Long-term oxygen therapy stops the natural decline of endurance in COPD patients with reversible hypercapnia.
BACKGROUND
Respiratory muscle weakness is one of the most important causes of hypercapnia in patients with COPD. There is evidence that stable hypercapnic patients will benefit from long-term oxygen therapy (LTOT).


OBJECTIVE
The prognostic role of reversible hypercapnia in COPD is still unclear. Early implementation of LTOT in these patients may influence endurance time and mortality.


METHODS
In this pilot study, we investigated 28 patients (26 males, 49-74 years) with COPD, advanced airflow limitation [forced expiratory volume in 1 s (percentage of predicted value) 40.8 +/- 10.2] and mild hypoxaemia (pO(2) 66.5 +/- 6.3 mm Hg). All patients had developed a moderate reversible hypercapnia during an acute exacerbation or during exercise testing (peak pCO(2) 48.0 +/- 2.5 mm Hg). Patients were allocated randomly to a control group (n = 14) or an LTOT group (n = 14). The two groups were well matched in terms of physiological data. Lung function, endurance time (cycle ergometer), dyspnoea score, blood gases and LTOT compliance were measured at baseline and every 6 months over a period of 3 years.


RESULTS
Endurance time increased from 6.4 +/- 2.7 min at baseline to 7.1 +/- 2.7 min after 1 year in the LTOT group and decreased from 6.1 +/- 3.0 to 4.9 +/- 3.8 min in the controls (p < 0.05). After 1 year, the end-exercise dyspnoea score was significantly lower in the LTOT group (4.5 +/- 1.5) than in the controls (5.7 +/- 1.9).


CONCLUSIONS
COPD patients with reversible hypercapnia and mild hypoxaemia benefit from LTOT in terms of endurance time and a reduction of exertional dyspnoea after 1 year.
Krankenhaus Kloster Grafschaft, Zentrum für Pneumologie, Beatmungs- und Schlafmedizin, Schmallenberg, Germany. p.haidl@t-online.de
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Haidl
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Clement
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Wiese
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Dellweg
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Köhler
D000368:Aged; D015992:Body Mass Index; D018450:Disease Progression; D005080:Exercise Test; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D010102:Oxygen Inhalation Therapy; D010807:Physical Endurance; D010865:Pilot Projects; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000628:therapy*