Review
Introduction
Incidence
Definition
Stage | Glomerular filtration rate (GFR) criteria | Urine output criteria |
---|---|---|
RIFLE classification
| ||
Risk
| Serum creatinine increased x 1.5 or GFR decrease >25% | <0.5 ml/kg/hr for ≥ 6 hours |
Injury
| Serum creatinine increased x 2 or GFR decrease >50% | <0.5 ml/kg/hr for ≥ 12 hours |
Failure
| Serum creatinine increased x 3 or GFR decrease ≥ 75% or an absolute serum creatinine ≥ 354 μmol/L with an acute rise ≥ 4 μmol/L | <0.3 ml/kg/hr for ≥ 24 hours or anuria for ≥12 hours |
Loss
| Persistent AKI, requiring RRT for > 4 weeks | |
End-stage kidney disease
| Requiring dialysis > 3 months | |
AKIN classification
| ||
Stage 1
| Serum creatinine increased ≥26.2 μmol/L or x 0.5 to 2 baseline | <0.5 ml/kg/hr for ≥ 6hours |
Stage 2
| Serum creatinine increased x 2 to 3 baseline | <0.5 ml/kg/hr for ≥ 12 hours |
Stage 3
| Serum creatinine increased > x 3 baseline or serum creatinine ≥ 354 μmol/L with an acute rise ≥ 44 μmol/L or initiation of RRT | <0.3 ml/kg/hr for ≥ 24 hours or anuria for ≥12 hours |
KDIGO classification
| ||
Stage 1
| Serum creatinine increased x 1.5 to 1.9 baseline or by ≥ 26.2 μmol/L | <0.5 ml/kg/hr for 6 to 12 hours |
Stage 2
| Serum creatinine increased x 2 to 2.9 baseline | <0.5 ml/kg/hr for ≥ 12 hours |
Stage 3
| Serum creatinine increased > x 3 baseline or serum creatinine ≥ 354 μmol/L with an acute rise ≥ 44 μmol/L or initiation of RRT | <0.3 ml/kg/hr for ≥ 24 hours or anuria for ≥12 hours |
Risk factors
Patient related factors | Surgical factors |
---|---|
Age | Duration of surgery |
Hypertension | Intra-peritoneal surgery |
Diabetes Mellitus | Length of CPB |
Chronic Obstructive Pulmonary Disease | Cross clamp time |
LVF, EF <40% | Hemolysis (cardiac surgery) |
Chronic kidney disease | Hemodilution (cardiac surgery) |
Emergency surgery | Use of IABP (cardiac surgery) |
Sepsis | |
Peripheral vascular disease | |
Cerebrovascular disease | |
Ascites |
Novel biomarkers
NGAL
KIM-1
IL-18
Cystatin C
Pathophysiology of AKI
Pre-renal | Intrinsic renal disease | Post-renal |
---|---|---|
Hypovolemia, for example, hemorrhage, diarrhea, vomiting | Ischemia from prolonged hypoperfusion | Obstructive causes, for example, prostatic hypertrophy, renal stones, urethral strictures, pelvic masses |
Hypotension, for example, sepsis | Glomerular disease, for example, glomerulonephritis, TTP, DIC | |
Low cardiac output state, for example, CCF, cardiac tamponade | Nephrotoxins, for example, aminoglycosides, NSAIDs, radiological contrast | |
Impaired renal autoregulation, for example, renal artery stenosis, ACEi/ARB/NSAIDs | Metabolic abnormalities, for example, hypercalcemia | |
Rhabdomyolysis, for example, crush injuries, burns |