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How travellers can avoid DVT on long-haul flights

The New Straits Times, January 20, 2002

By Dzulkifli Abdul Razak

What have the WTC and DVT in common ? The answer: Air travel risks. While the risks in the former are rather obvious, it may not be so for the latter.

DVT stands for deep vein thrombosis, a residual risk related to flying. In fact, the Sept 11 issue of the New England Journal of Medicine (NEJM) published new evidence associating DVT with long-haul flights. It suggests these flights enhance the risk of reduced blood flow in the lungs (pulmonary embolism) with the distance travelled.

Although such incidences have also been reported after road trips or other modes of transportation, (even after evenings at the theatre), long air flights seem to pose a greater risk.

There are no reliable statistics about the incidence of travel-related DVT illnesses after long journeys, but according to the UK Aviation Health Institute, an estimated 30,000 passengers every year develop a thrombosis of this type, and "in several dozen of them the outcome is fatal".

In France, The Sirius study published in 2001 also shows that longhaul flights are indeed associated with an increased risk of blood clot.

DVT refers to the formation of a blood clot (thrombus) within a deep vein.

For instance, when seated or immobilised for a long time without contracting the muscles in the legs, blood can pool in the veins.

Although generally blood clots are absorbed into the bloodstream, they can also block blood flow in the veins, either causing partial or complete blockage.

The condition will become dangerous if the clot breaks free from a vein wall and makes its way from the legs to a pulmonary artery, impeding blood flow in the lungs.

Despite other evidence linking air travel with the syndrome, the NEJM study is deemed as the first to show an association between long haul flights and blood clots.

But some contend that immobilisation alone is not a major problem if there is no other illness that predisposes DVT.

It has been suggested that apart from being seated in a crammed "economy-like" class environment with minimal movement, there are multiple factors involved. One such risk factor is pregnancy as there is an increased tendency for the blood to form clots. Those taking birth control pills or hormone replacement therapy may also be at increased risk because estrogen increases the risk of clotting. Others at high risk for DVT include those with varicose veins, some types of cancers, or liver diseases.

Always break journey and take a short stroll whenever possible while travelling.

At the same time, drink plenty of water regularly, to keep the body hydrated. Avoid alcohol and caffeineted drinks during flight, since they can result in dehydration.

The warning signs and symptoms of DVT include pain and sudden swelling in the areas where the clot is located. Others include tenderness and redness in the affected area, warmth, fever, rapid heart beat, sudden unexplained cough, joint pain and soreness. Alert the crew if any of these happen.

Although some airlines still rejected any link between cramped air travel and DVT, many have begun giving passenger advice on how to prevent DVT .So, before travelling the next time, not only dress casually in loose-clothing, but also make the necessary preparations to avoid DVT. Bon voyage! 

* Recommended website: http://www.doh.gov.uk/dvt  

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