Anesthesia and Mineralocorticoid Abnormalities
-
adrenal cortex
- androgens
- mineralocorticoids (e.g., aldosterone)
- Increases distal tubular sodium reabsorption in exchange for (increased secreation of) potassium and hydrogen ions.
- So, increases extracellular fluid volume while tending to produce a hypokalemic metabolic alkalosis.
- aldosterone levels are increased by:
- renin-angiotension system (angiotensin II)
- adrenocorticotropic hormone (ACTH)
- hyperkalemia
- hypovolemia
- hypotension
- CHF
- surgery
- glucocorticoids (e.g., cortisol)
- metabolic actions
- increased gluconeogenesis
- inhibition of peripheral glucose utilization
- increased blood glucose concentration
- required for bronchial and vascular smooth muscle responsive to catecholamines
- some mineralocorticoid (aldosterone like) effect
- anterior pituitary ACTH secretion (principal regulator)
- diurnal rhythm
- stimulated by stress
- inhibited by circulating glucocorticoids
- endogenous cortisol production = 20 mg/day
- metabolic actions
- catecholamines (epinephrine, norepinephrine, dopamine)
- 80% epinephrine
- stimuli to release
- cholinergic preganglionic fibers of the sympathetic nervous system
- hypotension
- hypothermia
- hypoglycemia
- hypercapnia
- hypoxemia
- pain
- fear
Clinical Manifestations
- Etiology
- Primary hyperaldosteronism (Conn's syndrome)
- unilateral aldosteronoma (50%)
- bilateral hyperplasia (40%)
- aldosterone secreting carcinoma (adrenal gland)
- Secondary hyperaldosteronism (via the renin-angiotensis system)
- congestive heart failure
- hepatic cirrhosis with ascites
- nephrotic syndrome
- renal artery stenosis
- Primary hyperaldosteronism (Conn's syndrome)
- Signs
- hypertension
- hypervolemia
- hypokalemia
- renal concentrating defect
- polyuria
- metabolic alkalosis
- decreased ionized calcium level
- tetany
- muscle weakness
Anesthetic Considerations
- Correct fluid and electrolyte abnormalities
- supplemental potassium
- spironolactone (potassium-sparing diuretic with antihypertensive properties)
Clinical Manifestations and Anesthetic Considerations
- Atrophy or destruction of both adrenals leads to combined deficiencies of both mineralocorticoids and glucocorticoids
- Isolated hypoaldosteronism
- unilateral adrenalectomy
- diabetes
- heparin therapy
- Signs
- hyperkalemic
- acidotic
- usually hypotensive
- Preoperative preparation
- exogenous mineralocorticoid (e.g., fludrocortisone)