• Dennis Scolnik, Allan L Coates, Derek Stephens, Zelia Da Silva, Elana Lavine, and Suzanne Schuh.
• Division of Pediatric Emergency Medicine, The Hospital for Sick Children, and University of Toronto, Toronto, Ontario. dennis.scolnik@sickkids.ca
• JAMA. 2006 Mar 15; 295 (11): 1274-80.

ContextChildren with croup are often treated with humidity even though this is not scientifically based, consumes time, and can be harmful. Although humidity using the traditional blow-by technique is similar to room air and no water droplets reach the nasopharynx, particles sized for laryngeal deposition (5-10 microm) could be beneficial.ObjectiveTo determine whether a significant difference in the clinical Westley croup score exists in children with moderate to severe croup who were admitted to the emergency department and who received either 100% humidity or 40% humidity via nebulizer or blow-by humidity.Design And SettingA randomized, single-blind, controlled trial conducted between 2001 and 2004 in a tertiary care pediatric emergency department.ParticipantsA convenience sample of 140 previously healthy children 3 months to 10 years of age with Westley croup score of more than 1 or 2 or higher (scoring system range, 0-17); 21 families refused participation.InterventionThirty-minute administration of humidity using traditional blow-by technique (commonly used placebo, n = 48), controlled delivery of 40% humidity (optimally delivered placebo, n = 46), or 100% humidity (n = 46) with water particles of mass median diameter 6.21 microm.Main Outcome MeasureA priori defined change in the Westley croup score from baseline to 30 and 60 minutes in the 3 groups.ResultsGroups were comparable before treatment. At 30 minutes the difference in the improvement in the croup score between the blow-by and low-humidity groups was 0.03 (95% confidence interval [CI], -0.72 to 0.66), between low- and high-humidity groups, 0.16 (95% CI, -0.86 to 0.53), and between blow-by and high-humidity groups, 0.19 (95% CI, -0.87 to 0.49). Results were similar at 60 minutes. Differences between groups in pulse and respiratory rates and oxygen saturation changes were insignificant, as were proportions of excellent responders; proportions with croup score of 0 at study conclusion; and proportions receiving dexamethasone, epinephrine, or requiring additional medical care or hospitalization.ConclusionsOne hundred percent humidity with particles specifically sized to deposit in the larynx failed to result in greater improvement than 40% humidity or humidity by blow-by technique. This study does not support the use of humidity for moderate croup for patients treated in the emergency department.Trial RegistrationClinicalTrials.gov Identifier: NCT00230841.

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