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12.12.04 AKI

Prevalence
  • 5% on ward
  • 15% critically ill
  • 40% mortality if on RRT

Aetiology
  • 80% pre-renal
    • Clinical assessment
  • 10-20% renal
    • Urine dip
  • 10% post-renal
    • Ultrasound

Definitions
  • RIFLE
    • Risk
    • Injury
    • Failure
  • Working
    • Acute onset
    • Deterioration in function
    • Retention of nitrogenous and non-nitrogenous substances:
      • Urea, cretinine
      • Potassium, water, protons
    • May be associated with a urine production problem
      • Anuria (< 50 ml/day)
      • Oliguria (< 300 ml/day)
    
Killers - Fix urgently, before taking history
  • Potassium
    • Check ABG
    • Wide QRS and flat P is a peri-arrest situation => Crash call
    • Calcium gluconate
      • Skin necrosis => Check the cannula
      • Acts fast (seconds) but only lasts 10 mins
    • Insulin-dextrose
      • Lasts 4-6 hours => Don't forget to hand over and recheck
  • Acidosis
    • Check ABG
    • 100 ml of 8.4% NaHCO3
  • Fluid 
    • ABG, CXR, SpO2
    • Diuretics
      • Furusemide 40 mg or 80 mg if acute-on-chronic
      • Try max. 2 boluses
      • Monitor urine o/p
    • GTN
    • CPAP
      • Keeps alveloi open and pushes fluid out
    • Dialysis

Aetiologies
  • Pre-renal
    • Hypovolaemia
    • Sepsis
    • Renal artery stenosis or thrombosis
  • Renal
    • HTN
    • Diabetes
    • Drugs (big 5)
      • Diuretics
      • NSAIDS
      • ACEi
      • Aminoglycosides
      • Contrast
    • GN
    • Rhabdomyolysis
    • Multiple myeloma
  • Post-renal
    • BOO
      • Stones
      • Prostate
      • Strictures
    • Strictures
    • Cervical cancer (in resource-poor settings)
    • Anti-cholinergics

Investigations
  • Bloods
    • FBC
      • Anaemia of chronic disease
      • WCC
    • CRP, ESR
    • Cultures
    • U+Es
    • Group + save
    • Glucose
    • CK
    • Bone profile
    • PSA
    • LFTs
    • Plasma electrophoresis
    • Autoantibodies if suspicion (2nd line)
  • Urine
    • Dip
    • UPCR
      • cf Nephrotic range > 3 g/24hr
    • Microscopy
    • MC+S
    • Electrophoresis

Management
  • Hypovolaemia
    • Fluid challenge
      • Monitor urine o/p
      • No response indicates the hypovolaemia has caused ATN => Need dialysis
  • Sepsis
    • Fluid challenge
      • No response indicates fluid is all going to interstitial space
      • => Need inotropes +/- RRT
  • Renal cause
    • Stop nephrotoxic drugs
      • Remember the PRN side!
  • Obstruction
    • Catheter (everyone should have one anyway, for monitoring)

Notes
  • Acute-on-chronic kidney injury causes a big jump in creatinine for a small reduction in GFR
    • Completely the opposite to the usual situation
  • When checking for the killers the key investigation is ARTERIAL BLOOD GAS
  • Patient may look and sound well, even though the killers are marching forwards
    • Sort them out straight away, before taking history
  • It's the CHARGE that normally keeps proteins in the glomerulus
  • Dysmorphic RBCs have been squeezed out of the glomerulus
  • Golden hour for antibiotics
  • Uraemia can cause pericarditis and tamponade



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