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

Abstract

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.