THE VALENTINE’S BOX of chocolates is now half eaten so that any credit gained from it is already waning. Lent has started, Easter is not far ahead and the holiday brochures, promising azure skies and seas, are beginning to fall through the letter box. The daydreams of cold, damp Britons, down to the Turkish delight and nuts in the chocolate box as they attempt to alleviate the gloom of February, have already been directed to faraway places. They are thinking of beaches, sun, sea and, if their Valentine’s evening was a success, perhaps sex.

They don’t remember the long wait in the airport lounge, the cramped seat and their neighbours in the central row who make it so difficult to follow doctors’ advice to wander about during a flight. Those listening to Tuesday’s early morning news programmes, or the World Service, will have heard that Boeing is introducing a long-range airliner to rival one announced by Airbus last month. The emphasis is slightly different. Boeing is aiming for longer flights, Airbus for bigger passenger loads.

Neither manufacturer has discussed the increased risk that long-haul flights carry in relation to deep vein thromboses (DVTs) and pulmonary embolism. Although it is true that any form of cramped travel, whether in a Ferrari, coach or aircraft, carries this danger, it is equally true that this is proportional to the time spent travelling. The longer haul the flight, the greater the number of people who will suffer a DVT.

The airlines are keen to play down the risk of their passengers developing DVTs that in a few unfortunate cases are complicated by pulmonary embolism. They are also enthusiastic about altering the term economy-class thrombosis to traveller’s thrombosis because, as they rightly say, this can occur in a passenger whatever class they travel.

Even so the inability to shift around and to walk about will compound any other factor known to increase the risk of a DVT when flying, and of all these the distance travelled is probably the most important.

There are few flights that are longer haul than London to Sydney. This now seems to be the benchmark by which long-haul travel is measured, but there has been no mention of its likely effect on the rate of pulmonary emboli.

Detailed research has shown that one person in ten has a deep-vein thrombosis after a long-haul flight but fortunately most don’t have any symptoms. On any long journey in which the passenger is still for hours at a time, blood pools in the veins of the legs and pelvis and may clot. If part of the clot breaks off and forms an embolus this can reach the lungs. If the embolus settles in a pulmonary artery the results, although they affect the lungs rather than the heart, are not unlike a heart attack and may be lethal. The passengers who are most in danger of developing DVTs and pulmonary emboli from flying are those who are overweight, smokers, people over 65, women on the Pill or pregnant, or those who have a history of thrombotic troubles, whether in the coronary arteries, in the cerebral vessels as a cause of a stroke or transient ischemic attack, in a lung or a lower limb.

The association between malignant disease and venous thrombosis is underestimated. Susan Mayor, writing in the BMJ, drew attention to the recent Dutch study reported in Jama (Journal of the American Medical Association). The risk of developing a DVT is especially high during the first few months after the diagnosis of the cancer and in those patients in whom the cancer has already spread. The chances of developing a DVT and pulmonary embolism is seven times greater in any patient with cancer compared with those without a malignancy. Those at greatest risk are people with blood cancers, followed by patients with lung cancers or gastrointestinal malignancies.

Prevention of DVTs includes taking an aspirin. For people who have uncontrolled high blood pressure, or a history of chronic indigestion and peptic ulceration, aspirin is unsuitable.

They should discuss an alternative treatment with their doctor. One possibility is Zinopin, a preparation that is a mixture of pycnogenol made from pine kernel and ginger. It is a natural remedy but, like aspirin, reduces the risk of DVTs.

Leg, foot and stretching exercises, regular walking about the plane and, for those in a high-risk group, the wearing of compression stockings reduces the danger of DVTs. All passengers should maintain a high fluid intake to prevent dehydration but should restrict their alcohol consumption to a couple of glasses of red wine.

E-mail Dr Thomas Stuttaford your questions on DVT
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