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

BackgroundSystematic reviews of approximately 13 randomized trials support treatment with intravenous magnesium sulfate (MgSO4) in patients with severe acute asthma; however, little is known about its actual clinical use.ObjectiveWe sought to examine the use of intravenous MgSO4 in the emergency department (ED) and physician attitudes toward its use.MethodsData for MgSO4 use were obtained from observational cohort studies of ED patients with acute asthma. Investigators were asked about MgSO4 through a brief Internet-based survey. The main outcomes were the percentage of sites reporting MgSO4 use and patient factors that potentially modified the use of this agent.ResultsAmong 9745 ED patients with acute asthma, 240 (2.5%) received MgSO4. Increasing age, previous intubation, higher initial respiratory rate, lower initial PEF, higher number of β-agonists in the ED, and use of systemic corticosteroids were associated with MgSO4 use (P < .01). Overall, 103 (87%) of 119 potential sites completed the survey. Most (92%) respondents stated their EDs had MgSO4 available, and 64% had recently used it. More respondents listed severity (96%) and failure to respond to initial β-agonists (87%) as factors prompting their use of MgSO4. Other factors, such as age, sex, and duration of exacerbation, less commonly influenced MgSO4 use.ConclusionMost ED physicians accept the efficacy of MgSO4 in acute asthma. Despite this belief and the ready availability of MgSO4, 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.