Nephrology Book

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Prerenal Failure

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  1. Epidemiology
    1. Accounts for 50-70% of all Acute Renal Failure
  2. Etiologies
    1. Extracellular fluid loss
      1. Burn Injury
      2. Diarrhea
      3. Diuresis
      4. Major upper gastrointestinal hemorrhage
    2. Extracellular fluid volume sequestration
      1. Pancreatitis
      2. Muscle crush injury
      3. Early Sepsis
    3. Inadequate Cardiac output
      1. Severe Congestive Heart Failure
      2. Cardiogenic Shock
    4. Renal Vasoconstriction
      1. Sepsis
      2. Liver disease
      3. NSAIDs inhibit cyclooxygenase
        1. Depletes renal vasodilatory eicosanoids
        2. Exacerbates vasoconstriction afferent arterioles
          1. Volume depletion
          2. Elderly
          3. Edema
      4. ACE Inhibitors lower renal perfusion
        1. Result in dilated efferent arterioles
        2. Decrease Glomerular Filtration Rate
  3. Pathophysiology
    1. Reduced cardiac output and renal perfusion pressure
    2. Results in afferent arteriole constriction
    3. Avid Sodium and Water reabsorption
    4. Oliguria
    5. Acute Tubular Necrosis if prolonged hypoperfusion
  4. Signs
    1. Impaired Cardiac output
      1. Neck vein distention
      2. Rales
      3. Gallup Rhythm
      4. Pedal edema
    2. Orthostatic Blood Pressure and pulse changes
    3. Weight loss
    4. Decreased fluid intake
    5. Decreased urine output
  5. Diagnostics
    1. Empiric volume replacement
    2. Invasive cardiac monitoring
  6. Labs
    1. See Renal Function
    2. Urine Sediment
      1. Normal sediment
      2. Hyaline casts
      3. Granular casts
  7. References
    1. Anderson (8/15/1993) Hospital Practice, p. 61-75

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