Pheochromocytoma Crisis
Causes:
➧ The action of unopposed high circulating levels of catecholamines
- α - receptors: Pressor response
- β - receptors: positive ino- and chrono-topic
Precipitating factors:
➧ Spontaneous
➧ Hemorrhage into pheochromocytoma
➧ Exercise
➧ Pressure on abdomen
➧ Urination
➧ Drugs: glucagon, naloxone, metoclopramide, ACTH, cytotoxics, tricyclic antidepressants
Clinical picture:
➧ History of poorly controlled Hypertension or accelerated Hypertension.
➧ Hypertension, palpitations, sweating, pallor, pounding headache, anxiety, tremulousness, pulmonary edema, feeling of impending death, hyperhidrosis, nausea and vomiting, abdominal pain, paralytic ileus, hyperglycemia, hypertensive encephalopathy, myocardial infarction, and stroke.
➧ Attacks build up over a few minutes and fade gradually over 15 min or can be more sustained (60 min).
➧ Signs of end-organ damage (Figure 1)
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| Figure 1: Hypertensive Retinopathy - Grade IV |
Biochemical Diagnosis:
➧ 24 h. urine collection for free catecholamines and metanephrines.
Management of Pheochromocytoma Crisis:
-Do not wait for biochemical confirmation of the diagnosis.
-Be aware of postural hypotension.
-Avoid histamine-releasing drugs.
-Surgical resection treatment of choice.
α-adrenergic blockers:
-Treatment with a-antagonists should precede β-antagonist treatment with 48 h. to avoid exacerbation of the crisis.
➧ Phentolamine: (short-acting) 2-5 mg IV repeated/5 min.
➧ Phenoxybenzamine: 1st choice because it’s irreversible and long-acting
10 mg/12h., then 20-40 mg/8 h.
➧ Prazosin, Terazosin & Doxazosin: are selective α1-blockers. Preferable for long term Rx due to favorable S/E
β-blockers:
-Control tachycardia.
-After adequate α-adrenergic blockage to prevent unopposed hypertension.
➧ Non selective b- antagonist: Propranolol: 1-2 mg/5-10 min. 30-60 mg/d. oral.
➧ Esmolol: 500 µg/kg/min. for 1 min., then 100-300 µg/kg/min.
➧ Metoprolol
➧ Labetalol: α and β blocker.
Catecholamine synthesis inhibitors:
➧ Metyrosine
-Inhibit catecholamine synthesis.
-Used when alpha &beta blockers are ineffective or poorly tolerated.
-Combined for difficult resections.
Calcium channel blockers:
-Inhibit norepinephrine mediated calcium transport.
Acute hypertensive crisis (pre/intra-op):
➧ Nitroprusside
➧ Phentolamine
➧ Nicardipine
Surgery and Post-operative care:
➧ Experienced surgeon/anesthetist team.
➧ Last α & β doses on the day of surgery.
➧ Avoid fentanyl, ketamine, morphine, atropine, halothane, and desflurane during surgery.
➧ Treat hypotension post resection with fluids and intermittent doses of vasopressors.
➧ 24 h. urine metanephrine & catecholamine level 1-2 wks post-surgery and annually for life.
➧ Lifelong glucocorticoid and mineralocorticoid therapy for bilateral adrenalectomy.
➧ Radiotherapy, cryoablation, and combination chemotherapy should be considered for malignant pheochromocytoma.
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