Flashcards in Steroids Deck (26)
what are adrenocortical steroids?
-produced and released by the adrenal cortex
-secretion controlled by the pituitary release of corticotropin (ACTH)
-two main classes: mineralocorticoids and glucocorticoids
where are mineralocorticoids secreted from?
the zona glomerulosa
where are glucocorticoids secreted from?
the zona fasciculata
describe mineralcorticoids and effects
-aldosterone responsible for 95% of activity
-maintains status quo regarding extracellular fluid volume
*maintains plasma concentrations of sodium and potassium
*conserves sodium to attract water into extracellular fluid
*maintains normal concentrations of potassium through excretion in urine
what stimulates secretion of mineralocorticoids?
-increased serum potassium
-cortisol responsible for 95% of activity
*essential for life
*not stored anywhere in body
what are physiologic effects of cortisol?
-increase gluconeogenesis (amino acids to glucose) *^BG
-protein catabolism (less amino acids stored causes muscle weakness if cortisol excessive)
-fatty acid mobilization (movement and oxidation of fatty acids in the cells)
-anti-inflammatory effects (decrease capillary permeability; stabilize lysosomal membranes)
-decreased immune response (decreased movement of leukocytes into inflamed areas; decreased eosinophils and leukocytes; interfere with formation of leukotrienes)
-increased number and sensitivity of beta-adrenergic receptors (*increasing myocardial and vascular response to catecholamine)
what stimulates cortisol secretion? What stops cortisol secretion?
ACTH (adrenocorticotrophic hormone) released from anterior pituitary
-stimulation for the secretion of ACTH is from hypothalamic neurohormones (corticotropin-releasing hormone and AVP, arginine vasopressin)
-increased levels of cortisol cause negative feedback on the hypothalamus to decrease the production of corticotropin-releasing hormone and on the anterior pituitary to produce less ACTH
describe cortisol release in the body
-daily secretion: 20 mg with more secreted during the day
-stress response: output increased up to 150 mg/day
50 mg/day- minor surgery
75-150 mg/day-major surgery
how long does cortisol last in the body?
-elimination 1/2 life is 70 min
-there is NO storage in the body!
*if pt. cant produce cortisol themselves, we must provide steroid coverage
which drugs are synthetic corticosteroids?
-methylprednisolone acetate (Depo-Medrol)
-methylprednisolone sodium succinate (Solu-Medrol)
which drugs are endogenous corticosteroids?
-cortisol, hydrocortisone (Solu-Cortef)
what are the effects of synthetic corticosteroids?
-suppression of hypothalamic-pituitary-adrenal (HPA) axis (when body needs to produce more cortisol d/t stress, it cant)
-skeletal muscle wasting
when is steroid coverage needed?
-the release of cortisol in response to the stress of surgery is decreased or eliminated
-HPA axis suppression (highly variable; occurs at different doses in different people)
*if taking steroids daily
*larger dose of steroids and longer the therapy, greater likelihood that suppression has occurred
-Critical illness-related corticosteroid insufficiency (CIRCI): adrenal response to stress is inadequate
what are signs and symptoms that steroid coverage is needed?
-unexplained vasopressor-dependent refractory hypotension (BP low for no explanation and only responds to vasopressor)
-hypovolemic shock with myocardial and vascular unresponsiveness to catecholamines
when should it be assumed that steroid coverage is needed?
-corticosteroid therapy has been used for more than two weeks within the previous year, assume some suppression has occurred
-anyone who has received corticosteroids equivalent to average daily adrenal output (hydrocortisone 20 mg/d) is considered depressed
-anyone who has received hydrocortisone equivalent of more than 20-30 mg daily for longer than two weeks during the previous year
*talk with surgeon and others on anesthesia care team
*keep some in room
what are the benefits of steroid coverage?
-prevention of life threatening secondary adrenal insufficiency: cardiovascular collapse, perioperative hypotension
what are the risks of steroid coverage?
-altered wound healing
-altered glucose metabolism (diabetics)
*limited effect if high dose steroid coverage is for a short time
what are the recommendation for steroid coverage for a minor surgery?
-usual morning dose OR
-preoperative corticosteroid dose (usual morning dose) + hydrocortisone 25 mg (or equivalent)
what are the recommendations for steroid coverage for a moderate surgery (colon resection, total joint)?
-hydrocortisone 50 mg IV, then 25 mg every 8 hrs for 24 hrs; then usual daily dose OR
-preoperative corticosteroid dose (usual morning dose) + hydrocortisone 50-75 mg or equivalent
what are the recommendations for steroid coverage for a major surgery (CV, thoracic)?
-hydrocortisone 100 mg IV at induction, 50 mg every 8 hrs for 3 doses; then taper rapidly down to daily dose (pediatric 2mg/kg IV)
-preoperative corticosteroid dose (usual morning dose) + hydrocortisone 100-150 mg or equivalent every 8 hrs for 48-72 hrs
what are pharmacologic effects on cortisol levels?
-etomidate suppresses the adrenal cortex synthesis of cortisol
-opioids in large doses may reduce the cortisol response to surgical stress
-volatile agents suppress the response to a lesser degree
what are equivalent doses of cortisol (hydrocortisone, Solu-Cortef) 20 mg?
-methylprednisolone (Solu-Medrol) 4 mg
-dexamethasone (Decadron) 0.75 mg
-prednisone (Deltasone) 5 mg
what are some clinical uses of corticosteroids?
-anti-inflammatory effect (prednisone)-palliative, not curative
-cerebral edema (dexamethasone)
-lumbar disc disease
-postintubation laryngeal edema (decadron)
-respiratory distress syndrome
how are corticosteroids used as antiemetics?
-unknown mechanism for antiemetic effect
*dexamethasone (Decadron) 0.5 mg/kg
*enhances effectiveness of 5-HT3 antagonists (6-10 mg)