Case 30 - pheochromocytoma Flashcards
What is pheochromocytoma?
- neuroendocrine tumor arising from adrenal gland
- specifically from chromaffin cells that syntehsize catecholamines
- result: proliferation of NE, Epi, dopamine
- can be part of a syndrome (MEN)
what are the signs and symptoms of pheochromocytoma?
dependent on which catecholamine excess is predominant
Norepi
- HTN
- h/a
- sweating
- pallor
- bradycardia
Epi
- palipations
- tachy
- panic/anxiety
- tremors
- hyperglycemia
Could there be anything else on your differential besides pheochromocytoma?
- thyrotoxicosis
- nuerolpetic malignant syndrome
- malignant hyperthermia
- pre-eclmpsia
How can you diagnose pheochromocytoma?
- s/sx + lab testing
- elevated levels of metaneprhine and normetanephrine in plasma and/or 24 h urine collection
imaging studies
- helps locate tumor and surgical planning
Echo
- consider obtaining to detect cardiomyopathy (2/2 pheo mediated HTN)
how is pheochromo managed preoperatively?
Initial goal –> block the toxic effects of catecholamines to prevent and reverse end-organ damage.
1) alpha adrenergic antagonists
- first line therapy
- blocks alpha 1 induced vasoconstriction
- Phenoxybenzamine or phentolamine - nonselective
- prazosin (-zosin) - selective alpha 1
- SE: orthostatic hypotension
2) CCB
* used as second agent to refarctory HTN from alpha blockers
3) BB
-
only use after alpha 1 blockade is achieved
- giving BB prior to alpha blockade leads to unopposed alpha 1 agonism –> further vasoconstriction
- typically given for epi secreting tumors or patients who developed tachy from vasodilator therapy.
- beta 1 selective or mixed beta and alpha
- mixed beta and alpha (labetolol) not used 1st line therapy due to weak alpha effects.
what are the intraop surgical and anesthetic considerations for pheochromo?
- surgical resection is definitive tx
- occlusion of draining vein (adrenal vein) is desirable early in procedure to decrease catecholamine release into circulation during manipulation of tumor
1) HD instability / blood loss
- large bore peripheral IV access
- arterial line –> serial abg, beat to beat monitor, HD instability
- CVC –> central circulation, vasoactive infusion, poor peripheral iv access, volume resuscitation
- PAC / TEE - cardiomyopathy, CHF, heart pressures, thermodilution CO
2) vasoactive infusions
- fast on and off, easy to titrate
- hypotension –> phenylephrine, norepi
- HTN –> nitroprusside or nitroglcerin
- SVT/ventricular dysrhythmia –> BB or lidocaine
what stimuli has been implicated in provoking catecholamine surges during procedure?
Factors: Anesthetic Factors, Surgical Factors, Medicatoins
Anesthesia:
- intubation
- light anesthesia
- pain with surgery
Surgical:
- skin incision
- surgical manipulation of tumor
Meds:
- SUX -> fasciculation of abdomen can compress tumor and cause catecholamine release
- meds with histamine release
- morphine, demerol, atracurium
- meds with undesider autonomic effects
- pancoronium, ephedrine, ketamine
most IV anes agents, opioids, neuromusuclar blockers, and inhaled agents are safe.
what are postoperative concerns in pheo patients?
- post op hypotension
- adrenal insuffiency -> lack of catecholamine output
- persistent adrenergic blockade from preop or intraop meds
- bleeding
- Post op HTN
- residual tumor
- stored catecholamines
