Continuous vs intermittent beta-agonists in the treatment of acute adult asthma: a systematic review with meta-analysis.

BACKGROUND Since the late 1980s, there has been considerable clinical and academic interest in the use of continuous aerosolized bronchodilators for the treatment of patients with acute asthma. These studies have suggested that this therapy is safe, is at least as effective as intermittent nebulization, and may be superior to intermittent nebulization in patients with the most severely impaired pulmonary function. OBJECTIVES To determine whether continuous nebulization offered an advantage over intermittent nebulization for the treatment of adults with acute asthma in the emergency department (ED). DESIGN Systematic review of randomized controlled trials of adults with acute asthma. OUTCOMES Change in pulmonary function tests as primary outcome, and admissions to the hospital and side effects as secondary outcomes. RESULTS Six studies including 393 adults with acute asthma were selected. No significant differences were demonstrated between the two delivery methods in terms of pulmonary function measures obtained after 1 h of treatment (standardized mean difference [SMD], -0.15; 95% confidence interval [CI], -0.35 to 0.05) and after 2 to 3 h of treatment (SMD, -0.19; 95% CI, -0.39 to 0.01). No significant heterogeneity was demonstrated (p > 0.5). At the end of treatment, there was a significantly greater decrease in pulse rate when the continuous nebulizer was used (weighted mean difference [WMD], -6.82; 95% CI, -8.67 to -3.90 beats/min; chi(2), 2.55; degrees of freedom [df], 4; p = 0.6). Additionally, the analysis showed a significant decrease of serum potassium concentration with the use of intermittent nebulization (WMD, 0.12; 95% CI, 0.24 to 0.01 mmol/L; chi(2), 0.5; df, 2; p = 0.8). However, this finding was obtained on the analysis of only two trials. Finally, at the end of the study period, no significant differences were identified between patients treated with continuous or intermittent nebulization with respect to hospital admission (relative risk, 0.68; 95% CI, 0.33 to 1.38; chi(2), 2.06; df, 1; p = 0.2). CONCLUSIONS Overall, this review supports the equivalence of continuous and intermittent albuterol nebulization in the treatment of acute adult asthma.