II. Diuretics Flashcards
1.
Furosemide (Lasix®) IV & IVP Dose
IV: 0.1-1.0 mg/kg
IVP: 10-20 mg
Hint: Michael’s FUR coat cost $10-20 at Burlington Coat Factory; but one (.1) FUR coat was 1 too many.
Examples of Loop Diuretics
- Bumetanide (Bumex®)
- Furosemide (Lasix®)
(-ide)
Loop diuretics target what area of the kidneys?
Thick ascending Loop of Henle
Loop diuretics inhibit reabsorption of what?
Na, Cl, Mg, Ca
…and K later on at the DCT. This is caused by the elevated Na delivery to the DCT; this stimulates the Na-K exchange pump, which reabsorbs some of the increased Na content while pumping out K into the DCT lumen (on its way to excretion); this is how Loop Diuretics can cause hypokalemia.
What area do Thiazide diuretics target?
the DCT
Hint: Z is at the distal end of the alphabet
What do thiazide diuretics cause?
inhibition of Na and Cl reabsorption
Marked increase in excretion of Na, K, Cl, CO ions
Increased K is excreted which can lead to hypokalemia; this occurs because there is increased Na content that reaches the collecting duct. At the collecting duct, some Na may be reabsorbed in exchange for potassium, leading to decrease serum potassium
Thiazide diuretics are often administered concurrently with what?
ACE-I
What are some adverse S/E of Thiazide Diuretics?
- Hypokalemia
- Orthostatic HTN
- Hyperglycemia
- Decreased Placental Perfusion
Which diuretic is considered a first line anti-HTN Tx?
Thiazide diuretics
Hydrochlorothiazide (HCTZ or Hydrodiuril®)
Which diuretic:
- decrease in ECF
- Desensitization of vascular smooth muscle to Ca release stimulated by NE (less VC)
thiazide
Which diuretic:
- increased production of prostaglandins resulting in renal VD and increased RBF
Loop Diuretics
this effect is inhibited if patient takes NSAIDS
T/F: Loop diuretics cause hypercalcemia.
FALSE
Loop diuretics cause a decrease in serum calcium, while thiazides cause an increase serum calcium.
Hint: “Loops LOSE calcium”
Indications for which diuretic:
- Pulmonary Edema
- CHF
- Renal Insufficiency
- Increased ICP
- Hypercalcemia
Loop Diuretics
Which diuretic can potentiate NDMR?
Loop Diuretics
Which diuretic:
- increases plasma osmolality and draws fluid from ICF
Osmotic Diuretic
Osmotic diuretics cause increased urinary excretion of what contents?
- H2O
- Na
- Cl
- CO2
Osmotic diuretics target what area of the nephron?
Loop of Henle
Thin Descending Loop of Henle
What is an example of an osmotic diuretic?
Mannitol
Mannitol is considered an aquaretic because mostly promotes H2O excretion and relatively small amount of Na.
How does Mannitol work on tubules?
By increasing water absorption into the PCT and Thin Descending LOH (Both of these portions are permeable to H2O), there is increased RBF through the tubules; this means there is less time for Na to be reabsorbed. Therefore, some Na is excreted along with a lot of H2O.
Mannitol is not typically prescribed for HTN, rather what is its main indications?
- Increased IOP (glaucoma)
- Increased ICP
- ARF prophylaxis
- Circuit prime for CPB
- Dx of acute oliguria
- Flush harmful stubstances out of kidneys (rhabdo induced myoglobin or hemolysis)
Which diuretic can worsen edematous states such as Pulmonary Edema?
Osmotic diuretics
Acute & transient increases in volume can lead to tissue injury from extravasation can lead to compartment syndrom
Which diuretic should be given centrally?
Osmotic
Mannitol dosage (weight based & IVP)
0.5-1 g/kg
IVP: 12.5-25 g
What is the MOA of K-sparing Diuretics?
Decreased Na reabsorption at the DCT
this inhibits the DCT Na-K pump from activating, therefore retaining serum K levels
Potassium-sparing diuretics may be prescribed alongside what other diuretics to prevent hypokalemia?
- Thiazide
- Loop
What are the two types of Potassium sparing diuretics?
- Spironolactone (Direct inhibition of Aldosterone receptor)
- Amiloride (Indirect inhibition of Aldosterone by blocking ENaC Channels)
What is the net result of potassium sparing diuretics?
- Increased excretion of Na & H2O loss through urine
- Decreased excretion of K & H+
Without a potassium sparing diuretic, what is the effect of Aldosterone?
it augments the renal tubular reabsorption of Na and Cl ions and increases the excretion of K
Which diuretic’s MOA targets the RAAS?
Potassium Sparing Diuretic (Spironolactone)
Spironolactone is a ____ to aldosterone.
competitive antagonist
Carbonic anhydrase inhibitors target what area of the tubule system?
Proximal Convoluted Tubule
T/F: Carbonic anhydrase inhibitors competitively inhibit carbonic anhydrase.
False
non-competitively inhibit, reversing the Na/H pump thus inhibiting Na reabsorption = Na & H2O are excreted
Bicarbonate binds with ____ to form carbonic acid.
Hydrogren
____ splits carbonic acid into water and carbon dioxide.
Carbonic Anhydrase Type 4
Carbonic anhydrase inhibitors end in ____.
-zolamide
Clinical indications of Carbonic Anhydrase Inhibitors:
- Altitude sickness
- Glaucoma
- Epilepsy
- Benign increased ICP
- HF
Most common Carbonic Anhydrase Inhibitor
Acetazolamide (Diamox®)
3 values we use to assess renal function:
- Cr
- GFR
- UO
Normal GFR
> 90
Normal Creatinine
0.8-1.2
normal UO
> 0.5 mL/kg/hr
Keep MAP between ____ mmHg to maintain autoregulation
80-160
During an aneurysm clipping, your neurosurgeon asks you to diuresis the patient; what do you do?
- Mannitol 0.5 mg/kg
- Lasix 10-20 mg IVP
What are three major general causes of fluid overload?
- CHF
- Renal Failure
- Cirrhosis
2 main general treatments for fluid overload:
- Dialysis
- Diuresis
Where is EPO produced?
kidneys
what are three hormones secreted to control BP?
- Angiotensin II
- Prostaglandins
- Kinins
Each kidney contains ____ nephrons.
1.2 Million
What are the 4 major reasons diuretics are administered?
- CHF
- Liver Cirrhosis
- HTN
- Kidney Dz
What are the 5 types of diuretics?
- Carbonic Anhydrase Inhibitors (“-zolamide”)
- Osmotic (mannitol)
- Loop (“-ide”)
- Thiazide (HCTZ)
- K-Sparing (spironolactone & amiloride)
Hint: COLT K
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Which diuretic should pregnant patients NOT be on?
Thiazides, b/c they decrease placental perfusion
What type of patients are best suited for thiazides?
patients with normal kidney function
5 conditions that Loop Diuretics treat & how:
- Severe edema: increase Na excretion to 25% of filtered load
- Hypercalcemia: Increase Ca excretion
- Hyponatremia: Impair free H2O reabsorption
- Oliguric ARF: increase urine volume
- Pulmonary Edema: Increase Venous capacitance
Hint: SHHOP
What will occur if a loop diuretic is administered to a hypovolemic patient?
Nephrotoxicity
What 2 electrolyte abnormalities may occur with Loop Diuretics?
- Hypokalemia
- Hypochloremia
Loops do lose Calcium as well (tx for hypercalcemia)
What happens to renal clearance of lithium if patient is on a loop diuretic?
it decreases
T/F: the occurrence of ototoxicity from loop diuretics is rare.
TRUE
Only loop diuretic we use?
Furosemide (Lasix®)
Onset of Lasix
5 min
Amount Lasix required to cause patient to begin making urine?
10 mg
Mannitol preparation
250 mg/cc
T/F: the onset of mannitol is faster than Lasix.
FALSE, slower
Which diuretic is used as a sweetner for breath freshners?
Mannitol
What value indicates oliguria?
<0.5 mL/kg/hr
Stage 3 Renal Failure GFR range
30-59
Stage 4 Renal Failure GFR range
15-29
