Pulmonary Function test and Exercise Capacity in COPD Smokers vs. Healthy Smokers.

Abstract

Objective: This study aims to compare the pulmonary function tests (PFTs) and exercise capacity of COPD smokers to those of healthy smokers, while also examining the relationship between smoking index and various metabolic variables.

Methods: This evaluative study was conducted in the Department of Respiratory Medicine at JLN Medical College, Ajmer, Rajasthan, from August 1, 2017, to October 30, 2018. The study aimed to compare cardiopulmonary exercise testing (CPET) parameters between COPD smokers and healthy smokers, focusing on identifying reasons for exercise limitations. The study received ethical clearance from the institution’s ethical committee prior to initiation.

Result: The study revealed significant findings regarding the impact of Chronic Obstructive Pulmonary Disease (COPD) on smokers compared to healthy smokers. Among the COPD smokers, 50% were classified as having moderate COPD, with 40% experiencing Grade 3 dyspnea and 20% reporting Grade 4, indicating a high prevalence of severe respiratory impairment. Pulmonary function tests showed that COPD smokers had a significantly lower FEV1/FVC ratio of 59.2 ± 10.5% and % predicted FEV1 of 55.6 ± 12.8%, compared to healthy smokers, who had values of 80.3 ± 5.2% and 91.2 ± 8.1%, respectively (p < 0.001 for both). Additionally, the 6-minute walk distance (6MWD) was markedly reduced in COPD smokers at 350.5 ± 80.2 meters versus 470.8 ± 65.5 meters in healthy smokers (p < 0.001). The time spent on cardiopulmonary exercise testing (CPET) was also lower for COPD smokers, averaging 5.3 ± 1.4 minutes compared to 8.2 ± 1.6 minutes for healthy smokers (p < 0.001). While no significant correlation was found between the smoking index and pulmonary function, a negative correlation was observed between the smoking index and 6MWD in both groups, indicating that higher smoking exposure is associated with reduced exercise capacity (COPD smokers r = -0.42, p = 0.01; healthy smokers r = -0.46, p = 0.02). Overall, these findings underscore the detrimental effects of COPD on lung function and physical performance in smokers.

Conclusion: In conclusion, this study effectively compared pulmonary function tests (PFTs) and exercise capacity between COPD smokers and healthy smokers. COPD smokers showed significantly impaired lung function, with an FEV1/FVC ratio of 59.2 ± 10.5% versus 80.3 ± 5.2% in healthy smokers (p < 0.001). Exercise capacity was also notably reduced, with a 6-minute walk distance (6MWD) of 350.5 ± 80.2 meters compared to 470.8 ± 65.5 meters in healthy smokers (p < 0.001). While a negative correlation was found between the smoking index and 6MWD, no significant correlation existed between the smoking index and pulmonary function. These results emphasize the severe impact of smoking on lung health and physical performance in COPD patients.