Slow‐responders to IV β2‐adrenergic agonist therapy: Defining a novel phenotype in pediatric asthma

Publisher Website
Google Scholar
Abstract
Objectives While aerosolized administration of β2-adrenergic receptor (β2-AR) agonists is the mainstay of treatment for pediatric asthma exacerbations, the efficacy of intravenous (IV) delivery is controversial. Failure to demonstrate improved outcomes with IV β2-AR agonists may be due to phenotypic differences within this patient population. Our hypothesis is that children who respond more slowly to IV β2-AR agonist therapy comprise a distinct phenotype. Methods Retrospective chart review of all children admitted to the ICU for status asthmaticus who were treated with IV terbutaline between December 2002 and September 2006. Results Seventy-eight children were treated with IV terbutaline according to guidelines that adjusted the dose by clinical asthma score. After examining the histogram of duration of terbutaline infusions, a 48-hr cutoff was chosen to define responsiveness. Thirty-eight (49%) children were slow-responders by this definition. There were no significant differences in baseline asthma severity or severity on admission between the slow-responders and responders. Slow-responders required significantly higher total doses of IV terbutaline, higher maximum administration rates, and had longer ICU and hospital length of stay. Conclusion There were significant differences in outcomes between the responders and slow-responders without differences in acute or chronic illness severity. Other factors may have lead to slower response to IV β2-agonist therapy. Pediatr Pulmonol. 2008; 43:627–633.