Relationship of Respiratory Muscle Strength and Walking Distance with Pulmonary Function, Quality of Life and Nitric Oxide in Chronic Obstructive Pulmonary Disease Patients

Abstract

Introduction: Respiratory muscle strength and walking distance have been associated with the severity of disease and is used in prescribing rehabilitation programs for persons with Chronic Obstructive Pulmonary Disease (COPD). Aim: To evaluate the correlation between respiratory muscle strength and walking distance with pulmonary function, plasma Nitric Oxide (NO) levels and Quality of Life (QoL) score in persons with stable COPD. Materials and Methods: The present cross-sectional study was conducted in 35 participants with moderate severity, stable COPD. Physical outcomes such as respiratory muscle strength (PImax), walking distance {6-minute walking distance (6MWD)} and pulmonary function {Forced Vital Capacity (FVC), Forced Expiratory Volume at one second (FEV1), and FEV1/FVC ratio} were evaluated. In addition, a total Clinical COPD Questionnaire (CCQ) and plasma NO levels were determined. The Pearson’s correlation test was analysed statistically. Results: The present results revealed that the participants had a significantly positive correlation on PImax with FVC (r=0.624, p<0.001), FEV1 (r=0.539, p<0.001), and NO (r=0.510, p<0.001), whereas, the 6MWD correlated positively to FVC (r=0.390, p=0.018), FEV1 (r=0.548, p<0.001), FEV1/FVC ratio (r=0.55, p<0.001) and NO (p=0.416, p=0.013), but negatively to the total QoL score (r=-0.579, p<0.001). Conclusion: This preliminary study demonstrates that respiratory muscle strength and walking performance possibly relate to pulmonary function and plasma NO among persons having COPD with moderate severity.

Keywords

• maximal inspiratory muscle pressure
• respiratory muscle strength
• six-minute walking distance