Intraoperative IV Heparin Dosing
For cardiovascular surgery requiring cardiopulmonary bypass, administer an initial bolus of at least 300-400 units/kg IV heparin, targeting an activated clotting time (ACT) >400 seconds. 1 For peripheral vascular and non-cardiac arterial procedures, use 100-130 units/kg IV bolus targeting an ACT >200 seconds (ideally 250-300 seconds). 2, 3
Cardiovascular Surgery with Cardiopulmonary Bypass
- Administer a minimum of 150 units/kg IV heparin as the initial bolus. 1
- For procedures estimated to last <60 minutes, give 300 units/kg. 1
- For procedures estimated to last >60 minutes, give 400 units/kg. 1
- The higher doses (300-400 units/kg) are strongly preferred based on the FDA label guidance for total body perfusion during open-heart surgery. 1
Percutaneous Coronary Intervention (PCI)
Without Glycoprotein IIb/IIIa Inhibitors
- Administer 70-100 units/kg IV bolus targeting ACT >300-350 seconds. 4
- The European Society of Cardiology recommends 70-100 units/kg when no GP IIb/IIIa inhibitor is planned. 4
With Glycoprotein IIb/IIIa Inhibitors
- Reduce the bolus to 50-70 units/kg IV targeting ACT >200-250 seconds. 4
- This lower dose reduces bleeding risk while maintaining adequate anticoagulation when combined with GP IIb/IIIa antagonists. 4
Peripheral Vascular and Non-Cardiac Arterial Procedures
- Administer 100-130 units/kg IV bolus as the initial dose. 2, 3
- Target ACT should be maintained at >200 seconds, ideally 250-300 seconds. 2, 3
- An initial dose of 100 units/kg achieves adequate ACT (≥200 seconds) in 78% of patients after 5 minutes. 3
- Approximately 11% of patients require additional heparin beyond the initial bolus to achieve adequate anticoagulation. 5
ACT Monitoring and Supplemental Dosing
Timing of ACT Measurements
- Measure baseline ACT before heparin administration. 2, 6
- Obtain the first post-heparin ACT at 5 minutes after the initial bolus. 2, 3
- Maximum heparin effect occurs later than 5 minutes; consider waiting 10-15 minutes before supplementing. 6
- Recheck ACT every 30-60 minutes during prolonged procedures. 2
Supplemental Heparin Dosing
- If ACT remains <200 seconds at 5 minutes, administer additional heparin using the patient's dose-response curve. 2
- Approximately 21% of patients require supplementation within 2 hours to maintain adequate ACT. 2
- After one additional dose, 91% of patients achieve ACT ≥200 seconds. 3
Target ACT Values by Procedure Type
| Procedure Type | Target ACT | Initial Heparin Dose |
|---|---|---|
| Cardiopulmonary bypass | >400 seconds | 300-400 units/kg [1] |
| PCI without GP IIb/IIIa | >300-350 seconds | 70-100 units/kg [4] |
| PCI with GP IIb/IIIa | >200-250 seconds | 50-70 units/kg [4] |
| Peripheral vascular surgery | >200 seconds (ideally 250-300) | 100-130 units/kg [2,3] |
Critical Pitfalls to Avoid
- Do not rely on a fixed 5,000 or 10,000 unit bolus. Weight-based dosing is essential as individual response to heparin is highly variable and unpredictable. 2, 5, 6
- Do not supplement heparin based solely on a 5-minute ACT. Maximum heparin effect may not occur until 10-15 minutes after administration. 6
- Do not assume adequate anticoagulation without ACT monitoring. An initial 10,000 unit bolus results in inadequate ACT (<300 seconds) in 11% of PCI patients. 5
- Monitor for heparin resistance. Patients show both initial sensitivity/resistance and variable rates of heparin consumption requiring individualized supplementation. 2