The six-minute walk test - a reliable test for detection of exercise-related desaturation in patients with chronic obstructive pulmonary disease.

INTRODUCTION: Exercise-induced desaturation is common in patients with moderate to severe chronic obstructive pulmonary disease (COPD). It provides additional information about physical capacity and disease evolution, and it is an important predictor of mortality.

Desaturation during Physical Exercise in COPD Patients - a Stable-over-time Phenomenon.

INTRODUCTION: Exercise-induced desaturation is a common finding in patients with moderate and severe COPD. It is an important marker in the course of disease that has a prognostic value for mortality risk. AIM: To monitor over time COPD patients with and without desaturation during 6-minute walking test (6MWT) and to assess the stability of that phenomenon. MATERIALS AND METHODS: A 6MWT was administered to 70 patients with COPD which ranged in severity from stage 2A to stage 4D (GOLD 2011); the patients had a mean age of 64.5±10.1, mean pack-years - 38.8±21, FEV1% = 46.4%±15.7%, FVC% = 73.7%±1.3%, MRC = 2.31±0.84, CAT = 20.8±6.6. Oxygen saturation was monitored during the test; indications for desaturation were a decrease of SpO2 by ≥4% and a fall in SpO2 to ≤88% for at least 3 min. The patients were followed-up for mean 40.9±22.3 months and tests were repeated. RESULTS: Patients were divided into two groups based on the decrease in SpO2: Group A included patients with desaturation (n=35) and Group B - patients with no desaturation (n=35). In 66 of the patients the desaturation profile was stable over time. Only two patients, who did not desaturated at baseline, experienced desaturation in the follow-up 6MWT and another two patients, who desaturated at baseline, did not have it later in the follow-up. CONCLUSION: Desaturation is a phenomenon that is persistent over time. Based on the results, it could be concluded that exercise-induced desaturation is a major marker of a particular COPD phenotype.