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

Management of Acute Kidney Injury (AKI)

The management of acute kidney injury requires immediate discontinuation of nephrotoxic medications, volume status optimization, treatment of underlying causes, and stage-based interventions with close monitoring of kidney function. 1

Diagnosis and Classification

AKI is diagnosed using the KDIGO criteria:

• Increase in serum creatinine by ≥0.3 mg/dL within 48 hours, OR
• Increase in serum creatinine by ≥50% from baseline within 7 days, OR
• Urine output <0.5 mL/kg/h for >6 hours 2, 1

AKI staging:

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

Initial Management

1. Identify and treat underlying cause:

   • Determine if AKI is prerenal, intrinsic renal, or postrenal 1
   • Perform thorough evaluation including urinalysis, urine microscopy, and renal ultrasound 1
   • Conduct rigorous search for infection with appropriate cultures 2

2. Medication management:

   • Discontinue nephrotoxic medications (NSAIDs, ACE inhibitors, ARBs, aminoglycosides) 1
   • Hold diuretics and beta-blockers temporarily 2, 1
   • Adjust medication dosages based on kidney function 1

3. Volume status optimization:

   • For hypovolemia: Administer isotonic crystalloids (500-1000 mL initial bolus) 1
   • For patients with cirrhosis: Use albumin 1 g/kg/day for two consecutive days (max 100g/day) 2, 1
   • Monitor for fluid overload with careful assessment of vital signs 2
   • Consider echocardiography or CVP monitoring in complex cases 2

Ongoing Management Based on AKI Stage

Stage 1 AKI:

• Daily monitoring of serum creatinine, BUN, electrolytes
• Maintain urine output >0.5 mL/kg/hr
• Ensure adequate renal perfusion 1

Stage 2 AKI:

• All Stage 1 interventions
• Consider nephrology consultation
• Evaluate need for more intensive monitoring
• Consider ICU admission if rapidly progressing 2

Stage 3 AKI:

• All Stage 2 interventions
• Urgent nephrology consultation
• Consider renal replacement therapy (RRT) for:
  • Refractory hyperkalemia
  • Volume overload unresponsive to diuretics
  • Severe metabolic acidosis
  • Uremic symptoms (encephalopathy, pericarditis, pleuritis) 1

Special Considerations

Hepatorenal Syndrome in Cirrhosis:

• If no response to albumin after 2 days and HRS criteria are met:
• Initiate vasoconstrictors (terlipressin or norepinephrine) with continued albumin 2
• Terlipressin dosing: Start at 1 mg every 4-6 hours, increase to maximum 2 mg every 4-6 hours if no reduction in serum creatinine by 25% after 3 days 2
• Continue treatment until serum creatinine returns to within ≤0.3 mg/dL of baseline for 2 consecutive days or for a maximum of 14 days 2

Contrast-Induced AKI Prevention:

• Use isotonic crystalloids for hydration before contrast exposure
• Consider N-acetylcysteine in high-risk patients
• Use lowest possible contrast dose 1

Monitoring and Follow-up

1. During acute phase:

   • Daily monitoring of serum creatinine, BUN, electrolytes
   • Track fluid balance and urine output
   • Reassess volume status frequently 1

2. Long-term follow-up:

   • Evaluate kidney function 3 months after AKI episode to screen for development of chronic kidney disease 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

Prognosis

• AKI is associated with increased mortality, particularly with higher AKI stages 1
• Significantly increases risk of developing chronic kidney disease 1
• Presence of proteinuria indicates worse prognosis 1
• Comorbidities such as diabetes worsen outcomes 1

Common Pitfalls to Avoid

1. Failing to identify and address the underlying cause of AKI
2. Continuing nephrotoxic medications during AKI
3. Inadequate fluid resuscitation in hypovolemic patients
4. Excessive fluid administration leading to volume overload
5. Delayed nephrology consultation for severe or progressive AKI
6. Neglecting long-term follow-up after AKI resolution

Remember that the clinical context of each individual patient must guide management decisions beyond AKI staging alone 2. The extreme heterogeneity of AKI means that treatment must be tailored to the specific cause and patient circumstances.