The Effect and Safety of Omitting Preoperative Alpha-adrenergic Blockade for Normotensive Pheochromocytoma

Pheochromocytoma and paraganglioma (PPGL) are rare neuroendocrine tumors originating from catecholamine producing chromaffin cells in the adrenal medulla and extra-adrenal paraganglia. The overall age-standardized incidence rate is 0.18 per 100,000 person-years in Korea. The classical clinical presentations that occur due to the release of catecholamine include headache, palpitation, sweating and hypertension. Excessive catecholamine release from PPGLs can induce life-threatening complication such as myocardial infarction, heart failure, cardiomyopathy, shock, arrhythmias, and stroke. The definitive treatment of PPGL is surgical excision of tumor. However, surgery is associated with a high risk of perioperative hemodynamic instability (HI). To avoid perioperative HI in patients diagnosed with PPGL, preoperative management including routine use of alpha blockade and volume expansion has been advocated by several guidelines.

While unstable hypertension and tachycardia should be controlled in patients with PPGL, there is controversial that all patients diagnosed with PPGL should undergo preoperative pharmacological treatment, especially alpha blockade. The most important risk of preoperative alpha blockade use is perioperative hypotension. The patients with prolonged preoperative alpha blockade may require intravenous fluid and vasopressors. In the recent randomized controlled trial comparing the efficacy of two different alpha blockade, 80-92% of patients reported mild to moderate side effect on alpha blockade.

The proportion of patients who are incidentally diagnosed with PPGLs are increasing. According to the recent study, the European registry for endocrine tumors revealed that incidentaloma were present in 43.4% (239/551 patients) of pheochromocytoma patients, 11.8% (65/551 patients) of patients were diagnosed as pheochromocytoma after adrenalectomy. Patients who were diagnosed with PPGL postoperatively did not undergo proper preoperative management to prevent perioperative HI. Most of them were normotensive patients and there were no specific findings on laboratory or radiologic examination suggesting PPGLs. In addition, a recent study reported that patients diagnosed with PPGL postoperatively may have no further higher risk of intraoperative hypertension than those diagnosed preoperatively despite insufficient preoperatively management of PPGL.

Therefore, it is a very important to study the relationship between HI and preoperative alpha blockade in normotensive patients diagnosed with PPGL. The department of endocrine surgery in Seoul National University Hospital intends to analyze the effect and safety of omitting preoperative alpha-adrenergic blockade for normotensive pheochromocytoma through a prospective randomized controlled trial. The patients is divided into two groups. The patients in control group take a phenoxybenzamine at least 2 to 5 weeks before surgery. If blood pressure is more than 130/80mmHg in the sitting position, the patient will take a more amount of phenoxybenzamine. If blood pressure is less than 90mmHg in the standing position, the patients will take a less amount of phenoxybenzamine. In the case group, there is no drug to be taken.

Primary outcome is to evaluate the percentage of time during surgery with systolic blood pressure more than 160mmHg or average blood pressure less than 60mmHg. And secondary outcomes are to evaluate hemodynamic instability in preoperative ward and postoperative ward.

Inclusion criteria

• Patients aged 19 to 70 years old
• Patients who consented to the study and obtained consent for the study
• Patients undergoing unilateral total adrenalectomy due to normotensive pheochromocytoma/paraganglioma with less than five times of upper limits of serum metanephrine

Exclusion criteria

• Patients under 18 or over 70 years old
• Pregnant women
• Patients with bilateral pheochromocytoma
• Patients suspected of malignant pheochromocytoma/paraganglioma or distant metastasis
• Patients requiring preoperative intensive care unit due to severe hemodynamic instability
• Patients with hypertension (the blood pressure measured more than two times is constantly greater than 140/90 mmHg) or already taking a antihypertensive medication
• Patients with a history of coronary artery disease
• Patients with a history of arrhythmia (atrial fibrillation, Paroxysmal supraventricular tachycardia)
• Patients with a history of cerebrovascular disease (cerebral aneurysm, cerebral infarction, cerebral hemorrhage)
• Patients judged unsuitable by the person in charge of the clinical trial