## Preoperative Management of Pheochromocytoma **Key Point:** Phenoxybenzamine is the gold standard for preoperative alpha-blockade in pheochromocytoma. It provides sustained, non-competitive alpha-adrenergic blockade, preventing catecholamine-induced hypertensive crises during surgery. ### Mechanism of Action - **Phenoxybenzamine:** Non-selective, non-competitive alpha-blocker (irreversible binding) - Provides sustained blockade independent of catecholamine concentration - Allows peripheral vasodilation and restoration of blood volume - Prevents intraoperative hypertensive surges ### Preoperative Protocol | Phase | Agent | Rationale | |-------|-------|----------| | **Week 1–2** | Phenoxybenzamine 10–20 mg BD–TDS | Alpha-blockade; titrate to BP control | | **After α-blockade established** | Beta-blocker (propranolol) | Prevent reflex tachycardia; NEVER give beta-blocker alone | | **Fluid management** | IV saline loading | Restore intravascular volume depleted by alpha-blockade | | **Intraoperative** | Continuous monitoring; phentolamine on standby | Manage hypertensive surges | **High-Yield:** Always establish alpha-blockade BEFORE beta-blockade. Giving a beta-blocker first (unopposed alpha effects) causes severe hypertension and coronary vasoconstriction. ### Why Phenoxybenzamine? 1. **Non-competitive binding** → sustained effect even with catecholamine surges 2. **Longer duration** (12–24 hours) → allows once or twice daily dosing 3. **Predictable BP control** → reduces intraoperative complications 4. **Proven safety record** in pheochromocytoma surgery **Clinical Pearl:** Patients on phenoxybenzamine often develop postural hypotension and reflex tachycardia. This is expected and managed with salt loading and beta-blockade (added only after alpha-blockade is achieved). **Mnemonic:** **PHENO** = **P**reoperative **H**ypertension **E**mergency **NO**-competitive blocker.
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