What is the immediate management for a patient with Acute Kidney Injury (AKI)?

Immediate Management of Acute Kidney Injury (AKI)

The immediate management of acute kidney injury requires prompt identification and discontinuation of all nephrotoxic medications, fluid resuscitation with isotonic crystalloids (preferably balanced solutions), and daily monitoring of renal function, electrolytes, and fluid balance. 1

Initial Assessment and Classification

1. Assess AKI severity using KDIGO criteria:

   • Stage 1: Increase in serum creatinine ≥0.3 mg/dL within 48h or 1.5-1.9 times baseline; urine output <0.5 mL/kg/h for 6-12h
   • Stage 2: Serum creatinine 2.0-2.9 times baseline; urine output <0.5 mL/kg/h for ≥12h
   • Stage 3: Serum creatinine ≥3.0 times baseline or ≥4.0 mg/dL or RRT initiation; urine output <0.3 mL/kg/h for ≥24h or anuria for ≥12h 1

2. Laboratory evaluation:

   • Serum creatinine, BUN, electrolytes
   • Complete blood count
   • Urinalysis
   • Fractional excretion of sodium 2, 3

Medication Management

1. Review and withdraw all nephrotoxic medications:

   • NSAIDs
   • ACE inhibitors and ARBs
   • Aminoglycosides
   • Other potential nephrotoxins 1

2. Avoid combining multiple nephrotoxins as each additional nephrotoxin increases AKI risk by 53%, with three or more nephrotoxins more than doubling the risk 4

3. Adjust medication doses based on estimated GFR 1

Fluid Management

1. Assess volume status carefully:

   • Hypovolemia: Provide fluid resuscitation
   • Euvolemia: Maintain fluid balance
   • Hypervolemia: Consider diuretics or renal replacement therapy 5, 6

2. For fluid resuscitation:

   • Use isotonic crystalloids (balanced solutions preferred over normal saline)
   • Implement goal-directed fluid therapy to optimize hemodynamics 1

3. Avoid fluid overload as interstitial edema can delay renal recovery 5, 6

4. Consider central venous pressure monitoring in hemodynamically unstable patients 1

Nutritional Support

1. Provide appropriate nutritional support:

   • 20-30 kcal/kg/day total energy intake
   • Protein intake:
     • 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
     • Up to 1.7 g/kg/day in patients on continuous RRT and hypercatabolic patients 1

2. Prefer enteral nutrition when possible 1

Monitoring and Follow-up

1. Daily monitoring of:

   • Vital signs
   • Serum creatinine and BUN
   • Electrolytes (particularly potassium)
   • Fluid balance
   • Urine output 1

2. Perform renal ultrasonography to rule out obstruction, particularly in older men with prostatic hypertrophy 2, 3

Renal Replacement Therapy Considerations

Consider RRT when:

• Severe metabolic acidosis persists
• Hyperkalemia is refractory to medical management
• Volume overload remains unresponsive to conservative measures
• Uremic symptoms develop 1

For hemodynamically unstable patients, continuous renal replacement therapy (CRRT) is preferred as the first-line modality 1

Nephrology Consultation

Consult nephrology for:

• All Stage 3 AKI patients
• AKI without a clear cause
• Inadequate response to supportive treatment
• Preexisting stage 4 or higher chronic kidney disease
• When renal replacement therapy is being considered 1, 2

Common Pitfalls to Avoid

1. Excessive fluid administration: Can lead to interstitial edema, delayed renal recovery, and organ dysfunction 5, 6

2. Continued use of nephrotoxic medications: The "triple whammy" of NSAIDs, diuretics, and ACE inhibitors/ARBs is particularly harmful 4

3. Inadequate monitoring: Failure to track daily renal function, electrolytes, and fluid balance can lead to missed opportunities for intervention 1

4. Delayed nephrology consultation: Early involvement of specialists improves outcomes in severe AKI 2

5. Overlooking post-discharge follow-up: AKI increases risk for chronic kidney disease, requiring follow-up every 2-4 weeks for 6 months after discharge 1