Continuous Intravenous Infusion
Magnesium sulfate 4-g to 6-g loading dose diluted in 100 mL fluid administered intravenously over 15 minutes, followed by continuous intravenous infusion at 1 to 2 g per hour. Discontinue 24 hours after delivery or last seizure.
If convulsions persist after 15 min, give up to 2 gram more intravenously as a 20% solution at a rate not to exceed 1g/min. If the woman is large (> 70 kg) then an additional 2 grams may be given slowly
Only give the next IM dose, or only continue the IV infusion if:
Respiratory rate > 16/min
Urine output > 25 ml/h
Patellar reflexes are present
If urine output < 100 ml in 4 h and there are no other signs of magnesium toxicity, reduce the IV infusion to 0.5 g/h.
If patellar reflexes are depressed and respiration is normal, withhold further doses of magnesium sulfate until the reflexes return and request magnesium level.
If there is concern about respiratory depression , stop magnesium, give oxygen by mask and give:
Calcium gluconate (10mL of 10% solution over 10 minutes)
ACOG TASK FORCE 2013
... For women with severe preeclampsia, the administration of intrapartum and postpartum magnesium sulfate to prevent eclampsia is recommended. For women with preeclampsia undergoing cesarean delivery, the continued intraoperative administration of parenteral magnesium sulfate to prevent eclampsia is recommended.