What are the management strategies for Acute Kidney Injury (AKI)?

Management of Acute Kidney Injury (AKI)

The management of acute kidney injury requires immediate withdrawal of nephrotoxic drugs, appropriate fluid resuscitation with isotonic crystalloids, and targeted interventions based on the underlying cause to prevent further kidney damage and reduce mortality. 1

Definition and Diagnosis

AKI is defined by the 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 is staged according to severity:

• Stage 1: Creatinine increase ≥0.3 mg/dL or 1.5-1.9× baseline; urine output <0.5 mL/kg/h for 6-12h
• Stage 2: Creatinine 2.0-2.9× baseline; urine output <0.5 mL/kg/h for ≥12h
• Stage 3: Creatinine ≥3.0× baseline or ≥4.0 mg/dL or RRT initiation; urine output <0.3 mL/kg/h for ≥24h or anuria for ≥12h 1

Initial Management Steps

1. Identify and treat underlying cause

   • Determine etiology: prerenal, intrinsic renal, or postrenal 2
   • Perform thorough investigation including history, physical exam, laboratory tests, and imaging as needed

2. Discontinue nephrotoxic agents

   • Immediately withdraw nephrotoxic drugs, vasodilators, and NSAIDs 1
   • Reduce or withdraw diuretics in all AKI patients 1

3. Optimize volume status

   • Use isotonic crystalloids rather than colloids for initial volume expansion 1
   • Normal saline or balanced crystalloid solutions are preferred first-line options 1
   • Avoid hydroxyethyl starches which increase AKI incidence 1
   • In patients with cirrhosis and ascites, consider albumin at 1 g/kg/day for two consecutive days 3, 1

4. Hemodynamic monitoring and support

   • Maintain adequate blood pressure with fluids and vasopressors if needed 4
   • Monitor urine output, vital signs, and when indicated, use echocardiography or CVP 3

Specific Management for Cirrhotic Patients with AKI

For patients with cirrhosis and AKI:

1. Preventive measures include:

   • Avoid nephrotoxic medications like NSAIDs
   • Avoid excessive diuretics or unmonitored nonselective beta-blockade
   • Avoid large-volume paracentesis without albumin replacement
   • Counsel patients to avoid alcohol use 3

2. When AKI is diagnosed:

   • Hold diuretics and nonselective beta-blockers
   • Discontinue NSAIDs
   • Treat the precipitating cause
   • Replace fluid losses with albumin 1 g/kg/d for 2 days if serum creatinine shows doubling from baseline 3

3. For Hepatorenal Syndrome (HRS-AKI):

   • When serum creatinine remains higher than twice baseline despite initial measures, initiate:
     • Albumin: 1 g/kg IV on day 1, then 20-40 g daily
     • Vasoactive agents (terlipressin, octreotide + midodrine, or norepinephrine)
     • Continue until creatinine returns to within ≤0.3 mg/dL of baseline for 2 consecutive days or for 14 days 3

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

Medication Management

• Adjust medication doses based on estimated GFR 1
• Review all medications for potential nephrotoxicity
• Consider drug levels for medications with narrow therapeutic windows

Renal Replacement Therapy (RRT)

Consider RRT when:

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

The optimal timing of RRT initiation remains controversial, with no consistent benefit demonstrated for early start dialysis 4

Monitoring and Follow-up

• Daily monitoring of serum creatinine, BUN, electrolytes, fluid balance, and hemodynamic parameters 1
• Monitor for signs of renal recovery: increasing urine output, decreasing serum creatinine, improved electrolyte balance 1
• Assess for potential discontinuation of RRT when kidney function has recovered sufficiently 1
• Refer to nephrology based on severity, with all Stage 3 AKI patients requiring nephrology consultation 1

Long-term Considerations

• AKI is not a "self-limited" process but is strongly linked to increased risk for chronic kidney disease, subsequent AKI, and future mortality 5
• Implement long-term follow-up for all patients who experience AKI, particularly those with severe AKI 6

Common Pitfalls to Avoid

• Delaying identification and treatment of the underlying cause
• Continuing nephrotoxic medications
• Inappropriate fluid management (either under-resuscitation or volume overload)
• Failing to adjust medication doses appropriately
• Neglecting long-term follow-up after AKI resolution