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Three Part Question

In [acute ischaemic limbs] is [low molecular weight heparin better than unfractionated heparin] at [improving outcome]?

Clinical Scenario

A 62 year old man with a longstanding history of peripheral vascular disease and atrial fibrillation presents to the emergency department with a 2 hour history of severe pain in the left forefoot. Examination reveals a cool, pale, pulseless left foot. You wonder whether low molecular weight or unfractionated heparin is better in this patient.

Search Strategy

Medline 1951 to September week 4 2005 using the DialogDatastar interface on ATHENS
Embase 1974 to September week 4 2005 using the DialogDatastar interface
Medline: ((Acute AND (ARTERIAL-OCCLUSIVE-DISEASES.DE.)) AND ((LEG.W..DE. OR LOWER-EXTREMITY.DE.) OR (UPPER-EXTREMITY.DE.))) AND (HEPARIN-LOW-MOLECULAR-WEIGHT.DE. OR HEPARIN.W..DE.). 13 papers found
Embase: (acute AND (LIMB-ISCHEMIA.DE.)) AND (HEPARIN.W..DE. OR LOW-MOLECULAR-WEIGHT-HEPARIN.DE.). 104 papers found

Search Outcome

Of the 104 papers found with Embase, 93 papers were irrelevant and the remaining corresponded with the 11 papers of relevance found with the Medline search. however, none of the 11 papers contained any data to answer the question posed.

Comment(s)

By consensus, the treatment of acute arterial thrombosis has been considered to be high dose anticoagulation and attempted revascularisation, depending on limb viability and the patient's condition, as opposed to acute occlusive embolism where an urgent thrombo-embolectomy may be indicated. However, differentiating between the two may be impossible in many cases. Faced with this situation, one may ask whether a therapeutic dose of LMWH is a safer alternative to unfractionated heparin.

Clinical Bottom Line

There have been no studies to investigate this question, and until further research sheds more light on this topic, an initial intravenous dose of 5000 IU of heparin remains the gold standard as part of the acute management of limb ischaemia.