Characterization of the Effect of Prolonged Therapeutic Hypothermia on Serum Magnesium and Potassium Following Neurological Injury.

Current American Heart Association/American Stroke Association guidelines for the management of spontaneous intracerebral hemorrhage suggest therapeutic hypothermia (TH) as a salvage therapy in patients with elevated intracranial pressure. Electrolyte disorders may develop at any stage of the cooling process. Such deregulation can place patients at an increased risk for arrhythmias and worsened neurologic outcomes. The impact of TH on serum electrolyte concentration has been described, but electrolyte changes and repletions are yet to be quantified. The primary objective of this study was to quantify the trends in serum potassium and magnesium concentrations during TH and determine the median amount of electrolyte repletions administered. This study was a single-center retrospective cohort conducted at Virginia Commonwealth University Health. Data were collected from neurosurgical patients with intracranial hypertension who underwent TH (<36°C) for ≥48 hours. Patients with a primary neurological insult cooled with the Arctic Sun^® 5000 Temperature Management System, who were ≥13 years of age at the time of therapy with a core body temperature of ≥36°C before therapeutic hypothermia, were eligible for inclusion. Forty-three patients meeting the inclusion criteria were analyzed. A total of 42 patients (98%) experienced hypokalemia (<3.5 mEq/L) during TH. A median of 45 mEq per day of potassium repletion was administered during the maintenance phase of cooling. Despite those repletions, patients remained hypokalemic 30% of the time. Median serum magnesium concentrations during the maintenance phase of TH remained consistently within goal range of 1.8-2.5 mg/dL. Five patients (12%) experienced at least one episode of cardiac dysrhythmia during the cooling period. Standard potassium electrolyte repletion protocols did not adequately maintain serum potassium concentrations above our target of 3.5 mEq/L in neurosurgical patients undergoing TH. Standard magnesium repletion protocols were sufficient to maintain a normal serum concentration in this patient population when magnesium sulfate was not used for other indications.