Health Department issues advice to air travelers on heading off blood clots

Friday, November 30th 2001, 12:00 am

By: News On 6

LONDON (AP) _ Passengers on long-haul flights should perform simple leg exercises in their seats and get up and walk around when possible to reduce the risk of developing blood clots in their legs, the British government advised Friday.

The commonsense guidance, which also advises people with conditions that make them more vulnerable to clots to seek their doctor's advice before a long trip, is a response to public fears that long plane journeys might cause deep vein thrombosis, potentially fatal blood clots in the calves.

Reports of passengers dying from clots after long flights have mounted recently, leading to speculation that cramped airplane seating could be to blame. In Australia, 2,700 passengers are seeking damages from airlines after suffering blood clots.

However, most experts do not think the problem is related to airplane conditions, but rather to the fact that passengers stay still for too long.

Clots occur when blood circulation slows, usually when people are immobile for too long. Some people are born with a propensity to form clots too readily; others acquire it. It's hard to tell who has a genetic vulnerability to them.

Nobody knows whether deep vein thrombosis, or DVT, is more likely to occur on long-haul flights than in any other situation where people remain still for long periods of time, such as on a train, in a car or in front of a computer. Researchers worldwide are trying to find answers.

``Information on the proportion of people who develop DVT related to air travel is limited, but the experts suggest this is small,'' the Health Department says. ``Also, it is not easy to decide whether the flight itself caused the DVT or whether these people were at risk for other reasons. This is because DVT ... (is) relatively common conditions anyway and more people than ever now travel by air every year.''

People who are more likely than normal to have trouble include those over 40, heart patients, people who have had one before, have relatives who have suffered one, those who have had recent surgery, who have ever had a stroke or cancer and women who are pregnant, on the Pill or hormone replacement therapy.

Besides the exercises, the government advised passengers to drink lots of water, not too much alcohol and to avoid sleeping pills, which cause immobility.

It's not clear whether taking an aspirin before a flight does any good. While aspirin works well as a clot preventer in the arteries around the heart, it is not as well proven in the veins, where clots form slightly differently

Earlier this year, the first scientific experiment to investigate the link found tiny clots in the calf veins of about 10 percent of passengers who flew for more than eight hours. However, the body makes and dissolves clots routinely and none of the clots in the study progressed to become a problem.

Experts estimate that every year, about one in 1,000 people is diagnosed with a blood clot in a leg vein.

Killer clots, where the clot breaks off, travels to the lung and blocks the flow of blood, are very rare.

The government advice mirrors that of the airline industry.