Steroids and Anesthetic Considerations Flashcards
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
Long term stress response and the effects of Mineralocorticoids?
- Retention of sodium & water by kidneys
2. Increased blood volume & blood pressure
Long term stress response and the effects of Glucocorticoids?
- Proteins & fats converted to glucose or broken down for energy
- Increased blood sugar
- Suppression of immune system
What is the normal daily output of cortisol?
20 mg
What is the Old maximum daily output of cortisol?
300 mg
- This is why we give 300 mg in the OR
What is the New maximum daily output of cortisol?
200 mg
Cortisol receptors on the heart cause?
Increase BP & HR
What increases cortisol levels the most?
Septic Shock
**What are the signs and symptoms associated with Acute Adrenal Crises?
- Neurologic - brain shuts off (don’t see in OR)
- Hemodynamic - massive vasodilation & decrease BP*
- **Metabolic =
- Hypoglycemic
- Hypovolemia
- Hyponatremia*
- Hyperkalemic*
- Metabolic acidosis
When treating AAC how should you replace the steroid?
Give steroid prep in a slow piggyback
- if given too fast the patient will bounce off the wall d/t sympathetic stimulation
What is the first sign of AAI?*
Hypotension not responsive to pressors = REFRACTORY HYPOTN**
- this is d/t not seeing the neuro response d/t ETT w/ sedation
Treatment of Acute Adrenal Crisis?
Hydrocortisone 100 mg IV - initially Hydrocortisone 200 mg IVPB over 24 hrs - Combined 300 mg Fluid replacement Glucose replacement & monitoring Hemodynamic monitoring Vasopressor & inotropic support as needed (Vaso & methylene blue)
What are the steroid replacements for minor surgical stress?
25 mg hydrocortisone or equivalent
inguinal hernia
What are the steroid replacements for Moderate surgical stress?
50 - 75 mg/dL of hydrocortisone or equivalent for 1-2 days, then resume preoperative dosage
(cholecystectomy, hysterectomy, colon resection)
What are the steroid replacements for Major surgical stress?
100 - 150 mg/dL of hydrocortisone or equivalent for 2-3 days then resume preoperative dosage
(AAA repair, cardiac bypass)
How does Etomidate inhibit Cortisol?**
Etomidate blocks 11 Beta-hydroxylase - the enzyme responsible for converting 11-deoxycortisol to cortisol
Does propofol inhibit cortisol?
No. Propofol does not inhibit the cortex therefore cortisol levels go up w/ surgery
When is decadron most efficacious?
If given prior to induction of anesthesia b/c its slow
- we don’t do this b/c of perineal burning
What is the most effective dose of Decadron? Onset? Peak? DoA?
4mg
- onset 1 hr
- peak 8 - 10 hr
- DoA 72 hr
Should you give 100 mg hydrocortisone for potential adrenal insufficiency and decadron for PONV preoperatively?
Do not give both if they are at risk.
Risk is not an indication for AAI hydrocortisone, only if in crisis.
How does septic shock decrease cortisol? and the treatment?
Sepsis increases nitric oxide = vasodilator
- Cytokines decrease #’s/affinity of glucocorticoid receptors for cortisol
- 200 mg hydrocortisone if decreased BP after vol. resuscitation & max vasopressors
Where do steroids work in the intrinsic pathway?
Steroids decrease the conversion of phospholipase A2 to Arachidonic Acid & decrease the conversion of AA to Cyclooxygenase & Lipoxygenase = decrease inflammation & pain
Given perineural Dexamethasone 4 mg compared w/ IV is associated with what outcomes?
- Decreased pain scores
- Reduced opioid consumption
- Less PONV
How long does the adrenal cortical suppression last?**
24- 48 hours
Is cortisol the same chemical structure as aldosterone?*
Yes
Where is cortisol transported to in the brain?*
Anterior pituitary