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89 Cards in this Set

  • Front
  • Back
When can you see rhabdomyolysis
1. hypothermia,
2. drug toxicity,
3. prolonged immobilization,
4. crush injury
What is the cause of renal failure in rhabdomyolysis?
tubular damage resulting from filtered myoglobin usually associated with hypovolemia
What are the urinary findings of rhabdo?
urine blood on dipstick with absence of RBCs in sediment
-due to myoglobinuria causing false positive reading
What is the treatment of rhabdo?
1. fluid resuscitation,
2. mannitol,
3. urine alkalinization
What is reabsorbed in the proximal convoluted tubule and loop of henle?
1. Na
2. K
3. bicarb
4. Cl
5. protein
6. water
Where is glucose reabsorbed in the kidney? When does spilling of glucose into the urine occur?
proximal convoluted tubule
-when plasma glucose is >180 mg/dl
What is the effect of ADH and where does it act?
reabsorption of water and concentration of urine
-distal convoluted tubules and collecting ducts
What factors decrease RBF and predispose to oliguria?
1. anesthetic effects,
2. SNS,
3. ADH,
4. renin-angiotensin-aldosterone system
Over what MAP is RBF autoregulated?
60-160 mmHg
How does the renin-angiotensin-aldosterone system work?
1. decreased renal perfusion pressure and decreased delivery of Na to distal convoluted tubule result in the release of renin from the juxtaglomerular apparatus
2. renin acts on alpha globulin in plasma to form angiotensin I,
3. angiotensin I goes to the lungs and is split by lungs to form angiotensin II,
4. angiotensin II goes to the adrenal cortex and causes secretion of aldosterone
5. aldosterone leads to HTN, hypokalemia, metabolic alkalosis due to increasing the Na and water reabsorption and H+ and K+ excretion in the distal convoluted tubule
What are laboratory tests of tubular fxn?
1. SG 1.003-1.030,
2. osmol 40-1400 mosm/L,
3. Na 130-260 mEq/L
What is normal creatinine clearance?
110-150 cc/min
What are urine Osm in prerenal and renal failure?
prerenal >400
renal 250-300
What is the Urine/Plasma osm in prerenal and renal failure?
prerenal >1.8,
renal <1.1
What is specific gravity? When is specific gravity not useful?
It is a measure of urine concentrating ability
-in the setting of glusocuria or diuretics
What Specific gravity is indicative of volume depletion?
>1.025
What do fatty casts in the urine indicate?
nephrotic syndrome
What does RBCs in the urine indicate?
trauma,
tumor,
infection
What does proteinuria indicate?
parenchymal disease
What can alter serum BUN?
1. increased protein intake,
2. GI bleeding,
3. dehydration,
4. the capacity of the liver to form urea from amino acids,
5. rate of incorporation of amino acids into tissue protein,
6. rate of release of amino acids from tissue protein(sepsis, trauma)
How do you calculate creatinine clearance and what are normal values?
CrCl = Urine Cr x Vol / Plasma Cr;
U = concentration of creatinine in the urine (after 24 hr collection),
V=urine volume,
P=concentration of creatinine in plasma;

nml 85-125ml/min in women,
95-145ml/min in men
what is the overall effect of activation of the renin-angiotensin-aldosterone system?
renovascular htn
What happens with stimulation/stretching of atrial stretch receptors?
-decreases sympathetic outflow and causes release of ANP
-ANP causes systemic vasodilation, decreased sodium reabsorption, and inhibition of renin and aldosterone release
What is the response of the atrial stretch receptors with contraction of the atria?
stimulate release of ADH with increased water retention
What happens to GFR at MAPs <50?
decreases rapidly
How do volatile anesthetics effect the kidney?
1. decrease RBF and GFR and thus UOP,
2. disrupt autoregulaion so that RBF becomes pressure dependent,
3. ADH increases
By how much does SCh increase serum [K]?
1 mEq/L
Should you use SCh in renal failure patients?
yes as long as their [K]<5.5,
-beneficial in renal patients due to its metabolism
What are the effects of adrenergic stimulation on the kidney?
release of renin
What can increase levels of ADH?
1. positive pressure ventilation,
2. fluid loss,
3. volatile anesthetics
How much of the nephron has to be lost before signs of chronic renal failure develop?
> 60%
What are manifestations of chronic renal failure?
1. infection (increased risk, major cause of death),
2. hyperglycemia (resistance to insulin),
3. hyperparathyroidism (inability to excrete PO4 leads to increase parathyroid hormone levels which produces osteodystrophy),
4. Acidosis (can have difficulty excreting H+),
5. Electrolytes (increased Mag, Cl, K, decreased Na, Ca),
6. coagulopathy (platelet dysfxn),
7. anemia,
8. cardiac failure
9. htn - activation of RAAS
When should you consider spinal in a patient with renal failure?
after coags are check,
-they can have abn in PT and PTT, also platelet dysfxn
How is vecuronium affected by renal failure?
It is an acceptable choice
-25% excreted in urine,
-elimination is mainly biliary,
-duration of drug is somewhat prolonged
How is rocuronium affected by renal failure?
-eliminated primarily by the liver and kidney
-renal excretion may account for 30% of elimination,
-may lead to longer duration of action
How is metocurine affected by renal failure?
primarily excreted by the kidneys (50-60%),
-increased duration
How is reversal of neuromuscular blockade affected by renal failure?
neostigmine is excreted renally,
-in the presence of severe renal dysfunction
(CrCl 10-50ml/min) the dose should be reduced by 50%,
-if CrCl <10ml/min (ESRD) the dose should be reduced by 75%
What inhaled anesthetic is the least metabolized and a good choice in patients with renal failure?
desflurane
What should you do in a renal transplant patient with low urine output in the recovery room?
evaluate renal blood flow with a renal scan;
-if ischemic period before reimplantation is >2 hrs a peroid of oliguria followed by diuresis is frequent
When should dialysis be done, in a patient that is on dialysis, before surgery?
6-24 hours prior to surgery
What is the main complication if dialysis is done too close to surgery? Too remote from surgery?
-volume depletion
-electrolyte disturbances
What cardiac complication can occur after release of the renal vascular clamp during renal transplantation?
Vfib and is most commonly due to hyperkalemia
Which are the loop diuretics? What are uses?
1. Furosemide
2. Ethacrynic acid
-treatment of increased ICP (alterations in BBB do not affect the ability of lasix to decrease ICP),
-heart failure
-pulmonary edema
What part of the kidneys are affected by thiazides?
cortical portion of the ascending loop of henle
-they inhibit Na and Cl reabsorption
How does spironolactone work?
competing with aldosterone in the renal tubule (in the absence of aldosterone, spironolactone has no significant renal effect)
-leads to hyperkalemia
How does acetazolamide work?
inhibits the reabsorption of bicarb and prevents the secretion of H+
-can lead to hypokalemic acidosis
What are types of osmotic diuretics and how do they work in the kidney?
1. urea,
2. mannitol;
-mannitol is freely filtered at the glomerulus and not reabsorbed,
-free water follows mannitol,
-urea greater than 60% is reabsorbed
What is the dose, onset, and duration of mannitol?
dose 0.5-1 g/kg,
onset 10-15min,
lasts for 2hrs
What can happen with a rapid rate of infusion of mannitol?
may cause vasodilation of vascular smooth muscle which can increase cerebral blood volume and ICP while decreasing SBP
-(dependant on dose and rate of administration)
How does urea affect ICP?
crosses the BBB and is associated with rebound increased ICP
What are vasopressin antagonists?
1. alcohol,
2. demeclocycline,
3. lithium
How does triamterene-amiloride work?
increases excretion of Na, Cl, and bicarb at the distal convoluted tubule,
-independent of aldosterone
What is rhabdomyolysis?
Necrosis or breakdown of skeletal muscle with release of the protein myoglobin
-characterized by massive acute elevations of muscle proteins, that peak quickly and usually resolve within days after the inciting injury has been id'd and removed
What is the functional unit of the kidney?
nephron - made up of the glomerulus and renal tubule
What is the glomerulus?
a capillary tuft intimately associated with Bowman's capsule
What forms the renal tubule?
1. Bowman's capsule
2. proximal convoluted tubule
3. loop of henle - medullary
4. loop of henle - cortical
5. distal convoluted tubule
What forms the collecting ducts?
Several distal convuluted tubules
Label the following picture
a
How much of CO goes to the kidneys?
20%
What are renal lab tests of renal function related to GFR?
1. BUN 10-20 mg/100cc
2. Cr 0.7-1.5 mg/100cc
3. CrCl 110-150 cc/min
What are the effects of aldosterone?
1. htn
2. hypokalemia
3. metabolic acidosis
If UOP falls, what tests can be used to determine whether the problem is renal or prerenal?
1. Urine Na
2. FENa
3. Urine osm
4. Urine/plasma osm
5. BUN/Cr ratio
What is the following in prerenal vs renal causes of decreased UOP?
Urine Na
FENa
Urine osm
Urine/plasma osm
BUN/Cr ratio
-Urine Na: pre <20-30, ren >40
-FENa: pre <1%, ren >3%
-Urine osm: pre >400, ren 250-300
-Urine/plasma osm: pre >1.8, ren <1.1
-BUN/Cr ratio: pre >20, ren <20
What does ketones in the urine indicate?
DKA
Starvation
What are problems seen as a result of renal failure?
1. Anemia - cardiac failure
2. acidosis
3. coagulopathies
4. electrolyte problems
5. infection
6. htn
7. hyperglycemia
8. hyperparathyroidism
What is felt to be a more accurate indicator of GFR, BUN or Cr?
Cr bc is is freely filtered and secreted, but not reabsorbed unlike BUN
What is one of the most powerful vasoconstrictors known?
angiotensin II
Which is felt more strongly postoperatively, ADH or aldosterone influence?
ADH influence which is the reason hyponatremia develops
What are common causes of chronic renal failure?
1. pyelonephritis
2. acute glomerulonephritis
3. interstitial nephritis
4. htn
Renal failure occurs when there are only ___% of functional nephrons.
5-10%
What is the cause of anemia in renal failure?
1. decreased erythropoietin pruduction by the kidney
2. uremic toxins which depress bone marrow function
What Hg level is well tolerated by pts with CRF? Why?
Hg of 5-7
-Due to compensatory mechanisms:
1. right shift of oxy-Hb dissociation curve due to inc intracellular 2,3-DPG
2. increased CO
Should you use Atracurium in renal failure?
Yes, it is an excellent choice bc of Hoffman elimination and ester hydrolysis
-does not depend upon hepatic metabolism or renal excretion
-<10% is excreated unchanged by the renal and biliary routes
Should you use Cisatracurium in renal failure?
Yes, it is independent of renal or liver function
What does severe anemia do to the blood:gas partition coefficient? What is the result?
Decreases it by 25%
-leads to increased speed of induction and faster awakening
How do the loop diuretics work?
inhibit Na and Cl reabsorption primarily in the medullary portion of the ascending loop of Henle
What are the side effects of loop diuretics?
Hypokalemia which increases the potential for dig toxicity and potentiates nondepolarizing agents
What are the K sparing diuretics which act independently of aldosterone?
1. amiloride
2. triamterene
What is the function of carbonic anhydrase?
It is an enzyme which converts CO2 + water -> bicarb + H+
-bicarb is reabsorbed
-H+ is secreted which is accompanied by reabsorption of Na and water
What is the overall effect of acetazolamide?
1. increased diuresis of a more alkaline urine
2. metabolic acidosis - hyperchloremic hypokalemic
When is mannitol contraindicated?
If the BBB has been disrupted - may enter the brain and bring fluid with it increasing ICP
Where do the following drugs act in the kidney?
Furosemide and other loop diuretics
thiazides
triamterene-amiloride
vasopressin antagonists
-Furosemide and other loop diuretics - medullary portion of ascending loop of henle
-thiazides - cortical portion of ascending loop of henle
-triamterene-amiloride - distal convoluted tubule
Is Thiopental an acceptable induction agent in CRF?
Yes, but it should be administered slowly to avoid hypotension
Should the induction dose of Thiopental be changed in CRF?
Yes, bc thiopental is 85% bound to plasma proteins and in uremia, with decreased protein amounts, there is less binding to albumin and other plasma proteins and thiopental is therefore availavle at receptor sites in greater amounts
Is thiopental a weak acid or weak base? How does this affect CRF?
It is a weak acid so the acidosis of renal failure results in more unionized, nonbound, and active drug - another reason for administering less
What is the pressor of choice in a pt with sepsis and oliguria?
Dopamine - has a unique ability to increase myocardial contractility, renal blood flow, and GFR
-Doses: 1-30 mcg/kg/min
1-2 - renal dose
2-10 - beta
>10 alpha
What is the MC coagulation defect in the setting of renal failure? What is the cause?
decreased platelet adhesiveness
-not completely known, but the accumulation of metabolic acids may interfere with factor VIII activity and subsequent platelet aggregation
Plasma Cr < ___ does not generally alter platelet function.
< 6 mg/dl
What is considered mild, mod, and severe dehydration based off % of body weight?
mild - mod = 3-6%
severe = 10%