Abstract

Background: The effect of heliox as a nebulizer beta(2)-agonist driving gas in acute asthma remains controversial. Objective: To perform a systematic review with a meta-analysis of randomized trials designed to evaluate the efficacy of heliox versus oxygen in driving beta(2)-agonist nebulization in patients with acute asthma. Methods: A search was conducted of all randomized controlled trials published before August 2013. Primary outcomes were change in spirometric measurements and severity composite score (pediatric studies); secondary outcomes were hospitalizations and serious adverse effects. Results: Eleven trials from 10 studies (697 participants) met the inclusion criteria (7 included adults and 3 included children). The mean duration of heliox therapy was 120 minutes and the most common helium-oxygen mixture used was 70:30. Patients receiving heliox presented a statistically significant difference for mean percentage of change in peak expiratory flow (17.2%; 95% confidence interval 5.2-29.2, P-.005). Post hoc subgroup analysis showed that patients with severe and very severe asthma showed a significant improvement in peak expiratory flow compared with those with mild to moderate acute asthma. Heliox-driven nebulization also produced significant decreases in the risk of hospitalizations (odds ratio 0.49, 95% confidence interval 0.31-0.79, P = .003) and severity of exacerbations (pediatric studies; standard mean difference -0.74, 95%% confidence interval -1.45 to -0.03, P = .04). There were no group differences for serious adverse effects. Conclusion: This review suggests that heliox benefits in airflow limitation and hospital admissions could be considered clinically significant. Data support the use of heliox as a nebulizing beta(2)-agonist driving gas in the routine care of patients with acute asthma. (C) 2014 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.