Nebulized epinephrine for croup in children.

Background: Croup is a common childhood illness characterized by barky cough, stridor, hoarseness and respiratory distress. Children with severe croup are at risk for intubation. Nebulized epinephrine (NE) may prevent intubation.
Objectives: To evaluate the efficacy and safety of NE in children presenting to emergency department (ED) or admitted to hospital with croup.
Search Strategy: We searched CENTRAL (The Cochrane Library 2010, Issue 4), containing the Cochrane Acute Respiratory Infections Group's Specialized Register, MEDLINE (1966 to November Week 1, 2010), EMBASE (1980 to November 2010), Web of Science (1974 to November 2010), CINAHL (1982 to November 2010) and Scopus (1996 to November 2010).
Selection Criteria: Randomized controlled trials (RCTs) or quasi-RCTs of children with croup evaluated in an ED or admitted to hospital. Comparisons were: NE versus placebo, racemic NE versus L-epinephrine (an isomer), and NE delivered by intermittent positive pressure breathing (IPPB) versus NE without IPPB. Primary outcome was change in croup score post-treatment. Secondary outcomes were rate and duration of intubation and hospitalization, croup return visit, parental anxiety and side effects.
Data Collection and Analysis: Two authors independently identified potentially relevant studies by title and abstract (when available) and examined relevant studies using a priori inclusion criteria, followed by methodologic quality assessment. One author extracted data while the second checked accuracy. We performed standard statistical analyses.
Main Results: Eight studies (225 participants) were included. NE was associated with croup score improvement 30 minutes post-treatment (three RCTs, standardized mean difference (SMD) -0.94; 95% confidence interval (CI) -1.37 to -0.51; I(2) statistic = 0%). This effect was not significant two and six hours post-treatment. NE was associated with significantly shorter hospital stay than placebo (one RCT, mean difference -32.0 hours; 95% CI -59.1 to -4.9). Comparing racemic and L-epinephrine, no difference in croup score was found after 30 minutes (SMD 0.33; 95% CI -0.42 to 1.08). After two hours, L-epinephrine showed significant reduction compared with racemic epinephrine (one RCT, SMD 0.87; 95% CI 0.09 to 1.65). There was no significant difference in croup score between administration of NE via IPPB versus nebulization alone at 30 minutes (one RCT, SMD -0.14; 95% CI -1.24 to 0.95) or two hours (SMD -0.72; 95% CI -1.86 to 0.42).
Authors' Conclusions: NE is associated with clinically and statistically significant transient reduction of symptoms of croup 30 minutes post-treatment. Evidence does not favor racemic epinephrine or LE, or IPPB over simple nebulization.