Recent news coverage has linked long-haul air travel with the dangers of deep-vein thrombosis (DVT), or blood clots. But are we all at risk, and is there anything we can do to prevent this condition?

In October 2000, a 28-year-old woman collapsed and died after a long-haul flight from Australia to London. Her death was the result of a blood clot, caused by deep vein thrombosis (DVT), which travelled to her lungs. This incident prompted a meeting hosted by the World Health Organisation for doctors and airline officials to discuss the problem. The outcome was that British Airways, and several other airlines, now issue information to passengers before and during flights advising them on general well being in the air.

Deep vein thrombosis is defined as the formation of blood clots, which usually originate in the lower legs. These clots are caused either by poor circulation, or being inactive for long periods of time. DVT occurs as blood collects in the veins of the lower legs, forming a clot. As this clot grows, parts of it, called emboli, can break off and travel through the blood. Complications develop when emboli become lodged in the lungs, or cause blockages in other parts of the circulation system like the brain and heart. The result is chest pain, shortness of breath and, in some cases, sudden death. Deep vein thrombosis effects men and women equally.

Economy-class syndrome, a term frequently used to describe DVT, is misleading because any passenger, regardless of ticket class, can be affected. Despite the recent publicity surrounding passenger deaths from DVT, a recent study in The Lancet journal argues that although there is a link between long-distance flights and ‘economy-class syndrome', most people are not at risk.

Dr John Scurr, a vascular surgeon at London's Middlesex Hospital, has done extensive research on DVT and claims most people have little cause for worry. In his study, he examined 200 passengers before and after they had been on long-distance flights. Although 10 per cent of passengers developed small blood clots, none of the clots developed into a serious problem.

Dr John Belstead, an A&E consultant who frequently sees cases of DVT at Ashford Hospital, a 10-minute drive from Heathrow Airport, agrees. ‘The risk of developing DVT is quite high, but the risk of dying from it is about one in a million,’ he says. Nonetheless, Dr Belstead advises wearing support stockings when flying, as they massage the legs and increase circulation. He also advocates taking aspirin before a flight, with permission from your doctor, as it can thin the blood and prevent clotting. If you get off a plane and have extreme swelling or pain in your legs, contact a doctor immediately.

In the past year, several airlines have introduced various DVT prevention measures that offer passengers a chance to get some exercise while flying. British Airways has launched Pilates in the air, Quantas now issues advice with passengers' tickets and runs an in-flight film on general health. Air Jamaica and the charter airline Air 2000 offer in-flight aerobics, whilst Emirates Airlines gives away free 'Airogyms', inflatable cushions that allow you to exercise your legs and increase circulation (£7.99, from www.airogym.com).

Symptoms for DVT include pain and swelling in the legs below the area where the clot is forming, as well as redness and warmth of the skin. It is possible, however, to have DVT without any symptoms. To prevent DVT, avoid alcohol and tobacco on long-haul flights, drink plenty of water, and get up from your seat to walk around every couple of hours, also avoid crossing your legs when seated, as this further restricts circulation. Those in a high-risk category should seek medical advice before flying.

Although air travel has recently been blamed as the main culprit of DVT, you don't have to be airborne to suffer from it. For example, you can get it from sitting at your desk too long. ‘Only five per cent of this type of DVT is connected with air travel,’ says Dr Paul Giangrande, a consultant haematologist at the John Radcliffe Hospital in Oxford. It seems that being immobile for long periods of time, and not flying itself, is what puts you at risk.

Other factors thought to increase the risk of blood clots include pregnancy, the contraceptive pill and the menopause drug HRT. People who have had recent surgery, or varicose veins removed are also more susceptible, as is anyone who has suffered from heart failure, cancer, obesity or blood-clotting problems.

*Visit The International Air Transport Association (IATA) website for more information on DVT.

*Check out BUPA’s website for a helpful DVT fact sheet.

*Have a look at British Airway’s website for useful travelling tips.