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
For hypotension (to keep MAP 70-90); drugs and doses? Name 3....
Also, name 2 more to treat hypotension with CHF:
doses?
1- Phenylephrine (20-200 µg IV boluses and/or CRI 0.1-1 µg/kg/min IV), or
2- Norepinephrine CRI (0.05-2 µg/kg/min IV), or
3- Dopamine (5-15 µg/kg/min IV)
For hypotension with CHF txt:
Epinephrine (0.1-1µg/kg/min IV) or
Dobutamine (2-15µg/kg/min IV)
Pheo’s continued: Intraop fluid needs typically?
and
With CHF
typically 10-20 mL/kg plus 3x EBL (estimated blood loss); and with CHF, 5-10 mL/kg/h
Intraoperative β-blockade with ________ is preferred because of its short half-life and can be given as boluses or constant rate infusion (CRI). Cardiac arrhythmias may be treated with _______ or _______.
preferred intraop beta blocker: esmolol
*Again, don’t use beta blocker until appropriate alpha adrenergic blockage (ie normal BP).
cardiac arrhythmias: lidocaine or esmolol
Why is end-tidal CO2 monitoring and prevention of hypoventilation important in pheo surgery?
Because an increase in arterial CO2 causes an increase in catecholamine release
What drugs increase the myocardium’s sensitivity to catecholamines, and thus should be avoided?
alpha-2 agonists, halothane
The most common complications after adrenal tumor removal?
The most common complications after adrenal tumor removal include dyspnea, hemoperitoneum, ventricular arrhythmias, anuric acute renal failure, and coagulopathies. Dogs with adrenocortical tumors are at increased risk of developing thromboembolism
In a study of adrenalectomy in 41 dogs, __% did not survive to discharge (Schwartz etal, 2008).
In a study of adrenalectomy in 41 dogs, 22 % did not survive to discharge (Schwartz et al, 2008).
According to Schwartz 2008, the intraoperative mortality rate was __%, and median survival was ___ days.
The intraoperative mortality rate was 4.8%, and median survival was 680 days.
According to Schwartz 2008 , Factors associated with a shorter outcome: Hints: Clinical signs? CBC? Chem? Coags?
According to Schwartz 2008 , Factors associated with a shorter outcome: Clinical signs? weakness and lethargy CBC? thrombocytopenia Chem? increased BUN, AST, decreased K Coags? increased PTT
According to Schwartz 2008, Factors associated with guarded prognosis?
Nephrectomy and intraoperative hemorrhage were associated with guarded prognosis.
According to Schwartz 2008, shorter survival times were also associated with postoperative____________ and _____________. (2 postop complications)
Shorter survival times were also associated with postoperative pancreatitis and renal failure.
Prognostic factors for improved survival for pheochromocytoma ? (Millard et al, 2009).
Prognostic factors for improved survival for pheochromocytoma include preoperative use of phenoxybenzamine, younger age, lack of intraoperative arrhythmias, and decreased surgical time (Millard et al, 2009).
Laparoscopic adrenalectomy performed in seven dogs with unilateral adrenocortical carcinoma (three right-sided, four left-sided) without invasion of the caudal vena cava resulted in no significant intraoperative complications; however, two dogs died within 48 hours of surgery as the result of __________ complications (Pelaez etal, 2008).
Laparoscopic adrenalectomy performed in seven dogs with unilateral adrenocortical carcinoma (three right-sided, four left-sided) without invasion of the caudal vena cava resulted in no significant intraoperative complications; however, two dogs died within 48 hours of surgery as the result of respiratory complications (Pelaez et al, 2008).
The left adrenal gland is near the transverse process of what vertebrae? How about the right adrenal?
left: L2
right: T13
Name the zones of the adrenal cortex and what they produce.
zona glomerulosa – mineralocorticoids
zona fasciculata – glucocorticoids
zona reticularis – sex hormones
The clearance half-lives of cortisol and aldosterone are:
60 and 20 minutes, respectively
Aldosterone promotes sodium reabsorption/excretion and potassium reabsorption/excretion.
sodium reabsorption
potassium excretion
______________ cells within the adrenal medulla synthesize catecholamines.
Chromaffin
Approximately what percent of dogs with naturally occurring hyperadrenocorticism have the pituitary dependent form?
80-85%
8yo FS JRT w/excessive panting
10a. An 8yo FS Jack Russell presents for excessive panting. On abdominal ultrasound, the right adrenal gland measures 1.9 cm at its widest width. Is this large according to this author?
yes. 1.5 cm is this author’s limit
What are the two most common functional adrenal tumors in the dog? How does looking at the opposite adrenal help to differentiate between the two?
- pheochromocytoma and cortisol-secreting tumor
- small contralateral adrenal -> cortisol-secreting tumor
- normal contralateral adrenal -> pheochromocytoma
LDDS test. Four hours after dexamethasone administration, the cortisol level is 4 mcg/dl (70% of what it was on baseline). Eight hours after dexamethasone administration, the cortisol level is 80% of baseline. Does this count as suppression?
No. Suppression is defined as:
4-hour below 1.5 mcg/dl or
4-hour less than 50% of baseline or
8-hour less than 50% of baseline
You suspect a pheochromocytoma and plan an adrenalectomy. What medication, given preoperatively for 2-3 weeks before adrenalectomy, has been shown to decrease perioperative mortality? What kind of medication is it (what receptor does it act on
- phenoxybenzamine
- a noncompetative alpha adrenergic antagonist
You suspect a pheochromocytoma and plan an adrenalectomy. What medications should you have in your emergency drug supply for surgery and why?
- Beta-blockers (propranolol and esmolol) for severe persistent tachycardia
- Lidocaine for pathologic ventricular arrhythmias
- Alpha-antagonist (phentolamine) or vasodilator (nitroprusside) for episodes of hypertension
Dogs with cortisol secreting adrenal tumors have impaired wound healing, systemic hypertension, hypercoagulation, and can develop pancreatitis after surgery. What medication can be given for 3-4 weeks preoperatively to reverse the metabolic derangements of hyperadrenocorticism? How does it work?
Trilostane
Competative inhibitor of 3-β-hydroxysteroid dehydrogenase, which mediates adrenal conversion of pregnenolone to 17α-hydroxyprogesterone
Why do Cushinoid dogs have hypertension, do we think? What medication can be used initially to treat their hypertension?
- Theories:
- increased activition of angiotensin I
- increased vascular responsiveness to catecholamines
- decreased concentrations of vasoldilator prostaglandins
- Medication: ACE inhibitors
When it occurs after adrenalectomy for Cushinoid dogs, thromboembolism is usually noted when?
Within 72 hours of surgery
How do these authors try to prevent thromboembolism in hyperadrenocorticoid patients getting adrenalectomy (same protocol as recent papers from UC Davis showing decreased mortality rates).
- heparinized plasma, followed by SQ heparin
- frequent short walks within 4 hours of recovery
You have diagnosed pulmonary thromboembolism in a patient after adrenalectomy. What can you do?
- oxygen (some but not all affected animals have poor response to oxygen)
- supportive care
- anticoagulants
- mechanical ventilation if needed
- theophylline
- sildenafil if there is pulmonary hypertension
- fluids to support pressures, but prevent right heart overload
Because of the acute loss of mineralocorticoids, development of hypo/hyper-natremia and hypo/hyper-kalemia is common within 72 hours of adrenalectomy and usually resolves in a day or two.
hyponatremia
hyperkalemia
If the serum sodium decreases below 135 mEq/L or if the serum pottasium increases beyond 6.5 mEq/L, then mineralocorticoid treatment is indicated. What mineralocorticoid do these authors suggest?
desoxycorticosterone pivalate (Percorten-V)
Are postoperative anticoagulant therapies indicated for animals with pheochromocytoma after adrenalectomy?
Nope. Not unless there’s something else also going on that would indicate anticoagulants.
Transection of which ligament helps to expose the right adrenal gland?
hepatorenal ligament
Caval thrombi are reported in __________ % of dogs with adrenocortical tumors and in _________ % of dogs with pheochromocytoma.
11 – 16% of dogs with adrenocortical tumors
35 – 55% of dogs with pheochromocytoma
Some surgeons advocate use of intraoperative hypothermia in dogs undergoing adrenalectomy inpreparation for temporary occlusion of the caudal vena cava. surface cooling is applied to achieve what esophageal temperature?
32 C (89.6 F)
What are the mortality rates reported for adrenalectomy for dogs with adrenocortical tumors and pheochromocytomas?
adrenocortical tumors: 19-60 %
pheochromocytomas: 18-47 %
What is the expected mortality for ferrets undergoing adrenalectomy?
Low (<2%)
Bilateral adrenal gland neoplasia is common in ferrets. What is the surgical treatment
subtotal bilateral adrenalectomy
What hormones are produced by the most common functional adrenal gland tumor in the ferret?
androgens
The remaining five dogs were discharged 72 hours after surgery and had survival times ranging from 7 to 25 months with resolution of clinical signs.The remaining five dogs were discharged 72 hours after surgery and had survival times ranging from __ to __ months with resolution of clinical signs.
The remaining five dogs were discharged 72 hours after surgery and had survival times ranging from 7 to 25 months with resolution of clinical signs.The remaining five dogs were discharged 72 hours after surgery and had survival times ranging from 7 to 25 months with resolution of clinical signs.
