Persistent Hypokalemia Following Open-Heart Surgery

Six patients who exhibited persistent hypokalemia after open-heart surgery with a dilute blood perfusion mixture are discussed. All these patients had acquired heart disease with heart failure as their predominant problem and had been on long-term diuretic treatment with oral potassium replacement. It was not possible to predict with any degree of certainty which patients would develop hypokalemia postoperatively, but the clinical points discussed indicated that frequent measurement of serum potassium was necessary until the value appeared stable. The authors think that the hypokalemia results from long-term tissue potassium depletion, and that hemodynamic improvement following open-heart surgery may facilitate the return of potassium into the cells and thus reduce the serum level.