Pheochromocytoma

Why examiners ask this

Pheochromocytoma is a two-act play: a hypertensive crisis the moment the tumor is handled, then a vasodilated, catecholamine-depleted collapse the moment the vein is tied. The examiner uses it to test whether you prepared the patient before you ever walked into the room, whether you can run a vasodilator infusion and a vasopressor infusion in the same hour, and whether you recognize the undiagnosed tumor that presents as unexplained hypertension and tachycardia under anesthesia. It stresses judgment, adaptability, and organization.

The 60-second answer

Decision points and the "why"

• Alpha blockade first, for 7–14 days — phenoxybenzamine is irreversible and non-selective, giving the most reliable blockade at the cost of reflex tachycardia and postoperative hypotension; doxazosin is selective and shorter-acting. I pick phenoxybenzamine for a large tumor with wild pressures, doxazosin for a routine adenoma. Calcium-channel blockers are the usual add-on when pressure is not controlled, not a substitute.¹
• Beta blockade only after alpha — unopposed beta blockade removes beta-2 vasodilation and leaves alpha constriction uncontested, so the pressure climbs and the heart fails against it. I add a beta-blocker only for tachycardia after at least 3–4 days of alpha blockade; labetalol is not used as initial therapy because its alpha effect is weak.¹
• Volume loading — chronic vasoconstriction contracts the plasma volume; I encourage salt and fluid during blockade and give 1–2 L of saline from the evening before surgery,¹ because the vasodilated patient after ligation needs a full tank, not a pressor alone.
• Drugs I avoid and why — succinylcholine fasciculations compress the tumor; ketamine, ephedrine and pancuronium release or mimic catecholamines; metoclopramide and droperidol provoke release; morphine and atracurium release histamine. I use propofol, fentanyl or remifentanil, rocuronium, and sevoflurane.
• Vasodilator choice during manipulation — nitroprusside acts in seconds and is gone in minutes, exactly the profile I need; nicardipine is safer in less experienced hands but lingers; magnesium 2–4 g blunts catecholamine release and arrhythmias. Phentolamine 1–5 mg boluses work but tachyphylaxis limits it.
• Laparoscopic approach — insufflation itself provokes catecholamine release, so I ask for the lowest workable pressure and expect a surge on pneumoperitoneum before the gland is touched.
• Anticipating the ligation — I ask the surgeon to warn me before the adrenal vein is clamped, stop the vasodilators ahead of it, and have the pressor primed, because the pressure can fall from 220 to 60 within a minute.

The complication they will inject

The surgeon grasps the tumor and the pressure climbs to 240/130 with ventricular ectopy. I tell the surgeon to stop handling the gland, deepen the anesthetic, start or escalate nitroprusside, whose average effective rate is about 3 mcg/kg/min,² give magnesium 2 g, and add esmolol 0.5 mg/kg for the tachycardia and ectopy. I watch the ST segments, because a crisis here precipitates ischemia or pulmonary edema. Once controlled I let the surgeon continue in smaller steps. The second act arrives ten minutes later: the vein is tied, the pressure reads 65/30 and phenylephrine does nothing. I stop the vasodilators, give 500 mL boluses, which is the first-line treatment,³ and move to norepinephrine and then vasopressin, because weeks of catecholamine excess have downregulated the alpha receptors and vasopressin acts through a separate receptor. If the tumor was never diagnosed, I treat the crisis the same way and ask the surgeon to abort once stable.

Pitfalls that cost points

• Describing the induction before saying the patient was alpha-blocked and volume-loaded.
• Giving a beta-blocker first or choosing labetalol as the alpha blocker.
• Running nitroprusside through the ligation and then wondering why the pressure will not come up.
• Reaching for ephedrine, which releases catecholamines from a tumor that has plenty.
• Forgetting postoperative hypoglycemia.

Rapid-why

Q: Why does hypoglycemia occur after resection? A: Catecholamines suppress insulin release and drive glycogenolysis; when they vanish, insulin rebounds and glucose falls, in about 5–15% of patients and usually within 4 hours, so I check it frequently and monitor glucose and hemodynamics for 24–48 hours.^3,1

Q: What else looks like this under anesthesia? A: Light anesthesia, malignant hyperthermia, thyroid storm, carcinoid and autonomic hyperreflexia; a rising end-tidal CO2 points toward MH.

Q: Why is an epidural not enough to prevent the surge? A: Neuraxial blockade removes sympathetic nervous output but does nothing to the catecholamines pouring directly from the tumor into the circulation; it does add to the post-ligation hypotension.

Q: Which syndromes carry a pheochromocytoma? A: MEN 2A and 2B, von Hippel-Lindau, and neurofibromatosis type 1; in MEN 2 I ask about medullary thyroid carcinoma and hyperparathyroidism.

Numbers to know

Links

• Perioperative hypertension, Intraoperative hypotension: differential and management, Vasopressors and inotropes: choosing and titrating, Malignant hyperthermia, laparoscopy
• Endocrine Society clinical practice guideline on pheochromocytoma and paraganglioma