Physiologic Surgery Response & Wound Healing Flashcards
Hormonal Stress Response
HDA axis releases ACTH -> Ach to pit which stimulates cortisol release from adrenals
ACTH is supposed to be inhibited with high cortisol levels, but this feedback look is blocked by the stress response
Get elevated cortisol and ACTH
Sympathetic Nervous System Stress Response
Catecholamines release from adrenal medulla
NE increases, causes tachycardia and HTN
Effects renal, pancreatic, and hepatic systems
Pituitary Gland Stress Response
Increased ACTH = increased prolactin and growth hormone
GH increases blood glucose levels
Get increased ADH which causes further ACTH increase
Adrenal Stress Response
Increased Cortisol release from ACTH increase - max in 6 hours, reaches 3-4X normal
Stimulates protein-breakdown gluconeogenesis - inhibits glucose use and promotes lipolysis
Thyroid Hormone Stress Response
Total and free T3 levels decrease after surgery
TSH decreases after 1st 2 hours and the normalizes
No real lasting effects, monitoring TSH does no good
Blood Sugar Stress Response
Increase in epinephrine, glucagon, cortisol, growth hormone, and inflammatory cytokines causes insulin resistance, decreased peripheral glucose utilization, impaired insulin secretion, increased lipolysis and protein catabolism
-causing hyperglycemia and ketosis
Degree of hyperglycemia is relative to the surgery severity
Increased hormones due to surgery
GH
ACTH
Prolactin
ADH
Catecholamines
Cortisol
Aldosterone
Glucagon
Renin
Unchanged and decreased hormones due to surgery
Unchanged: TSH, LH, FSH
Decreased: Insulin, Testosterone, Estrogen, T3
Carbohydrate, Protein, and Lipid Metabolism Stress Response
Go into a catabolic state with increased cortisol and cytokines - get skeletal and visceral muscle breakdown
-Muscle wasting and weight loss <0.05 kg/day
Lipolysis and ketone production with FA oxidation = increase acetone
Catabolism promotes glucose production
-glucose homeostatic mechanism rendered ineffective
Water and Electrolyte Metabolism Stress Response
ADH increase = water retention and concentrated urine for 3-5 days post op
Renin increase promotes Angiotension 2-1 and aldosterone secretion
-get sodium and water reabsorption @ DCT
The bigger the surgery, the more electrolyte/glucose imbalance
Increased Cytokine Release
Interleukin 6 is the most important cytokine w/ surgery
- biggest player in trauma response, peaks 12-24 hrs out
Cause post-op fever, granulocytosis, hemostasis, tissue damage and healing problems
Cytokine production is limited by cortisol levels - negative feedback
Opioids and Stress Response
Opioids suppress hormonal response on HPA secretion
High dose fentanyl, morphine
May prolong recovery time, and pt may require ventilatory support
Anesthetic Drugs and Stress Response
Etomidate: suppresses cortisol production
Benzodiazepines: inhibit steroid production @ level of pituitary
Clonidine: Dials back SNS response
-Centrally active anti-HTN that works on alpha-2 receptors
Regional Anesthesia
Less hormone response with regional than with general
Cytokine release remains unaltered
Reduced thromboembolic complications
Improved pulmonary function
Reduced paralytic ileus
Stress Response Modifications
Surgical technique
Nutrition
Hormone Therapy
Normothermia
Surgical technique: Decreased cytokine release w/ minimally invasive surgery
Nutrition: glutamine, arginine, omega-3 FA enteral feeds improve recovery
Hormone Therapy: Insulin infusion +/- glucose to reduce excess protein breakdown
Normothermia: Reduced metabolic response to surgery
