A life-threatening clot

While not a disease in itself, PE corresponds to the respiratory complication of blood clots formation (also called thrombosis), usually occurring in the deep veins of the legs and known as Deep Vein Thrombosis or DVT. About 50 per cent of DVT lead to pulmonary embolism

Today PE represents a public health issue: in a country like France with a population of 65 million, more than100,000 cases occur every year and the mortality rate is around 15 per cent. 

The typical form in usually easy to diagnose but in most cases, the symptoms of PE are non-specific and rather misleading, which delays diagnosis and exposes the patient to rapid and life-threatening complications. 

The embolism occurs when a fragment or the entire DVT detaches from the vein of the limb and travels up through the circulatory system to the right side of the heart to become wedged in a pulmonary artery. A large clot results in a massive embolism of one of the main pulmonary arteries triggering a major disturbance in blood oxygenation and causing cardio-respiratory shock. Fortunately, in most DVT cases, the PE is the result of small clots, leading to fewer and less impressive symptoms. Left untreated, a minor PE can however worsen to a more serious condition especially in the elderly. 

The typical symptoms of severe PE are acute chest pain, shortness of breath and signs of circulatory failure with hypotension, accelerated heart rate, anxiety and general body weakness. Less dramatic PE may present moderate chest discomfort, abdominal pain, cough with blood sputum, sweating, agitation or syncope. 

Any suspicion of PE should prompt a clinical examination of the lower limbs to look for DVT. The common DVT signs are pain, oedema and skin changes in one leg. An ultrasound of the deep vein circulation quickly confirms the DVT. The discovery of DVT in a patient presenting chest pain is highly suggestive of PE. 

Diagnosis is confirmed with a chest CT scan, which visualises the clot and assesses the degree of severity of the blood flow obstruction.

There are many predisposing factors linked to a higher risk of clot formation. Conditions causing slower venous blood flow such as venous insufficiency (varicose veins), weak cardiac function and prolonged immobilisation, for example in patients who remain bedridden following surgery or injury or in long haul travel; procedures damaging the vein structure such as after orthopaedic or abdominal surgery, trauma or due to vein-toxic chemotherapies; inherited blood diseases and some medicines such as oestrogen pills, which cause abnormal levels of key substances involved in clot formation. Pregnancy, smoking, obesity and cancers also increase the risk of blood clots.

Treatment of PE requires anticoagulant treatment, which is initially given intravenously and then orally for at least 3 to 6 months. Given early, anticoagulants reduce PE mortality to less than 5 per cent. More serious PE may be treated with clot dissolving agents (called fibrinolytics) or with interventional or surgical procedures to directly remove the clot.

Prevention of PE is based on the prevention of clot formation. Preventive anticoagulation is routinely carried out during many surgeries. During prolonged immobility such as a long flight, it is recommended to stand up and walk as often as possible and at least every couple of hours, drink a lot of water to prevent dehydration and limit or refrain from alcohol or coffee which favour dehydration. 

Compression stockings can also help. If pain suddenly occurs in a swollen leg during a flight, the person should lie down until the medical team arrives. An anticoagulant may be proposed for those at high risk of blood clots on long-haul flights. 

 

DR GERARD LALANDE is Managing Director of CEO-HEALTH, which |provides medical referrals for expatriates and customised executive |medical check-ups in Thailand. He can be contacted at [email protected]