Pulmonary Embolism (DVT/PE)
Clot formation within the deep venous system, usually of the calf, thigh, or pelvic veins. The clot can cause a local problem at site of formation or dislodge, leading to thromboembolism in various parts of the body, particularly the lungs
(pulmonary embolism).
Causes
- Venous stasis (slowing of blood flow)
- Increased coagulability states
- Endothelial injury
Risk factors
- Immobilisation, prolonged bed rest, surgery, limb paralysis
- Heart failure, myocardial infarction
- Blunt trauma, venous injury including cannulation
- Oral contraceptive pills, pregnancy and postpartum
- Malignancies and chemotherapy
- Long distance air travel
Clinical features
- 50% of cases may be clinically silent
- Pain, swelling and warmth of the calf, thigh, and groin
- Dislodgement of the thrombus may lead to pulmonary embolism characterised by dyspnoea, tachycardia, chest pain, hypotension
- Half of the cases of PE are associated with silent DVT
Differential diagnosis
- Cellulitis, myositis, phlebitis, contusion
- For PE: any other cause of dyspnoea and chest pain
Investigations
- Compression ultrasound +/- doppler
- In case of pulmonary embolism: chest CT angiogram
- Other useful tests (not specific): blood D-dimer, ECG, Chest X ray, echo cardiogram
Management
- Enoxaparin (Low molecular weight heparin-
LMWH) 1 mg/kg every 12 hours for at least 5 days- No monitoring is required
- Plus warfarin 5 mg single dose given in the evening, commencing on the same day as the heparin
- Maintenance dose: 2.5-7.5 mg single dose daily, adjusted according to the INR 2 -3
If enoxaparin not available
- Unfractionated heparin given as: 5000 units IV bolus and then 1000 units hourly or 17500 units subcutaneuosly 12 hourly for 5 days. Adjust dose
according to activated partial thromboplastin time (APTT) - Or 333 units/kg SC as an initial dose followed by 250 units/kg SC every 12 hours
- Plus warfarin as above
Notes
- Monitor for bleeding complications
- See section for treatment of warfarin overdose and PGD 2015 monograph on protamine for excessive heparin dose
- Do not start therapy with warfarin alone because it initially increases risk of thrombus progression
Prevention
- Early mobilisation
- Prophylaxis with enoxaparin 40 mg SC daily in any acutely ill medical patient and in prolonged admission