Traveller's thrombosis (DVT)

30 November -0001

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Clotting of blood, usually occurring in the lower legs, is known as deep venous thrombosis (DVT).

This has become known in the press as "economy class syndrome" but the term is misleading.

Individuals seated in cars, buses and trains may all be at risk, and cases of DVT occurring in flight have been reported in travellers in premium cabins as well as economy.

The term 'traveller's thrombosis' is much more accurate.

Research

Reduced blood flow may lead to DVT. Although most of the scientific research relates to hospital patients during the period immediately after surgery, it is clear that prolonged immobility can often be a key factor in the development of a blood clot. Specific studies examining traveller's thrombosis have looked particularly at how many DVT sufferers have travelled in the weeks preceding their diagnosis.

It is clear from the studies of which we are aware, that there is indeed an association between long journeys and the occurrence of DVT. However, thromboses can occur after car, bus, rail or air travel and there is no conclusive evidence that flying in itself is a specific risk factor.

In addition, at least 75% of DVTs in these studies occurred in passengers who already had at least one of the risk factors listed as follows.

Risk factors

Some people are more susceptible to DVT than others. Generally, the risk of thrombosis increases once you are over 40 years of age but there are a number of additional risk factors including:

Previous personal or family history of DVT
Abnormality of blood clotting factors
Certain forms of cardiac disease
Previous history or currently suffering from malignant disease
Hormone treatment including the oral contraceptive pill and oestrogen containing hormone replacement therapy
Pregnancy
Recent major surgery or injury, particularly affecting the lower limbs or abdomen
Recent immobilisation for a day or more

Some research has also suggested that, in addition, there may be an added risk from tobacco smoking, obesity and varicose veins.

Signs and symptoms

DVT is most common in the lower limbs and may occur without any obvious signs or symptoms. The general symptoms, where they occur, are pain, swelling and discolouration of the affected limb. The leg may also feel warm to touch and there may be congestion of the superficial veins.

The clinical diagnosis of DVT is not easy. It can mimic many other medical conditions and expert investigation is required to confirm the diagnosis.

Pulmonary embolism

In some cases, small pieces of clot may detach and be carried through the blood stream to the heart and onward into the lungs causing a pulmonary embolus. This usually occurs only where there is already an extensive clot in the leg and may happen many hours or days after the formation of the clot.

It may result in serious consequences including chest pain, shortness of breath and even sudden death.

Advice

Advice to avoid the development of DVT for all passengers:

Drink adequate fluids
Avoid smoking
Avoid beverages which contain alcohol and/or caffeine both before and during the flight
Avoid crossing legs when seated
Walk around the cabin whenever you can
Stand up in your seat area and stretch your arms and legs
Carry out the foot and leg exercises advised in the Well Being section of the British Airways Highlife in-flight magazine and the Well Being section of the British Airways website
Wear loose fitting comfortable clothes when travelling

If you have any of the additional risk factors listed previously, you should seek medical advice before travelling. In particular, you should discuss:
The advisability of anti-embolic stockings
The advisability of low dose aspirin before flight
The advisability of anti-coagulant medication or other prophylactic measures before flight

More information can be found on this at the British Airways site