The Doctor's notebook | Action Medical Research

Touching Lives - June 2007

The Doctor's notebook

What is DVT?

Now that the holiday season is upon us and airports are full of people jetting off to exotic locations, it’s an opportune time to address deep vein thrombosis (DVT) — a blood clot that can be caused by long periods of immobility such as long-haul flights. In extreme cases, it may lead to a pulmonary embolism (clot on the lung).This is the result of small pieces of the clot detaching and travelling through the bloodstream to the lungs, and can result in shortness of breath, chest pains and even sudden death.

How to spot it

DVT is quite difficult to spot, as the symptoms tend to be similar to a range of other conditions. It can cause swelling and discolouration of the affected area, usually the lower leg, yet there may be no symptoms at all. A type of ultrasound called Doppler ultrasound can show how fast blood is flowing in a vessel, and thus indicate if someone might be suffering from a DVT.

Those at risk

With the number of long-haul flights ever increasing, the number of individuals at risk from DVT has also naturally increased. Despite being dubbed ‘economy class syndrome’ by the media, the condition can also affect first class passengers, though the cramped seating found in standard class may increase the risk. It’s not exclusively limited to long-haul air passengers either — any mode of transport that entails long periods of immobility could be a danger. Some people are also more susceptible than others. As a general rule, the risk is greater over the age of 40, and this can be compounded by other factors, including previous thrombotic episodes, recent surgery, dehydration, congestive heart failure and pregnancy or having recently had a baby. Research has also suggested that smoking, obesity and varicose veins can increase the risk of developing DVT in-flight. For people without a predisposing condition though, travellers most at risk are those who fail to move around and exercise during the flight.

Preventing DVT

There are various ways to minimise the risk of developing DVT when flying. Regularly standing up and moving about the aircraft can be difficult with the trolley services and hundreds of other passengers on the plane. My advice is to start seated with both feet flat on the floor, raise the toes and then lower the toes and raise the heels — toes up, heels up, toes up, heels up! This contracts the lower leg muscles that then contract your leg veins to keep the blood flowing to prevent DVT. Keeping the feet elevated by use of the seat’s footstool is also advised, but still keep doing ‘toes up, heels up’ as often as you can. Elastic flight socks are especially designed to reduce the risk of DVT, and are available from pharmacies.They work by applying a gentle pressure round the ankles, which helps push the blood back up from the leg veins to the heart. Drink plenty of water throughout the flight and try to avoid alcohol and diuretics such as coffee and cola, as dehydration is another risk factor.Taking one low-dose aspirin the day before and the day of the flight may also help prevent clotting.


DVT can be treated with blood thinning agents (anticoagulants) such as warfarin and heparin. Low doses of aspirin are believed to have a similar effect, although this is not conclusively proven.The treatment of established DVT is by administering an enzyme called tissue plasminogen activator, which dissolves the clot.

Rare condition

It is important to stress that DVT is actually quite rare, and should not put people off air travel. Only a tiny minority should ever need medication in-flight to prevent it, and for most of us, simple precautions such as stretching the legs every half hour are the best advice to follow. If you have any concerns at all about DVT, or your risk of developing it, consult your doctor. TL

For information and advice on a wide range of health topics, visit Dr Steele’s website

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