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Q&A

Hypertension

Poster Session 2

(639) Eclampsia and adverse effects: comparison between 1 versus 2 grams per hour intravenous magnesium sulfate

Tuesday, February 13, 2024
3:30 PM – 5:00 PM  
Location: Prince George's Exhibit Hall CDE, Lower Atrium Level
Objective:

While magnesium sulfate (MgS) is recognized as effective treatment for prevention of eclampsia, there is no consensus regarding the appropriate maintenance dosage.

Our research compared the efficacy, serum Mg concentrations and adverse effects rate of a maintenance dose of 1 g/h and 2 g/h of MgS in the prevention of eclampsia.

Study Design: A retrospective cohort study of all women with severe pre-eclampsia/eclampsia, who were treated with MgS between August 2005 and September 2019. Women received a loading dose of 4 g MgS sulfate for 20 minutes, after which MgS was administered at 2 g/h until July 2013 (N=375) and afterwards was given at 1 g/h (N=306). MgS was administered up to 48h before delivery and 24h after delivery. Serum Mg concentrations were measured every 8 hours. The primary outcomes were (1) the rate of eclampsia and (2) the rate of the total adverse effects. Assuming that the rate of eclampsia will be 0.5% and 3% in the 2g/h versus 1 g/h groups, 680 women were required (5% one sided alpha, 80% power). This sample size was sufficient to detect 10% difference in the rate of adverse effects between 2 g/h and 1 g/h (40% versus 30%, respectively, 5% one sided alpha, 86% power).  

Results: Groups' outcomes are presented in the table. While there was no difference between the 1 g/h versus 2 g/h groups regarding the rate of eclampsia (2 (0.7%) versus 1 (0.3%), respectively; P=0.45), patients treated with a maintenance dose of 1 g/h suffered from fewer adverse effects compared with 2 g/h (40 (13%) versus 162 (43%), respectively; P< 0.0001). Additionally, both maximal and mean serum magnesium levels were significantly lower in patients treated with 1 g/h, and more patients from this group did not reach a serum level of 4.8 mg/dL which is the accepted therapeutic level (48 (16%) versus 305 (81%) in the 1 g/h versus 2 g/h, respectively; P< 0.0001).

Conclusion:

We conclude that 1 g/h is the preferred maintenance dose due to the lower rate of adverse effects and the same efficacy of treatment. Additionally, we concluded that the accepted therapeutic window for MgS needs to be re-evaluated.