Question

A patient presents with headache, palpitations, and diaphoresis with elevated 24-hour urine metanephrine levels. Which drug is given preoperatively?

• A. Phenoxybenzamine
• B. Esmolol
• C. CCB
• D. Labetalol

Hint:

Pheochromocytoma presents with headache, palpitations, sweating and raised metanephrines. Alpha blockade is classically required before beta blockade.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The patient presents with the classic triad of Pheochromocytoma (headache, palpitations, sweating) confirmed by elevated metanephrines. Management requires careful blood pressure control before surgery.
Step 2: Detailed Explanation:

Pathophysiology: Pheochromocytomas are catecholamine-secreting tumors. Excess epinephrine and norepinephrine cause severe hypertension and tachycardia.

Preoperative Principle: The most critical rule is "Alpha blockade before Beta blockade." If you give a beta-blocker alone, it will block skeletal muscle vasodilation (via \(\beta_2\) receptors), leaving alpha-mediated vasoconstriction unopposed, which can cause a life-threatening hypertensive crisis.

Traditional approach: Phenoxybenzamine (Option A) is a non-selective, irreversible alpha-blocker traditionally used first.

Labetalol (Option D): Labetalol is a combined \(\alpha\) and \(\beta\) adrenergic antagonist. While some traditionalists avoid it initially due to its higher \(\beta\) than \(\alpha\) blocking ratio (approx. 1:3), it is frequently used in clinical practice for rapid BP control when both tachycardia and hypertension are present. As per the answer key provided, Labetalol is the chosen response.

Preoperative Goals: The goal is to control blood pressure and restore intravascular volume (which is usually depleted due to chronic vasoconstriction) before surgical resection of the tumor.

Step 3: Final Answer:
Preoperative preparation for pheochromocytoma aims to antagonize the effects of catecholamines, often utilizing combined blockers like Labetalol or sequential alpha and beta blockade.