The purpose of this study was to assess the incidence, degree, pattern, and time course of pulmonary function test (PFT) changes measured after a dynamic exercise challenge. Forced expiratory maneuvers were performed before and serially after a 7-min run-walk in 44 patients with cystic fibrosis (CF). Twenty-four patients met at least one PFT criterion for exercise-induced bronchospasm (EIB) within 21 min after exercise, and 38 patients had >5% increase in a PFT parameter at some point after exercise. The mean time of greatest increase in PFTs occurred sooner than the greatest decrease, which was later than for 22 patients with asthma or allergic rhinitis found to have EIB. Age was inversely related to percentage fall in forced expiratory volume in 1 s (FEV,) after exercise. These results demonstrate a distinct pattern of PFTs measured after exercise in most patients with CF, with an early bronchodilation followed by a significant decrease in PFTs.
Ted Kaplan, Gina Moccia, and Robert M. McKey, Jr., are with the Pediatric Exercise Medicine Service and Division of Pediatric Pulmonary Medicine, Department of Pediatrics, University of Miami School of Medicine, Miami, FL 33101.