Clinical characteristics of COPD patients with early-onset desaturation in the 6-minute walk test

Exercise-induced desaturation in chronic obstructive pulmonary disease (COPD) frequently has prognostic implications. Desaturation within the first minute of the walk 6-minute walk test will probably also occur in daily life activities and translate into hypoxaemic respiratory failure at rest in later years. This study aimed at comparing these patients with those who desaturate after the first minute and determine potential markers.

We conducted a cross-sectional, retrospective study collecting data on respiratory function tests, cardiovascular comorbidity, body mass index, pack-year index, 6-minute walk test outcomes, BODE index, and Charlson comorbidity index. Patients who desaturated during the first minute of the test were referred to as early desaturators compared to the non-early ones.

We observed a higher mean body mass index in early desaturating patients, and an inverse relation as to the body mass index categories <25, 25-29, and ≥30. Early desaturators had a lower FEV₁/FVC index. The mean distance walked in the test was shorter in early than in non-early desaturators, and they desaturated more deeply.

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.