This study suggests that CPAP compared with ST improves ventilation in children with bronchiolitis and hypercapnoea.

Background: Osmotic agents, such as inhaled dry powder mannitol, may increase mucociliary clearance by rehydrating the airway surface liquid and thus act as disease-modifying treatments in cystic fibrosis (CF). This is the first therapeutic trial of inhaled mannitol in children with CF; it was compared with recombinant human deoxyribonuclease (rhDNase), the current best established mucolytic treatment. Methods: 38 children were recruited to an open crossover study. Subjects underwent an initial bronchial provocation challenge with dry powder mannitol. Those children with a negative challenge were randomly allocated to one of three consecutive 12-week treatment blocks (inhaled mannitol alone, nebulised rhDNase alone and mannitol + rhDNase). The primary outcome was forced expiratory volume in 1 s (FEV 1 ). A number of secondary outcome measures were also studied. Results: Twenty children completed the study. Bronchoconstriction and cough associated with mannitol administration contributed to the high attrition rate. The mean increase in FEV 1 following 12 weeks of treatment was 0.11 litres (6.7%) (p = 0.055) for mannitol alone, 0.12 litres (7.2%) (p = 0.03) for rhDNase alone and 0.03 litres (1.88%) (p = 0.67) for rhDNase and mannitol. None of the secondary clinical outcomes was statistically significantly different between treatments. Conclusions: Inhaled mannitol was at least as effective as rhDNase after 3 months treatment. There was a marked individual variation in tolerance to mannitol and in response to treatment however. Children who do not respond to rhDNase many benefit from a trial of inhaled mannitol. The combination of mannitol and rhDNase was not useful. Trial registration number: NCT00117208Many processes contribute to airway obstruction and progressive lung damage in cystic fibrosis (CF), including the production of abnormally viscid mucus, mucus hypersecretion and defective mucociliary clearance (MCC). Previous therapeutic approaches aimed at improving airway clearance have included suppression or eradication of bacterial infection and attenuation of inflammation. Mucolytic agents have also been used to reduce sputum viscosity. Recombinant human deoxyribonuclease (rhDNase) is a now a well established and widely used adjunctive treatment for CF. DNA derived from neutrophil degradation is present in very high concentrations in the sputum of patients with CF and is a major contributor to the viscosity of airway secretions. rhDNase cleaves this extracellular DNA, improving mucus rheology. Several studies have now clearly demonstrated improvements in lung function and fewer chest exacerbations in patients treated with rhDNase.1-3 It may also reduce neutrophilic airway inflammation. 4 There is widespread variation in the individual responses to rhDNase, 3 5 however, and a significant number of patients derive no clinical benefit.Epithelial airway surface liquid (ASL) volume regulation is critical for normal MCC, and airway dehydration is now thought to be a key initiating event in the pathogenesi...

We report that 24% of children with CF had a positive airway challenge with inhaled mannitol. This compares with a previously reported 12% of subjects in a study including both adults and children. We could not identify factors predictive of a positive mannitol challenge in our children.

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