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

Management of Acute Kidney Injury (AKI)

The management of AKI requires immediate identification and treatment of underlying causes, discontinuation of nephrotoxic medications, optimization of hemodynamics with appropriate fluid management, and consideration of renal replacement therapy for severe cases. 1

Diagnosis and Assessment

• AKI is diagnosed when:

  • Serum creatinine increases by ≥0.3 mg/dL within 48 hours, OR
  • Serum creatinine increases by ≥50% from baseline within 3 months, OR
  • Urine output is reduced below 0.5 mL/kg/h for >6 hours 2, 1

• KDIGO staging system:

  Stage	Creatinine Criterion	Urine Output Criterion
  1	Increase ≥0.3 mg/dL in 48h or 1.5-1.9× baseline	<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 increase to ≥4.0 mg/dL or RRT initiation	<0.3 mL/kg/h for ≥24h or anuria for ≥12h

Step 1: Identify and Address Underlying Causes

• Conduct thorough investigation to determine AKI etiology:

  • Pre-renal (hypovolemia, decreased cardiac output)
  • Intrinsic renal (ATN, glomerulonephritis)
  • Post-renal (obstruction) 2

• Rigorous search for infection:

  • Diagnostic paracentesis for spontaneous bacterial peritonitis in cirrhotic patients
  • Blood and urine cultures
  • Chest radiograph 2

• Specific diagnostic workup:

  • Urinalysis with microscopy
  • Urine chemistry (sodium and urea)
  • Renal ultrasound
  • Selected urinary biomarkers (NGAL can help distinguish ATN from HRS) 2, 1

Step 2: Discontinue Nephrotoxic Medications

• Immediately discontinue:

  • NSAIDs
  • ACE inhibitors/ARBs
  • Diuretics
  • Aminoglycosides (unless no suitable alternatives available)
  • Contrast agents
  • Non-selective beta-blockers (especially in cirrhotic patients) 2, 1

• Avoid "triple whammy" combinations of NSAIDs, diuretics, and ACE inhibitors/ARBs 2

• If aminoglycosides are necessary:

  • Administer as single daily dose rather than multiple doses
  • Monitor drug levels when treatment exceeds 24 hours 2

Step 3: Optimize Hemodynamics and Volume Status

• For hypovolemic patients:

  • Use isotonic crystalloids rather than colloids for volume expansion 2, 1
  • Avoid starch-containing fluids as they are associated with harm 2

• For patients with cirrhosis:

  • Administer albumin 1 g/kg/day (maximum 100 g) for 2 days if serum creatinine shows doubling from baseline 2
  • For tense ascites with AKI, therapeutic paracentesis should be combined with albumin infusion 2

• For patients with bleeding:

  • Replace with packed red blood cells to maintain hemoglobin 7-9 g/dL 2

• Monitor fluid status using:

  • Urine output
  • Vital signs
  • Echocardiography or CVP when indicated 2, 1

• Use vasopressors in conjunction with fluids for patients with vasomotor shock 2, 1

Step 4: Manage Hepatorenal Syndrome (if applicable)

If serum creatinine remains higher than twice baseline despite initial measures:

1. Administer albumin 1 g/kg IV on day 1, followed by 20-40 g daily

2. Add vasoactive agents:

   • Terlipressin: Start with 1 mg every 4-6 hours (total 4-6 mg/day)
     • Increase to maximum 2 mg every 4-6 hours if no reduction in creatinine by day 3
     • Alternative: continuous IV infusion starting at 2 mg/day
     • Contraindicated if serum creatinine ≥5 mg/dL or oxygen saturation <90%
   • If terlipressin unavailable: Midodrine (7.5-12.5 mg TID) plus octreotide (100-200 μg SC TID)
   • Alternative: Norepinephrine continuous infusion (0.5-3 mg/h) 2

3. Continue therapy until:

   • Serum creatinine returns to within ≤0.3 mg/dL of baseline for 2 consecutive days, OR
   • For a total of 14 days 2

Step 5: Consider Renal Replacement Therapy (RRT)

Indications for RRT:

• Refractory hyperkalemia

• Severe metabolic acidosis

• Volume overload unresponsive to diuretics

• Uremic symptoms

• Certain toxin ingestions 1

• Continuous therapies are preferred in hemodynamically unstable patients 3

• Timing of RRT remains controversial, but fluid overload is an important determinant for initiation 3

Step 6: Post-AKI Follow-up

• Evaluate kidney function 3 months after AKI episode to screen for development of chronic kidney disease 1
• Monitor for resolution, new onset, or worsening of pre-existing kidney disease 1
• Adjust medications as kidney function recovers 1
• Regular monitoring of renal function every 1-3 months based on severity 1
• More frequent monitoring when eGFR <45 mL/min/1.73 m² 1

Important Caveats and Pitfalls

• AKI significantly increases mortality risk, particularly with higher AKI stages 1, 4
• Even transient episodes of AKI negatively impact mid-term survival 2
• AKI increases risk of developing chronic kidney disease 1, 5
• Presence of proteinuria indicates worse prognosis 1
• Comorbidities like diabetes significantly worsen outcomes 1
• Early application of therapeutic measures as a bundle is advised for prevention and treatment of AKI 3