Term
2 main types of pancreatic tissues
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Definition
Acini
Islets of Langerhans
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Term
What do acini do?
What do the Islets of Langerhans do?
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Definition
secrete digestive juices into duodenum
secrete hormones into the bloodstream
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Term
What are the 3 cell types within the islet of Langerhans, what percentage are they and what do they each do? |
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Definition
Alpha cells -secrete glucagon
(located around periphery, ~ 20% of islets)
Beta cells -secrete insulin
(in center, ~80%)
Delta cells -secrete somotostatin
(scattered throughout) |
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Term
What is the other name for somatostatin?
Where else in the body is somatostatin released from? |
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Definition
growth hormone inhibiting hormone
- from GI tract
-hypothalamus
(stored in the anterior pituitary) |
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Term
What does somatostatin do? |
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Definition
inhibits both insulin & glucagon secretion |
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Term
Insulin is a small ____ comprised of __ amino acid chains linked to each other by 2 ______
How long does insulin circulate in plasma unbound?
Binds to receptors on ________
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Definition
Insulin is a small protein comprised of 2 amino acid chains linked to each other by 2 disulfide bridges
10-15min (the pancreas secretes a basal rate of insulin every 10-15min)
Binds to receptors on target cell membrane |
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Term
How many subunits does the insulin receptor consist of? Where are they each located?
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Definition
4 subunits:
2 alpha subunits lie outside the cell membrane
2 beta subunits penetrate the membrane
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Term
Where does insulin bind to on the insulin receptor?
What activates the beta subunits of the insulin receptor?
What do the activated beta subunits then act as?
What does this do? |
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Definition
alpha subunits
binding of insulin to the alpha subunits activates beta subunits
activated beta subunits then act as an enzyme (a local tryosine kinase)
phosphorylates additional enzymes |
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Term
What are the 5 enzyme types that can be activated by tyrosine kinase when activated by insulin? |
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Definition
1. Glucose transporter
(normally lives inside the cell until activated by tyrosine kinase and then it goes to cell membrane to let glucose in)
2. Protein synthesis
3. Fat synthesis
4. Glucose synthesis
5. Growth & gene expression |
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Term
Insulin is an anabolic or catabolic hormone?
Where in the body does it stimulates uptake, storage, and use of glucose?
It increases cellular permeablility for what 3 things? |
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Definition
Insulin is an anabolic hormone
80% of cells, esp. mm, adipose tissue, & liver
amino acids, potassium, phosphate ions
(as glucose permeability incr, so does K+ & phospate permeability) |
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Term
Is insulin needed for glucose transport into resting or active mm?
What happens to glucose that is not needed for energy in the muscle?
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Definition
resting only (exercising mm can take up glucose without insulin)
excess glucose stored as glycogen
Insulin stimulates transport of amino acids into the muscle cells & promotes protein synthesis. |
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Term
Is insulin required for uptake of glucose into the liver?
What does insulin stimulate in the liver?
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Definition
No
stimulates hepatic processing of glucose
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Term
What 2 things does insulin promote in the liver?
What 2 things does insulin inhibit in the liver? |
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Definition
promotes storage of glucose as glycogen
promotes conversion of excess glucose into FFA
inhibits breakdown of liver glycogen into glucose
inhibits gluconeogenesis
(insulin stimulates anabolic processes & inhibits catabolic processes) |
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Term
Insulin promotes the conversion of excess glucose into FFA. Then what happens to these fatty acids? |
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Definition
the liver then packages these fatty acids into VLDL & triglyderides & transports them to adipose tissue
(again a storage and anabolic function) |
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Term
Insulin promotes fat ___ & ___ by adipose cells
Insulin inhibits which hormone to prevent the breakdown of fats in adipose cells? |
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Definition
Insulin promotes fat synthesis & storage by adipose cells
Insulin inhibits hormone sensitive lipase inside fat cells
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Term
Actions of insulin on Protein metabolism & growth
Insulin promotes protein ____ & _____.
Stimulates transport of ______ into the cell.
Increases the translation of ___, thus forming new proteins.
Inhibits protein _____.
Depresses ________ in the liver.
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Definition
Insulin promotes protein synthesis & storage.
Stimulates transport of amino acids into the cell.
Incr. the translation of mRNA, thus forming new proteins.
Inhibits protein catabolism.
Depresses gluconeogenesis in the liver. |
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Term
*Insulin functions synergistically with ___ hormone?
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Definition
growth hormone
(both insulin & growth hormone needed for growth to occur; on their own will not have much of an effect) |
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Term
Does the brain need insulin for glucose uptake? But? |
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Definition
No...the brain needs a very constant supply of glucose to function and insulin helps to keep that balance in the body. |
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Term
What are 8 things that increase insulin secretion? |
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Definition
Incr blood glucose
incr blood free fatty acids
incr blood amino acids
GI hormones(gastrin, cholecystokinin, secretin, gastric inhibitory peptide)
Glucagon, growth hormone, cortisol(Counter-regulatory hormones)
Parasympathetic stimulation: Ach
Insulin resistance; obesity
Sulfonylurea drugs (glyburide, tolbutamide) |
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Term
What are 4 things that decrease insulin secretion? |
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Definition
Decr blood glucose
Fasting
Somatostatin (GHIH)
alpha-agonists |
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Term
Glucagon, growth hormone, & cortisol all have what effect on blood sugar levels? |
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Definition
Glucagon, growth hormone, & cortisol are counter regulatory hormones that increase glucose & insulin secretion for net effect of incr blood glucose |
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Term
What second messanger does glucagon use? |
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Definition
Binding of glucagon stimulates adenylate cyclase & production of cAMP. cAMP acts as a 2nd messenger to stimulate other pathways. |
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Term
Functions of glucagon
It is a catabolic or anabolic hormone?
Stimulates what 2 things in the liver?
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Definition
It is a catabolic hormone
glycogenolysis and gluconeogenesis
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Term
T/F: The production of new glucose by gluconeogenesis can sustain the hyperglycemic effect even after depletion of glycogen stores |
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Definition
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Term
*Insulin & glucagon function as a ___ unit.
They function ______ at every level. |
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Definition
* Insulin & glucagon function as a bihormonal unit.
They function antagonistically at every level. |
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Term
What do insulin & glucagon do together? (2)
Name 3 main tissues sensitive to insulin & glucagon |
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Definition
-they maintain nutrient availability to tissues which are
sensitive to these hormones
-they also maintain a relatively constant blood
concentration of glucose for the brain (an insulin independent tissue)
mm, adipose tissue, and liver
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Term
*What are the 2 cell types that make up the bihormonal unit to secrete glucagon and insulin?
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Definition
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Term
What are 3 anabolic processes?
Is insulin increased or decreased for these to occur?
Is glucagon increased or decreased for these to occur? |
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Definition
Lipid synthesis
protein synthesis
glycogen synthesis
incr insulin
decr glucagon |
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Term
What are 6 catabolic processes?
Is insulin increased or decreased for these to occur?
Is glucagon increased or decreased for these to occur? |
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Definition
lipolysis
fatty acid oxidation
ketogenesis
glycogenolysis
proteolysis
gluconeogenesis
decr insulin
incr glucagon |
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Term
What determines whether the hormonal response to insulin & glucagon will be anabolic or catabolic? |
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Definition
insulin-glucagon ratio = net effect |
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Term
Insulin-Glucagon Ratio
What happens following a meal?
Is the net effect anabolic or catabolic? |
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Definition
Blood glucose incr, stimulating insulin & inhibiting glucagon
This results in anabolic processes & prevents further incr in glucose (in the blood)
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Term
Insulin-Glucagon Ratio
What happens following fasting or exercise?
Is the net effect anabolic or catabolic? |
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Definition
The alpha-beta unit detects fall in glucose, resulting in a decr in insulin secretion & an incr in glucagon secretion.
The net effect is catabolic, thus maintaining critical blood glucose levels |
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Term
In poorly treated or untreated DM, plasma levels of glucagon are often markedly increased. Why does glucagon secretion occur?
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Definition
Alpha cells think they're starving b/c glucose not getting into cells (alpha cells insulin dep.), so they secrete glucagon
makes the problem worse (incr blood glucose even more) |
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Term
T/F glucose is essentially the only fuel the brain can use?
How much glucose does the brain use per hour?
Glucose concn is kept w/in very narrow limits, normally varying only about __% |
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Definition
True
4 gm/hr
Glucose concn is kept w/in very narrow limits, normally varying only about 50% |
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Term
Type I: IDDM
insulin deficiency is __ or ___
Pancreas & plasma contain __ or __ insulin
Requires ____ therapy
Prone to _____
Associated w/ _____ antibodies
Genetic component on chromosome _ may be partly responsible for susceptibility. Genetic link is ___.
Accounts for ___% of all DM.
Begins before age ___, usually around ___, but has been diagnosed in utero.
Usually begins abruptly in a ____ child, often following an infection.
T/F: This type of DM is easy to control |
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Definition
insulin deficiency is severe or absolute
Pancreas & plasma contain little or no insulin
Requires insulin therapy
Prone to DKA
Associated w/ anti-islet cell antibodies
Genetic component on chromosome 6 may be partly responsible for susceptibility. Genetic link is weak
Accounts for 10% of all DM.
Begins before age 40, usually around puberty, but has been diagnosed in utero.
Usually begins abruptly in a slender child, often following an infection. (could be what triggers autoimmune response)
FALSE:
labile & difficult to control |
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Term
Type II: NIDDM
__ insulin deficiency. Circulating insulin levels may be ...?
Pancreas contains ____ insulin
Often controlled by _______
Clinical course more ____
Accounts for __% of all DM.
Begins insidiously usually in an ____ person over the age of 40, although is occurring more frequently in children now.
T/F: Insulin withdrawal always causes DKA |
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Definition
Relative insulin deficiency. Circulating insulin levels may be low, normal, or high.
Pancreas contains considerable insulin
Often controlled by diet and/or oral hypoglycemic agents
Clinical course more stable
Accounts for 90% of all DM.
Begins insidiously usually in an obese person over the age of 40, although is occurring more frequently in children now.
FALSE: usually does NOT cause DKA |
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Term
Gestational diabetes occurs in 2-3% of pregnancies.
Presents as glucose intolerance w/ usual onset at ___ wks.
Does glucose tolerance correct after delivery?
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Definition
Gestational diabetes occurs in 2-3% of pregnancies.
Presents as glucose intolerance w/ onset at 24-30 wks.
usually
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Term
What is the etiology of secondary diabetes?
What are 4 things that can cause this? |
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Definition
secondary to pancreatic insult or excessive demand
pancreatic disease
drugs (glucocorticoids)
acromegaly
cushing's disease |
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Term
Is there a stronger hereditary link in Type I or Type II DM?
Type I has been associated w/ certain ___ antigens & is an ____ process
Type II has no strong autoimmune basis & is usually precipitated by _____
Insulin mediated stimulation of __ ___ is impaired in NIDDM |
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Definition
stronger genetic link in Type II
Type I has been associated w/ certain HLA antigens & is an autoimmune process
Type II has no strong autoimmune basis & is usually precipitated by obesity
Insulin mediated stimulation of tyrosine kinase is impaired in NIDDM |
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Term
Pathophysiology of DM
Insulin deficiency decreases glucose uptake in mm and fat cells. As glucose entry into cells diminishes, ____ is released from the _____ = more hyperglycemia.
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Definition
As glucose entry into cells diminishes, glycogen is released from the liver
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Term
Pathophysiology of Diabetes
What BS level exceeds the kidney's ability to reabsorb glucose & thus glucose is found in the urine (sweet urine)
What systemic effects result? |
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Definition
As BS approaches 180, the capacity of the renal tubules to reabsorb glucose is exceeded, so glucose is excreted into urine.
Urine glucose acts as an osmotic diuretic, resulting in excretion of water & salts in the urine. Cellular dehydration occurs. |
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Term
The decreased insulin/glucagon ratio also stimulates lipolysis & protein catabolism. The increased lipolysis results in the formation of ___, which results in what metabolic state?
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Definition
Increased lipolysis results in the formation of ketoacids, which results in metabolic acidosis.
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Term
What is the target range for glucose introp? |
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Definition
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Term
What are 5 deleterious effects of hyperglycemia? |
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Definition
impaired wound healing
hyperosmolarity
osmotic diuresis
impaired phagocyte fcn
electrolyte disturbances
I HOPE |
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Term
When in the day should we schedule surgery for DM pts?
When should we d/c hypoglycemic agents |
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Definition
early in the day to limit duration of fasting
evening before Sx |
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Term
T/F: it is ok to proceed w/ elective surgery if pt has hyperglycemia, electrolyte imbalance, or ketoacidosis.
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Definition
FALSE!!
Do not proceed w/ elective surgery under these circumstances
if pt has life-threatening infection, it is ok to proceed w/ surgery even if BS>200--surgery may be the definitive treatment for the infection & should not be cancelled b/c of high glucose levels --- BUT no sx with ketoacidosis -- must hydrate first per lec! |
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Term
T/F As part of the preop eval of a DM pt, we need to evaluate for limited joint mobility (prayer sign) & limited neck extension as potential for difficult airway.
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Definition
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Term
What does the presence of autonomic neuropathy put the pt at risk for (2)? |
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Definition
risk of aspiration on induction
introp CV lability |
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Term
The HbA1C evaluates avg blood glucose levels from the past ___ days? What is the target level for HbA1C?
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Definition
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Term
What are 9 s/s of autonomic neuropathy? |
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Definition
- resting tachycardia
- orthostatic hypotension
- absent beat-beat variation w/deep breathing
- cardiac dysrhythmias (QT abnormalities)
- sudden death syndrome
- gastroparesis--vomiting, diarrhea, abd distension
- bladder atony
- impotence
- asymptomatic hypoglycemia
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Term
IDDM pts undergoing major surgery should be treated w/insulin.
Which route of admin is better: SQ or IV? why?
If a pt has an insulin infusion pump, how should it be set? |
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Definition
IV route more reliable, but requires close monitoring - check every 1-2hrs at least---hypothermia & vasoconstriction may interfere w/ SQ absorption
leave on basal rate of infusion pump and check sugars throughout case. |
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Term
How do the stress of anesthesia & surgery affect insulin requirements?
T/F: Type I diabetics are much more sensitive to insulin, and will require smaller doses to control glucose? |
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Definition
increase insulin requirements d/t incr catecholamines & cortisol = inc BS.
True |
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Term
When insulin administered for glucose levels >300, when should you start administering glucose as well? Why? |
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Definition
when BS reaches 250-300 --- to prevent cerebral edema which can occur when glucose levels are dropped too rapidly |
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Term
Do you need to utilize RSI and use a cuffed tube with DM pts that have gastroparesis or autonomic neuropathy?
Why might hyperglycemia occur in diabetic pt in OR?
How do IAs affect insulin release?
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Definition
ABSOLUTELY
d/t increases in plasma catecholamines & cortisol
IAs may impair release of insulin in response to glucose |
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Term
Epidural & spinal anesthesia versus GA in preserving glucose tolerance? |
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Definition
Epidural & spinal anesthesia preserve glucose tolerance presumably owing to inhibition of the catecholamine response to surgery
GA depress insulin release in response to inc BS |
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Term
What can cardiac autonomic neuropathy result in?
What may be the most effective drug therapy in these cases? |
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Definition
Bradycardia & hypotension that develop suddenly & are unresponsive to IV admin of atropine and/or ephedrine
epi=most effective |
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Term
What is the most critical step in management of IDDM pt periop?
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Definition
check glucose levels frequently
check q 1-2 hrs before, during, & after surgery until pt fully awake & alert |
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Term
What is the treatment of hypoglycemia?
<60
60>BS<120
How many gm of glucose in 100ml D5W? |
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Definition
Admin D50W for glucose <60
Admin D5W for glucose levels 60>BS<120
D5W 100ml = 5 gm glucose
(remember brain uses 4gm/h) |
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Term
HbA1C:% = avg BS level
5% =
6% =
7% =
8% =
9% =
10% = |
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Definition
HbA1C:
5% - 100
6% - 135
7% - 170
8% - 205
9% - 240
10% - 275
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