When to use heparin versus heparin-free dialysis in patients undergoing rigid dialysis, considering individual risk factors such as bleeding disorders or history of clotting?

Anticoagulation Strategy Selection for Hemodialysis

Use heparin-free dialysis (or regional citrate) for patients with active bleeding risk, recent surgery/trauma, or bleeding disorders; use standard heparin anticoagulation for all other patients requiring routine hemodialysis.

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Standard Heparin Anticoagulation (Default Approach)

For routine hemodialysis without contraindications, use unfractionated heparin (UFH) as the standard anticoagulant 1, 2.

Dosing Protocol

• Initial bolus: 25-50 units/kg IV (or 5,000 units for average adult) 1, 2
• Maintenance infusion: 500-1,500 units/hour continuous infusion 1
• Alternative intermittent dosing: 5,000-10,000 units IV every 4-6 hours 2

Advantages of Standard Heparin

• Short half-life (1-2 hours) allows rapid reversal if bleeding occurs 1
• No dose adjustment needed for renal impairment and not cleared by dialysis 1
• Low cost and proven efficacy with widespread clinical familiarity 1
• Reversible with protamine if urgent reversal needed 2

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Heparin-Free Dialysis: When to Avoid Heparin

Absolute Contraindications to Heparin 3, 2

• Active major bleeding at any site, tissue, or organ
• Severe thrombocytopenia (especially with positive antiplatelet antibodies)
• History of heparin-induced thrombocytopenia (HIT) or HIT with thrombosis (HITTS)
• Known hypersensitivity to heparin or pork products
• Uncontrolled bleeding state (except disseminated intravascular coagulation)

High Bleeding Risk Situations Requiring Heparin-Free Approach 4, 5, 6

• Recent surgery (especially within 48-72 hours post-operatively)
• Recent trauma or invasive procedures
• Active gastrointestinal bleeding or ulcerative disease
• Recent intracranial hemorrhage, subarachnoid hemorrhage, or subdural hematoma 4
• Recent brain, spinal cord, or ophthalmologic surgery 3
• Congenital or acquired bleeding disorders (hemophilia, von Willebrand disease)
• Severe uncontrolled hypertension (systolic >200 mmHg, diastolic >110 mmHg) 3
• Advanced age >60 years with multiple comorbidities 4
• Liver failure with elevated INR >1.5 3
• Presence of microbleeds on MRI suggesting cerebral amyloid angiopathy 4

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Alternative Anticoagulation Strategies

Regional Citrate Anticoagulation (Preferred Alternative)

Regional citrate is the preferred alternative for patients with high bleeding risk who are NOT in acute HIT 3, 1.

When to Use Regional Citrate

• Subacute HIT A, subacute HIT B, or remote HIT requiring dialysis circuit anticoagulation only 3
• High bleeding risk patients who need circuit anticoagulation but cannot tolerate systemic effects 4, 1
• Patients with past history of HIT requiring ongoing renal replacement therapy 3

Advantages of Regional Citrate 3, 1

• Similar efficacy to heparin with superior safety profile
• Reduced bleeding risk compared to systemic anticoagulation
• Reduced HIT risk compared to heparin
• More cost-effective than alternative non-heparin anticoagulants (argatroban, danaparoid)
• Familiar to clinicians and inexpensive

Critical Limitation

• NOT appropriate for acute HIT requiring systemic anticoagulation 3

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Acute Heparin-Induced Thrombocytopenia (HIT)

For patients with acute HIT requiring dialysis, use argatroban, danaparoid, or bivalirudin rather than other non-heparin anticoagulants 3, 1.

First-Line: Argatroban 3, 4, 1

• Preferred agent due to lack of renal clearance
• Dosing for continuous hemodialysis: 100 μg/kg bolus, followed by continuous infusion 1
• Dosing for intermittent hemodialysis: 250 μg/kg bolus, followed by continuous infusion 1
• No dose adjustment needed in renal failure 1
• Low rates of complications: new thrombosis 0-4%, major bleeding 0-6% 1

Alternative Agents 3

• Danaparoid: 3,750 units bolus (2,500 units if weight <55 kg) before first two sessions, then 3,000 units (2,000 units if weight <55 kg) for subsequent sessions 1
  • Caution: Accumulates in renal failure, more difficult to use than argatroban 3, 1
• Bivalirudin: Requires dose reduction in severe renal impairment 1
  • 1.0 mg/kg/hour for CrCl <30 mL/min
  • 0.25 mg/kg/hour for patients on hemodialysis

Agents to Avoid in Acute HIT with Dialysis 3

• Fondaparinux and rivaroxaban: Little data and greater dependence on kidneys for clearance 3

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Heparin-Free Dialysis Technique (Without Alternative Anticoagulants)

When no anticoagulant can be used, employ mechanical strategies to prevent circuit clotting 5, 7.

Technical Modifications 5, 7

• High blood flow rates (>240 mL/min) to minimize contact time
• Intermittent saline rinsing of the extracorporeal circuit
• Prophylactic changing of dialyzer and blood lines during session (at approximately 2-hour intervals)
• Heparin-free priming of dialyzer and blood lines
• Close monitoring throughout treatment

Expected Outcomes with Heparin-Free Technique 5

• System clotting rate: Approximately 3% with prophylactic equipment changes
• Blood loss if clotting occurs: 100-250 mL per event
• Effectiveness: Slightly reduced compared to heparinized dialysis
• Cost: Higher due to equipment changes and increased nursing time

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Low-Dose Heparin Strategy (Intermediate Risk)

For patients with moderate bleeding risk who can tolerate some systemic anticoagulation, use reduced-dose heparin 4, 6.

Approach 4, 6

• Omit or reduce the initial bolus dose to avoid immediate anticoagulant spike
• Use maintenance infusion only at lower rates (250-750 units/hour)
• Monitor activated partial thromboplastin time (aPTT) regularly 4

Evidence Base

• Low-dose heparin shows lower bleeding rates (10%) compared to regional heparin (19%) in high-risk patients 6
• Similar circuit clotting rates (3-5%) compared to standard protocols 6

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Special Considerations

Recent Intracranial Hemorrhage 4

• Discontinue all anticoagulants for at least 1-2 weeks after event
• If dialysis urgently needed: Use heparin-free technique or regional citrate
• When anticoagulation must resume: Intravenous heparin at reduced doses may be safer than oral anticoagulation

Patients with Past History of HIT (>100 Days) 3

• If HIT antibodies are absent: Short-term heparin re-exposure may be considered for single procedures 3
• If HIT antibodies still present: Use regional citrate or alternative non-heparin anticoagulants 3
• For ongoing dialysis: Regional citrate preferred over heparin 3

Monitoring Requirements 4, 8

• Activated clotting times to guide heparin dosing in standard protocols
• Platelet counts periodically in all patients receiving heparin
• Hematocrit and occult blood in stool for bleeding surveillance
• Individual dose titration required as patient responses to heparin vary markedly 8

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Common Pitfalls to Avoid

• Do NOT use low molecular weight heparins (LMWHs) without anti-Xa monitoring in dialysis patients due to accumulation risk and bleeding complications 1, 9
• Do NOT use fondaparinux or rivaroxaban in acute HIT with dialysis due to renal dependence 3
• Do NOT use regional citrate for acute HIT requiring systemic anticoagulation 3
• Do NOT assume heparin-free dialysis is as effective as standard protocols—it requires closer monitoring and equipment changes 5
• Do NOT use dabigatran in dialysis patients (80% renal elimination, contraindicated when CrCl <15 mL/min) 1