Effects of Hemodialysis and of Glucose-Insulin Administration on Plasma Potassium and on the Electrocardiogram

Hypopotassemia was produced in dogs by hemodialysis or by intravenous administration of glucose with insulin. Both methods resulted in a similar decrease in plasma K concentration and similar ECG changes although K was withdrawn from the cells during dialysis while it entered the cells during glucose-insulin infusion. The maximal plasma K decrease occurred after two hours of dialysis or glucose-insulin infusion; administration of glucose-insulin after dialysis resulted in no further plasma potassium decrease. However, dialysis after glucose-insulin infusion caused further lowering of plasma potassium. The ECG changes were evaluated in relation to changes in plasma K concentration. The most consistent effects of hypopotassemia were in decreasing order: increased duration of the QRS complex, increased duration of the QT c interval and increase in amplitude of the P wave. Correlation coefficients (R) between these ECG changes and the plasma K decreases were of the order -0.48 to -0.54. The ECG changes failed to show even a weak correlation with absolute plasma K concentrations or with calculated changes in intracellular K.