Intravenous β agonists are not indicated in severe acute asthma

Question Are intravenous β agonists ever indicated in patients with acute asthma?

Synopsis Intravenous β agonists are occasionally given to patients with severe acute asthma, particularly when there is a concern that the inhaled β agonist may not be getting into the small airways. In this well designed meta-analysis, the authors identified 15 studies. Some studies compared inhaled plus intravenous β agonists with inhaled alone, others intravenous β agonists with intravenous methylxanthines, and others intravenous β agonists with inhaled β agonists. All studies enrolled patients with severe asthma, although the criteria varied somewhat. The authors used the Jadad score to assess the quality of trials; it gives points for adequacy of randomisation, blinding, and allocation concealment. The studies were of variable quality, with less than half given a rating of “strong” (Jadad score 3 to 5). Results from all studies and from only those that were methodologically strong showed that there was no evidence of benefit but some evidence that adverse effects were increased with intravenous β agonists.

Bottom line There is no evidence to support the use of intravenous β agonists in patients with exacerbations of severe asthma.

Level of evidence Systematic reviews (with homogeneity) of randomised controlled trials.