Control of hypertension during cardiopulmonary bypass with urapidil and phentolamine.

The vasodilating effect of 6-(3-[4-(o-methoxy-phenyl)-piperazin-1-yl]-propylamino)-1,3-dimethyluracil (urapidil, Ebrantil) and phentolamine was investigated during extracorporeal circulation in patients undergoing coronary artery bypass (CABG) operations. To compare the vasodilating effect, 10 patients received 2 times 25 mg urapidil, and another 10 patients 2 times 5 mg phentolamine when mean arterial blood pressure (MAP) exceeded 100 mgHg. Both drugs caused a significant (p less than 0.01) decrease in mean arterial blood pressure and total peripheral resistance (TPR), using constant flow (Qecc). Central venous pressure (CVP), measured in the inferior vena cava, showed no significant change, while a marked volume loss (delta V) in the oxygenator was observed. There was no significant difference in the measured cardiovascular parameters in the two groups of patients. The peripheral vasodilating effect of urapidil, expressed in mg was found 5 times weaker than that of phentolamine. Urapidil was found effective in the treatment of hypertension during extracorporeal circulation.