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57 Cards in this Set
- Front
- Back
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What are the two parts of the adrenal gland? |
- Adrenal cortex- Outer part of the adrenal that secrete and synthesize steroid hormone * Androgens * Mineralcorticoids (Aldosterone) * Glucocorticoids (Cortisol) - Adrenal medulla- inner part of the adrenal that contains neurons and releases neurotransmitters (catecholamines) * Epinephrine * Norepinephrine * Dopamine (very small amount) |
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What are the three layers of the adrenal cortex and what do they secrete? |
- Zona glomerulosa- Outer most layer * Secretes mineralcorticoid hormones (Salt) - Zona fasciculata- Middle layer * Secretes cortisol and other glucocorticoids (Sugar) - Zona reticularis- Innermost layer * Secretes adrenal androgenic hormones (Sex) "The cortex Gets Fun Rewards- Salt, Sugar, Sex" |
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What is cortisol? What is the physiologic process that causes the adrenal cortex to produce cortisol? |
- The prototypical glucocorticoid, accounts for 95% of the glucocorticoids released from the adrenal cortex. - The hypothalamus synthesizes and releases corticotropin releasing hormone (CRH) - CRH causes the anterior pituitary to secrete corticotropin (ACTH) - ACTH stimulated the adrenal cortex to make cortisol |
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What stimulates ACTH release? What inhibits ACTH release? |
Stimulates: - CRH - Sleep-waking perioid - Stress - Hypoglycemia - Sepsis - Trauma - Decreased plasma cortisol - Alpha-adrenergic receptor stimulation Inhibits: - Elevated plasma cortisol - Opioids |
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How is ACTH regulated? |
- Direct negative feedback loop on the hypothalamus, which inhibits release of CRH. This decreases ACTH production - When cortisol levels are high, ACTH production is reduced |
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What is the importance of cortisol? |
- One of the few hormones essential to life. * Maintains blood pressure * Maintains normal vascular permeability, tone, and cardiac contractility * Participates in carbohydrate and protein metabolism * Participates in fatty acid mobilization * Participates in electrolyte and water balance * Participates in the antiinflammatory response * Facilitates the conversion of norepinephrine to epinephrine in the adrenal medulla |
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How do the cells respond to cortisol production? |
- There is a hyperglycemic response to cortisol secretion - This reflects gluconeogenesis and inhibition of peripheral use of glucose by the cells. |
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How does cortisol affect sodium and potassium? |
- Retention of sodium - Excretion of potassium *Glucocorticoids have some mineralcorticoid and androgenic effects that become apparent with hormone excess or supraphysiologic replacement dosages |
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How does cortisol affect gluconeogenesis? How does it affect blood glucose? |
- Rate of gluconeogenesis increases 6- to 10- fold in the presence of cortisol - Inhibits peripheral utilization of glucose so it increases blood glucose and worsens diabetic control |
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How much cortisol is produced daily? When is it typically released? |
- 15- 30 mg per day - Most of this is produced and released in the morning (diurnal) - Increased levels in relation to stress * Physical, mental, surgery |
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What stimulates the hypothalamic- pituitary- adrenal (HPA) axis? |
- Surgery - Degree of activation depends on duration of surgery and type & depth of anesthesia - CRH, ACTH, and cortisol levels increase during surgery * Deep general and regional anesthesia will blunt this response |
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What regulates aldosterone secretion? |
- Renin- Angiotensin- Aldosterone- System (RAAS) - Serum concentrations of potassium |
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How does aldosterone contribute to fluid and electrolyte balance in the ECF? |
- Resorption of Na+ in the distal renal tubules * Water follows Na+ * Na+ & H2O resorption expands the ECF volume and elevates arterial BP - Promotes renal excretion of K+ & Hydrogen ions |
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What stimulates aldosterone secretion? |
- Angiotensin II from RAAS - ACTH secretion - Hyperkalemia - Hypovolemia - Hypotension - CHF - Surgery |
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What innervates the adrenal medulla? |
-Innervated by preganglionic cholinergic fibers of the SNS - Can be thought of as analogous to a postganglionic neuron - Preganglionic fibers run directly from the spinal cord to the adrenal medulla |
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What stimulates the adrenal medulla to secrete catecholamines? |
- Hypotension - Hypothermia - Hypoglycemia - Hypercapnia - Hypoxia - Pain - Fear |
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What receptors are stimulated by norepinephrine release? What are the physiologic effects? |
- Alpha and beta receptors - Increase the heart rate - Inhibit GI function - Dilate pupils |
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What receptors are stimulated by epinephrine release? What are the physiologic effects? |
- Beta receptors - Chronotropic and inotropic effects on the heart - Less vasoconstriction than norepinephrine |
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What is Conn's syndrome? |
- Another name for primary hyperaldosteronism. - Characterized by an excess of aldosterone due to a functional tumor that acts independently of physiologic stimulus Can be associated with: * Adrenocortical hyperplasia * Pheochromocytoma * Primary hyperparathyroidism * Acromegaly * Unilateral or bilateral adenoma |
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What is the result of Conn's syndrome? |
- Hypokalemic metabolic alkalosis - HTN (DBP 100- 125 & may be resistant to trx) - HA - Polyuria - Skeletal muscle weakness - Nocturia - Muscle cramps - Hypomagnesemia - Hypernatremia - Glucose intolerance |
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What is secondary hyperaldosteronism? What are causes of it? |
- The stimulus for excess aldosterone resides outside the adrenal gland - Present when there is increased circulating serum renin levels as a result of reduced renal blood flow
- Causes: * Renovascular HTN * Obstructive renal artery disease (atheroma, stenosis) * CHF * Hepatic cirrhosis w/ acites * Nephrotic syndrome |
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What is Bartter's syndrome? |
- Aldosteronism causedby hyperplasia of the juxtaglomerular apparatus - Not accompanied by hypertension |
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What is the treatment for hyperaldosteronism? |
Medical management: - Supplemental K+ - Treat hypertension if present
- Spironolactone - Aldosterone antagonist, K+ sparing diuretic with antihypertensive properties Surgical management: - Surgical excision if its an aldosterone-secreting tumor - Bilateral adrenalectomy may be necessary for multiple aldosterone-secreting tumors |
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What is the anesthesia management for hyperaldosteronism? |
- Preop correction of K+ and HTN - Avoid hyperventilation = decrease K+ - Only use Sevoflurane if kidney function is ok - Consider CVP or PAC for monitoring volume status - EKG may show prominent U-waves & arrhythmias - Low K+ may potentiate muscle relaxants- low and slow - Assess for hypovolemia with orthostatic BP - Consider exogenous cortisol if bilateral adrenalectomy |
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What is hypoaldosteronism? What causes it? |
- Hyperkalemia without renal insufficiency suggests hypoaldosteronism. - Causes * Atrophy or destruction of both adrenal glands * Unilateral adrenalectomy * Diabetes/ESRD * ACEI therapy |
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What are s/s of hypoaldosteronism? What is the treatment? |
S/S: * Hyperglycemia * Hyperchloremic Metabolic Acidosis * Orthostatic hypotension * Heartblock Treatment: * Treatpreop w/ an exogenously administered mineralocorticoid (fludrocortisone) * Increase Na+ intake |
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What is Cushing's syndrome? What are the two forms of Cushing's Syndrome? |
- A diverse complex of symptoms, signs, and biochemical abnormalities caused by excess glucocorticoid hormone - Two forms: * ACTH dependent - Inappropriately high ACTH concentrations stimulate the adrenal cortex to produce excessive amounts of cortisol * ACTH independent - Excessive production of cortisol by abnormal adrenocortical tissue that is not regulated by secretion of CRH and ACTH - CRH and ACTH are depressed |
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What are causes of independent ACTH? |
* Exogenous administration of steroid hormones (most common cause) * Intrinsic hyperfunction of the adrenal cortex (adrenocortical adenoma) * ACTH production by a non-pituitary tumor (ectopic ACTH syndrome) * Hypersecretion by a pituitary adenoma ACTH dependent= Cushing’s disease |
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What is the difference between Cushing's disease and Cushing's syndrome? |
The term 'Cushing's disease' refers to Cushing's syndrome that is cause by the oversecretion of ACTH by a pituitary tumor. |
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What are S/S of Cushing's syndrome? |
- Muscle wasting - Muscle weakness - Osteoporosis - Central obesity - Abdominal striae - Glucose intolerance - HTN - Mental status changes - Insomnia - Oligomenorrhea/ amenorrhea - Moon face |
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What is the treatment for Cushing's syndrome? |
- Transsphenoidal microadenomectomy - Anterior pituitary resection (85- 90%) - Pituitary irradiation and bilateral total adrenalectomy may be necessary in some pts. - Ectopic ACTH-secreting tumor is treated by surgical resection - Because the contralateral adrenal gland is preoperatively suppressed, exogenous glucocortocoid replacement may be necessary for several months until adrenal function returns. |
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What are preoperative considerations for Cushing's? |
- Correct the hypokalemia - Correct the blood sugar - Correct BP - Correct hypervolemia w/spironolactone |
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What are the intraoperative considerations for Cushing's? |
- At risk for fractures during positioning 2° osteoporosis - Regional ok may be difficult with osteoporosis - Etomidate transiently decreases synthesis and release of cortisol - Muscle relaxants * Preoperative weakness may indicate sensitivity * Use muscle relaxants w/different pathways-Cisatricurium - Once tumor resected may need to start corticosteroids and may see transient Diabetes Insipidus - Supplemental steroids * If cause is exogenous, patient’s adrenal glands will not be able to respond to perioperative stress. - Risk for thromboembolus r/t obesity, HTN, elevated Hct, and increased Factor VIII levels |
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What is the anesthetic management for an adrenalectomy? |
- IV hydrocortisone 100 mg a 8 hours - Significant blood loss secondary to highly vascularized tumor - High risk for pneumothorax secondary to unintentional penetration of the pleura |
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What is adrenal insufficiency? What are the two types of adrenal insufficiency? |
- Destruction of the adrenal glands - Primary * The adrenal glands cannot produce enough hormones * Addison's disease is the idiopathic autoimmune destruction of the adrenal gland ( most common U.S. cause) * Tb is a worldwide cause of adrenal insufficiency * HIV is the most common infectious disease cause in the U.S. - Secondary * Suppression or disease of the hypothalamic/pituitary axis * Only a glucocorticoid deficiency * Causes are iatrogenic - Pituitary surgery - Pituitary irradiation - Use of synthetic glucocorticoids (most common) |
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What are clinical manifestations of adrenal insufficiency? |
- Weakness & fatigue - Weight loss - Vomiting - Abdominal pain - Diarrhea - Hypoglycemia - Orthostatic hypotension - Hypovolemia - Hyponatremia - Hyperkalemia - Metabolic acidosis * Secondary adrenal insufficiency resembles primary except not associated with hypovolemia, hyperkalemia, or hyponatremia since mineralcorticoid secretion is preserved |
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Which disease is associated with hyperpigmentation of the skin? |
Addison's disease |
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Which induction agent should NOT be used in individuals with adrenal insufficiency and why? |
- Etomidate * Suppresses adrenal function by inhibiting enzymes that are essential for the production of corticosteroid hormones. * Even one-time use showed decreased adrenal function |
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What is Addisonian crisis? What causes it? What are s/s? |
- Sudden onset of severe adrenal insufficiency - Medical emergency with high M & M - Cause: * Steroid- dependent pt. who did not receive adequate steroid dose for period of stress, infection, acute illness, sepsis - S/S: * Circulatory collapse * Fever * Hypoglycemia * Depressed mentation |
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How long after discontinuation of long-term steroid use will it take for adrenal function to return to normal? |
6 - 12 months for adrenal function to return to baseline |
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How long after abrupt withdrawal of steroids would symptoms begin to appear in a patient on a long-term exogenous steroid regimen? |
24 - 36 hours |
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What is the required dose of steroid therapy a pt. needs to have received in the past in order to require perioperative steroid supplementation? |
- All patients who have received the equivalent of 20 mg/day of prednisone by any route of administration for a period of more than 3 weeks any time in the previous 12 months should be considered unable to respond to surgical stress. - Doses between 5 and 20mg should be supplemented as well - >8 mg/day on long term basis should be supplemented |
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What are the recommended replacement regimens for steroid therapy? |
- Bolus option: Administer 100 mg hydrocortisone q 6° IV beginning the evening before or on the morning of surgery for moderate to major surgery - Continuous infusion option: 100mg IV hydrocortisone at time of induction followed by an infusion of 10 mg/hr during the subsequent 24°. |
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What are anesthetic considerations for someone with adrenal insufficiency? |
- If a pt. is unresponsive to usual therapeutic interventions, they may have adrenal insufficiency - Treat the cause - Replace circulating glucocorticoids - Replace H2O and sodium deficits * D5NS is best fluid choice - Hemodynamic support with vasopressors - Metabolic acidosis and hyperkalemia resolve with fluid and steroid administration - Use caution with drugs that cause myocardial depression - Use caution with muscle relaxants |
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What is pheochromocytoma? What causes it? |
- Catecholamine secreting tumor that arises from chromaffin cells of the sympathoadrenal system - Precise cause is unknown, usually an isolated finding (90% of the cases) - 10% are inherited as an autosomal dominant trait - May be a part of multiple endocrine neoplasia (MEN) syndrome or von Hippel- Lindau syndrome |
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What does a pheochromocytoma commonly secrete? Do pheochromocytomas secrete catecholamines in response to another hormone or physiologic response? |
- Mostly they secrete norepinephrine, either alone or with a small amount of epinephrine (85:15) - 15% secrete epinephine alone - Small amount secrete dopamine - Most pheochromocytomas are not under neurogenic control and secrete catecholamines autonomously |
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What are the s/s of pheochromocytoma? |
- Significant hypertension (150- 180s/120s) - Variable presentation and often dependent on the catecholamine that is being secreted - May see: * HA * Sweating * Pallor * Palpitations * Orthostatic hypotension from hypovolemia - Norepiphenrine-secreting: * Systolic and diastolic HTN * Reflex bradycardia - Epinephrine-secreting: * Systolic HTN * Diastolic hypotension * tachycardia |
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How is the cardiovascular system affected by pheochromocytoma? |
- Increased SVR - Normal CO - Slightly decreased plasma volume * Desensitized CV system and a downregulation of adrenergic receptors explains the normal findings |
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What type of cardiomyopathies are seen in pheochromocytoma? What does the EKG look like? |
- Both dilated and hypertrophic cardiomyopathies * Can be reversed if treated early before fibrosis occurs - LV outflow obstruction - EKG: * High or peaked P-waves * Elevation or depression of ST-segment, * Flat or inverted Ts * Prolonged QT * LAD * Arrhythmias |
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Why do individuals with pheochromocytoma have elevated blood glucose? |
- Secondary to catecholamine stimulation of glycogenolysis and inhibition of insulin release |
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How is pheochromocytoma diagnosed? |
- 24 hour urine collection for measurement of metanephrine and catecholamines * > 220 pg/dL - Plasma-free metanephrine level (most sensitive test) * > 400 pg/dL - Clondine suppression test * Administer clonidine. If it has no effect, positive result - Glucagon stimulation test (safest provocative test) * Glucagon acts directly on tumor to stimulate catecholamines. * > 2000 pg/mL is positive result - CT or MRI |
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What is the preoperative management for pheochromocytoma? |
- Alpha blockade first * Phenoxybenzamine- Noncompetitive a1- antagonist with some a2-blocking properties * Long DOA so d/c 24- 48 hours before surgery - Goal is normotension - Eliminate ST-segment and T-wave changes on ECG - Administer betablocker after alphablocker if tachycardia presents - CCB and ACEI good for HTN |
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What is the most common cause of death in the immediate postoperative period after excision of a pheochromocytoma? |
Hypotension |
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What is the preferred vasodilator for hypertensive episodes during surgical excision of a pheochromocytoma? |
- Nitroprusside - Nitroglycerin will reduce the BP, but the amount required to control it often results in tachycardia. |
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Why is orthostatic hypotension common in patients with pheochromocytoma? |
Chronic HTN = hypovolemia and impairment of the vasoconstrictor reflexes. |
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What alpha blockers may be used in place of phenozybenzamine in the treatment of pheochromocytoma? |
Prazosin, doxazosin, and terazosin. |
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At what point during surgical excision of a pheochromocytoma should you expect hypotension and how should you treat it? |
- Following ligation of the vein draining the tumor. - To prevent hypotension, the patient should undergo volume expansion until a PCWP of 16-18 mmHg is reached prior to ligation of the vein. - Vasopressors should be utilized only after adequate volume expansion has been achieved. |
