BRONCHIAL LABILITY IN CYSTIC FIBROSIS

Abstract. We investigated the airway's response to exercise in cystic fibrosis (CF). Due to the reported high incidence of allergy in CF we tried to demonstrate the well documented post‐exercise bronchospasm of asthma in patients with CF. Subjects ran on a treadmill for 6 minutes at a speed of three miles per hour and a gradient of 15°. For the 12 controls studied, the mean % rise in peak expiratory flow rate (PEFR) during excercise was 4.7% and the mean % fall in PEFR during recovery was 0.7%. For the eight atopic asthmatics studied the mean % rise in PEFR was 12.2% and the mean % fall in PEFR was 33.7%. For the 29 patients with CF, the mean % rise in PEFR was 20.3% and the mean % fall in PEFR was 3.1%. Patients with CF showed no statistically significant post‐exercise constriction compared with the controls, while asthmatic patients showed a post‐exercise % fall in PEFR significantly greater than seen in controls (p<0.001) or in CF patients (p<0.001). No patient with CF showed post‐exercise bronchospasm, nor was there any difference between patients with CF who had positive skin tests to common allergens and those who did not in their pattern of bronchial lability. It is suggested that the general desensitization therapy should not be instituted in patients with CF merely on the basis of positive skin tests, without more stringent criteria such as characteristic seasonal variation in respiratory symptomatology, family history of atopy and positive bronchial inhalation provocation tests.