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Gen Med Unit 4 > Acute Renal Failure (injury) > Flashcards

Acute Renal Failure (injury) Flashcards

1
Q

What are the 3 types of arf?

A
  1. prerenal
  2. intrarenal
  3. postrenal
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2
Q

What kidney functions are decreased in arf?

A
  1. inability to maintain acid-base balance
  2. inability to maintain electrolyte balance
  3. Accumulation of nitrogenous wastes (Azotemia), urine creatinine
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3
Q

Epidemiology of ARF

A
  1. 5% of hospital pts
  2. 30% of ICU admissions
  3. 25% of hospitalized pts
    Pts with arf have higher mortality risk
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4
Q

ARF definition

A

Abrupt or rapid decline in renal filtration, thus ↓renal function

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5
Q

sxs of arf

A 
1. Generally secondary to uremia
Nausea/Vomiting
Malaise
Altered mental status (delirium)
Hypertension or Hypotension
Pericardial friction rub: rubbing sound with beat due to backup of fluid around the heart. Only when hypervolemic
Arrhythmias
Rales: crackling sound when fluid is around the alveoli. Only when hypervolemic
Abdominal pain
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6
Q

How prevalent is prerenal failure?

A

Most common type of arf, 60-80% of cases

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7
Q

Pathophys of prerenal arf

A

Kidneys do not recieve enough blood to be filtered

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8
Q

Results of prerenal arf

A 
Impaired blood flow results in:
Hypoxemia 
Decreased GFR
Decreased renal perfusion
Increased tubular re-absorption of Na+ & H2O

Results in electrolyte imbalances and metabolic acidosis

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9
Q

Which type of arf is metabolic acidosis a result of ?

A

prerenal

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10
Q

Causes of prerenal arf

A

Disruption of blood flow to kidneys:
Significant hypotension
Dehydration / hypovolemia
Renal artery stenosis (RAS)
Impaired cardiac output: low ejection fraction
Heart failure, MI, cardiac tamponade(hear friction rub and decreased heart sounds), shock
Liver failure
Severe Burns: loss of fluids into third spaces
Diuretic therapy
Hemorrhage

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11
Q

Is prerenal arf reversible or irreversible?

A
  1. reversible with early detection and treatment
  2. No damage to kidneys early in process
  3. Prolonged decrease in the blood flow to the kidneys can cause permanent damage to the kidney tissues (ischemia)
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12
Q

Another name for postrenal failure

A

Obstructive failure

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13
Q

How common is postrenal failure?

A

5-10% of all arf cases

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14
Q

What causes postrenal failure?

A
  1. Obstruction of urethra:
    Urethral stricture
    BPH: Most common cause in males
    Prostate CA
  2. Obstruction of one or both ureters: Kidney stone(s)
    Cancer of urinary tract/reproductive tract organs or structures
  3. Obstruction at bladder level
    Bladder stone
    Blood clot
    Neurologic disorders of bladder/anticholinergics
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15
Q

Pathophysiology of postrenal failure

A
  1. Obstruction leads to increased intraluminal pressure (hydronephrosis)  kidney arteriole parenchymal damage (local ischemia)  affects renal blood flow and tubular filtration  decreased GFR
  2. UTI often associated
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16
Q

Is postrenal arf reversible or irreversible?

A
  1. Reversible, Unless obstruction is present long enough to cause damage to kidney tissue
  2. Once the blockage is removed, the kidneys usually recover in 1-2 weeks if there is no infection or other problem
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17
Q

What is the most complicated type of arf?

A

Intrarenal arf

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18
Q

How common is intrarenal arf?

A

25-40%

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19
Q

What is primary parenchymal damage & what arf is it related to?

A
  1. Primary renal parenchymal damage
    Problems with filtering function of the kidney
    Problems with blood supply within the kidney
    Problems affecting the kidney tissue that handles salt and water processing
  2. Intrarenal
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20
Q

What is the pathophys of intrarenal failure?

A

Results from damage to filtering structures of kidney

Nephrotoxicity or inflammation damages delicate epithelial layers of nephrons

Nephrotoxins damage renal cortex

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21
Q

What are 3 causes of intrarenal failure and which is most prevalent?

A

Acute Tubular Necrosis (ATN)
Accounts for 85% of cases of primary acute kidney failure

Acute Glomerulonephritis

Acute Interstitial Nephritis (AIN)

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22
Q

How is ATN diagnosed?

A

FENa (fractional excretion of Na+) >3%

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23
Q

What color will urine be in ATN? Describe the casts found in ATN

A

“Tea colored” due to Tubule lumen is often filled with cellular debris or heme-pigment precipitate
Granular muddy brown casts

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24
Q

Pathophys of ATN

A

Characterized by necrosis of the epithelial cells within the renal tubules
Due to toxicity or ischemia

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25
Q

What part of the tubule is affected in ATN?

A

PCT and TALH

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26
Q

What antimicrobial exogenous toxins can cause ATN?

A
  1. Aminoglycosides (Gentamicin, Tobramycin, Vanco): antimicrobial
  2. Amphotericin B: anti fungal
  3. Cephalosporins: used very frequently
  4. IV Acyclovir: anti-viral, Herpes
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27
Q

How does hypovolemic shock cause ATN?

A

Decreased blood supply to the kidneys

Hypovolemic shock caused by trauma, septicemia, and pancreatitis

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28
Q

What immunosuppressive exogenous toxins can cause ATN?

A

Cyclosporine: used for organ transplant as an anti-rejection drug

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29
Q

When can radiographic contrast dyes cause ATN?

A
  1. Pre-existing factors:
    DM, renal insufficiency, age, dehydration, CHF,
    NSAIDs, ACE inhibitors, Metformin
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30
Q

What can be given to reduce ATN risk with radiographic contrast dyes?

A

N-acyteylcystine/ Mucomyst given pre and post contrast dye

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31
Q

How should you manage a pt who is on metformin and needs contrast dye?

A

Stop metformin before the test, cannot be put back on metformin until the BUN/Cr levels are rechecked and back to normal

32
Q

What endogenous toxins can cause ATN?

A
  1. Myoglobinuria
    - Released by necrotic muscle
    - Clogs the distal tubule causing injury
  2. Hyperuricemia: high uric acid in blood
    -Asst with chemo (Leukemia/Lymphoma)
    -Prevent by giving Allopurinol prophylactically
  3. Hemoglobin:
    Transfusion reaction (hemolysis)
  4. Bence Jone protein: Multiple myeloma
33
Q

What causes Myoglobinuria?

A

Rhabdomyolysis, crush injury, seizures, ETOH abuse, cocaine abuse

34
Q

Definition of acute glomerulonephritis

A

Glomeruli damaged by infection, autoimmune, or vascular disorders

35
Q

What 2 primary infectious agents can cause glomerulonephritis?

A

Group A beta hemolytic strep, S. aureus bacteremia

36
Q

What autoimmune disorders can cause acute glomerulonephritis?

A

SLE, HUS, TTP

37
Q

What vascular disorders can cause Acute glomerulonephritis?

A

Small vessel vasculitis (Wegener’s Granulomatosis, “Goodpasture Syndrome”)

38
Q

What is the most prevalent cause of Acute interstitial nephritis?

A

Medications (>70% of cases)

PCN, Cephalosporins, Sulfonomides (diuretics), NSAIDs, Rifampin (TB), Phenytoin (antiseizure), Allopurinol (gout)

39
Q

What infectious agents can cause AIN?

A

Streptococcal, CMV, Histoplasmosis, Leptospirosis, Rocky Mt. Spotted Fever

40
Q

What autoimmune disorders can cause AIN?

A

SLE, Sjogren syndrome, Sarcoidosis, cryoglobinemia

41
Q

General ARF sxs

A 
Azotemia symptoms
Malaise
Nausea, vomiting, diarrhea
Confusion, seizures, coma
Hypotension
Edema
Decreased urine output
Pericardial friction rub 
Asterixis (tremor)
Hypertension
42
Q

Define oliguria

A

Oliguria - <500 mL/d

50% are non-oliguric

43
Q

Define anuria

A

<100 mL/d

Suggests obstruction

44
Q

ARF diagnostic studies: BUN/CR results

A

Increased

45
Q

ARF diagnostic studies: K+

A

INcreased

46
Q

ARF diagnostic studies: HCO3-

A

Decreased

47
Q

ARF diagnostic studies: Hgb/Hct

A

Decreased

48
Q

ARF diagnostic studies: pH

A

Decreased (metabolic acidosis)

49
Q

ARF diagnostic studies: Urinalysis

A

Decreased sg

proteinuria

50
Q

ARF diagnostic studies: Urine sediment

A

casts

cellular debris: renal tubule epithelium

51
Q

ARF diagnostic studies: CrCl

A

Decreased, reflects # of functional nephrons

52
Q

What are RBC casts indicative of?

A

Glomerulonephritis

AIN

53
Q

What are Hyaline casts indicative of?

A

Nonspecific

Concentrated urine or w/ diuretics

54
Q

What are granular casts indicative of?

A

“Muddy brown”

ATN

55
Q

What are epithelial casts in urine indicative of?

A

ATN
AIN
Glomerulonephritis

56
Q

What are WBC casts indicative of?

A

Pyelonephritis
AIN
Glomerulonephritis

57
Q

What are broad casts indicative of?

A

Advanced chronic kidney disease

58
Q

What are waxy casts indicative of?

A

Nonspecific

Acute and chronic kidney diseases

59
Q

What might an EKG show in arf?

A

Tall peaked T waves (↑ K+)

Wide QRS

60
Q

When are imaging studies beneficial in arf?

A

Postrenal
Renal ultrasound
Hydroureter and hydronephrosis

61
Q

When are CT/MRI indicated in arf?

A

Indicated if renal U/S normal and suspect ARF

Indicated if complex cyst or mass seen on U/S

62
Q

Kidney biopsy indications

A 
Unexplained acute renal injury
Acute nephritic syndrome
Unexplained proteinuria & hematuria
Systemic Dz assoc. w/ kidney dysfunction
Suspected transplant rejection
Guide Treatment
63
Q

Kidney biopsy contraindications

A 
Bleeding disorder
 Thrombocytopenia
 Uncontrolled HTN
Solitary kidney
Ectopic kidney
Horseshoe kidney
ESRD
Multiple cysts
Renal infection
Neoplasm: known cancer
Hydronephrosis
64
Q

What are some complications of arf?

A 
Arrhythmias
CHF
Cardiac Tamponade
Increased risk for infection
Electrolyte abnormalities 
GI bleeding 
Multiple organ failure
Anemia / thrombocytopenia
Acid-Base imbalance 
Encephalopathy / seizures
65
Q

What are the goals of treating arf?

A

Pinpoint the exact cause of the kidney failure

  1. Determine degree to which accumulating wastes and water are affecting the body
    - Impacts treatment decisions about medications and the need for dialysis
66
Q

When is dialysis recommended?

A

Dialysis recommended when serum Creatinine reaches 8mg/dl

67
Q

What are supportive treatment for arf?

A
  1. Adequate hydration
    Isotonic IV fluid replacement (D5W, NS or LR until Na+ reaches 125-130 mEq/L, then ∆ to ½ NS)
    Attention to improving renal perfusion and oxygenation
    Prevent fluid overload
  2. Attention to serum K+ & Na+
  3. Avoid nephrotoxic drugs if possible
68
Q

What medications can be given for arf?

A
  1. Loop diuretics: Inhibit co-transport of Na+/K+/Cl – in ascending Loop of Henle
  2. Dopamine: Dilates renal & splanchnic arterioles by activating dopaminergic receptors
69
Q

What diet are ppl with arf put on?

A

High calorie diet

Low protein, low Na+, low K+

70
Q

How can fluid and electrolyte balance be maintained in arf?

A

IV fluids with electrolytes

Hemodialysis or peritoneal dialysis

71
Q

How can edema be prevented in arf?

A

Fluid restriction

72
Q

How is oliguria treated in arf?

A

Loop diuretics

73
Q

How is severe hyperkalemia treated in arf?

A

Avoid ACE inhibitors, K+ sparing diuretics

D50 IV, insulin, IV bicarbonate

74
Q

What is the mortality rate in arf ppts with additional comorbidities?

A

70%

75
Q

What factors increased mortality rates?

A

Advanced age
Severe underlying disease
Multisystem organ failure

76
Q

What is the prognosis for atn?

A

Because the tubular cells continually replace themselves, the overall prognosis for ATN is good if the cause is corrected, and recovery is likely within 7 to 21 days

Gen Med Unit 4 (7 decks)

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