Physiological Requirements to Perform the Glittre Activities of Daily Living Test by Subjects With Mild-to-Severe COPD

BACKGROUND: The Glittre activities of daily living (ADL) test is supposed to evaluate the functional capacity of COPD patients. The physiological requirements of the test and the time taken to perform it by COPD patients in different disease stages are not well known. The objective of this work was to compare the metabolic, ventilatory, and cardiac requirements and the time taken to carry out the Glittre ADL test by COPD subjects with mild, moderate, and severe disease. METHODS: Spirometry, Medical Research Council questionnaire, cardiopulmonary exercise test, and 2 Glittre ADL tests were evaluated in 62 COPD subjects. Oxygen uptake ((V)over dot(O2)), carbon dioxide production, pulmonary ventilation, breathing frequency, heart rate, S-pO2, and dyspnea were analyzed before and at the end of the tests. Maximum voluntary ventilation, Glittre peak (V)over dot(O2)/cardiopulmonary exercise test (CPET) peak (V)over dot(O2), Glittre (V)over dot(E)/maximum voluntary ventilation, and Glittre peak heart rate/CPET peak heart rate ratios were calculated to analyze their reserves. RESULTS: Subjects carried out the Glittre ADL test with similar absolute metabolic, ventilatory, and cardiac requirements. Ventilatory reserve decreased progressively from mild to severe COPD subjects (P < .001 for Global Initiative for Chronic Obstructive Lung Disease [GOLD] 1 vs GOLD 2, P < .001 for GOLD 1 vs GOLD 3, and P < .001 for GOLD 2 vs GOLD 3). Severe subjects with COPD presented a significantly lower metabolic reserve than the mild and moderate subjects (P = .006 and P = .043, respectively) and significantly lower Glittre peak heart rate/CPET peak heart rate than mild subjects (P = .01). Time taken to carry out the Glittre ADL test was similar among the groups (P = .82 for GOLD 1 vs GOLD 2, P = .19 for GOLD 1 vs GOLD 3, and P = .45 for GOLD 2 vs GOLD 3). CONCLUSIONS: As the degree of air-flow obstruction progresses, the COPD subjects present significant lower ventilatory reserve to perform the Glittre ADL test. In addition, metabolic and cardiac reserves may differentiate the severe subjects. These variables may be better measures to differentiate functional performance than Glittre ADL time.