Comparison of Magnesium Sulphate Protocols by Weight-Adjusted Versus Two Grams Per Hour for Preventing Convulsion in Preeclampsia: A Randomised Controlled Trial QC01-QC04
Dr. Metha Songthamwat,
45/5, Phorniyomrd Muang, Udonthani-41000, Thailand.
Introduction: Magnesium Sulphate (MgSO4) is the most effective drug used for seizure prevention in preeclampsia; however, the dosage of MgSO4 is still in controversy. Maternal weight is an important factor for the serum MgSO4 level; however, there has not been any weight-adjusted regimen of MgSO4 reported.
Aim: To compare the effectiveness of weight-adjusted versus standard two grams per hour (g/hr) protocols of intravenous MgSO4 for preventing convulsion in preeclampsia.
Materials and Methods: A randomised controlled trial was conducted with 86 preeclamptic women from January 2018 to September 2018. The study group (43 cases) received MgSO4 4 g loading followed by a weight-adjusted protocol starting with 1.2-1.5 g/hr depending on maternal weight. The control group (43 cases) received MgSO4 4 g loading followed by 2 g/hr. The serum Mg level was monitored at two and four hours after MgSO4 injection, The MgSO4 dosage was adjusted and continued until 24 hours after delivery. The percentages of those who achieved a therapeutic level of MgSO4 (4.8-8.4 mg/dL) in the first four hours were compared between the two groups. Clinical signs of Mg toxicity were monitored. Maternal and neonatal outcomes were evaluated.
Results: At four hours after treatment, the proportion of participants who achieved a therapeutic level were 11.6% in the study group and 41.9% in the control group (RR 0.28, 95% CI 0.11 to 0.68, p-value <0.01). The 2 g/hr protocol for those participants whose maternal weight was <80 kg had a higher proportion who achieved a therapeutic level (p-values >0.001). However, both protocols had similar low proportions who achieved a therapeutic level for those whose maternal weight was >80 kg (8% in maternal weight 80-99.9 kg, 0% in maternal weight >100 kg). No clinical MgSO4 toxicity was observed. Maternal and neonatal outcome were not statistically significant.
Conclusion: Maternal bodyweight is important for MgSO4 dosage adjustment. In those patients whose maternal bodyweight is <80 kg, a 2 g/hr maintenance dose is more effective than a lower dose; however, in patients whose maternal bodyweight is >80 kg, higher dose is required for achieving therapeutic level. A low dose is not sufficient for any weight range. At least 2 g/hr is minimum required for preventing convulsion in preeclampsia.