Diuretics

Question 1

two aspects of perfusion think renal function

Answer 1

bad renal function, how its addressed on bypass

Question 2

PROXIMAL CONVULTED TUBULe diuretics

Answer 2

CARBONIC ANHYDRASE INHIBTORS ADENOSINE ANTAGONIST

Question 3

thick ascending limb loop of henle drugs diuretics

Answer 3

loop diuretics

Question 4

distal convoluted tubule diuretics

Answer 4

thiazides

Question 5

cortical collecting tubule diuretics

Answer 5

K sparing diuretics adenosine antagonists

Question 6

medullary collecting ducts diuretics

Answer 6

vasopressin antagonists

Question 7

common uses for diuretiucs

Answer 7

CHF,HEPATIC ASCITES,NEPHROTIC SYNDROME,HTN,

Question 8

Hepatic ascites

Answer 8

increased portal vein pressure liver starts to sweat fluid. end stage liver failure colloid pressure decreases because of decreased protein. goes into abdomen. think african kids starving

Question 9

nephrotic syndrome

Answer 9

high aldosterone levels. lose glucose amino acids and proteins. colloid pressure goes down. causes fluid overload

Question 10

htn

Answer 10

stiff arteries need fluid relief

Question 11

diuretic categories

Answer 11

carbonic anhydrase inhibitors. loop diuretics, thiazides, potassium sparing diuretics

Question 12

1: Carbonic Anhydrase (CA) Inhibitors

Answer 12

least important to us not very strong. • *Work by inhibiting carbonic anhydrase in the proximal tubule epithelium
• Carbonic anhydrase catalyzes
• With CA blocked, the reaction shifts to the right and bicarbonate accumulates in the urine.
odium is less able to be exchanged for H+ in the tubules so H+ is retained while Na+ is lost (with the bicarbonate).
* Sooo…urine becomes more alkaline (explain), water follows the bicarbonate into the tubules (causing diuresis) and the patient experiences a metabolic acidosis (explain again).

Question 13

-Acetazolamide

Answer 13

(Diamox) Carbonic Anhydrase (CA) Inhibitor. Rarely used in cardiovascular surgery (why?) causes metabolic acidosis
-You may see patients on acetazolamide who have glaucoma
…or high-elevation sickness

Question 14

2: Loop Diuretics

Answer 14

• Act on the ascending Loop of Henle

-Also called “High Ceiling” diuretics because the dose-response curve is close to linear (that is, there’s no “ceiling”)

Question 15

how loop diuretics work

Answer 15

Loop diuretics work by blocking the co-transport of Na+/K+/2Cl ̄ from the tubular lumen back into circulation.
• So much NaCl is not resorbed that downstream nephron sites cannnot compensate for that loss.

Question 16

loop diuretics are most

Answer 16

efficacious (what’s this?) of all diuretics and work incredibly fast (within minutes when given IV).
• Called the “yellow zipper” drugs of human medicine (or the “waiting room puddle” drugs in veterinary medicine) work fast. good for bypass

Question 17

loop diuretics additional mechanism

Answer 17

Loops” also work to increase renal blood flow by inducing the expression of COX-2
• COX-2 is referred to as the “ungood” cyclooxygenase NSAIDS (what’s this?) preferentially block in inflamed tissues

Question 18

cyclooxygenase produces

Answer 18

prostaglandins which are powerful

vasodilators of renal arteries.

Question 19

nsaids may

Answer 19

may interfere with loop diuretic function in
compromised patients (hepatic cirrhosis,
nephrotic syndrome)

Question 20

loop diuretics doc for

Answer 20

patients w/ renal function. pulmonary edema because they act fast

Question 21

doc for hypercalcemia and hyperkalamia

Answer 21

loop diuretics

Question 22

loop diuretics aka

Answer 22

non potassium sparing diuretics

Question 23

loop diuretics perfusion uses

Answer 23

1) Get rid of extra fluid on bypass (duh!)
*Chemical “hemoconcentrators”
2) Get rid of excess K⁺
What is normal K⁺ again?
3) Help maintain urine production/renal
function (**!!!) in low output states on
bypass (what might these be?) may be deliterious. may be giving lasix when you dont need it like when youre down on flow

Question 24

sides of loops

Answer 24

hypotension,hyperuricemia, hypokalemia,hypomagnesemia,ototoxicity (aminoglycoside antibiotics)

Question 25

furosemide

Answer 25

lasix. • Very commonly used during and peri-bypass. • Very inexpensive • Has been used forever • Wide margin of safety/therapeutic window therefore the potential for “We always put some lasix in the pump” mentality • ~2 hour duration of action when given IV (on pump)

Question 26

ethacrynic acid

Answer 26

edecrin. Loop diuretic. Less commonly used than furosemide • Like furosemide but greater potential for oxotoxicity

Question 27

Bumetanide and Torsemide

Answer 27

``` (Bumex) and (Demadex). -Like furosemide and ethacrynic acid -Much less frequently used -Generally utilized as “physician’s preference” or when desired response is not achieved by furosemide. ```

Question 28

Thiazide Diuretics

Answer 28

``` Act on the cortical region of the Ascending Loop of Henle *Also called “Ceiling Diuretics” because of their “flattening” dose/response curve ```

Question 29

thiazide diuretics. how they work

Answer 29

-Thiazide diuretics work blocking Na⁺/Cl¯ transport/reabsorption on the luminal side of the thick part of the Ascending Loop of Henle and the Distal Convoluted Tubule. -Consequently, NaCl concentrates in the tubular fluid (and H₂O obediently follows = increased urine production)

Question 30

thiazide caveot

Answer 30

This also means that thiazides have to actually get into the tubular lumens via renal excretion… …so thiazides lose efficacy in patients with decreased renal function. need high urine production to get in. lasix can work on blood side

Question 31

Thiazide Diuretics similar to loops because

Answer 31

Like “Loops”, thiazides increases renal blood flow through COX-2 inducement of prostaglandin synthesis. • Structurally related to Acetazolamide, but cause much more diuresis.

Question 32

original diuretic used for edema

Answer 32

chlorothiazide. *Chlorothiazide is the only thiazide available for parenteral use (of relevance to you!) *Typical adult pump dose is 500mg

Question 33

thiazide effects on electrolytes

Answer 33

increased urinary excretion of Na,K, vol. decrease excretion of calcium (sparing)

Question 34

Thiazide Diuretics | Perfusion Uses

Answer 34

Like the “Loops” thiazides get rid of extra (edema) fluid and potassium. - systemic vascular resistance due to relaxation of arteriolar smooth muscle *So how do these two effects synergize?getting rid of fluid and creating more capacitance for fluid by dilating These are “second-line” treatments (after “Loops” for the edema of heart failure. -HTN

Question 35

thiazide advantage over loop

Answer 35

``` Thiazides promote the reabsorption of calcium. *Compared to “Loops”, long-term use results in significantly less decrease in bone density (hip fractures are decreased by 1/3rd) ```

Question 36

ince thiazides can (uniquely) cause the production of hyperosmolar urine (what’s this?) it’s used in diabetes insipidus (?)

Answer 36

allows people to concentrate urine because of lack of adh

Question 37

potassium sparing diuretics

Answer 37

• Function in the collecting tubules (ducts) to | prevent Na⁺ reabsorption and K⁺ excretion. Antagonize aldosterone

Question 38

mineralocorticoids(aldosterone) is produced

Answer 38

in glomerulosa

Question 39

zona fasciculata

Answer 39

glucocorticoids | cortisol

Question 40

Zona reticularis

Answer 40

androgens | testosterone precursors

Question 41

Potassium-Sparing Diuretics • Used to treat HTN, often in combination with

Answer 41

thiazides. not efficacious by themselves

Question 42

potassium sparing are problematic in

Answer 42

patients with hyperkalemia | (like who?) like patients on bypass or renal failure

Question 43

Potassium-Sparing Diuretics | Direct Aldosterone Antagonists

Answer 43

Resemble sex steroids chemically. Used as adjunctive therapy in heart failure – Statistically decreases mortality and helps prevent pathological “remodeling” of the heart

Question 44

diuretic of choice for | liver failure patients with edema

Answer 44

*Spironolactone

Question 45

Potassium-Sparing Diuretics Direct Aldosterone Antagonists ***Ineffective when

Answer 45

used on patients with Addison’s Disease because they have hypo adrenal function. not producing aldosterone. so giving this drug will have no effect

Question 46

Potassium-Sparing Diuretics | Indirect-Acting Aldosterone Antagonists

Answer 46

*Block the Na⁺ transport channels affected by aldosterone rather than aldosterone itself. -VERY similar to direct aldosterone antagonists except they can be used in Addison’s Disease patients (why?)

Question 47

5: Osmotic Diuretics

Answer 47

``` Small non-metabolized molecules filtered through the glomerulus that osmotically carry water with them. Given parenterally as they cause severe diarrhea if given orally (why?) good for renal patients • Mannitol very commonly given on bypass or added to the prime solution • Urea and glucose rarely (if ever) used (so feel free to ignore) ```

Question 48

Osmotic Diuretics works

Answer 48

Work in the proximal tubule and the descending Loop of Henle which permit the free passage of H₂O

Question 49

Osmotic Diuretics | Perfusion Relevance

Answer 49

Commonly used to “draw” fluid into the intravascular space and decrease interstitial edema but…why might this be controversial? because it increases hct.

Question 50

Osmotic diuretics used to maintain flow

Answer 50

for renal failure. prevents accumulation of crap in kidneys. also good for cerebral edema. good for patients who smash their head

Question 51

Osmotic Diuretics -Problematic in patients

Answer 51

``` oliguric(little urine)/anuric (no urine) renal failure (why?) will go into urine and pull fluid and cause htn. ```

Question 52

dont give mannitol when urine output is less than

Answer 52

<50ml/hour for three | hours after a 12.5 gram IV dose, AVOID.

Question 53

Mannitol is excreted (not metabolized) within

Answer 53

one hour, so repeat doses can be given. -MUST be given slow IV or profound transient hypotension will occur due to skeletal muscle vasodilation “And I will be quite ANNOYED. crank up flow it will wear off

Question 54

Mannitol (Osmitrol) is a small molecule

Answer 54

categorized as a “sugar alcohol” With its familiar cousins xylitol and sorbitol.

Question 55

Mannitol is usually supplied

Answer 55

``` as a 20% solution. *What does this mean??! 20g per 100 ml • RULE #1 when giving mannitol: “Check the bag/bottle for precipitated crystals!!!! ```

Question 56

Check the mannitol bag/bottle for precipitated crystals!!!! because

Answer 56

beacause it will concentrate in the crystalsand you wont be giving as much plus its crystals dummy