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Acute Kidney Injury

Definition​

One of the following:

  • ↑ serum creatinine of ≥ 26 μmol/L within 48 hours
  • ↑ serum creatinine of 1.5x in last 7 days
  • Urine output < 0.5 mL/kg/hour for 6 hours

Management​

STOP AKI

  • Sepsis + hypoperfusion
  • Toxicity (drugs, contrast)
  • Obstruction
  • Parenchymal disease

Fluid management​

Assess volume status
  • L/S BP
  • HR
  • JVP
  • Cap refill
  • Consciousness level
  • Lactate
  • Weight
  • If hypovolaemic, give fluids bolus (250 - 500 mL of isotonic fluid e.g. Plasma-lyte or Hartmann's) with regular review until fluid replete.
  • If ≥ 2 L given and remains hypoperfused consider further circulatory support.
  • Too much fluid is harmful (pulmonary oedema, delayed recovery).
  • If euvolaemic and passing urine, give maintenance fluids (estimated daily output + 500 mL).

Monitoring​

  • Consider urinary catheter + hourly input/output.
  • U+Es, bone profile, venous bicarbonate at least daily whilst creatinine rising.
  • Blood gas + lactate if septic/hypoperfused.
  • Daily weights.
  • Regular fluid assessment.

Investigations​

  • Urine dip for blood and protein (P:CR if protein present).
  • USS ≤ 24 hours (≤ 6 hours if pyonephrosis suspected).
  • Inflammatory markers, CK, LFTs.
  • If platelets low, send blood film, LDH, reticulocyte count for HUS/TTP/accelerated HTN with MAHA.

Supporting recovery​

  • Treat sepsis.
  • Maintain perfusion.
  • Stop NSAIDs, ACE-i, ARBs, metformin, potassium-sparing diuretics (these will need re-introducing).
  • Adjust drug doses as per renal function.
  • If hypotensive stop antihypertensives, if underfilled stop diuretics.
  • Minimise iodinated contrast.

Managing complications​

Hyperkalaemia​

  • If ECG changes give calcium gluconate.
  • If K > 6.5 mmol/L or ECG changes give insulin-dextrose (effective ≤ 4 hours).
  • If bicarbonate < 22 mmol/L and not overloaded, give 1.26% bicarbonate IV 500 mL over 1 - 4 hours (beware hypocalcaemia).
info

Lowering whole body potassium ultimately requires recovery of function or RRT (haemodialysis, filtration).

Pulmonary oedema​

  • GTN infusion.
  • Consider furosemide ≥ 80 mg bolus, then further boluses or infusion of 10 mg/hour if successful.
  • Resolution will require recovery of renal function or RRT.

Acidosis​

  • Ensure acidosis is renal in origin (↑ anion gap, gases, lactate, ketones).
  • Sodium bicarbonate reserved for correction of hyperkalaemia; correction of acidosis is by recovery of renal function.
  • pH < 7.15: refer to Critical Care if appropriate.
  • RRT may be indicated.
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Indications for RRT

  • Pulmonary oedema
  • Hyperkalaemia
  • Severe uraemia
  • Severe acidosis
  • Insufficient urine output

... refractory to medical management.

Contacts​

Renal SpR​

# 45626

  • All AKI with proteinuria + haematuria
  • Suspected autoimmune disease/glomerulonephritis/myeloma
  • MAHA
  • HTN
  • Poisoning
  • Progression of AKI to stage 3, complications not resolving

Urology/IR​

#45705

  • Obstruction

ITU​

# 45715

  • > 1 organ failure
  • Unstable
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