Recommended Heparin Perfusion Dosing
For venous thromboembolism (VTE), the recommended heparin perfusion dose is an initial bolus of 80 units/kg followed by a continuous infusion of 18 units/kg/hour, with dose adjustments based on aPTT monitoring. 1
Initial Dosing Recommendations by Indication
For Venous Thromboembolism (DVT/PE):
- Initial bolus: 80 units/kg IV (maximum not specified in guidelines)
- Initial infusion: 18 units/kg/hour 1
- Alternative fixed-dose approach: 5,000 units IV bolus followed by infusion of at least 32,000 units/day 1
For Acute Coronary Syndromes:
- Initial bolus: 60-70 units/kg IV (maximum 5,000 units)
- Initial infusion: 12-15 units/kg/hour (maximum 1,000 units/hour) 1
For ST-Elevation Myocardial Infarction with Fibrinolytic Therapy:
- Initial bolus: 60 units/kg IV (maximum 4,000 units)
- Initial infusion: 12 units/kg/hour (maximum 1,000 units/hour) 1
Monitoring and Dose Adjustment
The FDA label recommends adjusting heparin dosage according to coagulation test results, with a target aPTT of 1.5-2 times normal (approximately 50-70 seconds) 2. This therapeutic range is based on evidence showing that patients who achieved therapeutic aPTT in less than 24 hours had lower mortality rates 1.
aPTT-Based Dose Adjustment Protocol:
| aPTT (seconds) | Bolus (U/kg) | Hold (min) | Rate Change | Repeat aPTT |
|---|---|---|---|---|
| < 50 | 50 | 0 | ↑ 10% | 4 hours |
| 50-59 | 0 | 0 | ↑ 10% | 4 hours |
| 60-85 (target) | 0 | 0 | No change | Next day |
| 86-95 | 0 | 0 | ↓ 10% | 4 hours |
| 96-120 | 0 | 30 | ↓ 10% | 4 hours |
| > 120 | 0 | 60 | ↓ 15% | 4 hours |
| [3] |
Special Considerations
Obesity:
- Standard weight-based protocols with maximum doses can lead to significant delays in achieving therapeutic anticoagulation in obese patients 4
- Underdosing is common in obese patients, with 89% receiving lower than recommended bolus doses and 76% receiving inadequate initial infusions 4
Pediatric Patients:
- Initial bolus: 75-100 units/kg IV over 10 minutes
- Maintenance infusion:
- Infants < 1 year: 28 units/kg/hour
- Children > 1 year: 18-20 units/kg/hour 3
- Target aPTT: 60-85 seconds 3
Cardiovascular Surgery:
- Initial dose: Minimum 150 units/kg
- For procedures < 60 minutes: 300 units/kg
- For procedures > 60 minutes: 400 units/kg 2
Dialysis:
- Initial dose: 25-30 units/kg
- Maintenance infusion: 1,500-2,000 units/hour 2
Pitfalls and Caveats
Delayed Therapeutic Effect: A significant proportion of patients (29%) may take more than 24 hours to achieve therapeutic anticoagulation, especially if underdosed 4
Weight-Based vs. Fixed Dosing: Weight-based dosing has been shown to achieve therapeutic anticoagulation more quickly and effectively than fixed dosing, with lower rates of recurrent thromboembolism 1
Monitoring Frequency: When initiating treatment with continuous infusion, check aPTT at baseline and approximately every 4 hours until stable, then at appropriate intervals 2
Bleeding Risk: Risk increases with higher heparin doses, concomitant use of fibrinolytic agents or glycoprotein IIb/IIIa inhibitors, recent surgery/trauma, and in patients with comorbidities, age >60 years, or hepatic dysfunction 1
Platelet Monitoring: Regular monitoring of platelet count is essential to detect heparin-induced thrombocytopenia 3
By following these evidence-based dosing recommendations and monitoring protocols, you can optimize the efficacy and safety of heparin perfusion therapy for your patients.