Management of Acute Kidney Injury (AKI)
The management of AKI should follow a structured approach that includes immediate discontinuation of nephrotoxic medications, volume optimization with crystalloids or albumin, and close monitoring of renal function, with consideration of renal replacement therapy for severe cases. 1
Initial Assessment and Classification
AKI is defined according to KDIGO criteria as:
- Increase in serum creatinine ≥0.3 mg/dL within 48 hours, OR
- Increase in serum creatinine ≥1.5 times baseline within 7 days, OR
- Urine output <0.5 mL/kg/h for 6 hours or more 1
AKI staging:
| Stage | Serum Creatinine | Urine Output |
|---|---|---|
| 1 | 1.5-1.9× baseline or ≥0.3 mg/dL increase | <0.5 mL/kg/h for 6-12h |
| 2 | 2.0-2.9× baseline | <0.5 mL/kg/h for ≥12h |
| 3 | ≥3.0× baseline or ≥4.0 mg/dL or RRT initiation | <0.3 mL/kg/h for ≥24h or anuria for ≥12h |
Step-by-Step Management Algorithm
1. Immediate Interventions (All AKI Stages)
- Review and withdraw all potentially nephrotoxic medications (NSAIDs, vasodilators, ACEi/ARBs) 2, 1
- Discontinue diuretics, especially in hypovolemic patients 2, 1
- Identify and treat underlying causes (infections, hypovolemia, etc.) 2
2. Volume Management Based on AKI Stage
For Stage 1 AKI:
- Close monitoring of renal function and urine output
- Plasma volume expansion in clinically suspected hypovolemia:
For Stage 2-3 AKI:
- Withdraw diuretics if not already done
- Volume expansion with albumin (1 g/kg/day, maximum 100 g/day) for 2 consecutive days 2, 1
- Use isotonic crystalloids rather than colloids for initial volume expansion 1
- Avoid hydroxyethyl starches which can worsen AKI 1
3. Monitoring and Follow-up
- Daily monitoring of serum creatinine, BUN, electrolytes, fluid balance, and urine output 1
- For patients who recover from AKI: check serum creatinine every 2-4 days during hospitalization and every 2-4 weeks for 6 months after discharge 2, 1
4. Nutritional Support
- Provide 20-30 kcal/kg/day total energy intake 1
- Protein recommendations:
- 0.8-1.0 g/kg/day in noncatabolic patients without dialysis
- 1.0-1.5 g/kg/day in patients on renal replacement therapy (RRT)
- Up to 1.7 g/kg/day in patients on continuous RRT and hypercatabolic patients 1
- Prefer enteral nutrition when possible 1
5. Renal Replacement Therapy Indications
Consider RRT when:
- Severe metabolic acidosis persists
- Hyperkalemia is refractory to medical management
- Volume overload remains unresponsive to conservative measures
- Uremic symptoms develop 1
RRT modality selection:
- CRRT for hemodynamically unstable patients
- Intermittent hemodialysis when vasopressor support has been stopped 1
Special Considerations
AKI in Cirrhosis
- For patients with cirrhosis and AKI, follow the International Club of Ascites algorithm:
- Stage 1: Remove risk factors, expand plasma volume if hypovolemic
- Stage 2-3: Withdraw diuretics, administer albumin 1 g/kg for 2 days
- If no response and hepatorenal syndrome criteria met: vasoconstrictors plus albumin 2
Conservative Fluid Management
- After initial resuscitation, aim for neutral then negative fluid balance to prevent interstitial edema which can delay renal recovery 3, 4
- Excessive fluid accumulation can lead to organ dysfunction, impaired wound healing, and nosocomial infections 3
Common Pitfalls to Avoid
- Failure to monitor for drug interactions and adjust medication doses in AKI 1
- Overlooking the impact of AKI on drug metabolism, which can affect hepatic drug clearance 1
- Excessive fluid removal with diuretics or extracorporeal therapy leading to hypovolemia and renal hypoperfusion 3, 4
- Delayed nephrology consultation for severe AKI (all Stage 3 AKI patients require nephrology consultation) 1
By following this structured approach to AKI management, focusing on removing offending agents, optimizing volume status, and providing appropriate supportive care, you can improve outcomes and reduce the risk of progression to chronic kidney disease.