Effects of pharmacologic treatment based on airflow limitation and breathlessness on daily physical activity in patients with chronic obstructive pulmonary disease

Abstract

Background: Improvement in the daily physical activity (PA) is important for the management of chronic obstructive pulmonary disease (COPD). However, the effects of pharmacologic treatment on PA are not well understood. We evaluated the effects of additional medications, including bronchodilator with or without inhaled corticosteroid, based on airflow limitation and breathlessness on the PA in COPD patients and the factors that could predict or affect the improvement in PA. Methods: A prospective non-randomized observational study was employed. Twenty-one COPD subjects without any other diseases that might reduce PA were recruited. The PA was measured with a triaxial accelerometer for 2 weeks, and pulmonary function tests and incremental shuttle walking tests were administered before and after 4-week treatment with an additional medication. Results: Bronchodilation was obtained by additional medication. The mean values of PA evaluated by metabolic equivalents (METs) at $3.0 METs and the duration of PA at $3.0 METs and $3.5 METs were improved by medication. The % change in the duration of PA at $3.5 METs was significantly correlated with the baseline functional residual capacity (FRC), residual volume, and inspiratory capacity/total lung capacity. However, the % change in the duration of PA at any intensity was not correlated with the % changes of any values of the pulmonary function tests or incremental shuttle walking test except the PA at $2.5 METs with FRC. Conclusion: Medication could improve the PA in patients with COPD, especially at a relatively high intensity of activity when medication was administered based on airflow limitation and breathlessness. The improvement was seen in the patients with better baseline lung volume, but was not correlated with the improvements in the pulmonary function tests or exercise capacity.