What is the protocol for heparin reversal in cardiac surgery patients?

Heparin Reversal Protocol in Cardiac Surgery

For cardiac surgery patients, protamine should be administered at a dose of 1.0-1.3 mg per 100 U of heparin initially administered, with individualized dosing based on ACT or heparin concentration measurements to avoid both under-reversal and protamine overdosing. 1

Standard Protamine Dosing Protocol

Initial Protamine Dosing

• For operations with short CPB duration (<90 minutes):
  • Use fixed-dose ratio: 1.0-1.3 mg protamine per 100 U heparin administered 1
  • Maximum protamine dose: 50 mg 1

Longer Operations (>90 minutes)

• For longer CPB duration, use one of these methods:
  • ACT-HDRC method (Heparin Dose Response Curve) 1
  • Heparin-protamine titration method 1
  • Target protamine-to-heparin ratio between 0.8-1.0 of initial heparin dose 1, 2

Administration Technique

• Administer protamine slowly to avoid hypotensive and anaphylactoid reactions 3
• Infuse over 5-10 minutes to minimize adverse reactions
• Have facilities to treat shock available 3

Post-Protamine Monitoring

Confirmation of Adequate Reversal

• Measure ACT or heparin level 5-10 minutes after protamine administration 1
• If evidence of residual heparin exists, administer additional protamine and recheck 1

Monitoring for Heparin Rebound

• Continue monitoring for potential heparin rebound (can occur 30 minutes to 18 hours after surgery) 3
• If bleeding occurs or coagulation tests indicate residual heparin, additional protamine may be needed 3

Special Considerations

Protamine Overdosing Prevention

• Avoid protamine-to-heparin ratios >1.0 as this can cause:
  • Coagulation abnormalities
  • Impaired restoration of post-protamine thrombin levels
  • Enhanced postoperative bleeding 1, 2
• Recent evidence suggests that even lower protamine doses (0.56:1 over total heparin dose) may be sufficient 4

Heparin Resistance Management

• For patients unable to achieve ACT >300 seconds despite >600 U/kg heparin:
  • Consider AT III deficiency
  • Treatment includes fresh-frozen plasma or AT III concentrate 1

Alternative Anticoagulation

• For patients with heparin contraindications (e.g., HIT, severe protamine allergy):
  • Use direct thrombin inhibitors: bivalirudin or argatroban
  • For bivalirudin: target ACT 2.5 times baseline during CPB
  • No specific reversal agents available for direct thrombin inhibitors 1
  • For HIT patients requiring CPB: consider intravenous antiplatelet agents (tirofiban or cangrelor) with heparin, or plasma exchange 2

Emerging Evidence

Recent research suggests that fixed protamine dosing (250 mg) may be comparable to ratio-based dosing in terms of achieving target ACT while conserving protamine, though this approach needs further validation before widespread implementation 5.

The use of Hemostasis Management System (HMS) for individualized heparin and protamine titration typically results in decreased protamine doses (up to 44% reduction over total heparin dose), potentially limiting protamine side effects including paradoxical anticoagulation 4.