Exclusion criteria were continuing treatment of status asthmaticus (corticosteroids and/or bronchodilators), chronic cardiopulmonary disease(hemodynamically significant cardiac disease, chronic lung disease/bronchopulmonary dysplasia requiring diuretics or oxygen), cystic fibrosis, Trisomy 21,immunodeficiency/transplant recipient, neuromuscular disease,admission directly to the PICU,previous nebulized HS use 12 hours after admission.