Can continuous renal replacement therapy be performed without systemic heparin in patients with high bleeding risk or coagulopathy?

CRRT Without Heparin: Evidence-Based Approach

Yes, CRRT can and should be performed without heparin in patients with high bleeding risk or coagulopathy, using either regional citrate anticoagulation as first-line or no anticoagulation at all if citrate is contraindicated. 1, 2

Recommended Anticoagulation Algorithm

For Patients with Increased Bleeding Risk or Coagulopathy

Regional citrate anticoagulation is the preferred strategy over heparin or no anticoagulation when citrate is not contraindicated (Grade 2C). 1, 2 This approach provides effective circuit anticoagulation without increasing systemic bleeding risk, as citrate acts regionally within the circuit and is metabolized before returning to the patient. 3

If citrate is contraindicated, run CRRT without any anticoagulation rather than using heparin. 2, 4 This is particularly important for patients with:

• Active major bleeding 4
• Severe thrombocytopenia 2
• Recent surgery (<48 hours) 5
• Spontaneous bleeding 5
• Prolonged aPTT >45 seconds 5

Citrate Contraindications to Screen For

Avoid citrate anticoagulation in patients with: 2, 6

• Severe liver dysfunction with inability to metabolize citrate 1, 4
• Shock with muscle hypoperfusion 6
• Baseline severe metabolic abnormalities 6

Performance of Anticoagulation-Free CRRT

Anticoagulation-free CRRT provides acceptable filter lifespan in most high-bleeding-risk patients. 7, 5 A systematic review found no significant difference in filter lifespan between anticoagulation-free and systemic heparin protocols. 7 In one study of post-cardiac surgery patients, 55% of circuits remained patent at 24 hours without anticoagulation, with mean filter life of 38 hours. 5

However, regional citrate anticoagulation is superior to no anticoagulation, providing approximately 23 hours longer filter lifespan and better azotemic control. 7 Meta-analysis demonstrates citrate reduces bleeding risk by 66% compared to heparin (RR 0.34,95% CI 0.17-0.65) with similar circuit survival. 3

Special Population: Heparin-Induced Thrombocytopenia

For patients with confirmed or suspected HIT, immediately stop all heparin products and use direct thrombin inhibitors (such as argatroban) or Factor Xa inhibitors (danaparoid or fondaparinux) (Grade 1A). 1, 2, 4

In HIT patients without severe liver failure, argatroban is preferred over other alternatives (Grade 2C). 1, 2, 4

Monitoring Requirements

For Regional Citrate Anticoagulation:

• Monitor ionized calcium, acid-base status, sodium, and electrolytes every 4-6 hours 6
• Track systemic ionized calcium levels to detect citrate accumulation, especially in liver dysfunction 2
• Monitor for hypernatremia 2
• Follow magnesium levels closely as magnesium-citrate complexes are lost in effluent 2
• Implement strict written protocols with mandatory staff education to prevent prescription errors 2, 6

For Anticoagulation-Free CRRT:

• Monitor circuit pressures and visual inspection for clotting 5
• Assess filter performance and azotemic control 7
• No systemic coagulation monitoring required 5

Common Pitfalls to Avoid

Do not use conventional coagulation parameters (aPTT, PT) to predict filter failure or determine need for anticoagulants before CRRT, as these show poor predictive performance. 7

Avoid regional heparinization during CRRT in patients with increased bleeding risk (Grade 2C). 1 The systemic effects of heparin are unpredictable in critical illness due to antithrombin consumption, heparin resistance, and nonspecific binding to acute phase proteins. 8

Never use subclavian vein access when possible due to high thrombosis and stenosis risk; prefer right internal jugular vein. 6, 4

Evidence Quality Discussion

The KDIGO guidelines provide the strongest framework, with Grade 1B recommendation for anticoagulation in standard patients and Grade 2C for citrate in high-bleeding-risk patients. 1 The 2021 systematic review and meta-analysis provides robust evidence that anticoagulation-free CRRT is feasible with acceptable outcomes. 7 The 2012 meta-analysis of RCTs demonstrates clear superiority of citrate over heparin for bleeding reduction. 3 These converging lines of evidence from guidelines and high-quality research support the algorithmic approach outlined above.