Pheochromocytoma Flashcards
Pheochromocytoma is a tumor of
CS
most pheo. dx:
definitive tx:
preoperative, perioperative, and postoperative management may be challenging
w. sx. even dogs with vena caval thrombi may experience a significant survival time of:
chromaffin cells of the adrenal medulla
if functional - hypertension and manifestations of the
elevated blood pressure, weakness, syncope, lethargy, vomiting, diarrhea, tachypnea, abdominal distention, tachyarrhythmias, bradyarrhythmias, and abdominal pain
abdominal imaging or during PM
surgical excision
18 months to greater than 4 years
MENS
multiple endocrine neoplasia syndrome
In humans this is a heritable constellation of two or more endocrine neoplasias (or hyperplasia), usually involving the parathyroid and thyroid glands in addition to the adrenal glands
most pheo dx.
PM 48-80%
do tumors met?
may be both locally invasive and metastatic
pheochromocytomas in humans secrete NE
what % have CS
30-50% (only 0.13% of all canine tumors)
what is budd-chiari like syndrome
resulting from tumor invasion and extension up the
caudal vena cava = occlusion of hepatic vein that drains liver = effusion
what % have causal vena cava involvment
15% to 38%
dx:
CXR -
Abd US how many detected
draw back to US:
better yet:
mineralization sometimes
65% to 83%
can’t ddx. from other adrenocortical tumors
if small may miss
CT, MRI, scintigraphy
MoA of diarrhea:
secrete hormone - vasoactive intestinal peptide
must r/o:
why
HAC
adrenal mass may look same and similar CS sometimes
urinary catecholamine:urine creatinine ratio:
increases could be ___ or ____
4x increase:
list 3 urine catecholamines:
___ was highly suggestive of pheochromocytoma:
false positives (5):
HAC or pheo
pheo
metanephrine, normetanephrine, vanillylmandelic acid
normetanephrine
excitement exercise vanilla-containing foods phenoxybenzamine tx. radiographic contrast agents
clonidine suppression test
should decrease serum catecholamine levels in
normal patients but not in patients with a functional pheochromocytoma (because catecholamine release from the tumor is not neurally mediated)
Provocation tests using( 4):
Moa:
recommended vs not recommended:
avoid as antiemetic/prokinetic:
metoclopramide, histamine, tyramine, and glucagon
increased secretion of catecholamines from the tumor, are not recommended because of the potential for inducing acute hypertensive crises
metoclopramide
Preoperative Treatment
a-antagonist
minimum:
phenoxybenzamine (non-comp. a-antagonist)
1 week before anesthesia
In humans, preoperative α-adrenergic
blockade decreased perioperative mortality from:
13-45% to 0-3%
α-Methylparatyrosine
-ve
competitively inhibits tyrosine hydroxylase -
interfering with catecholamine biosynthesis
significant side effects and has not been studied in veterinary patients with pheochromocytoma
GA
avoid:
safe GA protocol:
BP control:
- anticholinergics
- barbituates
- acepromazine - long-lasting α-adrenergic antagonists may complicate intraoperative or postoperative treatment -especially if animal is pretreated w phenoxybenzamine
opioid
benzo
propofol
iso/sevo
nitroprusside for hypertension
esmolol SVT
lidocaine
GA - blood type
If a venotomy is anticipated for removal of a thrombus:
removal of tumor can cause 1 of 2 things:
1.
if invading into caudal vena cava
external cooling may protect tissues during intraoperative interruption of blood flow and ischemia
Surgical manipulation = catecholamine release
Sx removal - CV collapse (no catecholamines)
= need NE and phenylephrine
elective vs emergent mortality:
another study found:
-ve prognostic indicators:
thorough abdominal exploration why?:
% current neoplasia:
6% for elective
50% emergency
intraoperative mortality was 4.8%
BUN, nephrectomy = shorter survival times
metastatic disease
15% metastasis
39% had locally invasive tumors
54%
post-op complications time frame:
%
complications:
24 to 72 hours postoperatively
30-51%
hypotension, bradycardia, ventricular arrhythmias, tachypnea, vomiting, and CPA, refractory hypertension after removal of
does postop hypertension resolve?:
bilateral adrenalectomy -supplement:
explain postoperative hypotension:
do you tx this hypotension with NE?:
also monitor:
may or may not resolve, even with full excision
GC & MC
- removal catech.
vs. 2. decreased sensitivity to catecholamines
no - noncatecholamine pressors
vasopressin
BG - hypogly bc lack of stim
medical management?:
chemo/radiation?:
phenoxybenzamine, b-blocker
unrewarding in humans
Px:
with vena caval thrombi:
prognosis is guarded, hw. patients surviving post op. okay
even so may experience significant survival times, reported from 1.5 to 4 years
