Pheochromocytoma

Question 1

What is pheochromocytoma? Where are they

located?

Answer 1

Pheochromocytoma occurs when cells that originate from the
neural crest develop into catecholamine secreting tumors. They
occur at any location that derived from the neural crest. They
have been documented at locations ranging from the neck to
the inguinal ligament.
Fleisher LA. Anesthesia and Uncommon Diseases. 6th ed.
Philadelphia, PA: Elsevier Saunders; 2012: 424.

Question 2

What are the symptoms that are indicative of

pheochromocytoma?

Answer 2

Extremely labile hypertension or a combination of hypertension,
sweating, and headache.
Fleisher LA. Anesthesia and Uncommon Diseases. 6th ed.
Philadelphia, PA: Elsevier Saunders; 2012: 424.

Question 3

Where are most pheochromocytomas located?

Answer 3

About 85% of pheochromocytomas are located in the medulla
of one of the adrenal glands. They are also occasionally found
in the spleen, broad ligament of the ovary, right atrium, or at the
bifurcation of the aorta.
Fleisher LA. Anesthesia and Uncommon Diseases. 6th ed.
Philadelphia, PA: Elsevier Saunders; 2012: 424.

Question 4

With what complex disorder are

pheochromocytomas associated?

Answer 4

Pheochromocytomas may occur in multiple endocrine neoplasia
(MEN IIA and MEN IIB), which consists of carcinoma of the
thyroid, and parathyroid hyperplasia. It is also associated with
neurofibromatosis, tuberous sclerosis, Sturge-Weber syndrome
and von Hippel-Lindau disease.
Fleisher LA. Anesthesia and Uncommon Diseases. 6th ed.
Philadelphia, PA: Elsevier Saunders; 2012: 424.

Question 5

How is the incidence of pheochromocytomas

distributed according to age and gender?

Answer 5

It occurs with equal frequency among males and females. It
most commonly appears between ages 30 and 50. About 10%
of all pheochromocytomas occur in children.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 392.

Question 6

Why is orthostatic hypotension common in patients

with pheochromocytoma?

Answer 6

Chronic hypertension results in hypovolemia and impairment of
the vasoconstrictor reflexes.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 392-393.

Question 7

In what proportions do pheochromocytomas release

norepinephrine and epinephrine?

Answer 7

Pheochromocytomas typically release 85% norepinephrine and
15% epinephrine.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 392.

Question 8

What is the most sensitive test for

pheochromocytoma?

Answer 8

Plasma free metanephrine levels greater than 220 pg/mL are
the test most sensitive for pheochromocytoma. The common
end-product of the metabolism of epinephrine and
norepinephrine via catechol-O-methyltransferase or monoamine
oxidase is vanillylmandelic acid. Urinary excretion of
vanillylmandelic acid is the oldest and least expensive test, but
is not very sensitive.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 393.

Question 9

What is the medical treatment for

pheochromocytoma?

Answer 9

Because the predominant problem in pheochromocytoma is the
oversecretion of norepinephrine, the administration of alphablocking
agents is indicated to reduce blood pressure, increase
intravascular volume, improve myocardial function, and allow
adrenergic receptors the opportunity to re-sensitize. During
critical management of a hypertensive crisis, nitroprusside may
be used.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 394.

Question 10

What is the most common symptom of
overmedication with phenoxybenzamine in the
treatment of pheochromocytoma?

Answer 10

Orthostatic hypotension.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 394.

Question 11

How does the release of catetocholamines in the
patient with pheochromocytoma compare with that of
a normal patient during periods of stress?

Answer 11

In the normal patient, periods of stress can result in
catecholamine levels between 200 and 2000 pg/mL. Patients
with pheochromocytoma can exhibit levels between 200,000
and 1 million pg/mL.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 393.

Question 12

What is the typical dosing regimen for
phenoxybenzamine in the treatment of
pheochromocytoma?

Answer 12

The usual dosing treatment begins at 10-20 mg BID with most
patients requiring between 60 mg and 250 mg a day.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 394-395.

Question 13

What is the most common cause of death in the
immediate postoperative period after excision of a
pheochromocytoma?

Answer 13

Hypotension
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 395.

Question 14

What alpha blockers may be used in place of
phenozybenzamine in the treatment of
pheochromocytoma?

Answer 14

Prazosin, doxazosin, and terazosin.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 394.

Question 15

How does phenozybenzamine affect alpha-1 and

alpha-2 receptors?

Answer 15

It produces noncompetitive alpha-1 blockade with mild blockade
of alpha-2 receptors.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 394.

Question 16

What side effect can occur from the alpha-2 receptor
blockade produced by phenoxybenzamine? What is
the recommended treatment for this side effect?

Answer 16

It can produce tachyarrhythmias. The recommended treatment
is beta-blockers.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 394.

Question 17

What is the treatment of choice if a
pheochromocytoma secretes primarily epinephrine
rather than norepinephrine?

Answer 17

Beta-blockers are the treatment of choice if it is primarily an
epinephrine-secreting tumor. During anesthesia, esmolol is
usually utilized for its short duration of action.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 395.

Question 18

What hemodynamic monitoring methods are typically
required for surgical excision of a
pheochromocytoma?

Answer 18

Standard monitoring plus an arterial catheter, a central venous
or pulmonary artery catheter, and a foley catheter. Some
practitioners will utilize transesophageal echocardiography for
closer monitoring of myocardial function.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 394-395.

Question 19

What are the expected hemodynamic changes that
occur during surgical excision of a
pheochromocytoma?

Answer 19

Hypertension usually results from manipulation of the tumor (the
tumor itself may contain as much as 800 mg of epinephrine
and/or norepinephrine) followed by hypotension after the tumor
is excised when the catecholamine levels fall abruptly.
Stoelting RK, Dierdorf SF. Anesthesia & Co-Existing Diseases.
5th ed. New York, NY: Churchill-Livingston; 2008: 392.

Question 20

What is the preferred vasodilator for hypertensive
episodes during surgical excision of a
pheochromocytoma?

Answer 20

Nitroprusside is preferred for the treatment of hypertension
(systolic pressures over 200 mmHg are common) during
surgical excision of pheochromocytomas. Nitroglycerin will
reduce the blood pressure, but the amount required to control
the blood pressure often results in tachycardia.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 394-395.

Question 21

At what point during surgical excision of a
pheochromocytoma should you expect hypotension
and how should you treat it?

Answer 21

Hypotension typically occurs following ligation of the vein
draining the tumor. To prevent hypotension, the patient should
undergo volume expansion until a pulmonary capillary wedge
pressure of 16-18 mmHg is reached prior to ligation of the vein.
Vasopressors should be utilized only after adequate volume
expansion has been achieved.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 395.

Question 22

What medication should be administered
intraoperatively if the patient is expected to undergo
bilateral adrenalectomy for removal of
pheochromocytomas?

Answer 22

Glucocorticoid therapy will be required if the patient undergoes
bilateral adrenalectomy.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 395.

Question 23

What is the most commonly prescribed alphablocker

for the treatment of pheochromocytoma?

Answer 23

Phenoxybenzamine
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 394.