Preoperative Hypokalemia and the Cardiac Patient

Abstract

Anesthetic management of the hypokalemic patient continues to be an enigma and concern for the surgical team. The primary concern is the potential risk of cardiac arrhythmias associated with hypokalemia and anesthesia. This concern has been fostered by the well known effect of cations on the electrophysiology of excitable cells¹ and of hypokalemia on the pacemakers of the heart² and by clinical reports which suggest that cardiac arrhythmias are made worse by respiratory alkalosis,^3,4 digitalis therapy⁵ and myocardial ischemia⁶ or infarction⁷ in the presence of hypokalemia. Therefore, it has been traditionally taught that a surgical patient should have a serum potassium of 3.0 mEq/L (undigitalized) and 3.5 mEq/L (digitalized) before being subjected to anesthesia. In spite of this time-honored recommendation, there are no hard data to substantiate that the incidence of intraoperative arrhythmias is increased in the hypokalemic patient. In fact, two recent prospective studies in 597 surgical patients did not demonstrate a correlation between intraoperative ventricular arrhythmias and preoperative hypokalemia,^8,9 even among the high risk cardiac surgical patients.⁹