The application of phenoxybenzamine in open heart surgery using cardiopulmonary bypass

The effects of vasodilator therapy upon organ blood flow, beta-glucuronidase activity in plasma and pulmonary surfactant were evaluated before and during cardiopulmonary bypass. Alpha adrenergic blockade with phenoxybenzamine increased the organ blood flow in the heart, brain, stomach, small intestine, large intestine, and liver, whereas it decreased the organ blood flow in the kidney, spleen, and lung. These changes were extremely similar to those observed at hemorrhagic shock. With 2 mg/kg of POB the organ blood flow tended to approach to control levels. The increase of beta-glucuronidase activity at hemorrhagic shock was considerably inhibited after intravenous drip of 2 mg/kg of phenoxybenzamine. We examined the changes of pulmonary surfactant biochemically. Pulmonary surfactant was decreased in endotoxin shock and similar changes were observed in cardiopulmonary bypass when perfusion time was extended to 3 hours. The decrease of pulmonary surfactant after bypass was inhibited by application of POB. From these results, we supposed that the circulatory dynamics during cardiopulmonary bypass might be similar to that of shock and the application of POB in cardiopulmonary bypass might be useful. We applied POB clinically and had good results.