Endocrine - Adrenal Flashcards
Adrenal Gland
Cortex 80-90%
Medulla 10-20%
Adrenal Gland Function
- Blood glucose regulation
- Protein turnover
- Fat metabolism
- Na+/K+/Ca2+ balance
- CV tone maintenance
- Modulates tissue response to injury or infection
- Stress response*
Adrenal Cortex
Zona glomerulosa - aldosterone (mineralocorticoid)
Zone fasciculata - cortisol (glucocorticoid)
Zona reticularis - androgenic
Adrenal Medulla
Epinephrine 80%
Norepinephrine 20%
Cushing’s Syndrome
Any excessive cortisol secretion
Exogenous steroids
ACTH dependent or independent
Cushing’s Disease
Inappropriate ACTH from anterior pituitary secretion
1° pituitary tumor
2° adrenal tumor
ACTH Dependent
Pituitary corticotrophy tumors (microadenomas)
Non-endocrine tumors - lung, kidney, or pancreas
Ectopic corticotrophin syndrome
ACTH Independent
Benign or malignant adrenocortical tumors
Cushing’s S/S
Sudden weight gain (central) Facial fat "moon face" Electrolyte abnormalities Systemic HTN Glucose intolerance Menstrual irregularities Decreased libido Skeletal muscle wasting Depression & insomnia Osteoporosis Hypercoagulable
Cushing’s Diagnosis
Plasma & urine cortisol levels
CRH stimulation test
Dexamethasone suppression test
Inferior petrosal sinus sampling
Cushing’s Treatment
Surgical
- Transsphenoidal microadenectomy
- Adrenalectomy
Irradiation
Cushing’s
Anesthetic Management
Preop evaluation - HTN, intravascular volume, electrolytes, hypokalemia metabolic alkalosis, CHF, glucose control
Positioning - osteoporosis/osteomalacia vertebral compression fractures
Skeletal muscle weakness - ↓muscle relaxants requirements (maintain 1 twitch)
Cortisol - 100mg IV glucocorticoid intraop
Blood loss - type & screen, CVP, A-line
Anesthetic agents - depress adrenal response to stress & ACTH
Cushing’s
Anesthetic Complications
Transsphenoidal microadenomectomy - VAE - Transient DI - Meningitis Adrenalectomy - Laparoscopic vs. open - Pulmonary complications
Conn’s Syndrome
Excessive aldosterone
Primary Hyperaldosteronism
Excessive aldosterone secretion from functional tumor
Secondary Hyperaldosteronism
↑circulating serum renin stimulates aldosterone release (renovascular HTN)
Conn’s S/S
Non-specific
Asymptomatic
Systemic HTN (headache, diastolic BP 100-125mmHg) reflects aldosterone induced Na+ retention ↑fluid retention
Hypokalemia - skeletal muscle cramps, weakness, metabolic acidosis
Hyperaldosteronism
Anesthetic Considerations
Correct ↓K+ Avoid hyperventilation → hypokalemia HTN (A-line) Assess cardiac/renal status Fluids w/ vasodilators & diuresis Monitor acid-base balance Replace exogenous cortisol 100mg/day
Addison’s Disease
1° adrenal insufficiency
- Most common cause idiopathic/autoimmune
- Asymptomatic until 90% adrenal cortex destroyed
Deficiency all adrenal cortex secretions - mineralocorticoids, glucocorticoids, & androgens
Addison’s S/S
Chronic fatigue Muscle weakness Hypotension Weight loss Anorexia Nausea/vomiting Diarrhea ↑BUN Hyponatremia Hyperkalemia Hypoglycemia Abdominal or back pain Hyperpigmentation
Addison’s Diagnosis
Baseline plasma cortisol level <20mcg/dL
Cortisol level <20mcg/dL after ACTH stim test
- Normal response >25mcg/dL
- Positive test indicates adrenal cortex impairment
Addisonian Crisis
Steroid-dependent who do not receive ↑dose during stress Stress → circulatory collapse - Hypoglycemia - Electrolyte imbalance - Depressed mentation 100mg IV cortisol Q4-6H Inotropic support
Addison’s
Anesthetic Considerations
Administer exogenous corticosteroids Continue steroid dose DOS Intraop hypotension - Measure CVP - Vasopressor - Fluids - Cortisol 100mg IV Measure blood glucose Monitor electrolytes (avoid LR) Avoid Etomidate Inhalational agents sensitive to drug-induced myocardial depression Titrate muscle relaxants d/t skeletal muscle weakness
Minor Surgery Cortisol
25mg hydrocortisone
Major Surgery Cortisol
100mg bolus followed by infusion at 10mg/hr
OR
100mg Q6H
Hypoaldosteronism
Congenital aldosterone deficiency
Hyporeninemia loss angiotensin stim
Non-steroidal inhibit prostaglandin synthesis - inhibit renin release & exacerbate condition in renal insufficiency
Hypoaldosteronism S/S
Hyperkalemic acidosis
Severe hyperkalemia
Hyponatremia
Myocardial conduction defects
Hypoaldosteronism Treatment
Mineralocorticoid-fludrocortisone
Liberal Na+ intake
Pheochromocytoma
Catecholamine-secreting tumor
Originates in adrenal medulla & related tissues
Most common young to mid-adult life
Pheochromocytoma S/S
1° - HTN continuous or paroxysmal - Headache - Diaphoresis/pallor - Palpitations or tachycardia Associated S/S - Orthostatic hypotension d/t volume depletion - Anxiety - Tremors - Chest pain - Epigastric pain - Flushing - Painless hematuria
Pheochromocytoma
Duration & Frequency
1hr or less
Daily to once every few months
Pheochromocytoma Diagnosis
Urine tests Plasma levels* NE/Epi breakdown products - Normetanephrine >400 - Metanephrine >220 CT/MRI
Pheochromocytoma Treatment
Surgical excision α blockade - Phenoxybenzamine α 1&2 - Prazosin selective α1 Restore intravascular volume ↓Hct Insulin release Persistent tachycardia β blockade (Esmolol) DO NOT ADMINISTER NON-SELECTIVE β BLOCKADE W/O α BLOCKADE (unable to maintain CO)
Pheochromocytoma
Preop Considerations
Optimize the patient
↑SVR → myocardial ischemia, ventricular hypertrophy, CHF, cardiomyopathy
Cerebral hemorrhage history
Hyperglycemia ↓circulating insulin w/ ↑glycogenolysis
Blood pressure <165/90 48hours prior to surgery
Standing BP >80/45
EKG w/o ST or T wave changes
<1 PVC Q5min
Pheochromocytoma
Anesthetic Considerations
Communication w/ surgeon Continue adrenergic blockade Fluid management: - Pre-hydrate hypovolemia - Falsely ↑Hct - Type & cross - Renal function - Fluid replacement plan Benzodiazepine & opioid pre-medication A-line
Pheochromocytoma
Induction & Laryngoscopy
Lidocaine 1-2mg/kg Opioid (no Morphine d/t histamine & catecholamine release) to blunt SNS response - Sufentanil 0.5-1mcg/kg - Fentanyl 3-5mcg/kg Propofol 3mg/kg Nitroprusside 1-2mcg/kg Phentolamine α blocker Esmolol β blocker Avoid drugs that release histamine
Pheochromocytoma
Intraop Considerations
MAC 1.5-2
Combined general anesthetic w/ continuous lumbar epidural
Muscle relaxant - Vecuronium or Rocuronium
Surgical ligation tumor venous drainage ↓catechols → prepare for hypotension
- DC antihypertensives
- ↓volatile inhalational agent
- Volume 1st
- Administer pressors (phenylephrine or norepinephrine)
NE infusion until vasculature adapts to ↓α stim
Pheochromocytoma
Cardiovascular Control
Nitroprusside preferred Phentolamine - tachyphylaxis, tachycardia, & longer duration Magnesium sulfate Ca2+ channel blockers Esmolol preferred Labetalol Metoprolol
Pheochromocytoma
AVOID
Histamine releasers (Morphine or Atracurium)
Halothane - sensitizes myocardium → epinephrine
Succinylcholine fasciculations → catechol release from tumor
Avoid ↑HR (Pancuronium or Atropine)
Metoclopramide → catechol release
Pheochromocytoma
Postop Considerations
Adequate analgesia - PCA & opioids
50% patients remain HTN
- Elevated catecholamine levels 10 days postop
- Continue antihypertensive therapy
Early extubation (young, no lung involvement)
Hypoglycemia d/t excess insulin release & ineffective lipolysis & glycogenolysis
Steroid supplementation d/t adrenal manipulation
Postop HTN > 10 days
- Occult tumors (repeat surgery)
- Volume overload
- Continue monitoring
