What is the preferred renal replacement therapy, Continuous Kidney Replacement Therapy (CKRT) or Sustained Low-Efficiency Dialysis (SLED), for patients with severe impaired renal function?

CKRT versus SLED for Patients with Severe Impaired Renal Function

For patients with severe impaired renal function, both Continuous Kidney Replacement Therapy (CKRT) and Sustained Low-Efficiency Dialysis (SLED) are acceptable modalities, with CKRT being preferred for hemodynamically unstable patients due to better management of fluid balance and hemodynamic stability.

Patient Assessment and Modality Selection

Hemodynamic Status

• Hemodynamically unstable patients: CKRT is preferred

  • Patients requiring vasopressor support 1
  • Patients with septic shock 2
  • Better fluid balance management in unstable patients 2

• Hemodynamically stable patients: SLED may be considered

  • Patients no longer requiring vasopressor support 1
  • Patients with stabilized blood pressure 2

Specific Clinical Conditions

• Increased intracranial pressure: CKRT is preferred due to lower risk of changes in intracranial pressure 1
• Severe metabolic derangements: CKRT provides more steady correction 3
• Fluid overload with respiratory compromise: CKRT offers more precise volume control 4

Advantages of Each Modality

CKRT Advantages

• Better hemodynamic stability for unstable patients 2
• More precise control of fluid balance 2, 4
• Steady correction of acid-base and electrolyte disturbances 3
• Continuous removal of uremic toxins 4

SLED Advantages

• Uses standard hemodialysis equipment 5
• Allows unrestricted access to patients during daytime for procedures and tests when performed nocturnally 5
• Requires fewer resources compared to CKRT 6
• Comparable clinical outcomes to CKRT in selected patients 6, 7

Practical Considerations

CKRT Prescription

• Deliver an effluent volume of 20-25 mL/kg/h 1
• Regional citrate anticoagulation is preferred when not contraindicated 1
• Monitor for electrolyte disturbances, particularly with citrate anticoagulation 1

SLED Prescription

• Typical duration: 8-12 hours per session 5, 7
• Blood flow rate: approximately 200 mL/min 6
• Often performed without anticoagulation in high bleeding risk patients 6
• Can achieve a delivered double-pool Kt/V of approximately 1.36 per completed treatment 5

Nutritional Considerations

• For critically ill patients with AKI on CKRT, provide 1.5-1.7 g/kg/day of protein 1
• For critically ill patients on SLED, protein requirements are similar at 1.5 g/kg/day 2
• Monitor for hypophosphatemia and hypokalemia, which may require supplementation during treatment 5

Transition Between Modalities

• Consider transitioning from CKRT to SLED when:
  • Vasopressor support has been discontinued 1
  • Intracranial hypertension has resolved 1
  • Fluid balance can be controlled with intermittent therapy 1

Outcomes

• Current evidence suggests similar mortality outcomes between CKRT and SLED 6, 7
• No significant difference in renal recovery rates between modalities 1, 6

Potential Complications to Monitor

• Hypotension during treatment (more common with SLED) 5
• Extracorporeal circuit clotting 5
• Electrolyte disturbances (hypokalemia, hypophosphatemia) 5, 3
• Inadequate ultrafiltration 5

Clinical Pearls

• Selection of RRT modality should be based primarily on patient characteristics, local resources, and expertise of personnel 1
• The timing of RRT initiation should be individualized, with prompt initiation for life-threatening indications 1
• Vascular access placement should prioritize right jugular or femoral veins with ultrasound guidance 1
• Regular monitoring of electrolytes is essential during both CKRT and SLED 3