Topic 4: Endocrine Flashcards
1
Q
When we are on bypass (heart and lungs are being bypassed)- what does it mean for drug administration?
A
Heart and lungs not perfused
- not able to secrete normal hormones
- not part of drug metabolism
2
Q
Deeper levels of anesthesia appear do what?
A
- To reduce or eliminate endocrine responses
- Also appear to reduce mortality
3
Q
Posterior lobe aka
A
Neurohypophysis
4
Q
Anterior Lobe aka
A
Adenohypophysis
5
Q
Pituitary Gland has what two functions?
A
neural and endocrine
6
Q
Posterior pituitary is what portion of the gland?
A
the “neurosecretory” portion—it’s essentially modified nervous tissue
7
Q
Posterior pituitary secretes what?
A
ADH (vasopressin)
Oxytocin
8
Q
Oxytocin does what?
released by what?
A
Positive feedback loop during labor
Milk letdown during lactation
The “Cuddle” hormone
released by post pituitary
9
Q
High concentrations of ADH (Vasopressin) do what to – peripheral vascular resistance?
A
May increase peripheral vascular resistance
10
Q
High concentrations of ADH (Vasopressin) do what to –cardiac contractility?
A
May decrease cardiac contractility
11
Q
High concentrations of ADH (Vasopressin) do what to coronary blood flow?
A
May decrease coronary blood flow
12
Q
High concentrations of ADH (Vasopressin) do what to renal vascular resistance?
A
Increases renal vascular resistance
13
Q
High concentrations of ADH (Vasopressin) do what to renal blood flow?
A
Reduces renal blood flow
14
Q
High concentrations of ADH (Vasopressin) do what to von Willebrand factor?
A
Stimulates release of von Willebrand factor
15
Q
High concentrations of ADH (Vasopressin) do what to hemostasis?
A
May improve hemostasis
16
Q
ADH (Vasopressin) is a potent regulator of what?
A
Regulates renal water excretion (POTENT)
17
Q
What Stimulates Vasopressin Release?
A
Increase plasma osmolarity Decreased BV or decreased (or perceived) BP Hypoglycemia Angiotensin II Stress Pain
18
Q
Venting keeps what low?
A
left atrial pressure low simulating low CBV (potent stimulant)
19
Q
Can Vasopressin release be stopped while on bypass?
A
Magnitude of increase can be reduced but not eliminated
20
Q
Pulsatile Flow effect on Vasopressin release?
A
No significant decrease during bypass – significant decrease immediately after – back to normal 48 hours post-op
-Strangely, no effect on U.O.
21
Q
How to prevent large Vasopressin release with Drugs?
A
Anesthesia with large doses of synthetic opioids Fentanyl (50 μg/kg) or sufentanil Regional anesthesia (Works for non-cardiac procedures)
22
Q
ADH concentrations increase markedly during CPB ___ of anesthesia or perfusion technique
A
irrespective
23
Q
Anterior portion secretes what kind of hormones?
A
trophic hormones that regulate:
- Adrenal cortex** (ACTH)
- Thyroid** (TSH)
- Ovaries/Testes
- Growth (HGH)
24
Q
Most damaging complication to pituitary
A
Pituitary Apoplexy
25
Pituitary Apoplexy is most common in what pts?
Rare, more common in patients with pituitary adenomas (benign tumor) usually diagnosed post hoc
26
Pituitary Apoplexy symptoms
```
Ptosis (droopy eyelids)
opthalmoplegia (paralysis muscles controlling eye)
nonreactive & dilated pupils
decreased visual acuity
hormonal defects
```
27
Pituitary Apoplexy treatment
Hormonal replacement (HGH) / hypophysectomy
28
Damage to pituitary usually blamed on what?
ischemia, hemorrhage, and edema of gland
29
produce norepinephrine?
Adrenal medulla
| Peripheral sympathetic & central nerve terminal
30
Epinephrine concentration increases how much over CPB from preoperative levels?
10 fold
31
Norepinephrine concentration increases how much over CPB from preoperative levels?
4 fold
32
EPI PEAK on bypass
When target temperature reached
33
NOREPI PEAK in bypass
After release of cross-clamp and rewarming
34
Prevention of Catecholamine release?
As with vasopressin, magnitude of increase can be reduced but not eliminated…and the adrenal medulla is just one honking big sympathetic nerve
35
Reduce Catecholamine release with Propofol?
Propofol infusion during bypass (4 mg/kg/hr) versus single bolus injection diazepam (0.1 mg/kg)
-Significant reduction of [catecholamine]
36
Reduce Catecholamine release with anesthesia?
Deep anesthesia versus light
-Greater depth (regardless of type) gives significant reduction of [catecholamine] and decreased mortality (documented in peds)
37
Reduce Catecholamine release with opiod general anesthesia?
High dose opiod general anesthesia (fentanyl or sufentanil) plus thoracic epidural versus high dose opiod anesthesia alone
--Significant reduction of [catecholamine] during and after bypass
38
Reduce Catecholamine release with spinal block ?
General anesthesia with high spinal block (bupivacaine) versus general anesthesia alone
-Significant reduction of [catecholamine]
39
Reduce Catecholamine release with pulsatile vs non-pulsatile flow?
Pulsatile versus non-pulsatile flow
| -Older studies – minimal difference due to “technique” and definition of “pulsatile”?
40
Cortisol
Corticosteroid (adrenal cortical hormone)
released in response to stress
increases blood sugar, increases stores of sugar in liver as glycogen
suppresses immune system
41
Cortisol increases what?
increases blood sugar
| increases stores of sugar in liver as glycogen
42
Adrenocorticotropic hormone
Corticotropin /
promotes increased production & release of corticosteroids and cortisol
Acts as an appetite suppressant, anxietomimetic, and (conversely) a pro-inflammatory
43
Adrenocorticotropic hormone promotes what?
promotes increased production & release of corticosteroids and cortisol
44
Adrenocorticotropic hormone acts as what?
Acts as an appetite suppressant, anxietomimetic, and (conversely) a pro-inflammatory
45
Adrenal Cortical Hormones (Cortisol and Adrenocorticotropic) Increase may be attenuated by what?
Deeper levels of anesthesia
| Addition of thoracic epidural
46
Carbohydrate metabolism regulated by: (5)
```
insulin
glucagon
cortisol
growth hormone
epinephrine
```
47
Glucose concentration increases?
Hyperglycemia—worse with hypothermia
| Stay elevated for many hours post-CPB
48
hypoinsulinemia
Insulin levels decrease—worse with hypothermia
49
Insulin resistance: Type I DM
do not require increased insulin doses
50
Insulin resistance: Type II DM
do require increased insulin doses
51
Atrial Natriuretic Factor does what? antagonist of what?
Incredibly efficacious vasodilator
Almost the exact physiologic antagonist of aldosterone
Peptides released from cardiac atria
52
Atrial Natriuretic Factor released from what?
Peptides released from cardiac atria
53
Atrial Natriuretic Factor release triggered by? (5)
- atrial distention (such as a-fib)
- Β-adrenergic stimulation
- Angiotensin-II
- Hypernatremia
- Endothelins (the most potent vasoconstrictors known)
54
the most potent vasoconstrictors known
Endothelins
55
Atrial Natriuretic Factor does what? (5)
- increased glomerular filtration rate
- inhibits renin release
- reduced plasma concentrations of aldosterone
- antagonize renal vasoconstrictors
- reduce arterial blood pressure
56
Interestingly, ANF helps prevent ______ myocardium and has other ______ on cardiomyocytes and cardiac vascular endothelium
“scarring” of ischemic
| anti-ischemic effects on
57
ANF concentrations reduced when on CPB?
Concentrations reduced during bypass
hypothermia
cross clamping
58
ANF concentrations rise when?
Concentrations rise during rewarming and post bypass
59
What happens to the relation between Atrial Naturetic factor concentration and atrial pressure during bypass and early post operative period?
normal relation lost during bypass and early post operative period
60
Renin-Angiotensin-Aldosterone regulates what?
atrial pressure, intravascular volume, electrolyte balance
61
what secretes renin ? why is renin secretion increased?
Juxtaglomerular apparatus secretes renin
| -increased secretion due to sodium depletion, decreased blood volume, reduced renal perfusion
62
Aldosterone (increased concentration) stimulates what?
stimulates readsorption of sodium and secretion of potassium and hydrogen ion by renal distal tubules
63
Angiotensin II (increased concentration) increases what? (2)
- increased blood pressure by direct vasoconstriction
| - stimulates release of aldosterone for adrenal glands
64
Research utilizing ACE-inhibitors and ARBS suggest that CPB temporarily breaks the linkage between what during and immediately post-bypass?
“breaks the linkage” between Renin-Angiotensin-Aldosterone and hypo- or hypertension
65
Eicosanoids metabolized by ?
lungs
66
Prostaglandins mostly related to ?
inflammation
67
Thromboxanes mostly related to?
injury
68
Endoperoxide prostaglandins H2 produces?
PGE2, PGF2alpha, PGD2
| prostacyclin (PGI2) or thromboxane (TXA2)
69
PGE generally
vasodilator
70
PGF2alpha, PGD2
pulmonary vasoconstrictor
71
PGI2
disaggregates platelets, potent vasodilator
72
TXA2
platelet aggregator, potent vasoconstrictor
73
Prostacyclin & thromboxane increase when?
during bypass and begin to decrease shortly thereafter
74
Aprotinin is what? affect on prostacyclin?
protease inhibitor – reduces increase in thromboxane – no effect on prostacyclin – better preservation of platelet function
75
CPB can induce “sick euthyroid syndrome”, what levels are low?
T3 and T4 levels are low but the thyroid gland is apparently “normal”
76
CPB can induce “sick euthyroid syndrome” resulted from what?
The result of disruption of the thyrotropic feedback loop
77
“sick euthyroid syndrome” does giving thyroxine help?
Mixed evidence whether giving thyroxine helps (trophic and pro-metabolic effects) or hurts (possible increased risk of MIs)
78
things that stimulate histamine release? (5)
-opioids (morphine / meperidine)
-muscle relaxants (tubocurarine)
-antibiotics
-heparin
-protamine
Concentration increases with administration of heparin – remains elevated
79
Ionized Ca %
50%
80
bound to protein Ca%
40%
81
chelated Ca%
10%
82
Blood concentration of Ca maintained by?
parathormone and vitamin D (bones / kidney)
83
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 BP
84
Second most abundant intracellular cation
Mg
85
Mg key factor in enzyme systems (5)?
- transmembrane electrolyte gradients
- energy metabolism
- synthesis various messaging substances
- function of ion channels
- hormone secretion and action
86
Mg Ionized, bound and chelated
| %'s?
Ionized (55%), bound protein (30%), chelated (15%)
87
is it possible have normal [plasma] but intracellular depletion of Mg?
YES
88
Mg does what during bypass?
Decreases during bypass
| Decreased levels may associated with cardiac dysrhythmias
89
Mg does what?
Helps suppress arrhythmias
- direct myocardial membrane effect
- direct / indirect effect on cellular sodium and potassium
- antagonism of calcium entry into the cell
- prevention of coronary arterial spasms
- antagonism of catecholamine action
- improves myocardial oxygen supply / demand ration
- inhibition of calcium current during plateau phase of myocardial action potential
90
Mg is antagonist of what?
- antagonism of calcium entry into the cell (inhibition of calcium current during plateau phase of myocardial action potential)
- antagonism of catecholamine action
91
Supplemental magnesium typical dose?
Typically ~ 2 grams post-cross clamp removal
92
Changes in potassium concentration caused by?
- 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)
93
Albumin may help reduce decrease in what concentration?
K
