Acute effect of exercise on ventilation inhomogeneity in adult cystic fibrosis patients

A bronchoconstrictor or bronchodilator response to exercise has been documented in cystic fibrosis. This could alter the distribution of ventilation, but no data are available. Overall ventilation inhomogeneity can be quantified by the slope of phase III (ΔN 2 /L). The aim of this study was to investigate the effect of exercise on ΔN 2 /L in adult patients with cystic fibrosis. We studied 12 (6 men) consecutive, Caucasian, ambulatory adult cystic fibrosis patients, after completion of a hospital based outpatient pulmonary rehabilitation program. Patients had (mean±SD): age=32±9 y, FEV 1 , %pred=42±20, FVC, %pred=64±21, FEV 1 /FVC, %=53±13, TLC, %pred=68±8, and DLco, %pred=68±14. Patients underwent an incremental cardiopulmonary exercise test (CPET). Simple spirometry and ΔN 2 /L were measured before and immediately after the completion of the CPET. All patients had a physiotherapy session for airway clearance on the same day and before the CPET. The maximum work rate (WRmax, %pred) was 59±25. ΔN 2 /L, %pred (463±216) and FEV 1 , %pred was abnormal in all patients. A very good relationship was indentified between ΔN 2 /L, %pred and FEV 1 , %pred (r= -0.872, p 2 /L, %pred was closely correlated to WRmax, %pred (r= -0.722, p=0.008). There was a significant improvement of FEV 1 by 4% (60 ml) post exercise (pre: 1.40±0.80, post: 1.47±0.83 L; p=0.049). ΔN 2 /L was significantly decreased by 16% post exercise (pre: 5.6±3.0, post: 4.6±2.6 %/L; p=0.019). In conclusion, ΔN 2 /L is increased in adult cystic fibrosis patients and is closely related to FEV 1 and WRmax. Furthermore, it is lower after exercise, thus indicating that exercise may improve the overall ventilation inhomogeneity in cystic fibrosis.