Hydroelectrolytic syndromes in neuroanesthesia and neurocritical care

Table 4 Magnesium disorders correction

Disorder	Treatment	Dose/route	Notes
Hypomagnesemia	IV magnesium sulfate	1-2 g IV over 1 hour, then 4-8 g IV over 12-24 h; in emergencies (e.g., torsades) 1-2 g IV over 15 min	Use central access for prolonged high-dose infusion; monitor serum Mg 2 h after start of infusion due to renal losses; faster infusion (e.g., in TdP) may be warranted
	Oral magnesium	Magnesium oxide or lactate 300-600 mg (12-25 mmol) PO 2-4 times daily	Use in mild, asymptomatic cases with intact GI tract; bioavailability limited; avoid if significant GI intolerance
Hypermagnesemia	Remove exogenous sources	Discontinue all magnesium-containing meds/infusions	Necessary first step; review all sources (IV fluids, TPN additives, supplements)
	Calcium gluconate	1-2 g IV over 5-10 min	Stabilizes cardiac membrane in severe elevations (> 4 mg/dL) or ECG changes; repeat PRN
	Loop diuretics + IV fluids	Furosemide 20-40 mg IV once, with isotonic saline bolus	Promotes renal Mg excretion; ensure adequate volume status; monitor electrolytes and renal function
	Hemodialysis	Standard-dialyze against low-Mg/zero-Mg bath	Reserved for refractory or life-threatening hypermagnesemia in renal failure

ECG: Electrocardiogram; GI: Gastrointestinal; IV: Intravenous; PO: By mouth; PRN: As needed; TPN: Total parenteral nutrition; TdP: Torsades de Pointes.