Randomised trial of ambulatory oxygen in oxygen-dependent COPD
- I. García-Talavera
- I. García-Talavera, Investigation Unit, Candelaria University Hospital, Santa Cruz de Tenerife, Spain
To the Editors:
I read with interest the article by Lacasse et al. 1, which found no benefit in using ambulatory oxygen (AO) in chronic obstructive pulmonary disease. I think that there were not enough patients in the study not to recommend its use. The authors have not shown the variations of oxygen saturation during the 6-minute walking test (6MWT). Oxygen therapy may improve exercise capacity in patients with desaturation during the walking test 2.
Liquid oxygen is better than gas from cylinders for AO therapy. The Enright and Sherill 3 reference values of a 6MWT are very different from those of Troosters et al. 4 or Gibbons et al. 5. The latter references may be preferable because the equation by Enright and Sherill 3 gives smaller values. In my opinion, the average partial pressure of oxygen at rest of the patients, 7.0 kPa (53 mmHg), was not very low. In patients with severe hypoxaemia, the results could possibly differ.
I believe that ambulatory oxygen therapy in chronic obstructive pulmonary disease should depend on each patient. A certain subgroup of patients with chronic obstructive pulmonary disease might benefit from ambulatory oxygen. The 6-minute walking test is a prognostic tool that gives a valuable insight into the normal activities of daily living.
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