Flashcards in Test 1 content-Endocrine Deck (68)
____ and ____ aren't totally perfused in total cpb and either cant ______ or make their usual contributions to _____
*Heart and lungs
Exposure to pump, oxygenator and tubing does what?
*traumatizes cellular blood elements
*Causes plasma protein to be absorbed and removed from circulation
*Stimulates and immune response
_____ and ____ alter blood concentrations or electrolytes, hormones and serum proteins
hemodilution and anticoagulation
Hypothermia reduces rate of _____, which does what?
biochemical reactions which further alters hormonal responses
Physiological alterations during cpb w/ non pulsatile perfusion
*changes in blood flow distribution between organs
*Some hormonal alterations during bypass could be lessened or prevented by using pulsatile perfusion
How are stress hormones affected/altered on cpb?
stress hormone levels increase
Why is summarizing lit on endocrine, metabolic and electrolyte response difficult?
*Different pt populations
-anesthetic and adjunct drugs
What portion of the pituitary gland secretes hormones?
What does the pituitary gland regulate?
*Regulate the adrenal cortex, thyroid, ovaries and testes
Gonadotropin responses during bypass
(not well analyzed or documented)
*Maggio saw significant preoperative decreases in testosterone conc. in men and increases in women undergoing cardiac surgery
*Estradiol levels increased in men and decreased in women
What is pituitary apoplexy?
*Rupture of a tumor/bleeding
*Rare issue typically in patients w/ pituitary adenomas (tumors)
Diagnosis of pituitary apoplexy and what can be done?
(CPB alone doesnt lead to hypopituitarism)
*Confirmed w/ CT or MRI
*Hormonal replacement and prompt hypophysectomy (removal of pit. gland)
Posterior pit. gland secretes ___ and ____ and is a potent regulator of?
*Vasopressin or other ADH's
*Renal water excretion
What does ADH do?
*Increases renal vascular resistance and at high conc. increases peripheral vasc. resistance. and reduces renal BF.
What does ADH stimulate in connection w/ the coagulation cascade and what does that do?
*Stimulates the release of von willebrand factor
*Perhaps improving hemostasis during and after cardiac surgery
General anesthesia and surgery are associated w/ ______
Increases in ADH
Stimuli that provoke ADH release include:
*Plasma osmolarity, decreased blood volume or pressure, hypoglycemia, angiotensin, stress and pain
An exaggerated ADH response to bypass can occur during these times:
*Dec. in circulating BV upon initiating bypass
*Transient hypotension that can occur at initiation of bypass
_____ during CPB curbs the exaggerated ADH response particularly after bypass but doesn't stop it from happening
At high conc. vasopressin (ADH):
*Increases peripheral vascular resistance
*Decreases cardiac contractility and coronary blood flow
Low systemic vascular resistance and high CO within the first 4 postop hours is what/
Vasoplegia is more likely in patients w/ ________
A pre op reduced ejection fraction and or in patients receiving chronic treatment w/ ACE inhib. and in patients w/ high ADH levels pre op
ADH concentrations ____ during CPB irrespective of anesthesia or the perfusion technique
Adrenal hormones catecholamines (products from adrenal medulla)
Adrenal cortical hormones
Elevations of plasma EPI and NE underlie many hemodynamic issues during bypass including:
*Peripheral vasoconstriction shifts in intra organ blood flow
With hypothermia there is an increase in EPI and NE levels
*NE: 4 fold inc.
*EPI: 10 fold inc.
NE and EPI peak at different times during bypass:
NE: Peaked at cross clamp removal and rewarming also rising again at 2-4 hours after surgery
EPI: Peaked at target hypothermic temp.
Main feature in the metabolic stress response
*Increased secretion of cortisol
CPB modifies cortisol responses to surgery by:
*Briefly decreasing upon initiation of CPB (likely due to hemodilution)
*During bypass levels increase significantly above baseline
*After bypass patients have elevated concentrations for more than 48 hours