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 Clinical Value of Simple Proximal Vein Ultrasonography Plus D-Dimer Vs Whole-Leg Colour Doppler Ultrasonography for the Diagnosis of Deep Vein Thrombosis (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) 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 Home Versus in-Patient Treatment for Deep Vein Thrombosis 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)

• ThrombolysisThrombolysis for Acute Deep Vein Thrombosis 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 Compression Therapy for Prevention of Post-Thrombotic Syndrome.
• Patient education