What is the recommended dose of heparin (anticoagulant) to add to the dialysate for patients with slow drainage during peritoneal dialysis?

Recommended Heparin Dosage for Peritoneal Dialysis Patients with Slow Drainage

For patients experiencing slow drainage during peritoneal dialysis, adding 500 units of heparin per liter of dialysate is the recommended dose to prevent fibrin formation and improve drainage. 1

Rationale for Heparin in Peritoneal Dialysis

Slow drainage during peritoneal dialysis is often caused by fibrin formation within the peritoneal cavity, which can obstruct the catheter and impair dialysate flow. Heparin works by:

• Preventing intraperitoneal fibrin formation
• Improving dialysate flow through the catheter
• Reducing the risk of catheter obstruction

Evidence-Based Dosing Recommendations

Research has demonstrated that 500 units of heparin per liter of dialysate is effective for:

• Significantly reducing fibrinopeptide A concentrations in dialysate (from 155.8 ± 15.7 ng/ml to 8.5 ± 2.0 ng/ml) 1
• Preventing intraperitoneal fibrin formation without causing systemic anticoagulation 1
• Maintaining catheter patency without increasing bleeding risk

Important Clinical Considerations

Safety Profile

• At the recommended dose of 500 units/L, heparin remains localized to the peritoneal cavity
• No detectable heparin activity in plasma even after 52 hours of continuous administration 1
• The low antithrombin III concentration (0.44 ± 0.13 mg/dl) in protein-poor dialysate is sufficient to inhibit thrombin activity 1

Alternative Dosing

• For patients with peritonitis or at the start of CAPD, where intraperitoneal AT-III levels are expected to be relatively increased, doses of 2.5-5 U/ml (2,500-5,000 units per liter) may be used 2
• The half-life of heparin activity in dialysate is 0.5-2 hours, with activity decreasing to 0.5-1.4 U/ml after 6 hours 2

Monitoring

• No routine coagulation monitoring is necessary as systemic absorption is minimal
• Visual inspection of the dialysate for clarity during drainage
• Monitor for improvement in drainage volumes and flow rates

Potential Pitfalls and Caveats

1. Systemic anticoagulation risk: While minimal at recommended doses, patients with recent surgery, trauma, or bleeding disorders should be monitored closely

2. Heparin-induced thrombocytopenia: Though rare with intraperitoneal administration, be vigilant in patients with history of HIT

3. Ineffective anticoagulation: If 500 units/L is insufficient to improve drainage:

   • Verify proper catheter position
   • Rule out mechanical obstruction
   • Consider increasing to 1,000 units/L if no improvement
   • Consider fibrinolytic therapy (e.g., tissue plasminogen activator) for persistent fibrin sheaths 3

4. Peritonitis: In the presence of peritonitis, higher heparin doses may be needed due to increased fibrin formation

By following these evidence-based recommendations, peritoneal dialysis patients experiencing slow drainage should see improvement in dialysate flow without systemic anticoagulation risks.