Some of us have quirky things we like to do that not everyone else does– dexamethasone for sore throats, ketamine for the agitated patient (or anything really), et cetera… This paper looks at one of those things – Magnesium in asthmatics.
This was a prospective, randomized open-label study of patients between 6 and 18 years of age over a two year period who presented to an ED in Asuncion, Paraguay and were admitted for a severe asthma exacerbation. Patients were excluded if given antibiotics before or during the ED visit, febrile, or if there was suspicion for infectious etiology. All patients enrolled had no relief despite 2 hours of treatment which included dexamethasone 0.2mg/kg IV, nebulized salbutamol every 20 minutes up to 5mg and nebulized albuterol every 2 hours. There were two treatment arms, each with 19 patients: one received a 50mg/kg bolus of MgSO4, while the other group received 50mg/kg/hr/4 hrs (ie, up to 2g / hr for 4 hours – up to 8g total). Physicians in charge of patient disposition, after the initial 8 hours, were not part of the study group and blinded to the treatment received. Primary outcome was discharge at 24 hours, with secondary outcomes total LOS and cost implications. The two groups were similar in terms of age, sex, initial Wood-Downes asthma score, and peak flows.
Despite the numerous downfalls to this study (single center, open-label, prospective, small sample size…), the results are intriguing- bolus magnesium had an average LOS of 48 hours vs 34 hours for high dose prolonged infusions, had a higher cost ($834 vs $603), and fewer patients with a LOS <24 hrs (10.5% vs 47.4%). It took almost two years to get under 40 patients in this single-center study, but still, there were no adverse events and no bounceback visits within a week from discharge. Interestingly, there were no obese patients in the study – so how applicable this study is to the US patient population, I do not know (plus, salbutamol is not widely used for acute asthma in the US). That, and even for this mag-o-phile 8g per hour for 4 hours seems like alot!
Should this change your practice? Not quite yet – unless you’re not giving magnesium. In the meantime, I’ll add another one to the list of trials I’d love to see.