Treatment of Deep Venous Thrombosis

D-dimer

• The body's fibrinolytic system is activated in the presence of thrombosis, which results in an increased concentration of D-dimer in the plasma.
• Elevated D-dimer levels are also present in many conditions other than thrombosis (e.g. severe infection/inflammation, cancer, trauma, surgery, pregnancy). Up to 90% of elderly hospitalised patients have elevated D-dimer concentrations as a consequence of infections and tissue damage.
• A normal D-dimer test result is enough to rule out DVT when, based on clinical presentation, the probability of DVT is no more than moderate.
• A normal D-dimer test result together with a negative ultrasonography result does, however, exclude the possibility of DVT with 90-95% probability.

Ultrasonography

• The investigation is reliable in the diagnosis of proximal DVT (femoral and popliteal veins) but less so in distal DVT.
• In practice, ultrasonography involving only the femoral and popliteal area is sufficient (2-point ultrasonography, videos Compression Ultrasonography of Veins Deep Venous Thrombosis (Compression Ultrasonography)).
• If the ultrasonography result is not consistent with the clinical picture and the D-dimer test is positive, ultrasonography should either be repeated in one week's time or venography is indicated.

Venography

• Venography (a contrast medium examination of the lower limb veins) is indicated if
  • the ultrasonography result is inconclusive
  • laboratory findings are unclear
  • no other explanation can be found for the symptoms.
• Plasma creatinine must be checked.
• The radiation exposure is minimal and, for example, pregnancy is not a contraindication to the investigation. However, an obstetrician should be consulted before the investigation is carried out.

Other laboratory tests

• Before treatment is started, a blood sample should be collected for the analysis of blood clotting factors (thrombophilia screening Evaluation of Thrombophilia and Prevention of Thrombosis) if the following apply to the patient (currently or in the past)
  • a positive family history
  • recurrent or idiopathic (no identified risk factors) thrombosis
  • massive thrombosis
  • a young patient
  • miscarriage
  • thrombi affecting both the venous and arterial vessels.

• The aim of treatment in lower limb DVT is to prevent
  • PE Pulmonary Embolism
  • the development of lower limb vein insufficiency.
• The decision on whether DVT can be treated in the primary health care depends on the clinical picture and the patient's home situation.
• Most cases are treated primarily at the patient's home.
• Hospital treatment is required for
  • DVT with severe symptoms
  • submassive and massive PE.

Management in primary care

• The treatment of both DVT with only a few symptoms and mild PE can be carried out at a health centre, by a district nurse or self administered by the patient. Based on the individual situation, the treating physician will decide where the treatment should be carried out.
  • Obese patients will need two daily injections because of the large doses needed.
  • Patients with several comorbidities or renal failure are usually not suitable for home treatment.
  • The patient must be supplied with written instructions on how to carry out the treatment.
• If treatment is carried out at home, the following must be ensured:
  • correct injection technique and correct dose
  • adequate monitoring of the anticoagulant therapy
  • instructions regarding compression bandages and stockings
  • monitoring the patient for possible complications (bleeding, emboli)
• A follow-up appointment should be made at the latest when the anticoagulant therapy is about to finish.
  • The patient is asked about his/her health and checked for signs of recurrence and post-thrombotic syndrome.

Anticoagulant therapy: dose and duration

• LMWH is principally used to treat
  • DVT below the knee and at the thigh level
  • more proximal thrombi provided no severe symptoms are present
• Dalteparin by subcutaneous injection 100 units/kg twice daily or 200 units/kg once daily.
• Enoxaparin by subcutaneous injection 1 mg/kg twice daily or 1.5 mg/kg once daily.
• Warfarin is started concomitantly, either 5 mg/day or with the estimated maintenance dose for 3 days and then as guided by INR readings.
• Heparin is continued
  • until INR has been within the target range (2.0-3.0) for 2 days
  • in any case for at least 5 days.
• Fondaparinux is an alternative for LMWH. It is suitable for patients with heparin allergy and for the treatment of heparin-induced thrombocytopenia (HIT).
• LMWH is suitable during pregnancy. Breast feeding is not a contraindication to warfarin.
• Patients treated for active cancer can be managed with LMWH for 3-6 months followed by warfarin.
• Duration of anticoagulant therapy, see table T2

Thrombolytic therapy (fibrinolytic therapy)

• Thrombolysis may be attempted if the thrombus
  • is recent (less than 1 week) and
  • extends above the inguinal ligament or proximally in an upper limb thrombosis and
  • causes severe symptoms and significant oedema.
• Thrombolysis can be considered if all the above criteria are fulfilled and the patient is not at an increased risk of bleeding.
• Local, catheter-directed thrombolysis is the treatment of choice if a radiologist competent in the procedure is available.

Surgical treatment

• Surgery is the first-line treatment approach if the viability of the limb is threatened and particularly if both thrombolytic and anticoagulant therapy are contraindicated.

Other treatment

• Immediate bandaging during the acute phase to ensure the competence of the communicating veins
  • Using an elastic bandage, the leg is bandaged from the foot to the knee gradually decreasing the pressure as the dressing advances proximally.
  • The bandage is applied in circular turns; a figure of eight bandage is too tight.
  • Catheter-directed thrombolysis is not a contraindication to bandaging.
  • If the swelling extends to the thigh, the leg should be bandaged up to the groin.
• The patient should mobilise as soon as clinically possible.
• Follow-up treatment with graduated compression stockings (Class II) for at least 2 years reduces the likelihood of post-thrombotic syndrome .
• Patient education