P002: ANESTHETIC MANAGEMENT OF AN UNDIAGNOSED PHEOCHROMOCYTOMA: SAFE PERIOPERATIVE CARE IN THE SETTING OF DIAGNOSTIC UNCERTAINTY
Dustin Horne, DO1; Garett Grant, MD1; Elias Bouyounes2
1AdventHealth Orlando Anesthesiology Residency Program; 2Edward Via College of Osteopathic Medicine
Background: Pheochromocytomas are catecholamine-secreting tumors arising from chromaffin cells of the adrenal medulla. Although classically associated with sustained hypertension, palpitations, headache, diaphoresis, and pallor, presentations may be variable, including paroxysmal hypertension or normotension. Pheochromocytomas are identified in approximately 0.1% of patients with sustained hypertension and account for about 5% of incidentally discovered adrenal masses. Diagnosis typically relies on plasma or urinary metanephrines greater than four times the upper limit of normal. However, equivocal or subthreshold elevations may occur, creating diagnostic uncertainty and potentially leading to inadequate preoperative optimization with alpha- and beta-adrenergic blockers. In such cases, anesthesiologists must anticipate significant hemodynamic instability and avoid triggers of catecholamine surge.
Case: The patient is a 56-year-old male scheduled for resection of a 2.3 cm right adrenal mass discovered incidentally during evaluation for nephrolithiasis. The patient had new-onset hypertension diagnosed the prior year. They also reported remote symptoms of palpitations, hot flashes, and right flank pain. Biochemical evaluation revealed slightly elevated but subdiagnostic total metanephrines, normal normetanephrine levels, and a slightly elevated cortisol level on low-dose dexamethasone suppression testing. Renin activity and DHEA levels were normal. Computed tomography demonstrated 66% contrast washout, favoring adrenal adenoma, though pheochromocytoma could not be excluded. Given the overall low clinical suspicion, preoperative alpha- and beta-adrenergic blockade was not initiated. After multidisciplinary discussion, the anesthesia plan incorporated enhanced monitoring and preparedness for potential hemodynamic lability. General anesthesia was induced with midazolam premedication followed by fentanyl, lidocaine, propofol, and rocuronium, ensuring adequate depth prior to intubation. Standard ASA monitors, arterial line, two peripheral intravenous lines, and central venous access were established. Maintenance was achieved with sevoflurane and hydromorphone. Continuous infusions of dexmedetomidine and magnesium were initiated, with nitroglycerin, phenylephrine, and vasopressin readily available. During adrenal manipulation, blood pressure fluctuations occurred but were effectively controlled with the above medications. Following tumor resection, hemodynamics stabilized. Final pathology with immunohistochemical staining confirmed pheochromocytoma.
Discussion: In conclusion, pheochromocytomas may go undiagnosed when symptoms and laboratory findings are inconclusive, resulting in inadequate preoperative alpha- and beta-adrenergic blockade. Even when preoperative suspicion is low, anesthesiologists must remain vigilant and prepared for catecholamine-mediated instability. Comprehensive monitoring, careful anesthetic technique, and ready access to vasoactive medications are critical to ensuring safe perioperative outcomes. Dexmedetomidine is a highly selective α2-adrenergic agonist that can blunt central sympathetic tone and improve hemodynamics, particularly during intubation. It also can reduce catecholamine-driven tachyarrhythmias and reduce anesthetic requirements. Magnesium inhibits catecholamine release from the tumor, causes smooth muscle relaxation leading to vasodilation, and stabilizes the myocardial membrane. In patients who are poorly optimized preoperatively, infusions of magnesium and dexmedetomidine may help reduce hemodynamic instability during the procedure and should be initiated early in the case.
