Steroids and Anesthetic Considerations Flashcards
(49 cards)
How does the hypothalamus know you need more cortisol?
CRH is stimulated in the anterior pituitary from decreased cortisol -> ACTH
When are cortisol levels the highest? Lowest?
Cortisol levels are highest in the morning (20ug/dL) and lowest at night (5ug/dL)
(this is why pts have MI’s in the AM)
What are 3 physiological factors that stimulate the HPA axis
- Hypoglycemia
- Trauma/sepsis
- Alpha & Beta agonists
Four factors that inhibit the HPA axis
- Adrenocorticotropic hormone (ACTH)
- Increased cortisol
- General anesthesia
- Etomidate
What is secreted from the Zona Glomerulosa?
Primarily mineral corticoid = Aldosterone
What is secreted from the Zona Fasiculata?**
Primarily glucocorticoid = Cortisol
What is secreted from the Zona Reticularis
Sex hormones
Stimulation of the HPA axis results in Cortisol, what are 4 systemic results of cortisol release in the body.
- Gluconeogenesis
- Protein mobilization
- Fat mobilization
- Stabilizes lysosomes
- Increase HR and BP allows for the flight or fight response
What happens when you take synthetic cortisol for long periods of time?
The body thinks it’s naturally produced cortisol and it creates a negative feedback and shuts off
How should you stop taking a steroid ?
Need to be weaned off slowly to wake up the system
Who should receive steroids preoperatively?
- Pts taking Prednisone 5 mg/d or equivalent for > 2 weeks within 1 yr. (Old method)
- Pts taking Prednisone 20 mg/d or equivalent for > 3 weeks within 1 yr. (New method).
The HPA axis dysfunction is dependent on the _______ and _______ of steroid therapy.
- Dose
2. Duration
How long does it take for Cortisol levels to return to normal after stopping glucocorticoid treatment?
10 - 11 months
- the brain is still able to work & send signals so much that the ACTH levels rise, increasing the risk of adrenal insufficiency
What determines the potency of mineralocorticoid and glucocorticoid therapy?
the chemical structure
introduction of fluorine enhances activity
What steroid is most like the body’s natural cortisol?
Hydrocortisone
Cortisol (Hydrocortisone) potency? Na retention? 1/2 life?
Potency = 1
Na Retention = 1
1/2 life = 8-12 hours
Prednisone potency? Na retention? 1/2 life?
Potency = 4
Na Retention = 0.8
1/2 life = 18-36 hours
Dexamethasone (Decadron) potency? Na retention? 1/2 life?
Potency = 25
Na Retention = 0
1/2 life = 36-54 hours
What is the drug of choice for Acute Adrenal Crisis?
Hydrocortisone
What are the various steroids and their Equipotent dosages?
What is the most potent?**
Hydrocortisone = 100 mg Prednisone = 25 mg Methylprednisolone = 20 mg Dexamethasone = 3.75 (4 mg) = 25x's the potency**
How are exogenous steroids absorbed?
- inhalation & mucosal and skin applications
If a patient with asthma or eczema uses a steroid everyday, do they need a steroid prep?*
Do they have HPA axis suppression?
No
What is the body’s physiologic short term stress response?
Hypothalamus -> signals preganglionic sympathetic fibers -> adrenal medulla = catecholamines =
- Increased heart rate
- Increased BP
- Liver converts glycogen to glucose
- Dilation of bronchioles
- Changes in bf patterns leading to increased alertness, decreased digestive system activity, & reduced UO
- Increased metabolic rate
What is the effect of a more prolonged stress response?
Hypothalmus (CRH) -> anterior pituitary (ACTH) -> adrenal cortex = mineralocorticoids & Glucocorticoids
Mineralocorticoids = Aldosterone
Glucocorticoids = Cortisol