Addition of intravenous aminophylline to beta2-agonists in adults with acute asthma
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BACKGROUND: Aminophylline has been used extensively in acute asthma, but its role is unclear especially with respect to any additional benefit when added to beta2-agonists. OBJECTIVES: To determine the magnitude of effect of the addition of intravenous aminophylline to beta2-agonists in adult patients with acute asthma treated in the emergency setting. SEARCH STRATEGY: Studies were identified from the following sources: The Cochrane Airways Group register (derived from MEDLINE, EMBASE, CINAHL standardised searches), hand searched respiratory journals and meeting abstracts. Potentially relevant articles were obtained, and their bibliographic lists were hand searched for additional articles. The search included searches of the database up to 1999. SELECTION CRITERIA: Randomised controlled trials comparing intravenous aminophylline versus placebo in adults with acute asthma and treated with beta-adrenergic agonists. Patients could be treated with or without corticosteroids or other bronchodilators. DATA COLLECTION AND ANALYSIS: A total of 210 abstracts were identified. Two independent reviewers selected a total of 27 eligible studies for possible inclusion, in which quality assessment was performed and a third reviewer was used to adjudicate disagreements. Peak expiratory flow (PEFR) and forced expiratory volume in the first second (FEV1) data were extracted and entered in Review Manager from these studies. Information not obtained from the authors was estimated from graphs. All data were entered and double checked by two reviewers. Results are reported as weighted mean differences (WMD) or odds ratio (OR), both with 95% confidential intervals (CI). MAIN RESULTS: Fifteen trials were included. Overall, the quality of the studies was only moderate; concealment of allocation was assessed as clearly adequate in only seven (45%) of the trials. The doses of aminophylline and other medications and the severity of asthma varied between studies. There was no statistically significant effect of aminophylline on airflow outcomes at any time period. The aminophylline treated group had higher values of PEFR at 12 (PEFR 8 L/min or 2.3%) and 24 hours (PEFR 22 L/min or 6.4%), but these were not significant (p>0.05). Two subgroup analyses were performed by grouping studies according to mean baseline airflow limitation (n = 11 studies) and the use of any steroids (n = 9 studies). There was no relationship between baseline airflow limitation nor the use of steroids on the effect of aminophylline. Aminophylline treated patients reported more palpitations/arrhythmias (OR: 2.9; 95% CI: 1.5 to 5.7) and vomiting (OR: 4.2; 95% CI 2.4 to 7.4), but no difference was found in tremor or hospital admissions. REVIEWER'S CONCLUSIONS: In acute asthma, the use of intravenous aminophylline did not result in any additional bronchodilation compared to standard care with beta-agonists. The frequency of adverse effects was higher with aminophylline. No subgroups in which aminophylline might be more effective could be identified. These results should be added to consensus statements and guidelines.
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