderate resting hypoxemia and supplemental oxygen therapy with sleep

Acknowledgments

Financial/nonfinancial disclosures: The authors have reported to the CHEST the following conflicts of interest: Dr Panos has contracted research with Novartis, Boehringer-Ingelheim, and Pearl Therapeutics. Dr Make has participated in two advisory boards for Respironics over the past 3 years. Dr Stoller has served as a consultant to Respironics, Talecris, CSL-Behring, Boehringer-Ingelheim, and Asthmatx and has presented lectures supported by Grifols, Baxter Healthcare, Talecris, Respironics, and

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    Funding/Support: This project is supported through federal funding from the National Heart, Lung, and Blood Institute, National Institutes of Health, Department of Health and Human Services [contracts HHSN268200736183C, HHSN268200736184C, HSN268200736185C, HHSN268200736186C, HHSN268200736187C, HHSN268200736188C, HHSN268200736189C, HHSN268200736190C, HHSN268200736191C, HHSN268200736192C, HHSN268200736193C, HHSN268200736194C, HHSN268200736195C, HHSN268200736196C, HHSN268200736197C, Y1-HR-7019-01, and Y1-HR-8076-01] in cooperation with the Centers for Medicare and Medicaid Services, Department of Health and Human Services.

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (http://www.chestpubs.org/site/misc/reprints.xhtml).

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