The time to desaturation in the 6MWD test can discriminate early desaturators who desaturate during their daily living activities and late desaturators who do not desaturate. Ambulatory oximetry would thus only be necessary in patients with a time to desaturation that ranges between 1 and 3'30''.

BACKGROUND: 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 P aO 2 > 60 mm Hg who desaturated during the 6-min walk test were followed for 5 years. Forty-eight patients had early desaturation (S pO 2 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 S pO 2 , lowest S pO 2 , and the time to S pO 2 < 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.

Background Comorbidities are a major cause of death in chronic obstructive pulmonary disease (COPD). The COPD‐comorbidity test (COTE) index was designed to measure comorbidity burden in this disease. The objective of this study was to compare the capability of COTE and the non‐COPD specific Charlson comorbidity index (CCI) to predict all‐cause mortality in real‐life conditions. Methods Retrospective observational study, carried out in two different series of consecutive COPD patients including, respectively, 790 and 439 subjects. The COTE and non‐age‐adjusted CCI indices were calculated and the values of the C‐statistic for predicting all‐cause mortality were compared for both indices. Results Median follow‐up was 54 months and there were 321 deaths within this period of time. The value of the C‐statistic for the CCI was significantly higher than for the COTE index in both groups. Conclusion When used in real‐life clinical practice, the value of the CCI to predict all‐cause mortality in COPD seems higher than that of the COTE index.

Overweight and obesity, as determined by body mass index, seem to behave like markers for early desaturation. This simple anthropometric measure might indicate point to potential early desaturation in COPD patients.