Adults with cystic fibrosis prefer hypertonic saline before or during airway clearance techniques: a randomised crossover trial

Question: Among adults with cystic fibrosis, does the timing of hypertonic saline relative to airway clearance techniques affect lung function, perceived efficacy, tolerability, or satisfaction with the entire airway clearance regimen, and is the preferred timing regimen stable over time?

Design: A randomised crossover trial with concealed allocation, intention-to-treat analysis, and blinded assessors.

Participants: 50 adults with cystic fibrosis and stable lung function at the end of a hospital admission.

Intervention: Participants performed 3 sessions of airway clearance techniques per day for 3 days. On each day, participants were randomised to inhale hypertonic saline either before, during, or after the airway clearance techniques. Participants readmitted within one year repeated the 3-day study.

Outcome measures: The primary outcome was the change in forced expiratory volume in one second (FEV(1)) from before to 2 hours after an entire airway clearance session. Secondary outcomes were change in forced vital capacity, perceived efficacy, tolerability, satisfaction, adverse events, and adherence.

Results: All 50 participants completed the study. The effects on lung function were non-significant or were of borderline statistical significance favouring inhalation of hypertonic saline before airway clearance techniques. Satisfaction was rated significantly worse on a 100mm scale when hypertonic saline was inhaled after the airway clearance techniques: mean differences 20mm (95% CI 12 to 29) compared to before the airway clearance techniques and 15 mm (95% CI 6 to 24) compared to during the techniques. Perceived effectiveness showed similar effects but other outcomes were unaffected. All 14 participants who were readmitted repeated the study and most preferred the same timing regimen. Conclusion People with cystic fibrosis could be encouraged to time hypertonic saline before or during airway clearance techniques to maximise perceived efficacy and satisfaction, even though lung function may not be better with these timing regimens.

Trial registration: ACTRN12611000673943.