Chronic hypokalemia and intraoperative dysrhythmias

To investigate whether chronic hypokalemia increases the occurrence of dysrhythmias during anesthesia, the authors recorded the intraoperative electrocardiograms of normokalemic (K+ = 5.0 -3.5 mEq/l; N = 88) and chronically hypokalemic patients (K+ = 3.4 - 2.6 mEq/l; N = 62). In each patient, serum potassium was measured and a 12-lead ECG was analyzed prior to surgery. No patient received potassium perioperatively. Lead II was monitored continuously during anesthesia, either by a Holter monitor (N = 81) or by a trained observer (N = 69). A variety of general anesthetic techniques were utilized, without consideration for the potassium level. The hypokalemic population had a higher incidence of hypertensive and ASA Class III patients (P = 0.03). Analysis of variance revealed no significant difference in the incidence of other characteristics between the hypokalemic and normokalemic groups: age, hypoxemia, cardiac disease, preoperative dysrhythmias, digitalis therapy, surgical site, anesthetic agent, and intubation. The method of ECG monitoring did not affect the incidence of dysrhythmias recorded. Multivariate analysis revealed that the occurrence of intraoperative dysrhythmias correlated with the presence of preoperative dysrhythmias only. The authors conclude that chronic hypokalemia per se is not associated with a higher incidence of intraoperative dysrhythmias.