[Morphine-"anesthesia"--coronary blood flow and oxygen consumption in patients with coronary artery disease]

The effects of large dose morphine-oxygen "anaesthesia" (6 mk/kg) on myocardial blood flow (argon wash-in), myocardial oxygen consumption, myocardial lactate balance and cardiovascular dynamics were studied in 8 patients on maintenance doses of beta-receptor antagonists undergoing two or three vessel coronary artery bypass operations. Measurements were performed in the awake state, 10 min after morphine infusion without surgical stimulation, during sternotomy and 3-4 h after the operation in the intensive care unit at normothermia. Large doses of morphine produced a 13% reduction in coronary blood flow and myocardial oxygen consumption. Mean arterial pressure was significantly reduced with two patients requiring administration of a vasopressor. During sternotomy arterial pressure and heart rate markedly increased, resulting in an increase in myocardial work as reflected by a 40% increase in myocardial oxygen consumption and coronary blood flow. 7 patients required vasodilator therapy. Myocardial lactate production was observed in 1 patient. During recovery blood pressure was reduced while heart rate was increased. Myocardial oxygen consumption was reduced by 18% while coronary blood flow had reached preinfusion levels indicating luxury perfusion after cardioplegia. Our data demonstrate that large doses of morphine as the sole "anaesthetic" fail to provide adequate reflex blockade during sternotomy and adversely affect myocardial oxygen balance in patients with coronary artery disease.