Q: What is the usual target of Magnesium level for vasospasm prevention after aneurysmal Subarachnoid Hemorrhage?



Answer: To prevent vasospasm and improve outcome after aneurysmal subarachnoid hemorrhage, it is recommended to keep a magnesium level of 3-4.5mEq/l

Central line is suggested for administration. Bolus Dose of 2g of MgSO4 is given over 30 minutes and maintenance rate of 1g of MgSO4/hr is recommended with goal of serum Mg level of 3-4.5 mEq/l. Serum Mg levels should be checked before starting the infusion, 2 hours after initiation, 2 hours after any dose or rate change and every 12 hours afterwards.

It is to note that ionized Ca and serum K levels should be checked twice a day. Calcium repletion is needed if Calcium level is less than 1.1mmol/L. Magnesium drip should be stopped if serum K is greater then 6 mmol/L or if there is a new prolongation of PR interval or onset of new AV block.