Extended Versus Short Infusion Rates for Intravenous Magnesium Sulfate in Refractory Hypokalemic Associated Hypomagnesemia

Objectives: Refractory Hypokalemia associated Hypomagnesemia is an electrolyte imbalance commonly found in debilitated hospitalized patients. Possible consequences of this dual electrolyte hypos disturbances, including but not excluded to, neuromuscular, neurologic, heart dysfunctions. The simplest and commonly used test to diagnose the accompanied hypomagnesemia in refractory hypokalemic patients, is a serum magnesium level (Mg+2). When replacing Mg+2via the IV route, approximately half of the dose is retained by the body while the remainder is excreted in the urine. The low retention rate is due to the slow uptake of large concentration of Mg+2. The primary purpose of this study is to determine whether an extended infusion of 2 grams MgSO4 over 12 hours twice daily for 5 days (Strategy I) compared to a standard infusion of 5 grams MgSO4 over 4 hours once daily for 5 days (Strategy II) results in a greater sustaining in Mg+2 level ≥2 mg/dl after at least 3 days from MgSO4 infusion off. Materials and Methods: We retrospectively reviewed refractory hypokalemic associated hypomagnesemia patients who received IV magnesium sulfate at our institution between 2018 and 2020 at standard infusion rate of 5 grams MgSO4 over 4 hours once daily for 5 days (Strategy II) or at extended infusion rate of 2 grams MgSO4over 12 hours twice daily for 5 days (Strategy I). All refractory hypokalemic associated hypomagnesemia patients whose chemistry data could be retrospectively retrieved via our institutional electronic health record (Hakeem), will be included in this study. Patients whose magnesium level exceeded 4 mg/dl during MgSO4 infusion days will be excluded. A chi square test will be conducted to evaluate the proportion of studied patients in both tested infusion strategies who had late magnesium level ≥2 mg/dL. An independent T-test will be conducted to compare the Mean±SD of %∆ Mg+2 between Strategy I and Strategy II. Results: There was no difference between the two strategies regarding Mg+2 levels above 2 mg/dL 4 hrs. after the end of the infusion, on the other hand, there was a significant difference in the percentage of patients maintaining Mg+2 levels above 2 mg/dL at least 72hrs after the end of infusion. Conclusion: The extended infusion of MgSO4 is significantly increases the percentage of patient retaining normal Mg+2 levels 72 hrs. after the end of the infusion, decreases the length of ICU and overall hospital stay, in addition to lowering 28-days ICU overall mortality rates.