Serum potassium changes during hypothermia and rewarming: a case series and hypothesis on the mechanism

Abstract

Introduction: Hypokalemia is known to occur in association with therapeutically induced hypothermia and is usually managed by the administration of potassium (K⁺).

Methods: We reviewed data from 74 patients who underwent a therapeutic hypothermia protocol at our medical institution.

Results: In four patients in whom data on serum K⁺ and temperature were available, a strong positive correlation between serum K⁺ and body temperature was found. Based on the close positive relationship between serum K⁺ and total body temperature, we hypothesize that serum K⁺ decreases during hypothermia owing to decreased activity of temperature-dependent K⁺ exit channels that under normal conditions are sufficiently active to match cellular K⁺ intake via sodium/K⁺/adenosine triphosphatase. Upon rewarming, reactivation of these channels results in a rapid increase in serum K⁺ as a result of K⁺ exit down its concentration gradient.

Conclusion: Administration of K⁺ during hypothermia should be done cautiously and avoided during rewarming to avoid potentially life-threatening hyperkalemia. K⁺ exit via temperature-dependent K⁺ channels provides a logical explanation for the rebound hyperkalemia. K⁺ exit channels may play a bigger role than previously appreciated in the regulation of serum K⁺ during normal and pathophysiological conditions.

Keywords: K+ exit channels; hypokalemia; hypothermia; rewarming hyperkalemia; sodium-potassium ATPase; temperature-dependent K+ channels.