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 emphasizes slowing disease progression, managing complications, and preparing for renal replacement therapy when necessary. 1

Definition and Classification

Acute Kidney Injury (AKI)

• Characterized by an abrupt decrease in kidney function occurring over 7 days or less 1
• Staged according to KDIGO criteria based on:
  • Serum creatinine increases
  • Urine output decreases
• Requires monitoring of serum creatinine and urine output at least every 48 hours 1

Chronic Kidney Disease (CKD)

• Defined by abnormalities in kidney structure or function persisting for >90 days 2
• Classified using a 3-dimensional approach:
  • Cause of CKD
  • GFR category (G1-G5)
  • Albuminuria category (A1-A3) 2

Acute Kidney Disease (AKD)

• Represents the transition period between AKI and CKD (7-90 days) 2, 1
• May occur with or without preceding AKI 2

Management Approaches

AKI Management

1. Immediate Interventions:

   • Discontinue all nephrotoxic agents when possible 1
   • Maintain optimal fluid status (euvolemia) 1
   • Use isotonic balanced crystalloids rather than 0.9% saline or colloids for volume expansion 1
   • Monitor serum creatinine, electrolytes, and fluid balance daily 1

2. Medication Management:

   • Review and adjust medication dosing based on current kidney function 1
   • Avoid nephrotoxic drug combinations 1
   • Particular caution with NSAIDs, aminoglycosides, and combinations of diuretics with ACE inhibitors/ARBs 1

3. Renal Replacement Therapy (RRT) Considerations:

   • Initiate for severe hyperkalemia, metabolic acidosis, volume overload, or uremic symptoms 1
   • Avoid subclavian catheters to preserve future vascular access 1

4. Follow-up:

   • All AKI survivors should have follow-up at 3 months to assess for CKD development 1
   • Failure to monitor AKI survivors can lead to delayed diagnosis of CKD 1

CKD Management

1. Progression Prevention:

   • Blood Pressure Control:

     • Target ≤140/90 mmHg for patients with albuminuria <30 mg/24h
     • Target ≤130/80 mmHg for patients with albuminuria ≥30 mg/24h 2, 1

   • Proteinuria Reduction:

     • Use ACE inhibitors or ARBs as first-line agents for patients with albuminuria >300 mg/24h 2, 1

   • Lifestyle Modifications:

     • Reduce sodium intake (<2g/day)
     • Maintain healthy BMI (20-25 kg/m²)
     • Quit smoking
     • Regular exercise (30 minutes, 5 times weekly) 2, 1

   • Glycemic Control:

     • Target HbA1c approximately 7% for patients with diabetes 2, 1

2. Complication Management:

   • Monitor and manage metabolic bone disease, anemia, and acidosis
   • Cardiovascular risk reduction (patients with CKD have higher cardiovascular risk) 2

3. Preparation for Renal Replacement:

   • Educate patients about RRT modalities (hemodialysis, peritoneal dialysis, transplantation)
   • Evaluate for kidney transplantation when appropriate 1

Key Differences in Approach

1. Timeframe:

   • AKI: Acute management over days to weeks
   • CKD: Long-term management over months to years

2. Focus:

   • AKI: Identifying and treating reversible causes, preventing further injury
   • CKD: Slowing progression, managing complications

3. Monitoring Frequency:

   • AKI: Daily or more frequent monitoring of kidney function and electrolytes
   • CKD: Regular but less frequent monitoring (typically every 3-12 months depending on stage)

4. Medication Approach:

   • AKI: Emphasis on avoiding nephrotoxic agents
   • CKD: Emphasis on nephroprotective agents (ACEi/ARBs)

Clinical Pitfalls to Avoid

1. Failing to recognize AKI-CKD connection:

   • AKI increases risk of developing CKD and worsens existing CKD 3, 4
   • CKD is a significant risk factor for developing AKI 5

2. Missing follow-up after AKI:

   • All AKI survivors require follow-up at 3 months to assess for CKD development 1
   • AKI survivors are at high risk for progression to advanced CKD 6

3. Suboptimal care for CKD patients with cardiovascular disease:

   • Persons with CKD often receive suboptimal cardiovascular care despite higher risk 2

4. Inappropriate fluid management:

   • Using 0.9% saline instead of balanced crystalloids in AKI can worsen hyperchloremic acidosis 1
   • Failure to adjust fluid management based on volume status in both AKI and CKD

5. Medication errors:

   • Not adjusting medication doses based on current kidney function
   • Continuing nephrotoxic medications in AKI
   • Failing to initiate ACEi/ARBs in proteinuric CKD

By understanding the distinct management approaches for AKI and CKD while recognizing their interconnected nature, clinicians can provide optimal care that addresses both immediate kidney injury and long-term kidney health.