Friday 23 June, 2006

Index: Anticoagulation

Posted in Best Topics, Michael Tam at 18:37 by Michael Tam

Original article by: Michael Tam

Our nemesis…
…the clot

This is an index page linking a series of articles on anticoagulation.

The delicate balance rages within the human body. At any one time, we are simultaneously at risk from both bleeding to death and transforming into one huge blood clot. The fact that we manage to stay alive at all is quite remarkable.

Anticoagulation with a number of different agents and dealing with the subsequent side-effects of our ministrations is neither simple nor done particularly well by many junior medical staff. In particular, warfarin regimens and adjustments of doses are often based more on voodoo and prayer to the warfarin god, than on any basis in evidence.

Hopefully, this series of articles will help bring some light to this murky field. More so than many of my other articles, I’ve tried to reference the evidence base for therapy.



  1. AmyWong said,

    How long should I use anticoagulation for DVT prophylaxis in sedentary elderly who’s s/p ORIF for intertrochanteric fx, indefinitely or 9-12 months?

  2. Michael Tam said,

    Firstly: Please read the disclaimer

    I am not a general physician, a haematologist or a trainee in either of those specialties. The following is from my experience and what I understand of the treatment of this condition.

    There is no easy answer to your question.

    The guidelines as per the most recent (seventh) American Conference of Chest Physicians (1) say that there is good evidence that post major orthopaedic (hip and knee) surgery, patients should have DVT prophylaxis for at least 10 days (with the best evidence for fondaparinux), usually with a low molecular weight heparin like enoxaparin. See my article on “anticoagulation for prevention of thromboembolism” (2).

    The difference between the recommendations of the seventh and sixth conference is that there is evidence to show that there is benefit in the DVT prophylaxis being extended to up to 30 days with a small reduction in the rate of lower limb DVT and pulmonary embolism.

    Pragmatically, I would recommend DVT prophylaxis with LMWH (enoxaparin sodium) for up to 30 days if the patient remains an inpatient. It is common practice for anticogulation to be ceased if the patient is sufficiently mobile for discharge home. Be aware however, that DVT prophylaxis should be given for a minimum of 10-14 days and it would probably be considered negligent if it were discontinued early (for example for an early discharge). Despite what some orthopods may think, aspirin should never be used alone for the purpose of venous thromboembolic prophylaxis (1) (2).

    With regards to the elderly patient who has a prolonged post-operative course, I have had quite a lot of experience during my work in rehabilitation. As per above, I would recommend DVT prophylaxis with enoxaparin for up to 30 days post-operatively. Unless there is an “acute” medical reason for continued inpatient care (as opposed to poor mobility), anticoagulation for DVT prophylaxis can (and arguably should) be discontinued at this stage. TEDS can probably be continued to be used though their efficacy on their own is questionable.

    If the patient develops an acute medical condition or complication during their rehabilitation (or, while awaiting a community placement option), then as per usual for acutely unwell medical patients, anticoagulation for DVT prophylaxis should be considered (with either unfractionated heparin or LMWH) (1).

    Remember, the otherwise well nursing home patient is not anticoagulated for the purposes of DVT prophylaxis in the community. There is no reason why an equivalent patient in hospital needs anticoagulation with heparin.

    The use of heparin even at prophylaxis dosage does significantly increase the risk of bleeding complications, especially if aspirin and/or NSAIDs are used concurrently.

    Reference articles

    (1) Geerts WH., Pineo GF., Heit JA., et al. Prevention of venous thromboembolism: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest. 126(3 Suppl):338S-400S, 2004 Sep.

    (2) Tam M. Anticoagulation for prevention of thromboembolism [electronic article]. The Medicine Box. Last updated 19 June 2006. [Link]

  3. AmyWong said,

    Hi Michael Tam,

    Thank you for your response. Although I was trained in the US, I find practicing here in Canada is very similiar. Both use the same guidelines.

    regards, Amy Wong

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