CHANGES IN PULMONARY FUNCTION AFTER SYMPTOM LIMITED GRADED EXERCISE TESTING IN COPD PATIENTS 1199

Abstract

Although exercise has a known bronchodilator effect in normals, it is thought that COPD patients experience air trapping. The purpose of this study was to invesigate whether symptom limited graded exercise testing (GXT) elicits changes in forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) in COPD patients, and if so what factors may best predict these changes. Seventy eight patients with a mean±SEM FEV1 of 1.51±0.0001 and FEV1/FVC% of 54.42±0.0014 underwent a symptom limited GXT using a treadmill. Maximal flow volume loops prior to and 1-2 minutes following the GXT were performed. Significant differences between pre and post GXT FEV1 (mean increase of 0.088 L, p<0.0001) and FVC (mean increase of 0.116 L, p<0.0001) were found. Using previously measured PFT data, GXT data, and smoking history, forward selection linear regression was performed to determine the best predictors of change in FEV1 and FVC with the following results: Change in FEV1=FEV1/FVC(0.0038)-%TLC pred(0.0038)+%RV pred(0.0025)-%change FVC post bronchodilator (0.0034)+%change FEV1 postbronchodilator (0.0114)-wt(0.001)+ age(0.0034)+ breathing reserve(0.0025)-0.275 (R=0.81) Change in FVC = FEV1% pred(0.0025)+ RV/TLC(0.7076)+%change FVC post bronchodilator(0.0019)+%change FEV1 postbronchodilator(0.0059)- wt(0.0014)+ cigarettes/day(0.0058)- peak RPE(0.0216)- 0.154 (R=0.66) Conclusion: Exercise elicited improvements in both FEV1 and FVC in contrast to what has been previously shown with COPD patients. Differences in severity of disease may account for the conflicting results. PFT results, GXT data, and smoking history proved useful in predicting changes.