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Anesthesia in Endocrine Disorders
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Description of protein or peptides?


Proteins or peptides- within the endocrine cells and stored for release by exocytosis


Examples of amines or amino acids


thyroid hormones and catecholamines

-byproducts of tyrosine


What are steroids derived from? examples


- Derived from cholesterol

examples: cortisol, aldosterone, and testosterone


What type of feedback is used in regulation of endocrine hormones? example


Negative feedback response

-Elevated T3 and T4 levels cause decreased TSH release from anterior pituitary gland


What 3 mechanisms regulate production and secretion of hormones?


1. Neural control
2. Biorhythms
3. Feedback


What hormones are produced by the anterior pituitary gland?


Five distinct cell types
1. Growth hormones
2. Thyroid stimulating hormone
3. Adrenocorticotropic hormone
4. Prolactin
5. FSH and LH


What hormones are produced by the posterior pituitary gland?


Oxytocin
Vasopressin


What are two diseases caused by adenomas on the pituitary gland?


Cushings syndrome
Acromegaly


What are elevated prolactin levels?


1000-4000m U/L


What is the firstline treatment for Prolactin secreting tumors?


Dopamine agonist
-bromocriptine
-cbergoline


What condition is caused by excess growth hormone? what gland?


Acromegaly
caused by excess GH production by the anterior pituitary gland in adulthood after the closure of the epiphyseal plates



What complication of acromegaly can affect airway management?


1. soft tissue overgrowth
2. macrognathia causing prognathia



What are cardiac and endocrine changes related to acromegaly?


1. HTN, Cardiomgaly, Impaired LV function
2. Impaired glucose tolerance, DM

Organomegaly of liver, heart, spleen, and kidneys


What are the 2 types of pharmacological treatment for acromegaly?


1. Dopamine agonists- few respond to this
2. Long acting somatostatin drugs (octreotide)- used if dopamine agonists fail


What is cushing's disease related to?


1. excess ACTH secretion by the anterior pituitary gland
2. adrenal adenoma
3. ectopic ACTH secreting neoplasm
4. secondary to treatment with glucocorticoids


What causes the symptoms related to hyperadrenocorticism?


1. related to hormones released by the pituitary gland
2. ACTH- causing relase of aldosterone, cortisol, and adrogens


What are the two main goals of anesthesia for transsphenoidal surgery?


CV stability- prevent HTN, tachycardia, and wide swings in BP

Maintenance of cerebral oxygenation


What happens if a patient is being hyperventilated during transsphenoidal surgery?


hypocarbia causes vasoconstriction of cerebral vasculature which causes lifting of the cerebrum and movement of pituitary gland away from surgical site


Major and CV manifestations of hyperthyroidism?


Weight loss, diarrhea, skeletal muscle weakness,and stiffnes

CV: increased LV function, inc EF, tachycardia, wide pulse pressure


what is the purpose of propylthiouracil and methimazole?


Prevent the body from making iodide and therefore the synthesis of TH


how long does medication therapy take to lower TH levels to normal? why?


6-8 weeks, bcause the thyroid stores enough hormone to maintain euthyroid levels for several months


What iodide conversion inhibitor prevents peripheral conversion of T4 to T3? what b-blocker does this also?



propylthiouracil
Propanolol, over 1-2 weeks


What is the goal for HR control in hyperthyroid patient?


<90 bmpm


Administration of glucocorticoid during a thyrotoxicosis event provides what benefit?


1. Reduce thyroid hormone secretion
2. prevent peripheral conversion of T4 to T3


main goal of intraoperative maintenance for a patient with hyperthyroid?


1. Acheive a depth of anesthesia that blunts SNS response to surgical stress
2. Avoid anesthetic drugs that mimic or induce SNS responses


What is the treatment plan for thyroid storm during surgery?


1. IV fluids with glucose
2. Sodium iodide 250mg po or IV
3. Propylthiouracil 200-400mg po
4. Hydrocortisone 50-100mg IV
5. Propanolol 10-40mg or esmolol
6. cooling blankets
7. Dig for HF and especially in face of AFib w/ RVR


When do symptoms of hypocalcemia present following thyroidectomy surgery?


24-96 hours post op


What is one of the first signs of hypocalcemia r/t removal of parathyroid glands?


Stridor progressing to laryngospasm
-first sign of hypocalcemic tetany


What are CV manifestations of hypothyroidism?


Due to low T4 and T3 levels:
1. Low CO
2. Bradycardia
3. Increased peripheral resistenance


What ventilatory responses are depressed in hypothyroid pt?


Hypoxia and hypercarbia
-augmented by sedatives, opioids, and general anesthetics


Manifestations of myxedema coma?


R/t hypothyroidism
1. hypothermia
2. HOTN
3. Hyponatremia
4. Hypoventilation
5. Coma or stupor


What is the risk of treating a hypothyroid patient with thyroid hormones?


May precipatate myocardial ischemia


Treatment for myxedema coma?


1. IV thyroid hormones 200-300mcg iV over 5-10min
2. Hydrocortisone 100mg IV
3. Fluid and electrolyte replacement
4. cover to conserve body heat, no warming blankets (peripheral dilation augments HOTN)


What is the relationship to albumin and calcium levels?


Calcium is highly bound to albumin

Inc or dec in albumin 1gm/dL=0.8 serum Ca change in same direction


How does acidosis and alkalosis influence iCa?


pH and temp influence Ca and albumin bonding
1. acidosis decreases bonding, therefore increases iCa
2. alkalosis increases bonding, therefore decreases iCa


What regulates PTH secretion by the parathyroid glands?


serum iCa concentrations


Function of PTH?


1. causes release of Ca from bones (resorption) (most rapid change of Ca levels)
2.Direct resportion of Ca at distal tubules of kidneys


What is the purpose of hydrooxylation of Vitamin D in the kidneys?


Hypocalcemia and hypophosphotemia cause the kidneys to metabolize 1,25 OH2D and decrease of 24,25 OH2D. This causes increased intestinal absorption of calcium and phosphate


At what serum Ca levels is treatment required before surgery can continue? treatment?


Serum Ca >15mg/dL
1. Intravascular volume expansion with NS, dilutes serum and dec by 2mg/dL or greater.
2. Diuresis, IV Furosemide to promote Ca excretion with Na excretion


What must be avoided during surgery if a rapid PTH assay is going to be used?


No propofol within 15 minutes of assay


What is the daily amount of endogenous cortisol production?


20mg


What 3 factors primarly influence the production of ACTH and CRF?


1. sleep-wake cycle
2. stress
3. glucocorticoid plasma concentrations (primarily cortisol levels)



How do glucocorticoids (cortisol) influence the immune system?


1. Anti-inflammatory effects (stabilize leukocytes and maintain capillary wall integrity)
2. Antagonize leukocyte migration inhibition factor->decrease response to local inflammation
3. Reduce killing potential of macrophages and monoctyes, not their activity though


How does the renin-angiotensin system regulate the release of aldosterone?


1. Juxtaglomeular apparatus surrounds the renal afferent arterioles
2. in response to hypoperfusion or SNS stimulation of the Juxta apparatus  renin is released
3. Renin splits angiotensinogen to form angiotensin I
4. Angiotensin I is converted to Angiotensin II by an enzymes in the lungs
5. Angiontensin II stimulates the adrenal cortex to produce aldosterone


What is angiotensin II?


Result of renin-angiotensin system
1. most potent endogenous vasopressor
2. Stimulates adrenal cortex to produce aldosterone


What are the S & S of Cushing syndrome?


1. Tuncal obesity and thin extremities that reflect muscle wasting and redistribution of fat
2. Osteopenia r/t impaired Ca absorption
3. Hyperglycemia, with DM in 20%
4. HTN and fluid retention
5. Risk of infection d/t immunosupressive effects of corticosteroids


Is Hypokalemia seen with an endocrine tumor?


no see with nonendocrine tumor


What is the difference between primary pituitary disease and adrenal tumors?


1. Exogenous glucorticoid administration causes decrease levels of cortisol and 17-hydroxycorticosteroid levels in PRIMARY PITUITARY because some negative feedback control exists


What diuretic is helpful in diuresing patient with Cushing's and normalizing intravascular volume?


Spironolactone, aldosterone antagonist
- helps normalize K+ concentrations


What adrenal cortex response does supraphysiologic hydrocortisone doses mimic?


Exerts significant mineralocorticoid activity


What percentage of patients with essential HTN have suppressed renin acitivity?


25% have depressed renin activity


What is the difference between primary and secondary hyperaldosteronism?


Primary- Increased aldosterone levels are not caused by increase renin. hyposecretion of renin that fails to increase in presence of hypovolemia. usually do not have edema
Secondary- there is an elevation in renin production


What is the differnce between primary and secondary adrenal insufficiency?


Primary- the adrenal gland cannot produce sufficient amounts of hormones

Secondary- There is a deficiency in ACTH production


What is the clinical significance of HPA suppression?


Chronic corticosteroid therapy causes a suppression of the hypothalmic-pituitary-adrenal response to stress, resulting in HOTN and possible cardiac collapse


What is the cause of hyperkalemia found in Addison's disease?


The adrenal glands are not able to produce aldosterone, which is a hormone responsible for the hemostasis of K+ concentrations.

Found in primary adrenal insufficency


what is the initial therapy for acute adrenal insufficiency?


1. isotonic crystalloid replacement
2. Hydocortisone 100mg then q 8 hours


What anesthesia suppresses the elevation of stress hormones?


1. Regional
2. Deep GA

-both block the sympathetic nervous system response


What patient populations require preop steroid supplementation?


5 daily doses of prednisone greater or equal to 20mg within the las 12 months


How much steroid supplementation is needed in preop for patient with history of taking steroids within last 12 months?


1. Not currently on: 200-300mg divided thourghout day, 25mg IVP at induction
2. Currently on: daily dose morning of sx and supplementation with daily dose at induciton


what exogenous glucocorticoids go through liver metabolism?


Prednisone and methylprednisolone


What exogenous glucocorticoids have the most mineralocorticoid effect?


Hydrocortisone and cortisone


What glucocorticoid has the strongest anti-inflammatory response?


Dexamethasone- 0.75mg is same as 30x the strength of cortisol

Prednisone- 5mg has 4x the strength as cortisol



What is the only important disease process associated with the adrenal medulla?


Pheochromocytoma- tumor that produce, stores, and secretes catecholamines

-usually localized tumor in right adrenal gland


What class of drugs is given initially to patients diagnosed with a pheochromocytoma, and must be started prior to surgery? names?


alpha-adrenergic blockers at least 10-14 days before surgery
-phenoxy-benzamine
-prazosin


What can labetalol do if given alone when treating pheochromocytoma?


can increase blood pressure


what drug can be used if emergent surgery is needed in untreated pheochromocytoma pt?


Nipride gtt @ induction
-start @ 0.5mcg/kg/min


What drugs must definetly need to be avoided periop in a pt with pheochromocytoma?


1. Histamine releasing drugs- morphine,
2. Catecholamine releasing drugs- pancuronium, ketamine, ephedrine


During removal of pheochromocytoma removal, what causes an abrupt decrease in BP? treatment?


Ligaion of the tumors venous supply. IV fluid replacement offsets HOTN caused by this. Phenylephrine maybe given if needed after fluid resuscitation


Diagnostic criteria for DI?


plasma osmolarity>295 mOsmol
hypotonic urine tonicity 2ml/kg/hr


What is the goal for treatment of hypovolemia r/t DI periop?


1. ADH infusion (100-200mU/hr)
2. isotonic crystalloid until osmolarity


What is secreted from a carcinoid tumor during carcinoid syndrome?


1. Histamine
2. Bradykinin
3. Serotonin
4. Prostaglandins
5. Kallikrein


What type of drugs could induce a response from a carcinoid tumor?


1. Histamine releasing (morphine)
2. Catecholamine releasing (ketamine)


What organ requires involvement with carcanoid tumor to  postentially develop into carcinoid syndrome?


Metasis of the carcanoid tumor to the liver. Carcanoid tumor metasis to the liver allows for direct release of secretions into the blood and bypassing of metabolism by the liver


What cardiac changes occur due to carcinoid tumors?


Pulmonic valve stenosis and tricuspid valve insufficiency
-primarly tricuspid valve insufficiency


What are common drugs used in anesthesia that cause histamine release?


Histamine
Atracurium
Mivacurium
Morphine
D-tubocurarine


Treatment of HOTN and HTN in carcinoid tumor?


HOTN: Avoid catecholamine releasing and B-agonists. Use: IV fluid administration, phenylephrine, octerotide, angiotensin

HTN: often associated w/ bronchospasm. Use: Nitroglycerin or Nipride



What drug is given prophylactically preoperative to patients with Carcinoid tumors?


Octreotide- synthetic analog of somatostatin
Dose:50-150mcg q 8 hour subq
-inhibits release of serotonin from tumor


What is the difference between epi and norepi secreting pheochromocytomas?


1. Epi secreting: Inc SBP, Dec DBP, tachycardia
2. Norepi secreting: HTN, narrow pulse pressure, bradycardia