In a recent review of vasopressin, it was stated that there were only two reported cases using bolus vasopressin (10–20 U) to restore blood pressure after pheochromocytoma resection.1This letter documents another rare case, using a lower dose of bolus vasopressin, for treatment of catecholamine-resistant hypotension after pheochromocytoma resection.

A 54-yr-old man (height, 180 cm; weight, 84 kg) underwent laparoscopic right adrenalectomy for treatment of pheochromocytoma. Preoperative medications included phenoxybenzamine, metoprolol, ramipril, and atorvastatin. Preinduction blood pressure was 129/74 mmHg, and heart rate was 57 beats/min. During manipulation of the adrenal gland, the patient developed hypertension, which was treated with sodium nitroprusside (up to 10 ml/h of 200 μg/ml) and esmolol (up to 5 ml/h of 10 mg/ml) infusions. After resection and discontinuation of the nitroprusside and esmolol, the patient developed hypotension. A norepinephrine infusion of 24 μg/min was only able to increase the patient's systolic blood pressure to the low to mid 80s. Two 0.4-U vasopressin boluses were administered, which increased the systolic blood pressure to 120 mmHg. The patient was started on a 4-U/h infusion of vasopressin resulting in maintenance of a systolic blood pressure at 110 mmHg while permitting a decrease in the norepinephrine infusion rate. Both infusions were continued throughout the rest of the surgery and were weaned several hours postoperatively. The patient did well and was discharged home on postoperative day 2.

There are now three previous reports of bolus vasopressin being used to treat hypotension after adrenal resection for pheochromocytoma.2–4Repeated bolus doses of 10–20 U followed by an infusion were required to treat hypotension after pheochromocytoma resection.2In another adult patient, an infusion of vasopressin required 20 min to achieve improvement in blood pressure during pheochromocytoma resection complicated by a large blood loss.3In an 11-yr-old patient, a 5-U bolus followed by an infusion was successful in treating postresection hypotension.4 

Although vasopressin infusions have been used in a variety of other situations, there are limited data to guide bolus dosing. Others report lower doses of vasopressin bolus. A 2-U bolus dose was used to treat anaphylactic shock.5As in this case, two 0.4-U boluses successfully treated hypotension secondary to both bowel retraction in patients having abdominal aortic resection repair and postreperfusion syndrome during liver transplantation.6,7Terlipressin (a vasopressin precursor) in doses of 1 or 2 mg successfully treated hypotension secondary to induction of anesthesia in patients chronically treated with renin–angiotensin system inhibitors.8Additional well-controlled studies must be conducted to establish the indications, safety, and efficacy of bolus vasopressin for rapid correction of hypotension, particularly catecholamine-resistant hypotension.

This patient adds to the small number of reported cases that suggest vasopressin can be safely and effectively used to treat postadrenalectomy catecholamine-resistant hypotension in patients with pheochromocytoma. Although vasopressin is a vasoconstrictor and it is not surprising that it can treat hypotension, there may be a specific need for vasopressin in some pheochromocytoma patients. First, vasopressin is effective in the presence of residual α-adrenergic blockade and down-regulation of those receptors. Second, in some patients with pheochromocytoma, there is an oversecretion of vasopressin, which may contribute to the induced hypertension.9,10It is possible that chronic oversecretion of vasopressin leads to a down-regulation of vasopressin receptors, thus contributing to the postresection hypotension. Whether preoperative determination of vasopressin over secretion will affect management is an open question. Catecholamines are also known to inhibit vasopressin release.11It has been proposed that chronic inhibition by catecholamines may down-regulate neurohypophyseal vasopressin synthesis, thereby preventing the acute high release of vasopressin during a hypotensive episode.2Last, the use of vasopressin can reduce the catecholamine dose, thus allowing one to avoid their undesirable side effects such as increased myocardial oxygen consumption and ventricular arrhythmias.

Albert Einstein Medical Center, Philadelphia, Pennsylvania.

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