Levels of plasma insulin and glucose after open-heart surgery

Plasma glucose, insulin, and potassium were measured in patients before, during, and after cardiopulmonary bypass surgery. Five per cent dextrose was used for the pump prime. In all patients, plasma glucose rose rapidly during bypass but insulin secretion was suppressed. The concentration of plasma growth hormone rose rapidly at this time. Five patients (Group II) received isoproterenol (Isuprel) intravenously immediately after cardiopulmonary bypass, and their plasma insulin rose to high levels, statistically significantly above those of the control group of 5 patients who did not receive isoproterenol. Administration of isoproterenol did not suppress the growth hormone levels. The mean level of serum potassium was lower in the Group II patients (high plasma insulin) at that time, but later, when insulin levels had fallen to resting values, their mean potassium level was above that of the control group in spite of their having received less potassium intravenously.