Changes in ionized calcium and related blood constituents in children after cardiopulmonary bypass

Abstract

Calcium is necessary for myocardial muscle contraction. The ionized calcium fraction in blood is the physiologically active component and can be readily measured with calcium-selective electrodes. Cardiopulmonary bypass (CPB) alters the relationship between calcium and related blood constituents, depending on the composition of the pump-prime and the quantity of blood products administered peri-operatively. Serial measurements of total and ionized serum calcium concentrations and related biochemical parameters were made in 115 consecutive children over a 24-hour period before and after CPB. Total and ionized calcium concentrations were consistently elevated in the immediate postoperative period, and though infants may, theoretically, benefit from calcium infusion after CPB, the uncritical use of calcium salts in children after cardiac surgery is not justified.