The use of magnesium sulfate in acute asthma: rapid uptake of evidence in North American emergency departments.

BACKGROUND

Systematic reviews of approximately 13 randomized trials support treatment with intravenous magnesium sulfate (MgSO(4)) in patients with severe acute asthma; however, little is known about its actual clinical use.

OBJECTIVE

We sought to examine the use of intravenous MgSO(4) in the emergency department (ED) and physician attitudes toward its use.

METHODS

Data for MgSO(4) use were obtained from observational cohort studies of ED patients with acute asthma. Investigators were asked about MgSO(4) through a brief Internet-based survey. The main outcomes were the percentage of sites reporting MgSO(4) use and patient factors that potentially modified the use of this agent.

RESULTS

Among 9745 ED patients with acute asthma, 240 (2.5%) received MgSO(4). Increasing age, previous intubation, higher initial respiratory rate, lower initial PEF, higher number of beta-agonists in the ED, and use of systemic corticosteroids were associated with MgSO(4) use (P < .01). Overall, 103 (87%) of 119 potential sites completed the survey. Most (92%) respondents stated their EDs had MgSO(4) available, and 64% had recently used it. More respondents listed severity (96%) and failure to respond to initial beta-agonists (87%) as factors prompting their use of MgSO(4). Other factors, such as age, sex, and duration of exacerbation, less commonly influenced MgSO(4) use.

CONCLUSION

Most ED physicians accept the efficacy of MgSO(4) in acute asthma. Despite this belief and the ready availability of MgSO(4), its ED use remains uncommon (2.5% of cases). In both practice and theory, emergency physicians appear to appropriately restrict its use to patients with severe acute asthma.