Magnesium Sulfate Administration

Prior to making any medical decisions, please view our disclaimer.

Administration of Magnesium Sulfate for Vasospasm Prevention After Aneurysmal Subarachnoid Hemorrhage

Purpose

To prevent vasospasm and improve outcome after aneurysmal subarachnoid hemorrhage by maintaining a magnesium level of 3-4.5mEq/l

Inclusion Criteria

• CT proven subarachnoid hemorrhage
• CTA or angiogram proven berry aneurysm
• Less than 72 hours post subarachnoid hemorrhage
• Hunt and Hess grade I-IV Fisher group II-III
• Age greater than or equal to18 years old
• Secured aneurysm

Exclusion Criteria

• Pregnancy
• Age less then 18
• Congestive Heart Failure (NY Heart Association Class 3 or 4)
• 2nd or 3rd degree heart block (caution in digitalized patients)
• Renal insufficiency (calculated creatinine clearance rate < 30ml/min)
• Known neuromuscular disease
• Concomitant use of neuromuscular blocking agents (cisatracurium, vecuronium etc.)
• Serum K > 6mmol/L
• Ionized Ca<1.1mmol/l
• Hypotension (SBP < 90mmHg or MAP < 60mmHg unresponsive to the administration of IV fluids and/or pressors)
• Ordered nifedipine (hypotension and NM blockade risk)

Guidelines for Use

• All magnesium administration must have a signed physician order, including a specific dose and rate. All rate changes require a physician order.
  • Abbreviated orders, "per protocol" and "as directed" should not be accepted
• To be used only in an ICU setting
  • Not for general care unit use
• Central line suggested, not required
• MgSO4 40gm/L SWI is a piggyback solution, NOT a mainline infusion
• Bolus Dose: 2g MgSO4 (50cc) over 30 minutes
  • Record BP, HR, RR every 10 mintues during bolus infusion
• Initial Maintenance Rate: 1g MgSO4/hr (25cc/hr)
• The Magnesium drip may be stopped and restarted at the discretion of the Neuro ICU fellow.
• Goal: serum Mg level = 3-4.5 mEq/l
  • The ICU fellow/resident must be called if Mg not within range.
  • Calcium po/ngt supplements administered during MGSO4 administration.
• Cardiac monitoring performed per ICU routine

Serum Mg levels are checked

• before starting the infusion
• 2 hours after initiation
• 2 hours after a dose or rate change
• every 12 hours afterwards (including dose changes)
  • special note that MGH labs may notify us that Mg levels are out of range
• Ionized Ca and serum K levels are checked twice a day
• Calcium repletion is desired if Calcium < 1.1mmol/L. Calcium maybe repleted over 30 minutes.

Protocol is discontinued for

• Ionized Ca less then 1.1mmol/L
• Serum K greater then 6 mmol/L
• Systolic blood pressure less then 80mmHg
• Patient need to go for neuro-interventional vasospasm treatment - require general anesthesia
• New prolongation of PR interval or onset of new AV block
  • Covering physician is to be notified with any of the above

Endpoints

• 14 days after aneuysmal subarachnoid hemorrhage
• transferring out of ICU

Potential side effects of MgSO4 infusions and goal serum Mg levels

• hot and/or flushed feeling
• nausea, vomiting, diarrhea
• local venous irritation
• generalized feeling of drowsiness
• hypotension (can be treated with Ca gluconate 0.5-2g infusion): cardiac depression, negative ionotropy, PR prolongation, AV block
• respiratory arrest
• hypocalcemia
• hyperkalemia

Serum Magnesium levels

• 1.4 - 2.1mEq/l
  • Normal
• 3 - 4.5mEq/l
  • Target
• 5 - 10mEq/l
  • EKG changes (PR and QRS prolongation)
• >10mEq/l
  • Loss of DTRs
• > 15mEq/l
  • Respiratory paralysis
• > 25mEq/l
  • Cardiac Arrest

Physician guide for titration

• Rate changes may only be made with a physician order

Most current Serum Mg level

• < 3mEq/l
  • Current infusion rate change: increase rate 0.5g/h (+12.5cc/h)
• 3-4.5mEq/l
  • Current infusion rate change: no change (target range)
• 4.6-5.5mEq/l
  • Current infusion rate change: decrease rate 0.5g/h (-12.5cc/h)
• > 5.5mEq/l
  • Current infusion rate change: stop infusion until < 5.5mEq/l then decrease rate 1g/h (-25cc/h)

Other Information

• please refer to MGH Critical Care IV Medication Guidelines
• MgSO4 comes from Material Management: 40gm in 1000cc sterile water injection (324.8mEq/L) and is stocked in the Blake 12 medication closet
• Y-site/co-administration compatible with: dobutamine, dopamine, esmolol, heparin, insulin, labetalol, mannitol, nicardipine, nitroprusside, norepinephrine, phenylephrine, potassium chloride, vasopressin. Please page the pharmacist covering for additional compatibilities or information.
• incompatible with: argatroban, hypertonic saline (1.5% & 1.5%, 3%, 23.4%), methylprednisolone, others
• 500mg MgSO4 = 48mg Mg++ = 4.06mEq = 2.03mmol
• Materials Management re-order #________________

References

1. Magnesium Sulfate in Aneurysmal Subarachnoid Hemorrhage. A randomized Controlled Trial. Stroke 2005; 36:1011-1015
2. Magnesium Sulfate Therapy after Aneurysmal Subarachnoid Hemorrhage. J Neurosurg 2002; 96: 510-514
3. Hypomagnessemia after Aneursysmal Subarachnoid Hemorrhage. Neurosurgery 2003; 52: 276-282
4. Magnesium Sulfate Reverses Experimental Delayed Cerebral Vasospasm after Subarachnoid Hemorrhage in Rats. Stroke 1991; 22: 922-927
5. Manual of High Risk Pregnancy and Delivery. Gilbert and Harmon; Mosby, 1993; 398
6. Magnesium and Its Therapeutic Uses: A Review; The American Journal of Medicine; 1994; 96: 63-76
7. MGH protocol for administration of MgSO4 for the Pre-Eclamptic/PIH patients

MGH Committee Review & Policy Updates

• MGH MESAC reviewed, amended & approved 10/25/05
• MGH Critical Care Committee submitted 10/05
• MGH Critical Care IV Medication Guidelines amendment submitted 11/05

Authoring Information

Reviewed/Approved by: Schwamm, Lee, M.D. on behalf of ASQT

Last updated: 7/7/2010

© 2021 Massachusetts General Hospital | 15 Parkman Street Boston, MA. 02114 | (617) 726-8459
Home | Contact Us | Donate | Sitemap | Disclaimer | Email the Webmaster