A 42-year-old woman with a confirmed diagnosis of pheochromocytoma (elevated plasma free metanephrines and positive imaging) is found to be hypertensive and tachycardic during the preoperative assessment. She has a history of asthma. Which agent should be avoided in her preoperative preparation?

Explanation

## Preoperative Pharmacotherapy in Pheochromocytoma: Contraindications **Key Point:** Non-selective β-blockers (especially propranolol) are contraindicated as monotherapy in pheochromocytoma and must be avoided in patients with asthma due to the risk of bronchospasm. ### Why Propranolol is Contraindicated #### 1. **General Principle: Never β-Block Before α-Block** - β-blockers alone cause unopposed α-adrenergic effects - Results in severe hypertension and potential hypertensive crisis - Must always follow α-blockade (phenoxybenzamine) by 7–10 days #### 2. **Asthma-Specific Contraindication** - Propranolol is a non-selective β-blocker that blocks β~2~-adrenergic receptors in bronchial smooth muscle - Blockade of β~2~ receptors removes the bronchodilatory effect of endogenous catecholamines - Results in unopposed α-adrenergic bronchoconstriction → **severe bronchospasm** - Asthma is an absolute contraindication to non-selective β-blockers ### Safe Alternatives in This Patient | Agent | Class | Advantage in Asthma | Role in Pheochromocytoma | |-------|-------|---------------------|------------------------| | **Phenoxybenzamine** | Non-selective α-blocker | No bronchial effects | First-line α-blockade | | **Doxazosin** | Selective α~1~-blocker | No bronchial effects | Alternative α-blocker | | **Phentolamine** | Non-selective α-blocker | No bronchial effects | Acute hypertensive crisis | | **Esmolol** | Selective β~1~-blocker | Minimal β~2~ effects; short-acting | Can be used if β-blockade needed after α-blockade | | **Labetalol** | Mixed α/β-blocker | Minimal asthma risk (weak β-block) | Acute intraoperative control | **High-Yield:** In asthmatic patients with pheochromocytoma, use **phenoxybenzamine or doxazosin** for α-blockade. If β-blockade is required (after α-blockade), use **selective β~1~-blockers** (esmolol, metoprolol) rather than non-selective agents. **Clinical Pearl:** Phentolamine (a short-acting α-blocker) is the agent of choice for acute hypertensive crises during pheochromocytoma surgery or in the emergency setting, and it is safe in asthma. **Mnemonic:** **"α before β"** — Always establish α-blockade first. In asthma: avoid propranolol; use selective β~1~-blockers or skip β-blockade if α-blockade alone achieves control.