Inhibition of Insulin Release in Infants Undergoing Deep Hypothermic Cardiovascular Surgery

Plasma immunoreactive insulin and glucose levels were studied in infants undergoing deep hypothermic cardiovascular surgery. In six receiving glucose infusions, marked hyperglycemia developed when body temperature was lowered below 30°C. With cooling, plasma immunoreactive insulin levels fell or remained low despite the development of hyperglycemia. On rewarming, plasma insulin concentrations rose markedly, and glucose levels fell despite continued glucose administration. In three infants given saline infusions rather than glucose, plasma glucose and immunoreactive insulin levels remained relatively stable during cooling. Five of these patients were studied when unanesthetized and at normal temperatures. Similar glucose infusions produced much smaller increases in plasma glucose levels, and yet circulating immunoreactive insulin levels increased. These observations indicate that reduction of exogenous glucose uptake is associated with a marked reversible inhibition of insulin release in infants undergoing deep hypothermic cardiovascular surgery.