Heparin

Uses
Prophylaxis of DVT and PE
Treatment of DVT and PE
Extracorporeal circuits

Contraindications
Haemophilia and other haemorrhagic disorders
Peptic ulcer
Cerebral haemorrhage
Severe hypertension
Severe liver disease (including oesophageal varices)
Severe renal failure
Thrombocytopenia
Hypersensitivity to heparin

Administration
• Prophylaxis of DVT and PE
   SC: 5000 units 8–12 hourly until patient is ambulant
• Treatment of DVT and PE
   IV: Loading dose of 5000 units followed by continuous infusion of
   1000–2000 units/h
   20 000 units heparin in 20 ml undiluted (1000 units/ml). Check APTT
   6 h after loading dose and adjust rate to keep APTT between 1.5 and
   2.5 times normal (or 2–3 depending on laboratory reference range)
   Start oral warfarin as soon as the patient is stable.

Unfractionated heparin nomogram:

APTT ratio	Infusion rate change (NB: do NOT use this for heparin infusion post-acute MI)
>7	Stop for 1 h, recheck APTT ratio and then
5.1–7.0	Reduce by 500 units/h
4.1–5.0	Reduce by 300 units/h
3.1–4.0	Reduce by 100 units/h
2.6–3.0	Reduce by 50 units/h
1.5–2.5	NO CHANGE
1.2–1.4	Increase by 200 units/h
< 1.2	Consider 2500 units IV bolus, increase by

• Haemofiltration
  1000 units to run through the system. Then a bolus of 1500–3000
  units injected into the pre-filter port, followed by 5–10 units/kg/h
  infused into the pre-filter port
  Dose is dictated by clinical need and filter life (ideally at least 2–3 days)

Adverse effects
Haemorrhage
Skin necrosis
Thrombocytopenia
Hypersensitivity
Osteoporosis after prolonged use

Cautions
Hepatic impairment (avoid if severe)