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Endocrine·CA-2

Pheochromocytoma Resection

Classic endocrine surgery requiring precise hemodynamic management and a solid understanding of adrenergic physiology.

The stem

A 42 y.o. male with a history of hypertension and episodic headaches is scheduled for a robotic-assisted left adrenalectomy for a suspected pheochromocytoma. PMH: BP 165/105, HR 98. He is currently on phenoxybenzamine.

Focus

Pre-operative alpha-blockade (Roizen criteria), intraoperative hypertensive crisis management, and post-ligation hypotension.

Examination relevance

The 'Golden Rule' of Pheo: Never beta-block before you alpha-block. Defend your choice of vasoactive agents (Clevidipine vs. Nitroprusside) and prepare for the massive drop in SVR once the tumor is clamped.

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Expert sample response

Managing a pheochromocytoma requires meticulous hemodynamic control and a deep understanding of adrenergic receptor physiology. My focus is preventing a hypertensive crisis during tumor manipulation and cardiovascular collapse after tumor ligation. I have confirmed that the patient has met Roizen criteria for adequate alpha-blockade (stable BPs, no EKG changes, orthostatic).

During tumor manipulation, I will use rapid-acting vasodilators like nitroprusside or phentolamine to manage BP spikes. If tachycardia develops, I will only then consider a beta-blocker, ensuring alpha-blockade is already solid to avoid 'unopposed alpha' activity. Once the adrenal vein is ligated, I expect a precipitous drop in SVR; I will be ready with aggressive fluid boluses and a norepinephrine infusion to maintain coronary and cerebral perfusion. I will also monitor glucose levels closely, as these patients often develop profound hypoglycemia after the catecholamine surge is removed.

Full walkthrough

What the Examiner Is Testing

This case tests whether you know the Roizen criteria for adequate pre-operative alpha-blockade, why you never beta-block before alpha-blocking, and what to do when the adrenal vein is ligated and the catecholamine source disappears. The examiner wants drug names, not vague references to "controlling the blood pressure."

The Board Trap

The trap is allowing beta-blockade before confirming adequate alpha-blockade. Beta-blockers in the presence of uncontrolled alpha-adrenergic activity cause unopposed alpha — the vasodilation from beta-2 blockade is removed while alpha-mediated vasoconstriction remains unchecked, potentially causing a hypertensive crisis severe enough to cause stroke or MI. This is the classic "Golden Rule" of pheo management.

Walk-Through: How This Case Plays Out

Examiner: The patient is on phenoxybenzamine pre-op. Has he been adequately prepared?

Me: I'd verify Roizen criteria before proceeding. I want BP below 160/90 for at least 24 hours pre-op, orthostatic hypotension present but not symptomatic, EKG without ischemic changes, and no more than 5 PVCs per minute on monitoring. The presence of orthostatic hypotension is actually reassuring — it means the alpha-blockade is sufficient and his intravascular volume has been restored. If those criteria aren't met, I'm requesting the surgeon delay.

Examiner: During tumor manipulation, the BP spikes to 220/130. What do you do?

Me: I would use sodium nitroprusside or phentolamine as my immediate vasodilators. Nitroprusside is my preference — it's fast, titratable, and I can turn it off quickly. I'd titrate to effect targeting MAP around 100. I would not use a beta-blocker at this point unless the alpha-blockade is confirmed solid — if he has any residual catecholamine activity, adding beta-blockade now risks unopposed alpha. I'd also have magnesium sulfate available for refractory hypertension.

Examiner: The surgeon ligates the adrenal vein. The BP drops to 70/30 within 60 seconds. What happened and what do you do?

Me: The catecholamine source is gone. All that vasopressor tone that was maintaining the BP has just been removed. I expected this — I had a norepinephrine infusion running and vasopressin primed. I'd push a norepinephrine bolus and open the infusion wide. Aggressive fluid resuscitation with balanced crystalloid — these patients are volume-depleted from the phenoxybenzamine. This is also when I start checking glucose closely, because catecholamine removal causes a rebound hypoglycemia from insulin release.

Examiner: Two hours post-op, his glucose is 38 mg/dL. What do you do?

Me: I would treat with 25-50 mL of 50% dextrose IV immediately and recheck in 15 minutes. Rebound hypoglycemia after pheo resection is a known complication — the catecholamine surge was suppressing insulin, and once the tumor is gone the beta-cells reactivate. I'd keep him on a dextrose infusion and check glucose every 30 minutes in the PACU.

Key Phrases That Score Points

  • "Roizen criteria verified before incision — orthostatic hypotension is a good sign, not a problem."
  • "Never beta-block before alpha-block — unopposed alpha causes hypertensive crisis."
  • "Nitroprusside for the hypertensive surge — titratable, fast on, fast off."
  • "Norepinephrine infusion primed before adrenal vein ligation — I know the crash is coming."
  • "Check glucose post-ligation — rebound hypoglycemia from insulin reactivation."

Why This Case Appears on the Boards

Pheochromocytoma tests adrenergic physiology applied to real clinical management. The examiner specifically uses it to probe the beta-before-alpha trap and the post-ligation crash — two events that require preparation, not reaction.