What is the management of hypotension (low blood pressure) post adrenalectomy (surgical removal of an adrenal gland) due to pheochromocytoma (a type of adrenal gland tumor)?

From the Guidelines

Management of hypotension after adrenalectomy for pheochromocytoma requires aggressive fluid resuscitation as the primary intervention, with the goal of maintaining a mean arterial pressure of at least 60 mm Hg, as recommended by the 2024 POQI international consensus statement on perioperative arterial pressure management 1.

Key Considerations

• Begin with crystalloids (normal saline or lactated Ringer's) at 10-20 mL/kg, reassessing response frequently, as hypotension can be prolonged and may require ongoing management 1.
• If hypotension persists despite adequate volume replacement, vasopressors should be initiated, with norepinephrine (starting at 0.01-0.1 mcg/kg/min) typically being the first-line agent, and phenylephrine (0.1-0.5 mcg/kg/min) as an alternative 1.
• Vasopressin (0.01-0.04 units/min) may be added for refractory cases, and the side-effect profile of drugs used in the treatment of hypotension must be taken into account 1.

Underlying Causes

• Hypotension occurs because tumor removal eliminates excess catecholamines that previously maintained vasoconstriction, resulting in vasodilation and relative hypovolemia, as noted in the 2024 ESC guidelines for the management of elevated blood pressure and hypertension 1.
• Additionally, preoperative alpha-blockade contributes to vasodilation, and patients with pheochromocytoma may have peripheral hypovolaemia due to the redistribution of volume from the periphery to the cardiopulmonary system 1.

Monitoring and Management

• Monitor for at least 24-48 hours post-surgery as hypotension can be prolonged, and consider continuous intraoperative arterial pressure monitoring to help reduce the severity and duration of hypotension 1.
• Steroid replacement (hydrocortisone 100 mg IV every 8 hours, transitioning to oral prednisone) is necessary if bilateral adrenalectomy was performed, and blood glucose should be monitored regularly as hypoglycemia may occur with the sudden drop in catecholamines 1.
• Electrolyte imbalances, particularly hypomagnesemia, should be corrected as they can worsen hypotension, and a passive leg raise (PLR) test may be useful in detecting whether inadequate preload is contributing to hypotension 1.

From the FDA Drug Label

For blood pressure control in certain acute hypotensive states (e.g., pheochromocytomectomy, sympathectomy, poliomyelitis, spinal anesthesia, myocardial infarction, septicemia, blood transfusion, and drug reactions). Phenylephrine Hydrochloride is an alpha-1 adrenergic receptor agonist indicated for increasing blood pressure in adults with clinically important hypotension resulting primarily from vasodilation, in such settings as septic shock or anesthesia.

The management of hypotension post adrenalectomy due to pheochromocytoma may involve the use of:

• Norepinephrine (IV) for blood pressure control in certain acute hypotensive states, including pheochromocytomectomy 2
• Phenylephrine (IV) for increasing blood pressure in adults with clinically important hypotension resulting primarily from vasodilation 3 Key considerations:
• Dosing and administration should be guided by the specific product labeling and clinical judgment
• Monitoring for potential adverse reactions and interactions is essential

From the Research

Management of Hypotension Post Adrenalectomy

The management of hypotension post adrenalectomy due to pheochromocytoma involves several strategies, including:

• Fluid management to correct irregularities in circulating plasma volume 4
• Use of vasoconstrictors, such as vasopressin, to achieve sufficient vasoconstriction and pressor effect without any complications 4
• Administration of catecholamine support, such as dopamine and norepinephrine, to maintain systolic blood pressure >90 mm Hg 5, 6
• Identification of clinical predictors of prolonged postresection hypotension, such as tumor size >60 mm, urinary epinephrine levels >200 μg/day, and urinary norepinephrine levels >600 μg/day, to manage patients more effectively 5

Anesthetic Management

Anesthetic management of patients undergoing adrenalectomy for pheochromocytoma is crucial to prevent severe hemodynamic variations, including hypertensive crisis and hypotension. Strategies include:

• Preoperative alpha-adrenergic blockade and subsequent intravascular volume expansion to avoid severe intraoperative hypotension 6
• Use of partial intravenous anesthesia and constant rate infusions of dexmedetomidine and maropitant to provide stable perioperative hemodynamic conditions 7
• Monitoring of intraoperative mean arterial pressures (MAPs) to prevent postoperative acute kidney injury (AKI) 8

Prevention of Postoperative Acute Kidney Injury

Prevention of postoperative AKI is crucial in patients undergoing adrenalectomy for pheochromocytoma. Strategies include:

• Optimizing hemodynamics, especially blood pressure after the adrenal vessel ligation and tumor is resected 8
• Avoiding prolonged exposure to hypotension, especially MAPs less than 65 mmHg 8