INCREASED PHYSIOLOGICAL DEAD SPACE DURING EXERCISE AFTER BRONCHODILATION IN CYSTIC-FIBROSIS

Bicycle ergospirometry was performed on 14 patients with cystic fibros is (CF), for evaluating the effects of salbutamol and theophylline on the ventilatory response to exercise. After 1 week without bronchodila tor therapy the patients cycled at 1/3 and 2/3 of their individual max imal working capacity (Wmax). The test was repeated three times after treatment with salbutamol, theophylline, or both drugs, respectively. After the combined therapy, physiological deadspace, ventilation, vent ilatory equivalent of oxygen, and end-expiratory oxygen pressure incre ased significantly during steady state exercise at 1/3 Wmax Similar, a lthough not statistically significant changes, were observed after mon otherapy with salbutamol or theophylline and during exercise at 2/3 Wm ax. These effects could not be predicted by any lung function tests at rest or by the Shwachman-Kulczycki score. The results indicate that i n some patients with CF bronchodilators can impair lung function durin g exercise. In conclusion, the effects of medication on exercise perfo rmance of patients with CF have to be considered. Especially, the use of bronchodilators requires a careful evaluation of their real benefit in each individual patient.