4. Endocrine Response- Exam 1 Flashcards
Deeper levels of anesthesia appear to do what to the endocrine response.
reduce or eliminate endocrine responses. Also appear to reduce mortality
the pituitary has what functions
Both neural (posterior lobe) and endocrine (anterior lobe) function
Posterior pituitary is the “______” portion—it’s essentially modified nervous tissue
neurosecretory
what does the pituitary secrete (not produce)
ADH (vasopressin)
Oxytocin
High concentrations of ADH:
- May increase ______ and ______
- May decrease ______ and ______
- Reduces _____
- Stimulates release of _______
- May improve ______
- May increase peripheral vascular resistance and renal vascular resistance
- May decrease cardiac contractility and coronary blood flow
- Reduces renal blood flow
- Stimulates release of von Willebrand factor
- May improve hemostasis
What Stimulates Vasopressin Release (6)
- Increase plasma osmolarity
- Decreased blood volume or decreased blood pressure or perceived decreased blood pressure
- Hypoglycemia
- Angiotensin II
- Stress
- Pain
bypass increases ADH release- how long does it persist
Persists hours post op
how does bypass initiate ADH release
- Initiation of bypass
- transient decrease in CBV and blood pressure
- Venting keeps left atrial pressure low simulating low CBV (potent stimulant)
how can the release of ADH be prevented
Magnitude of increase can be reduced-not eliminated
- Pulsatile flow
- Anesthesia with large doses of synthetic opioids. –Fentanyl (50 μg/kg) or sufentanil
Anterior Pituitary secretes ______ hormones
trophic
Anterior Pituitary secretes trophic hormones that regulate what 4 things
Adrenal cortex** (ACTH)
Thyroid** (TSH)
Ovaries/Testes
Growth (HGH)
what is the Most damaging complication to pituitary
Pituitary Apoplexy
Pituitary Apoplexy symptoms
Ptosis (droopy eyelids)
opthalmoplegia (paralysis muscles controlling eye) nonreactive & dilated pupils
decreased visual acuity
hormonal defects
Pituitary Apoplexy is caused by
Damage to pituitary usually blamed on ischemia, hemorrhage, and edema of gland
Pituitary Apoplexy treatment
Hormonal replacement (HGH) / hypophysectomy
Adrenal medulla produces what 2 catecholamines
Epinephrine & norepinephrine
besides the adrenal medulla, where is NE produced
Peripheral sympathetic & central nerve terminal
Epinephrine concentration increases ___ fold over and Norepinephrine concentration increases __ fold preoperative levels
10 fold
4 fold
when are peak levels of epi and NE seen
after initiation of bypass- when cooled to 32C
how can the increase in epi and NE be prevented (4)
magnitude of increase can be reduced- not eliminated
- Deep anesthesia
- Propofol infusion during bypass (4 mg/kg/hr)
- High dose opiod general anesthesia (fentanyl or sufentanil) plus thoracic epidural
- General anesthesia with high spinal block (bupivacaine)
Adrenal Cortical Hormones include
Cortisol
Adrenocorticotropic hormone
describe Cortisol
- Corticosteroid
- released in response to stress
- increases blood sugar and stores of sugar in liver as glycogen
- suppresses immune system
describe Adrenocorticotropic hormone
- Corticotropin
- promotes increased production & release of corticosteroids and cortisol
- Acts as an appetite suppressant, anxietomimetic, and (conversely) a pro-inflammatory
Carbohydrate metabolism regulated by what 5 things
insulin glucagon cortisol growth hormone epinephrine
Hyperglycemia occurs when Glucose concentration increases. What may worsen this response and how long are levels elevated?
worse with hypothermia
Stays elevated for many hours post-CPB
hypoinsulinemia occurs when Insulin levels decrease. What may worsen this
worse with hypothermia
whats the difference between type 1 DM and type 2 DM insulin resistance?
Type I DON’T require increased insulin doses
Type II DO require increased insulin doses
define type 1 DM
Critter doesn’t produce or kidneys don’t respond toVasopressin (Antidiuretic Hormone/ADH)
–absolute insulin deficiency
define type 2 DM
These critters produce variable amounts of insulin
–relative deficiency of insulin (Non-Insulin-Dependent)
Atrial Natriuretic Factor:
Incredibly efficacious _______
Almost the exact physiologic antagonist of ______
Peptides released from _______
Incredibly efficacious vasodilator
Almost the exact physiologic antagonist of aldosterone
Peptides released from cardiac atria
Atrial Natriuretic Factor Release is triggered by what 5 things
atrial distention (such as a-fib) Β-adrenergic stimulation Angiotensin-II Hypernatremia Endothelins (the most potent vasoconstrictors known)
Atrial Natriuretic Factor Cause: increased \_\_\_\_\_\_ rate inhibits \_\_\_\_\_ release reduced plasma concentrations of \_\_\_\_\_\_\_ antagonize renal \_\_\_\_\_\_\_\_ reduce \_\_\_\_\_\_\_\_ pressure
increased glomerular filtration rate inhibits renin release reduced plasma concentrations of aldosterone antagonize renal vasoconstrictors reduce arterial blood pressure
Interestingly, ANF helps prevent “______” of ischemic myocardium and has other anti-ischemic effects on cardiomyocytes and cardiac vascular endothelium
scarring
when are concentrations of ANF reduced during bypass
hypothermia
cross clamping
when are concentrations of ANF increased during bypass
rewarming
post bypass
what does the Renin-Angiotensin-Aldosterone regulate
atrial pressure
intravascular volume
electrolyte balance
what does the Juxtaglomerular apparatus secrete?
renin
when does the Juxtaglomerular apparatus increase secretion of renin
sodium depletion
decreased blood volume
reduced renal perfusion
Renin catalyzes conversion of what? where does this happen?
angiotensinogen to angiotensin I in blood
increased activity
Angiotensin-converting enzyme converts to what? where does this happen?
angiotensin II
blood walls of pulmonary vasculature (primary)
what does increased concentration of angiotensin II do?
increased blood pressure by direct vasoconstriction
stimulates release of aldosterone for adrenal glands
what does increased concentration of aldosterone do?
stimulates readsorption of sodium and secretion of potassium and hydrogen ion by renal distal tubules
Research utilizing ACE-inhibitors and ARBS suggest that CPB temporarily “______” between Renin-Angiotensin-Aldosterone and ________ during and immediately post-bypass
breaks the linkage
hypo- or hypertension
Eicosanoids are metabolized by?
lungs
Prostaglandins mostly related to?
inflammation
Thromboxanes mostly related to?
injury
Endoperoxide prostaglandins H2 produce what?
PGE2, PGF2alpha, PGD2
prostacyclin (PGI2) or thromboxane (TXA2)
what is PGE2
vasodilator
what is PGF2alpha and PGD2
pulmonary vasoconstrictor
what is PGI2
disaggregates platelets, potent vasodilator
what is TXA2
platelet aggregator, potent vasoconstrictor
what are Prostacyclin & thromboxane trends during CPB
increase during bypass and begin to decrease shortly thereafter
what is Aprotinin and what does it do
protease inhibitor
reduces increase in thromboxane
no effect on prostacyclin
better preservation of platelet function
Thyroid response to low [T3] + [T4] or low temp:
Anterior Pituitary produces ____
______ releases TRH
Anterior Pituitary produces and releases ____
Thyroid follicles release ____
Increased [T3] + [T4] in the blood restores ______
TRH Hypothalamus TSH T3 and T4 homeostasis
what thyroid condition can CPB induce
sick euthyroid syndrome
what is the sick euthyroid syndrome
The result of disruption of the thyrotropic feedback loop.
–T3 and T4 levels are low but the thyroid gland is apparently “normal”
what is Histamine
Potent vasodilator
what stimulates the release of Histamine (5)
opioids (morphine / meperidine) muscle relaxants (tubocurarine) antibiotics heparin protamine
when do concentrations of Histamine increase
Concentration increases with administration of heparin – remains elevated
Calcium:
Ionized (__%)
bound to protein (__%)
chelated (__%)
Ionized (50%)
bound to protein (40%)
chelated (10%)
blood concentration of calcium is maintained by what
maintained by parathormone and vitamin D
bones / kidney
During bypass major changes in calcium concentrations are caused by
type of fluids used and addition calcium
is Parathormone secretion affected by bypass
nope
If Ca++ levels are too high what happens
Thyroid releases calcitonin
Increased Ca++ deposition in bones
Decreased Ca++ uptake by intestines
Decreased Ca++ reabsorption from urine
If Ca++ levels are too low what happens
Parathyroid releases PTH
Increased release of Ca++ from the bones
Increased Ca++ uptake by the intestines
Increased Ca++ reabsorption from urine
Give extra calcium only when the following three conditions are present (per your book):
1) ready to terminate bypass
2) ionized calcium is reduced
3) need to increase contractility and blood pressure
what is the Second most abundant intracellular cation
magnesium
magnesium is the Key factor in enzyme systems such as (5):
transmembrane electrolyte gradients energy metabolism synthesis various messaging substances function of ion channels hormone secretion and action
Magnesium:
Ionized (__%)
bound protein (__%)
chelated (__%)
Ionized (55%)
bound protein (30%)
chelated (15%)
is it possible have normal [plasma] of magnesium but intracellular depletion
yep
what are magnesium trends during CPB and what are they associated with?
Decreases during bypass
–Decreased levels may associated with cardiac dysrhythmias
magnesium helps suppress arrhythmias by:
- direct ____________ effect
- direct / indirect effect on ____ and ______
- antagonism of ______ entry into the cell
- prevention of _____
- antagonism of _______ action
- improves ________ ration
- inhibition of _______ current during plateau phase of myocardial action potential
myocardial membrane cellular sodium and potassium calcium coronary arterial spasms catecholamine myocardial oxygen supply / demand calcium
is supplemental magnesium is good
yep
dose of magnesium? when do you give it?
Typically ~ 2 grams post-cross clamp removal
Changes in potassium concentration caused by what 8 things
- cardioplegia
- anesthetic drugs
- priming solutions
- renal function
- carbon dioxide tension
- arterial pH
- hypothermia (decrease as cool, increase as warm)
- insulin treatment of hyperglycemia moves glucose and potassium into cell)
Hyperkalemia not uncommon with what?
multi-dose high-K protocols
Hypokalemia may be increasing as the use of what increases
Custodial CP
what may help reduce decrease in potassium concentration
Albumin
