← Back to All Calculators
Pharmacology / Drug Dosing
Heparin Infusion Protocol

Heparin Infusion Protocol (UFH)

Weight-based unfractionated heparin dosing with aPTT adjustment

Patient & Indication
Required (20–300)
Bolus (units)
Bolus (mL) @100 U/mL
Infusion (units/hr)
Infusion (mL/hr) @100 U/mL
aPTT Adjustment Table (target 50–70 sec)
aPTT (sec)RebolusRate ChangeHold
< 3580 U/kgIncrease by 4 U/kg/hrNone
35–4940 U/kgIncrease by 2 U/kg/hrNone
50–70NoneNo change (therapeutic)None
71–90NoneDecrease by 1 U/kg/hrNone
91–120NoneDecrease by 2 U/kg/hr30 min
> 120NoneDecrease by 3 U/kg/hr60 min
Standard concentration: 25,000 units in 250 mL NS = 100 units/mL. Check aPTT 6 hours after initiation or any rate change. Monitor platelets every 2 days for HIT. For STEMI/PCI, use ACT-guided protocol-specific dosing.

Select a Template for your Cv