adrenal gland Flashcards
The right adrenal gland capsule can be continuous with the _______ ________ of the CVC.
tunica externa
What % adrenal neoplasia invade CVC, phrenicoabdominal veins, or renal vasculature?
25%
Vascular invasion may cause signs of ascites, edema, or venous distention.
Ultrasonography has a sensitivity and specificity of ___% and ___%, respectively for detection of tumor thrombus.
Sens 80%, Spec 90%
Indications for open adrenalectomy? (vs. laparoscopic)
Vascular invasion of the mass into surrounding vessels and large masses (>6 cm)
Post op mineralocorticoid replacement drug name and dose?
Fludrocoritsone Acetate (Florinef) 0.2 mg/kg PO q 12 h for 2-7 days postop
Yes, fludrocortisone is much less reliable than desoxycorticosterone for normalizing serum electrolyte abnormalities; however the effects of fludrocortisone last only a day (vs 28 days with one deoxycorticosterone injection.
Pulmonary thromboembolism is a common life-threatening complication of adrenal sx, particularly in dogs with adrenal neoplasia. Thromboprophylaxis: anti-coagulant drug name and dose?
Name of a thrombolytic agent that can be used to treat PTE?
Heparin (Unfractionated) 35 units/kg SC q 12 hours the day after surgery, then taper over the next 4 days. Hetastarch (10-20 mL/kg IV on the 5th postop day)
(Fossum says that you can start heparin during surgery for thromboprophylaxis)
Thrombolytic agent: Streptokinase
Pheochromocytomas are catecholamine-secreting tumors of the _________ tissue, which usually arise in adrenal medullary tissue.
chromaffin
Pheochromocytomas are also known as ____________?
paragangliomas
Rare sequel of pheochromocytoma that I have never heard….and wanted to remember
Colonic perforation is a rare sequela of excessive glucocorticoid secretion. Corticosteroids may inhibit collagen synthesis and increase collagen breakdown. They also may cause breakdown of the mucosal barrier and inhibit normal immune responses.
Pheochromocytomas are tumors of the adrenal medulla that secrete excessive amounts of catecholamines (primarily ___________, but also ________ and __________) & also other vasoactive peptides (e.g., ______ _______ ________, ___________, ________, and _________.
- primarily norepinephrine, but also epinephrine and dopamine
- other vasoactive peptides: vasoactive intestinal polypeptide, somatostatin, enkephalin, corticotropin)
Primary hyperaldosteronism secondary to adrenal adenoma or carcinoma occurs in middle-aged and older cats with what serious secondary effects? (name 2)
hypokalemic polymyopathy and/or systemic hypertension
Aldosterone stimulates renal sodium reabsorption and potassium excretion
Although pheo’s classically have been reported as benign, recent reports suggest that regional invasion and distant metastases (liver, regional lymph nodes, lungs, spleen, ovaries, diaphragm, and vertebrae) occur in as many as ____% of affected dogs.
50 %
Other tumors rarely arising from the adrenal medulla include
neuroblastoma and ganglioneuroma
in case you need differential diagnoses
Methods of evaluating for adrenal enlargement on ultrasound?
1- Compare the maximal width versus the length of the gland, which should be less than approximately 30%.
2- The width of the gland should not be larger in diameter than the diameter of the adjacent aorta.
3- Absolute measurements have also been reported (e.g., the canine adrenal should be less than 7.4mm; the feline adrenal should be less than 4.3mm).
Administration of contrast agents in patients with pheo should be done very cautiously. Why? (specific side effect)
severe hypertension
If ultrasound or contrast-enhanced CT (more sensitive for vascular invasion than ultrasound) are not performed, then consider performing ____ ____ ____ ______ before surgery if CVC thrombosis is suspected
caudal vena cava angiography
At surgery, pheochromocytomas may be identified grossly by application of what solution/substance?
This solution, which oxidizes catecholamines, forming what color pigment? within 10 to 20 minutes after application to the surface of a freshly sectioned tumor?
Zenker’s solution (potassium dichromate or iodate)
dark brown pigment
_____________ blockade is used to control blood pressure in patients with pheochromocytoma. Name examples of drugs
Adrenergic (e.g., phenoxybenzamine, phentolamine, prazosin)
In one study, phenoxybenzamine-treated dogs undergoing adrenalectomy for pheochromocytoma had a __ % mortality rate, while untreated dogs had a ____% mortality rate. Was this difference statistically significant (Herrera etal, 2008).
phenoxybenzamine-treated dogs undergoing adrenalectomy for pheochromocytoma had a significantly decreased mortality rate compared with untreated dogs (13% vs. 48%, respectively) (Herrera etal, 2008).
PREOP management: Check for arrhythmias or congestive heart failure in animals with pheo. An initial dose of_____ mg/kg of phenoxybenzamine administered orally every 12 hours should be followed by incremental increases every 2 to 3 days until blood pressure is within normal range (see also under discussion of anesthesia).
0.25 mg/kg with incremental increases every 2-3 days
This process may take 1 to 2 weeks before the patient is adequately blocked. Maximum dose is 2mg/kg.
When do you start phenoxybenzamine ideally?
This should be started as soon as the diagnosis of pheochromocytoma has been made and approximately 10 to 14 days before surgery. Fossum says treatment for several weeks before sx is recommended.
If cardiac arrhythmias are present, a ________may be added, but only after the phenoxybenzamine dosage has been determined to be adequate and blood pressure has returned to normal.
If cardiac arrhythmias are present, a β-blocker may be added, but only after the phenoxybenzamine dosage has been determined to be adequate and blood pressure has returned to normal.
α- and β-blockade will allow the return of a normal fluid volume; however, they may unmask what 2 conditions?????
α- and β-blockade will allow the return of a normal fluid volume; however, they may unmask renal insufficiency and anemia.
α-Adrenergic blockade has been shown to drastically reduce the incidence of _______ _________ _______, thereby reducing ________.
severe perioperative hypertension;
reducing mortality
What pre-anesthetic drugs should you avoid with pheo?
Avoid ketamine, xylazine, medetomidine, dexmedetomidine, atropine, glycopyrrolate, and acepromazine.
Intraop maintenance of BP (keep MAP 70 - 90 mm Hg); Drug options for treating hypertension intraop:
For hypertension (to keep MAP 70-90)
1- Phentolamine (0.02-0.1mg/kg IV) bolus and/or CRI (0.5-3µg/kg/min IV) and
2- Nitroprusside (0.5-5µg/kg/min IV) or
3- Nitroglycerin (1-5µg/kg/min IV) and
4- Esmolol (0.05-0.25mg/kg IV) boluses every 2-5 minutes to effect and/or CRI (50-200µg/kg/min IV) to maintain normal heart rate
