Background: In acute asthma inhaled beta2-agonists are often administered to relieve bronchospasm by wet nebulisation, but some have argued that metered-dose inhalers with a holding chamber (spacer) can be equally effective. Nebulisers require a power source and need regular maintenance, and are more expensive in the community setting.
Objectives: To assess the effects of holding chambers (spacers) compared to nebulisers for the delivery of beta2-agonists for acute asthma.
Search strategy: We last searched the Cochrane Airways Group trials register in January 2006 and the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 4, 2005).
Selection criteria: Randomised trials in adults and children (from two years of age) with asthma, where spacer beta2-agonist delivery was compared with wet nebulisation.
Data collection and analysis: Two reviewers independently applied study inclusion criteria (one reviewer for the first version of the review), extracted the data and assessed trial quality. Missing data were obtained from the authors or estimated. Results are reported with 95% confidence intervals (CI).
Main results: This review has been updated in January 2006 and four new trials have been added. 2066 children and 614 adults are now included in 25 trials from emergency room and community settings. In addition, six trials on in-patients with acute asthma (213 children and 28 adults) have been reviewed. Method of delivery of beta2-agonist did not appear to affect hospital admission rates. In adults, the relative risk of admission for spacer versus nebuliser was 0.97 (95% CI 0.63 to 1.49). The relative risk for children was 0.65 (95% CI: 0.4 to 1.06). In children, length of stay in the emergency department was significantly shorter when the spacer was used, with a mean difference of -0.47 hours (95% CI: -0.58 to -0.37). Length of stay in the emergency department for adults was similar for the two delivery methods. Peak flow and forced expiratory volume were also similar for the two delivery methods. Pulse rate was lower for spacer in children, mean difference -7.6% baseline (95% CI: -9.9 to -5.3% baseline).
Authors' conclusions: Metered-dose inhalers with spacer produced outcomes that were at least equivalent to nebuliser delivery. Spacers may have some advantages compared to nebulisers for children with acute asthma.