The effect of intravenous magnesium sulfate infusion on serum levels of sodium and potassium in patients with aneurysmal subarachnoid hemorrhage.

Abnormal serum sodium levels are frequently observed among patients with aneurysmal subarachnoid hemorrhage (SAH) and may worsen cerebral edema or mass effect. Low serum potassium levels (hypokalemia) are also common among patients with aneurysmal SAH and are associated with prolonged QT interval and ventricular arrhythmia. Recent meta-analysis suggests that MgSO4 infusion improves the clinical outcome in patients after aneurysmal SAH; however, MgSO4 infusion may theoretically exacerbate electrolyte disturbance. We retrospectively reviewed the prospectively collected demographic and laboratory data of 100 patients after aneurysmal subarachnoid SAH in a neurosurgical center in Hong Kong. 51 patients had daily magnesium sulfate infusion for 14 days (Group 1) and 49 patients were managed similarly, without magnesium sulfate infusion (Group 2). Days of hypernatremia (mean+/-SD) were 2.0+/-2.7 for group 1 and 2.0+/-2.5 for group 2, p = 0.999; days of hyponatremia (mean+/-SD) were 2.7+/-3.1 for group 1 and 2.0+/-2.9 for group 2, p = 0.230; days of hypokalemia (mean+/-SD) were 4.5+/-3.1 for group 1 and 4.5+/-3.2 for group 2, p = 0.819. Hyperkalemia was uncommon in both groups. There was also no statistically significant difference between the two groups when the data were re-analyzed as severe hyponatremia, severe hypokalemia and severe hyperkalemia. Magnesium sulfate infusion was safe and did not seem to exacerbate the duration of electrolyte disturbance associated with aneurysmal subarachnoid hemorrhage.