Exercise desaturation in patients with COPD is a pathophysiological phenomenon that is not wholly understood and whose clinical consequences are still unclear.
METHODS:
Eighty-three patients with moderate to severe COPD and PaO2 > 60 mm Hg who desaturated during the 6-min walk test were followed for 5 years. Forty-eight patients had early desaturation (SpO2 fell below 90% less than one minute after starting the walk test). Spirometry, blood-gas measurements, and 6-min walk tests were performed every 6 months. We recorded 6-min walk distance, baseline SpO2, lowest SpO2, and the time to SpO2 < 90%. In each control, stable patients with severe hypoxia at rest who required long-term oxygen therapy were identified.
RESULTS:
Upon completion of the study, 65% of the early desaturators had developed severe hypoxemia and required long-term home oxygen, versus 11% in the non-early desaturators (P < .001).
CONCLUSIONS:
In patients with moderate to severe COPD, desaturation within the first minute of the 6-min walk test predicts the need for long-term home oxygen at 5-year follow-up.
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