Deep Venous Thrombosis (DVT) Factsheet

What is DVT?

Deep venous thrombosis (DVT) is a blood clot occurring in one of the deep veins in a leg. It can occur during surgery and long distance air journeys when it is know colloquially as "economy class syndrome". However, first class passengers are not immune!

DVT is known to be the cause of eleven deaths over three years in the Heathrow neighbourhood, and more elsewhere in the UK.

What Causes DVT?

Sitting or lying in cramped conditions for a prolonged period of time can cause the blood to flow too slowly through the veins of the legs thus causing a clot to form. This is potentially dangerous as the clot can travel through the venous system to the heart and obstruct the lung circulation, sometimes fatally. This is known as pulmonary embolism.

A further factor in a very small proportion of cases is an inherited condition where the blood coagulation process is defective - it is called hypercoagulability - when the blood clots too quickly. This condition is diagnosed by a blood test taken when the patient has suffered from repeated blood clots without apparent cause.

How Do We Prevent a DVT?

Firstly, always take an adult 300mg aspirin tablet on the day you travel. If you are unable to tolerate aspirin, an alternative prescription medication is clopidogrel.

Next, always take some exercise on the aeroplane. A walk around the cabin every hour is the ideal, even on overnight flights. You should also do leg stretching exercises during the flight.

Avoid alcohol and salted nuts on the plane, as they will disturb your water and electrolyte balance. Ensure that you have an adequate water intake on the flight, as there will be increased fluid loss through respiration and perspiration occurring at high altitude. This fluid loss must be replaced so that the blood does not become thick and, as a consequence, more likely to coagulate.

If you know you have a clotting problem, further measures must be taken: compression stockings and heparin-like anticoagulant injections given before travelling.

How Do I Know if I Have a DVT?

The commonest symptom is pain in a calf, together with swelling in the affected leg (not both legs). However, a problem may not become evident until after the journey.

Always see a doctor promptly if you think you have a DVT or suddenly become breathless.

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