The effect of obesity on dyspnea, exercise capacity, walk work and workload in patients with COPD

COPD and obesity are major public health problems that cause mortality and morbidity all over the world. The combined of COPD and obesity is predicted to increase further in the coming years. Obesity primarily affects the pulmonary system by altering respiratory functions, exercise capacity, pulmonary gas exchange, and endurance and power of respiratory muscles. In this study, we aimed to compare the dyspnea sensation, exercise capacity, walk work and workload in obese COPD patients compared to preobese and normal overweight COPD patients.

218 patients with COPD were included in the study. According to the WHO criteria for body mass index (BMI), the patients were classified as normal-weight (BMI=18.5-24.9 kg/m2), pre-obese (BMI= 25-29.9 kg/m2) and obese (BMI= 30-39.9 kg/m2). All patient respiratory function tests and arterial blood gas analysis were performed. The mMRC dyspnea scale was used to assess the dyspnoea of the patients. The exercise capacities of the patients were determined by the 6-min walking test. Walk work and workload were calculated based on 6 minutes walking distance. The obtained values were compared between the three groups.

The FEV1/FVC ratio and TLCO value in pulmonary function tests are significantly higher in obese COPD patients than in other patients, while the VC value is significantly lower in patients with COPD (p= 0.001, p< 0.001, p= 0.01). Partial carbon dioxidewas significantly higher in obese COPD patients compared to other patients (p= 0.001). Dyspnea perceptions and walking distances did not differ significantly between groups. Walkwork and workload were significantly higher in obese COPD patients (p< 0.001, p= 0.005).

Obesity causes partial changes in blood gas and pulmonary function tests of patients with COPD. At the same time, it increases walkwork and workload. Despite all these changes, it has no negative effect on dyspnea perception and exercise capacity.