Rebound stridor in children with croup after nebulised adrenaline: does it really exist?

Sakthivel, Muthukumar; Elkashif, Sami; Al Ansari, Khalid; Powell, Colin V.E.

Nebulised adrenaline/epinephrine is recommended for use in severe and life-threatening croup [5] , although some guidelines use it for those children with moderate symptoms [6] . Nebulised adrenaline has been associated with a clinically and statistically significant transient reduction in croup symptoms 30 min post-treatment [5] and can "buy time" for steroids to act. Children with croup develop swelling of inner mucosal layers of the larynx and trachea. Nebulised adrenaline is thought to act by stimulating α-adrenergic receptors in subglottic mucous membranes, producing vasoconstriction and decreased mucosal oedema. The clinical effect is sustained for at least 1 h, but disappears after 2 h. Studies of nebulised adrenaline treatment of croup have used both racemic and l-adrenaline. One small trial found that l-adrenaline (5.0 mL, 0.1% (1:1000)) was as effective and safe as racemic adrenaline (0.5 mL, 2.25%) [7] . When racemic and l-adrenaline are compared, there is no difference in croup score at 30 m (standardised mean difference 0.33, 95% CI −0.42-1.08), but at 2 h l-adrenaline shows a small reduction in croup score compared with racemic adrenaline (standardised mean difference 0.87, 95% CI 0.09-1.65) [5] .