Weight-based heparin nomogram (Raschke)
Initial bolus and infusion, and aPTT-guided rate changes, for unfractionated heparin.
Inputs
1 of 3Actual (total) body weight
Indication
Step
Needed to adjust.
units/kg/h
Needed to adjust.
seconds
Patient values are shared with every calculator.
When to use
- Starting or adjusting a heparin infusion when the institution uses an aPTT nomogram.
Pearls and pitfalls
- aPTT targets depend on the local reagent; follow the institution's calibrated range or anti-Xa 0.3–0.7 units/mL.
- Check aPTT 6 hours after any change.
- Use actual body weight; many protocols cap the dosing weight.
Why use
The published nomogram with the arithmetic, so the dose is checkable at the bedside.
VTE: 80 units/kg bolus, 18 units/kg/h. ACS: 60 units/kg (max 4000), 12 units/kg/h (max 1000). Adjust by aPTT.