Acute renal failure Flashcards

1
Q

definition and diagnostic criteria for acute kidney injury

A

an abrupt (within 48 hours) reduction in kidney function currently defined as an absolute increase in serum creatinine of either >.3 mg/dL or a percentage increase of >50% or a reduction in UOP (documented as oliguria of 6hr

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2
Q

epidemiology of ARF

A

1% all patients admitted to hospital. 10-30% patients admitted to ICU.

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3
Q

etiology of ARF

A

hemodynamic- not enough blood. parenchymal (acute tubular necrosis, acute GN, vasculopathy, acute interstitial nephritis. obstruction

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4
Q

oliguric renal failure

A

functionally urine output less than that required to maintain solute balance (can’t excrete all solute taken in). defined as urine output <400 ml/24 hr

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5
Q

anuric renal failure

A

defined as urine output <100 ml/24 hr. less common-suggests complete obstruction, major vascular catastrophy, or more commonly severe ATN

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6
Q

is the renal failure acute or chronic?

A

lab values don’t discriminate between acute vs chronic. oliguria supports a diagnosis of acute renal failure.

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7
Q

clues to chronic disease

A

pre-existing illness-DM, HTN, age, vascular disease
uremic sxs-fatigue, nausea, anorexia, pruritis, altered taste sensation, hiccups
small, echogenic kidneys by US

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8
Q

pre-renal ARF

A

anytime you don’t get enough blood to the kidney (NSAIDS/cox2 inhibitors). anything that interrupts blood flow to kidney

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9
Q

intra renal ARF

A

kidney ds itself causes intra renal failure

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10
Q

post-renal ARF

A

anything that obstructs the kidney some will cause anuria but most wont. urine not getting out.

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11
Q

5 key steps in evaluating acute renal failure

A
  1. obtain a thorough history and physical; review the chart in detail.
  2. do everything you can to accurately assess volume status
  3. always order a renal us
  4. look at the urine
  5. review urinary indices
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12
Q

symptoms of ARF

A

fever, rash, joint pains, myalgias, concern for SLE, vaculitis, acute interstitial nephritis. dyspnea-heart failure. hemoptysis-goodpasture’s, wegener’s. preceding bloody diarrhea-HUS. preceding pharyngitis- post strep gn, post infectious GN.

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13
Q

urine output of ARF

A

abrupt anuria: acute obstruction, severe acute GN, sudden vascular catastrophe. slowly diminishing: ureteral stricture, prostatic enlargement. presence of hematuria: painless-suggests GN, painful-suggest ureteral obstruction

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14
Q

ARF physical exam findings

A

skin-new rashes: livedo reticularis-atheroemboli, SLE, cryoglobulins. petechiae-HSP. malar rash-SLE
eye: papilledema-malignant HTN. Roth’s spots-endocarditis.
CV: rub-suggestive of uremic pericarditis, lupus. gallop-suggesting CHF

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15
Q

BUN creatinine ratio

A

> 20:1 suggests prerenal or obstruction. can be elevated by anything leading to increased urea production/absorption-GI bleed, TPN, steroids, drugs

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16
Q

when to renal bx

A

exclude pre and post-renal failure, and clinical findings are not typical for acute tubular necrosis. extra-renal manifestations that suggest a systemic disorder. heavy proteinuria. RBC casts

17
Q

ischemic acute renal failure

A

a form of ATN often following a prerenal insult. late proximal tubule and medullary thick ascending limn most susceptible. severity of renal failure correlates with duration of insult. treatment is to optimize renal perfusion, avoid additional nephrotoxic insults and other supportive measures.

18
Q

acute interstitial nephritis etiology

A

allergic/drug induced
autoimmune: sarcoid, sjogren’s, SLE
toxins: chinese herb nephropathy, heavy metals, light chain cast nephropathy
infiltrative: leukemia, lymphoma
infections (legionella, CMV, HIV, toxoplasma

19
Q

acute interstitial nephritis clinical presentation

A
non-oliguric ARF
fever in allergic and infectious types (excepts NSAID type)
rash in allergic type (except NSAID use)
eosinophilia 
UA: WBC casts, eosinophiluria, hematuria
20
Q

rhabdomyolysis

A

often develops in the setting of crush injury, especially if superimposed circulatory shock
hallmarks of diagnosis (CK >10,000 + dipstick for blood but no RBCs.

21
Q

treatment of rhabdo

A

volume expansion (judiciously if severe oliguria or azotemia) fasciotomy when indicated for compartment syndrome (second wave phenomenon) avoid calcium repletion unless neuromuscular manifestations present. rebound hypercalcemia in recovery phase