Comparison of phentolamine and urapidil in controlling acute intra-operative hypertension in patients subjected to coronary artery bypass surgery.
Intra-operative hypertensive episodes are a frequent problem in patients undergoing coronary artery bypass grafting. The haemodynamic effects of the alpha-adrenergic blocking drugs phentolamine and urapidil, two alpha-adrenergic blocking drugs with a different alpha-receptor subtype specificity, when used to control intra-operative hypertension were evaluated. Ten patients received phentolamine (about 25 micrograms kg-1 min-1) and ten patients received urapidil (about 100 micrograms kg-1 min-1) to return arterial blood pressure to control levels. Both drugs decreased arterial pressure to baseline values within 2-3 minutes by reducing the elevated systemic vascular resistance. Treatment with phentolamine was accompanied by a marked increase in heart rate with a concomitant increase in cardiac index and the rate-pressure product. Urapidil caused no change in heart rate, but the cardiac index increased. Urapidil lowered the rate-pressure product significantly. Both drugs reduced mean pulmonary artery and pulmonary capillary wedge pressures. The different selectivity of phentolamine and urapidil to alpha 1-and alpha 2-adrenergic receptors induces the diverse haemodynamic effects. We conclude that the use of urapidil is the superior regimen when an alpha-adrenergic blocking agent is favoured as a vasodilator.
D000208:Acute Disease; D000310:Adrenal Gland Neoplasms / Q000601:surgery; D000768:Anesthesia, General; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D001026:Coronary Artery Bypass; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*; D007431:Intraoperative Complications / Q000188:drug therapy; D008297:Male; D008875:Middle Aged; D010646:Phentolamine / Q000627:therapeutic use*; D010673:Pheochromocytoma / Q000601:surgery; D010879:Piperazines / Q000627:therapeutic use*
D000959:Antihypertensive Agents; D010879:Piperazines; C015568:urapidil; D010646:Phentolamine