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65 Cards in this Set
- Front
- Back
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Low CO associated w/ heart failure decreases renal perfusion & results in fluid retention via what mechanisms?
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Increased Filtration Fraction
Increased Aldosterone & ADH |
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What should be the main treatment in a patient with CHF and edema?
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Treat the underlying pathophysiology by increasing cardiac output. Also, diuretic therapy is useful but not the main goal.
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The excess volume of edema is usually contained in the:
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Interstitial space
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Diuresis removes fluid from (plasma/interstitium) first followed by fluid from the (plasma/interstitial) volume?
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1. Plasma
2. Interstitial *interstitial fluid volume rapidly equilibrates w/ the plasma volume |
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Patients with severe hepatic damage develop edema in the peritoneal cavity as a result of:
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Increased hepatic portal pressure & lack of plasma proteins
*fluid lost in the peritoneal cavity contains fluid w/ proteins |
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Excess fluid (ascites) in the peritoneal cavity equilibrates slowly with the fluid in the vascular space. The rate of diureses must be ________ in order to prevent a further decrease in plasma volume.
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Slow
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What adverse effects of diuretic drugs are prevented by using the smallest effective dose?
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1. Hypokalemia
2. Hypomagnesemia 3. Disorders of acid-base balance |
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Acetazolamide inhibits what enzyme?
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Carbonic Anhydrase
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How does Acetazolamide get into the tubule?
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Filtered
Secreted via the organic acid transport system |
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Acetazolamide inhibits 85-90% of the Carbonic Anhydrase in the proximal tubule, but only 35% of total ________ reabsorption is inhibited.
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HCO3-
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What is the MOA of Acetazolamide?
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Blockade of CA prevents re-absorption of filtered HCO3- & thus Na+ & H20
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Acetazolamide increases the urinary pH from 6 to _____?
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8.2
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Acetazolamide increases Na+ delivery to the distal nephron. What effect dos this have on K+ secretion?
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K+ secretion is markedly increased
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What are the therapeutic uses of Acetazolamide?
(he emphasized this in lecture) |
Glaucoma--decreases the production of aqueous humor and therefore intraocular pressure decreases
Altitude sickness--loss of HCO3- in urine leads to a metabolic alkalosis which then leads to increased respiration which can help to oxygenate RBCs and relieve some of the side effects of being @ a higher altitude Alkalinization of urine--increases the loss of acidic drugs in drug intoxication (Aspirin poisoning) |
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What are the toxicities associated with Acetazolamide?
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Hyperchloremic metabolic acidosis due to loss of HCO3- & impairment of H+ secretion
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Why does the anion gap not change in metabolic acidosis produced by Acetazolamide?
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When HCO3- is lost, the body retains Cl-
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What drug is an osmotic diuretic agent?
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Mannitol
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Is Mannitol:
Freely filtered? Reabsorbed? Secreted? Metabolically inert? |
Freely Filtered--Yes
Reabsorbed--No Secreted--No Metabolically inert--Yes |
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What is the route of administration of Mannitol?
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i.v.
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The urine flow rate increases from 1 ml/min to _______ when Mannitol is given.
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10 ml/min
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Mannitol increases the urinary excretion of what ions?
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Na, K, Mg, Ca, Cl, HCO3, PO4
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What are the therapeutic uses of Mannitol?
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1. Prevent complete renal failure in patients w/ ARF
2. Decrease intraocular pressure in Glaucoma 3. Decrease intracranial pressure if intracranial bleeding is NOT involved 4. To prevent the renal toxicity of certain compounds such as Cisplatin, Amphotericin B, Cyclosporine, Myoglobin *THE SOLUTION TO POLLUTION IS DILUTION* |
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You should give ________ w/ Mannitol to prevent volume depletion.
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Normal Saline
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What is the treatment for crush injury?
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Mannitol + Normal Saline
*washing out the myoglobin in the renal tubules to prevent ARF |
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What are the toxicities associated with Mannitol?
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Overexpansion of intravascular volume leading to CHF & pulmonary edema
Headache, nausea, hyponatremia |
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What drugs are the Loop diuretics?
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1. Bumetanide
2. Ethacrynic acid 3. Furosemide |
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How do the loop diuretics enter the tubule?
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Filtered
Secreted via the organic acid transport system |
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Loop diuretics produce a (slow/rapid) diuresis of (short/long) duration?
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1. Rapid (15 minutes)
2. Short (2-3 h) |
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What is the MOA of the loop diuretics?
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Inhibits the NKCC transporter in the medullary and cortical segments of the Loop of Henle resulting in decreased reabsorption of NaCl.
Results in a vigorous natriuresis (25-30% of the filtered load) occurs since the limited reabsorptive capacity of the distal tubule cannot absorb the extra NaCl sent from the loop of Henle |
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What affects can large doses of Furosemide have in the proximal tubule?
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Inhibition of carbonic anhydrase & thus affect Na+ reabsorption in the proximal tubule
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What is the effect of the loop diuretics inhibition of the NKCC symporter in the Macula Densa?
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Immediate increase in GFR b/c tubuloglomerular feedback is blocked
Immediate increase in Renin secretion resulting in increase in plasma Ang II and causes chronic secondary hyperaldosteronism |
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What is the effect of loop diuretics on renal synthesis of vasodilatory prostaglandins?
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Drugs stimulate PG synthesis
PGs contribute to an immediate increase in RBF & GFR |
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Why does K+ secretion increase in patients taking loop diuretics?
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1. Increased sodium delivery to distal tubule
2. Increased tubular flow 3. Secondary hyperaldosteronism |
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How does hyperaldosteronism caused by loop diuretics cause metabolic alkalosis?
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Since you are losing Cl- you are retaining HCO3-
Aldosterone stimulates H+ secretion in the Intercalated cell * can be corrected with KCL |
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What is the effect of loop diuretics on Ca and Mg reabsorption in the TAL?
on urate reabsorption in the proximal tubule? |
Enhanced
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What is the effect of loop diuretics on urine concentration/dilution?
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Kidney can't make a concentrated or dilute urine
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Loop diuretics can increase urine flow rate from 1 ml/minute to ______?
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8 ml/minute
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What are the therapeutic uses of the loop diuretics?
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Acute pulmonary edema
Management of edema in cardiac, hepatic, and renal disease (ckd, nephrotic syndrome) Hypercalcemia--in pts. w/ hypercalcemia due to tumors, they are not usually hypervolemic so you have to give them volume replacement w/ normal saline simultaneously to prevent hypocvolemia |
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What are the toxicities/side affects of Loop Diuretics?
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"Had Shhhot"
Hyperuricemia--inc. abs. of urate Azotemia--in severe renal dis. Dilutional hyponatremia Secondary Hyperaldosteronism hypokalemia hypomagnesemia hyperglycemia--FUROSEMIDE only tinnitus/rev. hear loss (esp.Ethacrynic acid) |
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How much can Thiazide diuretics increase the fractional excretion of sodium?
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5-10%
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Are all thiazides orally active & equally efficacious?
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YES
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Where do Thiazides & Metolazone act in the nephron?
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Distal Tubule
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Metolazone inhibits Na+ re-absorption where else other than the distal tubule?
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Proximal Tubule--mechanism does not involve CA
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Thiazides/Metolazone inhibit the (active/passive) reabsorption of _______ in the distal tubule?
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Active; NaCl
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At LARGER doses, some Thiazides inhibit __________ and exert some activity on sodium re-absorption at the proximal tubule. Urinary pH rises from 6 to 7.4.
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Carbonic Anhydrase
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Drugs impair the ability of the Kidney to produce a (dilute/concentrated) urine, so the urine is always (hypotonic/hypertonic)?
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1. Dilute
2. Hypertonic |
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Excessive water intake in patients taking Thiazide diuretics can cause?
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Dilutional hyponatremia
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What is the effect of Thiazides on Ca2+ and Mg2+ excretion?
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Calcium: Decrease
Magnesium: Enhanced |
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The progressive contraction of the ECF volume by Thiazides leads to activation of?
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Sympathetic Nervous System --> Increased Renin secretion --> Ang II stimulates Aldosterone synthesis --> Secondary hyperaldosteronism
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What are the therapeutic uses of Thiazides/Metolazone?
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1. Hypertension
2. Edema due to CHF, mild renal failure, hepatic cirrhosis, premenstrual weight gain, hormone therapy w/ estrogen 3. Management of hypercalcinuria in patients w/ renal calculi composed of calcium salts 4. Diabetes insipidus--decreases in plasma volume caused by the natriuresis increases the efficiency of solute/water reabsorption in the proximal tubule |
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What is the potential effect of hypomagnesemia?
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Cardiac dysrhythmias
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What side effects are the same for Loop diuretics and Thiazides?
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All the same except:
Loop --> Increase Ca excretion Diuretics --> Decrease Ca excretion |
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What drugs are the K+ sparing diuretics?
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Spironolactone
Amiloride Triameterene |
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What is the MOA of Spironolactone?
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1. Blocks Aldosterone receptors in the distal tubule
2. Diuretic activity requires the presence of Aldosterone 3. A weak diuretic drug, only 2-3% of the filtered Na+ is excreted 4. Increased excretion of water, Na+, Cl-, HCO3-, and decreased excretion of K+ |
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What is the duration of action (half-life) of Spironolactone?
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Very long t(1/2) = 24 hours
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What are the therapeutic uses of Sprinolactone?
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1. Used w/ a Thiazide diuretic drug to enhance diuresis & lessen the hypokalemia caused by Thiazide
2. Refractory edema (nothing else works) 3. Primary hyperaldosterism 4. Cirrhosis & Nephrotic syndrome--decreases the effect of Secondary hyperaldosteronism 5. Heart failure--decreases LV wall stiffness |
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A patient is on Hydracholorthiazie and taking oral potassium supplements to prevent hypokalemia. You decide to prescribe Spironolactone. What should you instruct the patient to do?
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STOP taking the oral potassium
Hyperkalemia = Cardiac Failure |
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What drug is a partial agonist at androgen, estrogen, and progesterone receptors and partially inhibits testosterone synthesis?
What is the use of this drug in males and females? |
Spironolactone
Males: treat gynecomastia, azoospermia Females: menstrual irregularity, hirsutism |
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What is the MOA of Triamterene & Amiloride?
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Inhibit Na+ reabsorption by blocking Na+ channels on the luminal membranes of principal cells in the distal tubule and collecting duct
Natriuresis is NOT dependent on the presence of endogenous aldosterone Weak diuretics; only 2-3% of the filtered load is excreted Inhibit secretion of H+ ion Increase the excretion of water, Na+, Cl- and HCO3- and decrease the excretion of K+ and H+ |
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Patients with what condition are most likely to develop Hyperkalemia when taking a K+ sparing diuretic?
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Severe renal failure
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What are the therapeutic uses of Triamterene and Amiloride?
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Use w/ a "loop" diuretic or a Thiazide to enhance sodium loss and lessen hypokalemia caused by the Thiazide
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The inhalation of ____________ slows mucus accumulation & increases mucus clearance from the lungs?
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Amiloride
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Toxicity and side effects of Triamterene and Amiloride include?
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Hyperkalemia--should not be given w/ K+ supplements
Can cause hyperkalemia in severe renal insufficiency |
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What are common combinations of diuretics?
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1. Thiazide + K-sparing diuretic
2. Loop diuretic + Metolazone |
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What combination can cause a massive sodium and potassium loss?
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Loop diuretic + Metolazone
*Blockage of Na+ reabsorption in the PT, DT, and TAL *Fractional Excretion of Na can reach 50% of filtered load |
