MEASUREMENT OF SYMPTOMS, LUNG HYPERINFLATION, AND ENDURANCE DURING EXERCISE IN CHRONIC OBSTRUCTIVE PULMONARY-DISEASE

Changes in lung hyperinflation, dyspnea, and exercise endurance are im portant outcomes in assessing therapeutic responses in chronic obstruc tive pulmonary disease (COPD). Therefore, we studied the reproducibili ty of Borg dyspnea ratings, inspiratory capacity (IC; to monitor lung hyperinflation), and endurance time during constant-load symptom-limit ed cycle exercise in 29 patients with CORD (FEV1 = 40 +/- 2% predicted ; mean +/- SEM). Responsiveness was also studied by determining the ac ute effects of nebulized 500 mu g ipratropium bromide (IB) or saline p lacebo (P) on these measurements. During each of four visits conducted over an 8-wk period, spirometry and exercise testing were performed b efore and 1 h after receiving IB or P (randomized, double-blinded). Hi ghly reproducible measurements included: endurance time (intraclass co rrelation R = 0.77, p < 0.0001); Borg ratings and IC at rest, at a sta ndardized exercise time (STD), and at peak exercise (R > 0.6, p < 0.00 01); and slopes of Borg ratings over time, oxygen consumption ((V) ove r dot O-2), and ventilation (R > 0.6, p < 0.0001). Responsiveness was confirmed by finding a significant drug effect for: change (Delta) in endurance time (p = 0.0001); Delta Borg(STD) and Delta Borg-time slope s (p < 0.05); and Delta IC at rest, at STD, and at peak exercise (p = 0.0001). With all completed visits, Delta Borg(STD) correlated better with Delta ICSTD than any other resting or exercise parameter (n = 115 , r = -0.35, p < 0.001). We concluded that Borg dyspnea ratings, and m easurements of IC and endurance time during submaximal cycle exercise testing are highly reproducible and responsive to change in severe COP D.