Preoperative and Intraoperative Management of Pheochromocytoma
Preoperative Management
Alpha-Adrenergic Blockade (Critical First Step)
Alpha-adrenergic blockade must be initiated 7-14 days before surgery with gradually increasing dosages to achieve blood pressure targets of <130/80 mmHg supine AND >90 mmHg systolic when standing 1, 2. This is the cornerstone of preoperative preparation and directly reduces perioperative morbidity and mortality.
Choice of alpha-blocker:
- Both phenoxybenzamine (non-selective α1/α2 blocker) and selective α1-blockers (doxazosin, prazosin, terazosin) are effective 1, 2
- Phenoxybenzamine may provide less intraoperative hemodynamic instability based on the PRESCRIPT trial, though both agents showed similar overall outcomes 1
- Selective α1-blockers are associated with higher peak intraoperative systolic pressures (209 vs 187 mmHg) but comparable surgical outcomes 3
Beta-Blockade (Only After Alpha-Blockade)
Never initiate beta-blockers before adequate alpha-blockade—this can precipitate fatal hypertensive crisis from unopposed alpha-adrenergic stimulation 2, 4. Beta-blockers (preferably β1-selective like esmolol) should only be added after alpha-blockade is established to control persistent tachycardia or tachyarrhythmias 1, 2.
Volume Expansion
High-sodium diet and administration of 1-2 liters of saline 24 hours prior to surgery, along with compressive stockings, must be employed to prevent orthostatic hypotension preoperatively and severe hypotension postoperatively 1, 2. This addresses the contracted intravascular volume that occurs with chronic catecholamine excess 5, 6.
Adjunctive Medications
- Calcium channel blockers may be used as adjuncts to alpha-blockers for refractory hypertension or as monotherapy in patients with normal to mildly elevated blood pressure or severe orthostatic hypotension 1, 2
- Metyrosine (alpha-methyltyrosine) can be added for additional catecholamine synthesis inhibition, though it requires careful monitoring for sedation and adequate volume maintenance 7
Preoperative Imaging and Evaluation
CT or MRI of the abdomen must be obtained immediately to localize the tumor and assess for bilateral disease, extra-adrenal paragangliomas, or metastases 2, 8.
Biopsy is absolutely contraindicated—it can trigger fatal hypertensive crisis 1, 2, 8.
Functional imaging (MIBG, FDG-PET) should be considered in:
- Patients ≤40 years of age 1
- Those with family history or known germline mutations (especially SDHB/SDHD) 1
- Large tumors (>3 cm) with higher malignancy risk 1
- Suspected extra-adrenal or metastatic disease 1
Common Pitfall to Avoid
The most dangerous error is initiating beta-blockade before alpha-blockade, which can cause unopposed alpha-receptor stimulation leading to severe hypertensive crisis and death 2, 4.
Intraoperative Management
Hemodynamic Monitoring
Continuous blood pressure and electrocardiogram monitoring are mandatory throughout the procedure 7. Invasive arterial monitoring is typically employed given the expected hemodynamic fluctuations 6.
Management of Hypertensive Episodes
Intraoperative hypertension should be treated with:
- Magnesium sulfate (first-line for many anesthesiologists) 2, 8
- Phentolamine (intravenous α-adrenergic antagonist) 2, 7
- Calcium channel blockers 2
- Sodium nitroprusside 2, 9
- Nitroglycerin 2, 9
Despite optimal preoperative preparation, hypertensive crises can still occur during tumor manipulation, and phentolamine should be immediately available 7.
Management of Tachycardia
Tachycardia can be treated with intravenous esmolol (β1-selective preferred) 2. Life-threatening arrhythmias may require beta-blockers or lidocaine 7.
Management of Post-Resection Hypotension
Following tumor removal, severe hypotension commonly occurs due to sudden cessation of catecholamine secretion and expanded vascular capacity 7.
Aggressive treatment is required:
- Large volumes of plasma or crystalloid to maintain blood pressure and central venous pressure within normal range 7
- Vasopressors (phenylephrine) may be needed 3
- This is why preoperative volume expansion is critical 1, 2
Surgical Approach Considerations
Laparoscopic adrenalectomy is the preferred approach for most pheochromocytomas, showing better intraoperative hemodynamic stability compared to open surgery 2, 10.
Open surgery should be considered for:
- Tumors >5-6 cm 2, 8
- High suspicion of malignancy or local invasion 2
- Previous adrenal surgery (though laparoscopy remains feasible) 10
For bilateral disease, functional tumors should be resected first due to perioperative hypertensive crisis risk 2.
Early ligation of the adrenal vein is recommended to minimize catecholamine release during manipulation 10.
Fluid Management Strategy
Patients receiving phenoxybenzamine typically require less intraoperative fluid (median 2977 mL) compared to those on selective α1-blockers (median 5000 mL crystalloid plus 1000 mL colloid) 3. However, adequate volume must be maintained regardless of preoperative regimen 7.
Postoperative Immediate Concerns
Hypoglycemia commonly occurs after catecholamine levels drop and requires close glucose monitoring 2, 8. This results from removal of catecholamine-mediated insulin suppression 6.
Key Perioperative Pitfalls
- Inadequate preoperative alpha-blockade duration (<7 days) increases intraoperative instability 1, 2
- Beta-blockade before alpha-blockade can be fatal 2, 4
- Insufficient volume expansion leads to severe postoperative hypotension 7
- Tumor biopsy can precipitate hypertensive crisis 1, 2
- Failure to have phentolamine immediately available during tumor manipulation 7