Deep Vein Thrombosis

Deep vein thrombosis can be a problem for anyone travelling for a long time in a sitting position, such as in a car or on a flight.

The muscles in the legs naturally pump blood back up from the ankles while you are moving about. But when you are flying the blood flow through the legs is reduced, because of the fact that you are sitting still for so long. There is also constant pressure on the back of the legs from the seat, and this also reduces the circulation back from the ankles. Cramped seating and a lack of leg room also mean that you don't have much chance to move your legs. Sleeping on a flight makes things worse still.

The result is that blood flow through the legs is reduced, and the blood moves more slowly, and is more likely to form a blood clot, which can clog a vein in the leg, and form a deep vein thrombosis (DVT).

The effect of this in most healthy people on short flights of less than four hours is nothing to worry about, but it is still a very good idea for everyone to tense the muscles in their legs regularly, and take some time to stretch their legs, especially on a long flight.

It is also a good idea to moderate the amount of alcohol, tea and coffee that you drink, as these can all help to dehydrate you, and this thickens the blood, and can increase the risk of blood clots. The dry atmosphere caused by the low humidity in the aircraft also dehydrates you more quickly. Drinking water or dilute squashes helps to keep you well hydrated, and reduces the risk of clots.

However if you have a risk factor which makes you more prone to deep vein thrombosis (DVT) then it is a good idea to use specially designed socks which gently squeeze your ankles, as this helps improve the blood flow back up the legs from the ankles. Ordinary socks that are just tight is not the answer, as to work properly the socks need to squeeze more at the ankles than further up the leg, and so must be carefully designed and accurately made.

Some risk factors that have been identified are -

• Passengers on flights of four hours or more duration
• People over 40 years of age
• People over six feet tall, or under five feet tall
• People with varicose veins
• People with heart disease
• People suffering from cancer
• Those with a history of blood clots
• Those who have recently undergone surgery
• Those who have had recent leg injuries
• Women taking the contraceptive pill

If you are in doubt about the health risks of you flying, then you should consult your doctor, who can give you individual advice.

If you have pains in your legs after a flight, then you should consult a doctor, and be sure to say that you have flown recently.