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Acute kidney injury

Kidneyfailure.jpg

Definition

Acute (over hours and days) deterioration of kidney function. This measured by serum urea and creatinine, often accompanied by oliguria and anuria[1].

Epidemiology

Common.jpg

Pathophysiology

There are lots of causes of acute renal failure:

Clinical Features

Very much depends on cause but oliguria and anuria are both signs of acute renal failure.

Investigations

Bloods

Other bloods could include: INR (hepatorenal syndrome), ESR (acute nephritis), LFT (hepatorenal syndrome), CK, LDH (marker of tissue breakdown), Protein electrophoresis, hepatitis serology, auto-antibodies

Urine

Send for microscopy and cultures.

Imaging

Management

Acute

  • Catherise for 24h urine
  • Do fluid chart
  • Consider a central venous line
  • Treat hyperkalaemia which commonly occurs
  • If dehydrated
    • fluid challenge of 250-500ml, either colloid or 0.9% saline over 30min
    • Repeat and aim for CVP of 5-10cm
  • If fluid overload
    • Nitrate infusion, furosemide or dopamine ('renal dose')
    • Consider dialysis
  • Acidosis
    • give sodium bicarbonate 50ml 8.4% iv
  • Suspicion of sepsis - cultures and antibiotics

Avoid nephrotoxic drugs (NSAIDS and be careful with gentamicin)

Underlying principles

Basically, you need to treat the cause first and foremost (so the kidneys stop failing) and treat hyperkalaemia (that makes them go intoo VF which is a whole world of rubbishness). Pulmonary oedema, pericarditis and tamponade are further life-threatning differentials which need to be considered followwed by treating volume depletion and sepsis.

Prognosis

About 60% of patients with ARF die, and approximately 10% of survivors go on to needing dialysis[2].

References

  1. Oxford Handbook of Clinical Medicine by M Longmore, et al 8th Edition - Acute Renal Failure: page 298
  2. "The epidemiology of acute renal failure in the world." by S Uchino - Curr Opin Crit Care. 2006 Dec;12(6):538-43.