Airway responsiveness to hyperosmolar saline challenge in cystic fibrosis: A pilot study

Hyperosmolar aerosols are used to assess airway responsiveness in subjects with asthma. Using a 10% NaCl aerosol, we investigated airway responsiveness in 23 cystic fibrosis (CF) subjects (12 females, 11 males; 19.1 ± 3.3 years) who had asthma-like symptoms. The pre-challenge predicted forced expiratory volume in 1 second (FEV₁) was 74.7 ± 21.5. The aerosol was generated by a MistO₂gen 143A ultrasonic nebulizer and inhaled for 0.5, 1, 2, 4, 8, 8, and 8 minutes or part thereof. Spirometry was performed before and 1 minute after each inhalation period. The challenge was stopped when a ≥20% fall from the baseline FEV₁ was recorded, after the last inhalation period, or when requested by the subject. We recorded different responses to 10% NaCl among subjects. In 7, the FEV₁ fell progressively throughout the challenge in a manner similar to asthmatics. By contrast, in 15 subjects the FEV₁ was higher at the completion of challenge compared to during challenge, i.e., the fall in FEV₁ was transient. In 7 of these subjects, the final FEV₁ at the end of the challenge was higher than the pre-challenge FEV₁. We conclude that inhaled 10% hyperosmolar saline causes either progressive and sustained or transient airway narrowing during challenge in the majority of CF subjects. The cause of the transient airway narrowing requires further investigation. Pediatr Pulmonol. 1996;21:282–289. © 1996 Wiley-Liss, Inc.