Evaluating the effects of MetaNeb® compared to usual airway clearance techniques during exacerbations of cystic fibrosis: A randomised controlled trial

<b>Background:</b> There are no objective data to show that MetaNeb® (Hillrom, USA) improves ventilation and aids sputum clearance in adults with cystic fibrosis (CF). <b>Aim:</b> To determine if MetaNeb® is superior to usual airway clearance techniques (ACT) in adults during an exacerbation of CF. <b>Methods:</b> Adults admitted to hospital with an exacerbation of CF and who were expectorating ≥30 mL/day of sputum were randomised to MetaNeb® (experimental intervention; EI) or their usual ACT (control intervention; CI) twice daily during admission. Outcomes included lung clearance index (LCI; minimal clinically important difference = 1 unit), resistance and reactance at 5Hz (Rrs₅ and Xrs₅), FEV₁ and sputum weight. Between-group comparisons were made at day 5 to 7 of admission using generalised linear mixed models. <b>Results:</b> Thirty participants (17 [57%] females) were randomised (median [IQR] age 30yr [22; 36], FEV₁ 56%pred [34; 76]). On completion of the intervention period, the effect of EI was greater than CI in regards to LCI (mean difference [95%CI] 1.10 units [0.34 to 1.87]). However, there were no between-group differences shown in Rrs₅ (0.21cmH₂O.s/L [-0.39 to 0.81]), Xrs₅ (0.17cmH₂O.s/L [-0.11 to 0.44]) and FEV₁ (-0.05L [-0.22 to 0.11]). There were also no between-group differences in treatment session or 24-hour sputum weight. <b>Conclusion:</b> MetaNeb® produced greater improvement in LCI compared to usual ACT during exacerbations in adults with CF, indicating better ventilation homogeneity. However, we are unsure if the true effect is clinically important. There were no between-group differences found for the other outcomes.