Exercise tolerance and dyspnea in patients with chronic obstructive pulmonary disease

Abstract

Peripheral muscle weakness and nutritional disorders, firstly loss of body weight, are common findings in patients with chronic obstructive pulmonary disease (COPD). The aim of this study was to analyse the impact of pulmonary function parameters, nutritional status and state of peripheral skeletal muscles on exercise tolerance and development of dyspnea in COPD patients. Thirty COPD patients in stable state of disease were analyzed. Standard pulmonary function tests, including spirometry, body pletysmography, and measurements of diffusion capacity were performed. The 6-minute walking distance test (6MWD) was done in order to assess exercise tolerance. Level of dyspnea was measured with Borg scale. In all patients midthigh muscle cross-sectional area (MTCSA) was measured by computerized tomography scan. Nutritional status of patients was estimated according to body mass index (BMI). Statisticaly significant correlations were found between parameters of pulmonary function and exercise tolerance. Level of airflow limitation and lung hyperinflation had significant impact on development of dyspnea at rest and especially after exercise. Significant positive correlation was found between MTCSA and exercise tolerance. Patients with more severe airflow limitation, lung hyperinflation and reduced diffusion capacity had significantly lower MTCSA. Exercise tolerance in COPD patients depends on severity of bronchoobstruction, lung hyperinflation and MTCSA. Severity of bronchoobstruction and lung hyperinflation have significant impact on dyspnea level.