AKI

• Aka Acute Renal Failure (ARF)
  • Acute, severe decrease in renal function
  • Hallmark is azotemia (increased bun and Cr), often with oliguria
  • Guidelines
• Definition and Staging (KDIGO 2012)
  • Azotemia: elevation of BUN and Creatinine with a decrease in GFR
  • 3 Types: Prerenal, Intrarenal, Postrenal
    • 80% recover completely, MCC of mortality is infection
    • Up to 75% of deaths are from infection, 2^nd mcc is cardiorespiratory
  • AKI is defined as any of the following:
    • Increase in serum Cr by ≥0.3mg/dl within 48hr
    • Increase in serum Cr to ≥1.5xbaseline (50%) within 7 days
    • Urine Volume <0.5 ml/kg/h for 6 hours (oliguria)
  • Acute Kidney Disease (AKD)
    • Definition: AKI or GFR <60 for <3 months or GFR decrease by >.35% or increase in SCr by 50% for 3 months
• Symptoms
• May be Oliguric, Anuric, or Nonoliguric
• MC weight gain and edema (+ H2O and Na+ balance)
• Fatigue, Anorexia, Nausea, Oliguria, Hematuria, Flank pain, AMS
• Staging
• Stage 1: Cr 1.5-1.9xbaseline or ≥0.3 increase, UOP <0.5ml/kg/h for 6-12h
• Stage 2: Cr 2.0-2.9xbaseline, UOP<0.5 for ≥12hours
• Stage 3: Cr 3.0xbaseline for Cr≥4.0 or dialysis
  • UOP <0.3 for ≥24h or anuria for ≥12h
• Proteinuria Urine Dipstick (Albumin)
• Trace: 15-30 mg/dL
• 1+ protein: 30-100 mg/dL
• 2+ protein: 100-300 mg/dL
• 3+ protein: 300-1000 mg/dL
• 4+ protein: >1000 mg/dL
• Diagnosis
  • Rule out prerenal failure (BUN:Cr, UNa, FeNa)
  • Rule out postrenal w/sonogram (KUB US)
    • May also be negative in postrenal
  • Get U/A
  • If negative
    • Biopsy
• Testing
• Finding the cause of acute kidney injury: which index of fractional excretion is better?
• Dipstick UA for blood, protein, WBC, nitrites, glucose
• Uric Acid as a Prognostic factor for in-hospital mortality in AKI
• Consider Acute Nephritis and consult when a pt with AKI and no cause has urine dipstick showing protein or blood in the absence of UTI, menses, or trauma due to catheterization
• Imaging
• Obtain US if AKI unknown
  • If pylonephrosis: get immediate US (within 6 hours)
  • Kidney size, hydronephrosis, hydroureter
  • Without cause of AKI: get urgent US (within 24 hours)
• Obtain CT scan if Nephrolithiasis is suspected
• Renal Arteriography if Renal Artery Occlusion is suspected
• Renal Biopsy
  • Glomerulonephritis or AIN
• Complications: Hypervolemia, Hyperkalemia, Metabolic Acidosis, Uremia, Infection
• Can cause non-anion or anion gap Metabolic Acidosis
  • Non-Anion Gap: Excretion Impaired, ammonia, bicarb reabsorption
  • Anion Gap: Retention in Uremia
• Acute Renal Failure (ARF)
  • Azotemia, volume retention, and weight gain
• Treatment:
• Unless in shock, use isotonic crystalloids rather than colloids for volume expansion to correct fluid imbalance
• Correct electrolyte imbalance
• Refer for immediate Dialysis if AKI is not responding to medical management plus: hyperkalemia, metabolic acidosis, uremic symptoms, fluid overload, pulmonary edema
  • RRT in AKI w/Sepsis in the ICU
  • IDEAL-ICU: AKI w/Sepsis in the ICU; No difference in mortality
    • NEJM
  • AKIKI: Early vs. Late in Severe AKI in the ICU; No difference in mortality
• Consider sodium bicarb if acidotic and mild AKI
• Anemia
  • No consequence of IV Iron to treat anemia
• Right jugular > Femoral vein for access with un-cuffed non-tunneled cath