Venous Thromboembolic Prophylaxis: A Trauma Surgeon's Perspective

Richard E. Buckley, M.D., FRCSC
Calgary, AB

There are many venous thromboembolism risk factors in trauma. These include: spinal cord injury, pelvic and spine fractures, head trauma, femoral venous line or vascular repair, multiple operations, older age (greater than 50 years), immobility (greater than three days), and lower extremity fractures. "Lower extremity fractures" is vague, but there is increasing incidence of clot likelihood after injury to the hip and pelvis with diminishing incidence down to the ankle. The risk becomes high enough that we must use thromboembolic prophylaxis at the level of the tibial plateau1. Tibial plateau fractures have venographic proven clots as much as 40% of the time in an occult group of non-prophylaxed patients6. When there is a prolonged operating time of greater than 100 minutes, or delay from injury to open reduction of more than 27 hours, there is twice the risk of DVT5,6.

Screening trauma patients for DVT detects more DVT, but it does not reduce pulmonary embolism or death. It should not be routine, but selective. Ultrasound screening is reasonable for patients who are unable to be prophylaxed (combination of intracranial bleed and lower extremity fracture, or if a patient is transferred from elsewhere and prophylaxis is not optimal). Patients should never have their low-molecular-weight heparin prophylaxis withheld before surgery. They should receive it the day/night before and it should be quick acting, low-molecular-weight heparin1.

A study by Borer (2005) demonstrated that routine screening protocols are not effective in preventing DVT/VTE. Routine screening is also not cost effective. This study involved almost 500 patients with pelvis and acetabular fractures2

A review of hip fractures in 2007 demonstrated that regional anaesthesia and general anaesthesia appear to produce comparable risks for most of the VTE outcomes studied. There is no evidence that regional anaesthesia reduces long-term mortality. It may reduce short-term mortality4.

For the trauma patient, the bleeding risk is during the first 24-36 hours perioperatively. The thrombosis risk climbs immensely 24-48 hours after surgery. It is during this time that early surgery must be performed in association with preventative thromboprophylaxis. Thus, the bleeding risk can be minimized (early surgery), but thrombosis risk can also be minimized (by timely prevention and thromboprophylaxis).

Early initiation of low-molecular-weight heparin is recommended in trauma, but contraindications include: intracranial bleeding, persistent uncontrolled active bleeding and incomplete spinal cord injuries. Notably, head injuries without hemorrhage are not contraindications, nor are complete spinal cord injuries, laceration of internal organs, or pelvic fractures1.

There is no evidence that prophylactic IVC filters are needed in any trauma group. The key word here is prophylaxis. They are indicated if other means of pharmacologic prophylaxis cannot be utilized. Filters don't reduce DVT risk, but in fact, increase DVT risk and they do not eliminate the need for an anticoagulant. They cost enormous amounts of money and need to be removed. Their only indication is that of recent proximal DVT, plus an absolute contraindication to full anticoagulation. A removable filter should also always be used1,3.

With regard to duration of prophylaxis in trauma, post-discharge prophylaxis would involve enormous risk, cost and logistics. There is very little evidence-based data about how long there should be aggressive in-hospital prophylaxis. Once a patient is mobilized there is no need for post discharge prophylaxis with any trauma patient if they do not have other indications for its use1.

Pharmacologic methods of prophylaxis include:

  1. Low-molecular-weight heparin.
  2. Enoxaparin: 40 mg sc, Q day, or 30 mg sc Q 12-8h.
  3. Dalteparin: 5000 units sc daily.
  4. Tinzaparin: 3500 units sc daily.
  5. Heparin: 5000 units sc, Q 12h or Q 8h.
  6. Fondaparinux: 2.5 mg sc, once daily1.

For virtually all patients (except those who have isolated fractures below the tibial plateau level where prophylaxis is not indicated), the recommended prophylaxis is low-molecular-weight heparin, sc, once daily, except in patients over the age of 80 or with a weight of less than 40 kg (half usual dose). The other exception is in patients who weigh more than 100 kg, or high risk trauma patients (spinal cord injury or major orthopaedic trauma) where the usual dose should be doubled1.

Aspirin is cheap, generally safe, and can be continued after discharge. However, it is not nearly as effective as the alternatives and it involves complications and deprives patients from more effective prophylaxis.

A.        Summary1

  1. There is no gold standard in 2008. Each Department/Division should set up VTE protocols and stick to them.
  2. Present Suggestions for Prophylaxis:
    a. Isolated fractures below the knee - No prophylaxis needed.
    b. Isolated fractures above the knee - Definitely require prophylaxis.
    c. Multiple trauma - Definitely require prophylaxis.

B.        What type of Venus Thromboembolic Prophylaxis

  1. Pharmacologic prophylaxis works best.
  2. Alternatives:
    a. Mechanical compression devices - Little evidence of their effectiveness.
    b. IVC filter only when indicated in situations where no other form of pharmacologic prophylaxis may be used (the filter must also be removed when anticoagulation is possible).
    c. Foot pumps - Little evidence of their effectiveness.

C.        Duration of Prophylaxis

Community standard suggests prophylaxis until patients are mobile and discharged from hospital.

References

  1. Geerts W.H., et al, Chest, 2008; 133:381S-453S.
  2. Borer D.S., et al, J Orthop Trauma, 2005; 19:92-95.
  3. Cherry R., et al, J Trauma, 2008; 65:544-548.
  4. Nathens A., et al, J Trauma, 2007; 62:557-562.
  5. Abelseth G., Buckley R., J Orthop Trauma, 1996; p 230-235.
  6. Goel D., Buckley R. et al, JBJS (B), in publication.

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