Diagnosis

• Ensure AKI considered if presents with illness and has CKD, or new onset urological symptoms
  • Investigate for AKI if
  • eGFR < 60 ml/min/1.73m2 (Stage 2)
  • Oliguria, Hypovolaemia, Neurological dysfunction reliance of carer for hydration
  • Nephrotoxic drugs: NSAID, ACE/ARB, Diuretic, Aminoglycosides, ioidiated contrast past wk
  • Heart Failure, Liver disease, Sepsis, Symptoms of urological obstruction
  • > 65 yrs, Hx of AKI
  • Deteriorating EWS
  • Children: Diarrhoea, Haematological malignancy

Investigation

• Measure serum creatinine, compare with baseline, noting in CKD a rise in creatinine may mean acute kidney injury on chronic versus worsening chronic
• CG50 track and trigger systems (EWS) used to identify patients at risk of AKI, EWS paeds aggregate weighted measure to include: HR, RR, SBP, GCS, Sats, Temp, Cap refill
• If at risk measure: urine output, weight (fluid balance), U+Es, Lactate, ABG

Detection criteria for AKI:

• Rise of serum creatinine of > 26 micromol/l in less than 48 hrs
• 50 % rise in serum creatinine over 7 days
• Fall in urine output < 0.5 ml/kg/hr for more than 6 hours (8 hr in children)
• Children: >25 % fall in eGFR over 7 days

Identify Cause

• Urinalysis: urine dip protein, blood, leucocytes, nitrates and glucose,
• Nephritis must be considered if haematuria & proteinuria w/o UTI or trauma or other cause known
• USS: do not routinely offer if cause of AKI has been identified, unless pyelonephritis or risk of urinary tract obstruction

Management

Preventing Acute Kidney Injury

• Contrast agents measure eGFR, at risk if:
  • eGFR < 40, diabetes, heart failure, renal transplant, hypovolaemia, > 75, increased volume or inter arterial use of contrast
  • Patients should be volume expanded
  • Stop ACE / ARB if eGFR < 40
• Surgery at risk if: emergency or intraperitoneal surgery, eGFR < 60, diabetes, heart failure, liver failure, > 65, Nephrotoxic drugs incl NSAIDs
• Consider temporarily stopping ACE inhibitors and ARBs in patients with diarrhoea, vomiting or sepsis until their clinical condition has improved

Urological Obstruction:

• Refer if obstructed single kidney, bilateral upper tract obstruction, pyonephrosis, complications due to obstruction

Pharmacological Management

• Loop diuretic: not routine in AKI but if fluid overload / oedema awaiting transplant or improving

Renal Replacement

• Discuss with nephrologist, whether benefit if significant co-morbidity, decide on overall condition
• Refer for replacement in following if not responding to medical management: hyperkalaemia, metabolic acidosis, uraemia leading to pericarditis, fluid overload / oedema
• Specialist: diagnosis of vasculitis, glomerulonephritis, myeloma; AKI w/o known cause; inadequate response; stage 3 AKI, CKD stage 4-5, eGRF < 30 following AKI

NICE Source: CG169 Acute kidney injury: prevention, detection and management. Summary compiled by Dr D P Sheppard MBBS.

NICE Guidance on a page By Dr D P Sheppard MBBS