Heparin Infusion (Unfractionated)

Dilution guide

Indication

ACS, PE, DVT, bridging anticoagulation.

Preparation

25 000 U in 500 mL NS (50 U/mL).

Dilution

25 000 U / 500 mL → 50 U/mL

Rate

Bolus 80 U/kg (max 5000 U), then 18 U/kg/h; titrate to APTT 1.5–2.5× control or anti-Xa 0.3–0.7.

Monitoring

  • APTT q6h until therapeutic, then daily
  • Platelets (HIT screen)
  • Hb

Common errors

  • Confusing low/high concentration vials
  • Missing weight-based bolus

Pearls

  • Protamine 1 mg per 100 U heparin (last 2 h) for reversal
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