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