β-agonist aerosol distribution in respiratory syncytial virus bronchiolitis in infants

Bronchodilator aerosols are frequently administered to infants with bronchiolitis but with little success. The efficacy of aerosol treatments depends mainly on adequate targeting of the aerosol particles to the inflamed airways. This study evaluated the lower respiratory tract distribution characteristics of nebulized bronchodilators in infants with acute bronchiolitis. Methods: Twelve infants (mean age ± SD, 8 mo ± 4 mo) who were admitted for acute respiratory syncytial virus bronchiolitis were treated with ^99mTc-albuterol aerosol. γ-Scintigraphy was used to assess total body and lung deposition as well as pulmonary distribution of the medication. Results: Of the total 6-min nebulized dose (i.e., drug aerosol dose leaving the nebulizer [not the nebulizer charge]), 1.5% ± 0.7% reached the right lung, with only approximately one third of that (0.6%) penetrating to the peripheral lung zone. There was 7.8% ± 4.9% deposition in the upper respiratory and gastrointestinal tracts and 10%-12% remained on the face. No correlation was found between any of the deposition indices and the clinical response data or any of the demographic parameters (e.g., height, weight, body surface area, or clinical score). Conclusion: Poor total aerosol deposition in infants may be related as much to their small conducting airways as to the disease state. There is considerable room for improvement in aerosol delivery in this age group, with greater emphasis on targeting narrowed peripheral airways with superfine aerosols.