What is the difference in management between Acute Kidney Injury (AKI) and Chronic Kidney Disease (CKD)?

Management Differences Between Acute Kidney Injury (AKI) and Chronic Kidney Disease (CKD)

The management of AKI focuses on identifying and treating reversible causes, preventing further injury, and supporting kidney function during recovery, while CKD management centers on slowing progression, managing complications, and preparing for renal replacement therapy when necessary.

Definitions and Timeframes

• AKI: Abrupt decrease in kidney function occurring over 7 days or less 1

  • Diagnosed by KDIGO criteria: increase in serum creatinine by ≥0.3 mg/dL within 48h, increase to ≥1.5 times baseline within 7 days, or urine output <0.5 mL/kg/hour for 6 hours 1

• AKD (Acute Kidney Disease): Abnormalities in kidney structure or function persisting for 7-90 days 2, 1

  • Represents a transition period between AKI and CKD

• CKD: Abnormalities in kidney structure or function persisting for >3 months 1

  • Characterized by GFR <60 mL/min/1.73 m² and/or markers of kidney damage

Management of AKI

1. Immediate Interventions

• Identify and treat underlying cause (sepsis, hypovolemia, obstruction, nephrotoxins) 1
• Discontinue all nephrotoxic agents when possible 2
• Ensure optimal volume status and perfusion pressure 2
• Monitor serum creatinine and urine output at least every 48 hours 2, 1

2. Medication Management

• Review and adjust medication dosing based on current kidney function 2
• Avoid nephrotoxic drug combinations (e.g., macrolide antibiotics with statins) 2
• Use caution with NSAIDs, aminoglycosides, and combinations of diuretics with ACE inhibitors/ARBs 1

3. Fluid Management

• Maintain euvolemia using balanced crystalloid solutions rather than 0.9% saline 1
• Avoid hydroxyethyl starches 3
• Monitor fluid balance daily in hospitalized patients 1

4. Renal Replacement Therapy (RRT) Considerations

• Consider RRT for severe hyperkalemia, metabolic acidosis, volume overload, or uremic symptoms 1
• Timing of RRT initiation remains controversial but is typically early in severe AKI 3
• Avoid subclavian catheters if possible to preserve future vascular access 2

Management of CKD

1. Long-term Disease Modification

• Implement strategies to slow CKD progression:
  • Blood pressure control: ≤140/90 mmHg for patients with albuminuria <30 mg/24h and ≤130/80 mmHg for patients with albuminuria ≥30 mg/24h 1
  • Use ACE inhibitors or ARBs as first-line agents for patients with albuminuria >300 mg/24h 1
  • Glycemic control in diabetic patients (target HbA1c ~7%) 1
  • Lipid management and dietary modifications 1

2. Complication Management

• Monitor and treat CKD-associated complications:
  • Anemia (erythropoiesis-stimulating agents, iron)
  • Mineral bone disorder (phosphate binders, vitamin D analogs)
  • Metabolic acidosis (oral bicarbonate supplementation)
  • Cardiovascular risk reduction

3. Monitoring and Follow-up

• Regular assessment of GFR using creatinine-based equations (eGFRcr) or combined creatinine and cystatin C (eGFRcr-cys) 1
• Assess albuminuria using urinary albumin-to-creatinine ratio (ACR) 1
• Monitor for progression based on GFR category (G1-G5) and albuminuria category (A1-A3) 1

4. Preparation for Renal Replacement

• Timely referral for vascular access placement when approaching ESRD
• Education about RRT modalities (hemodialysis, peritoneal dialysis, transplantation)
• Evaluation for kidney transplantation when appropriate

Key Differences in Management Approach

1. Timeframe:

   • AKI: Urgent/emergent management over days to weeks
   • CKD: Chronic management over months to years

2. Reversibility Focus:

   • AKI: Primary goal is to identify and treat reversible causes to promote recovery 3
   • CKD: Focus on slowing progression as the condition is typically irreversible

3. Medication Adjustments:

   • AKI: Frequent dose adjustments based on rapidly changing kidney function
   • CKD: More stable dosing with periodic adjustments as disease progresses

4. Monitoring Frequency:

   • AKI: Daily monitoring of creatinine, electrolytes, and fluid balance 1
   • CKD: Monitoring every 3-12 months depending on stage and stability

5. RRT Approach:

   • AKI: Temporary support with focus on recovery, often using continuous modalities
   • CKD: Preparation for long-term RRT with focus on sustainability and quality of life

The AKI-to-CKD Continuum

AKI is not always a self-limited process and can lead to CKD through maladaptive repair mechanisms 4. Risk factors for AKI progression to CKD include:

• Advanced age
• Diabetes mellitus
• Decreased baseline GFR
• Severity of AKI
• Low serum albumin 5

All AKI survivors should have follow-up at 3 months to assess for CKD development 1, as they have up to 16.8 times higher risk of developing CKD compared to those without kidney dysfunction 1.

Common Pitfalls to Avoid

• Failing to identify and address the underlying cause of AKI
• Relying solely on serum creatinine without calculating eGFR 1
• Overlooking albuminuria as a marker of kidney damage 1
• Inadequate medication review during AKI or CKD management 1
• Failure to monitor AKI survivors for CKD development 1
• Neglecting acid-base and electrolyte disturbances during renal support for AKI 6

By understanding these key differences in management approach, clinicians can optimize outcomes for patients with kidney disease across the spectrum from acute injury to chronic disease.