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Thinner Blood, Less 'Coach Class Syndrome'

Study finds heparin helps high-risk fliers on long hauls

WEDNESDAY, Nov. 28, 2001 (HealthDayNews) -- A "lighter" version of the blood thinner heparin protects people at high risk for blood clots when they travel on long flights, new research shows.

An international study found that a single injection of the drug a few hours before take-off eliminated almost all clotting problems among 82 people who took the shot. People with a history of heart disease or stroke are most at risk for developing clots on lengthy flights.

Deep vein thrombosis (DVT), a potentially life-threatening disorder in which blood clots form in the deep veins of the legs, has become a worry for fliers on trips of more than 10 hours. Dubbed "coach class syndrome," the phenomenon is linked to prolonged confinement in cramped quarters. Dehydration at high altitudes also can thicken blood and increase chances of clotting, experts say.

In most cases, the clots are simply painful, but if they travel to your lungs, heart or brain, they can be deadly. Until recently, supportive stockings were the primary preventive measure for DVT on long flights.

The issue first surfaced last year when two athletes traveling to the Summer Olympics in Sydney, Australia, were later diagnosed with DVT. The discussion as to whether plane travel caused the condition heated up considerably in October 2000 when a 28-year-old woman coming off a 20-hour flight from Australia collapsed and died before reaching the hospital in London. An autopsy showed she died from DVT.

"Heparin is the standard treatment for thrombosis [clots]. We have a problem. We have a solution," says lead study author Gianni Belcaro, a researcher with the University of Chieti, in Italy. "It's a very simple answer to the problem. The results showed almost zero incidence. If you use it properly, there are no side effects." The heparin used in the study is made of molecules that are about one-third the size of the standard heparin that given after heart attacks and other events that may give rise to clots.

One DVT expert says the study, which was presented at this month's American Heart Association's Scientific Sessions 2001 Conference, in Anaheim, Calif., reinforces current practice.

"I thought it was interesting and not surprising," says clotting expert Dr. Jack Hirsh of Ontario, Canada. "We've been suggesting this to our patients for a long time. It's reassuring to have this study back it up. People now have a second choice on long flights."

Hirsch says only high-risk patients should consider a shot of this heparin before taking long treks in planes.

"The frequency of serious events is extremely low, almost non-existent, in low-risk people. It should be confined to high-risk patients," he says.

Belcaro says though many insurance companies may not cover the cost of a shot of heparin in this instance, high-risk travelers probably wouldn't mind paying the typical $25 fee for an injection.

The study, conducted in Italy, England and Australia, included 300 high-risk subjects randomly put into one of three groups before taking a long flight: one group took no drugs; people in the second group each took 400 milligrams of aspirin, which also thins the blood, once a day for three days before a flight; and each of the third group had a single injection of a weight-adjusted dose of "light" heparin two to four hours before flight. All participants had ultrasound examinations of their legs 24 hours before and after their flights.

Of the 82 drugless people who completed the study, 4.8 percent developed DVT, and two people developed superficial thrombosis after the flight. Of the 84 subjects in the aspirin group, 3.6 percent developed DVT, and two people developed superficial thrombosis. Of the 82 in the heparin group, none developed DVT and only one person developed superficial thrombosis.

Belcaro says his group is working on three more studies looking at more specific groups of at-risk people and other possible treatments.

That kind of research is exactly what Hirsh suggests: a huge study that looks more closely at which health conditions put people at the greatest risk for DVT on flights of more than 10 hours.

What To Do

Belcaro suggests people with heart disease or a history of stroke avoid long flights altogether. And if a long flight is the only alternative, make sure you walk around the cabin periodically while you're in the air, he says.

For you travelers not at risk for DVT, wearing tight stockings on long flights should prevent the possibility of getting the condition, recent research shows.

For more on the problem, also known as "economy class syndrome," try Wright State University or the World Health Organization.

The BBC News also has a rundown on DVT and Emma Christoffersen, the woman who died from DVT after a long plane ride.

SOURCES: Interviews with Gianni Belcaro, Ph.D., University of Chieti, Chieti, Italy; Jack Hirsh, M.D., director, Henderson Research Center, McMaster University, Hamilton, Ontario; Nov. 13, 2001, presentation, American Heart Association Scientific Sessions 2001 Conference, Anaheim, Calif.
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