Pheochromocytomas are functionally active,
catecholamine-secreting tumours of chromaffin tissue. The mainstay of pharmacological
therapy is preoperative treatment with oral
phenoxybenzamine. This
drug irreversibly alkylates alpha-1-adrenergic receptors on vascular smooth muscle and renders them nonfunctional, thereby causing vasodilatation. The duration of action of a single dose is approximately 24 h. Therefore, postoperative
hypotension is a hazard of
therapy with
phenoxybenzamine if adequate plasma volume repletion is not provided.
Prazosin, a short-acting, competitive alpha-1 blocker, has been used preoperatively, but has been criticized for its failure to adequately prevent perioperative hypertensive episodes. We report the case of a 73-year-old woman who was admitted for elective
pheochromocytoma resection. Preoperative
therapy with
phenoxybenzamine was impossible because of the patient's refusal to take the
drug. Preoperative
antihypertensive preparation was therefore performed with
prazosin 30 mg/24 h and
metoprolol 100 mg/24 h. During the surgical preparation of the
tumor,
sodium nitroprusside was started at an average infusion rate of 4.1 micrograms/kg/min. After resection of the primary
tumor, when the
sodium nitroprusside infusion was stopped the patient exhibited an increase in systolic blood pressure (BP) up to 210 mg Hg. This
hypertensive crisis was managed with
sodium nitroprusside,
nitroglycerin, and
esmolol. A multilocular
pheochromocytoma was diagnosed. Further stimuli due to tumour palpation resulted in repeated increases in BP. In this manner, two additional areas of tumour could be diagnosed by BP peaks after reduction of the
sodium nitroprusside infusion. After complete resection of a total of three tumours, no further
hypertensive crises occurred. The patient's postoperative course was uneventful. We conclude that in this patient presenting with an unsuspected multilocular
pheochromocytoma, the lack of permanent alpha-blockade was probably helpful in allowing complete resection of all the tumours.