Humidified air inhalation for treating croup: a systematic review and meta-analysis

Background. Croup (laryngotracheobronchitis) is a common cause of upper airway obstruction in children. Treatment with humidified air was previously widely used and is still commonly recommended as home treatment. Objective. To assess the efficacy of humidified air in the treatment of croup. Design. Systematic review and meta-analysis. Data sources. We searched the Cochrane Central Register of Controlled Trials, MEDLINE and EMBASE. Review methods. We included randomized controlled trials with or without blinding. All studies treating children with a clinical diagnosis of croup with warm or cool humidified air delivered by steam or humidified tent whether inpatients, attenders at the Emergency Department or in the community were eligible. Main results. Three studies in emergency settings provided data on 135 patients with moderate croup for the main outcome (croup score). The combined results from 20 to 60 minutes in the three studies marginally favoured the treatment group with a weighted standardized mean difference of -0.14 (95% confidence interval = -0.75 to 0.47). No outcomes were significantly different between the groups. Conclusions. The croup score of children managed in an emergency setting with mild to moderate croup probably does not improve greatly with inhalation of humidified air. There is insufficient evidence to exclude either a small beneficial or a harmful effect