Review Article

Care of the Critically Ill Emergency Department Patient with Acute Kidney Injury

Table 1

Classifications to define AKI.
(a) RIFLE classification [11]

RIFLE categorySCr/GFR criteriaUrine output criteria

Risk↑ SCr ≥150–200% (1.5–2 fold) OR decrease of GFR >25%Urine output <0.5 mL/kg/hour for 6 hours
Injury↑ SCr >200–300% (>2-3 fold) OR decrease of GFR >50%Urine output <0.5 mL/kg/hour for 12 hours
Failure↑ SCr >300% (>3 fold) from baseline or decrease of GFR >75% OR serum creatinine ≥4 mg/dL with an acute rise of ≥44 μmol/LUrine output <0.3 mL/kg/hour for 24 hours or anuria for 12 hours
LossComplete loss of renal function for >4 weeks
End stage kidney diseaseNeed for RRT for >3 months

(b) AKI Network classification [12]

AKIN stageSerum creatinine criteriaUrine output criteria

1↑ SCr ≥26.4 μmol/L in ≤48 hours OR ↑ SCr ≥150–200% (1.5–2 fold) from baseline<0.5 mL/kg/h for >6 h
2↑ SCr >200–300% (>2–3 fold) from baseline<0.5 mL/kg/h for >12 h
3↑ SCr >300% (>3 fold) from baseline OR SCr ≥354 μmol/L with an acute rise of ≥44 μmol/L OR treatment with RRT<0.3 mL/kg/h for 24 h OR anuria for 12 h

(c) KDIGO classification [3]

Stage Serum creatinine criteria Urine output criteria

1 1.5–1.9 times baseline OR ≥0.3 mg/dL (>26.5 μmol/L) in ≤48 hours<0.5 mL/kg/h for 6–12 hours
2 2–2.9 times baseline<0.5 mL/kg/h for ≥12 hours
3 ≥3 times baseline OR increase in SCr to ≥4.0 mg/dL (353.6 μmol/L) OR initiation of RRT<0.3 mL/kg/h for ≥24 hours OR anuria for ≥12 hours

Abbreviations: GFR: glomerular filtration rate; RRT: renal replacement therapy; SCr: serum creatinine.
Only one criterion needs to be met to be classified as AKI; if both are present, the criterion which places the patient in the higher stage of AKI is selected.