Heparin Titration & aPTT-Driven Nomogram
Order: heparin 18 units/kg/hr. Patient weighs 80 kg. Bag is 25,000 units in 250 mL.
- Pump (mL/hr)
- Heparin bag 25,000/250
- aPTT lab result
- Weight in kg
- 1
Units per hour
18 units × 80 kg = 1,440 units/hr.
- 2
Concentration
25,000 units / 250 mL = 100 units/mL.
- 3
Pump rate
1,440 ÷ 100 = 14.4 mL/hr. Round to pump precision: 14 mL/hr.
- 4
Titrate by aPTT
Recheck aPTT in 6 hr. Adjust by protocol nomogram, never freelance.
70 kg patient on weight-based heparin protocol: bolus 80 u/kg, then 18 u/kg/hr. Bag: 25,000 units in 250 mL D5W. Compute bolus volume, initial pump rate, then re-titrate when aPTT returns at 92 sec (target 60–80): nomogram says decrease rate by 2 u/kg/hr.
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70 kg patient on heparin protocol
Given: 18 units/kg/hr; bag = 25,000 u / 250 mL
- 1
Units per hour
70 × 18 = 1260 u/hr
aPTT high → cut 2 units/kg/hr
Given: New dose 16 u/kg/hr, same 70 kg patient
- 1
New units/hr
70 × 16 = 1120 u/hr