WHO probes deep vein thrombosis and world travel

(CNN) -- International medical experts and officials from 16 major airlines across the globe are taking part in talks about deep vein thrombosis and air travel at meetings today and Tuesday at the World Health Organization headquarters in Geneva, Switzerland.

The talks, which are closed to the public, will include reviews of scientific evidence concerning the condition, which has been linked to the low mobility fostered by long-haul flights and other forms of protracted travel in cramped spaces, such as automobile and train trips.

"It's the first time that airlines of the world have gotten together under the auspices of the WHO to talk about a problem that has been booming in the past year or so," Jarnail Singh, chairman of Singapore Airlines' civil aviation medical board, told Reuters, calling the sessions "very important."

Deep vein thrombosis, also called traveler's thrombosis and DVT, is caused by blood clots that can form when blood pools -- most often in the legs -- during long periods of inactivity. The danger occurs when these clots break off and travel to the lungs, brain or heart, causing heart attack and stroke.

Sometimes called "economy-class syndrome," the condition has been blamed for at least 30 deaths in three years at just one hospital in London, England. A study of cases at Ashford Hospital, just minutes from the city's Heathrow Airport, revealed that though deaths are relatively rare, the condition is causing growing concern.

"It's the red-eye flights from the west of the United States and the Far East, and also from Australia," Dr. John Belstead told CNN. "It's mostly people who sleep in their seats."

John Scurr, a British vascular surgeon who studied 200 people flying long distances before and after their trip, is due to publish his findings soon in The Lancet, a medical journal.

In October, 28-year-old Briton Emma Christofferson died after collapsing at Heathrow at the conclusion of a 12,000-mile flight from Sydney, Australia. Shortly thereafter, British Airways became one of the first airlines to warn its passengers about the potential dangers of DVT. Others have also begun showing videos and giving tips on how to avoid the condition during long flights.

Eating a light meal and drinking nonalcoholic beverages may decrease the risk of DVT, according to Japanese researchers, who found that consuming snacks and fluids increased oxygen levels in the body by 21 percent and oxygen in the brain by 48 percent.

"After eating and drinking, blood volume may be increased," said Dr. Makoto Matsumura, assistant professor of cardiovascular surgery at the Saitama Medical School north of Tokyo, Japan.

Increased blood volume helps to keep circulation going, lessening the chance that blood can pool in the legs.

Opinion remains divided on exactly how -- or even whether -- airline travel is related to DVT. Dutch scientists have concluded that there is no increased risk for most travelers on trips averaging 8 hours. More research is needed on longer trips, they said.

Physicians also have recommended that travelers get up and walk periodically during long trips. If this is difficult, legs and ankles should be flexed and weight should be shifted in the seat. Alcohol and caffeine intake should be limited, doctors said.

The European Commission said last month that it was funding the largest-ever study into the effects of flying on passenger health.

This week's talks are being organized by WHO's cardiovascular disease unit.

CNN Medical Correspondent Rhonda Rowland and CNNFN Correspondent Tom Bogdanowicz and Reuters contributed to this report.

Doctors, airlines warn of blood clot risk
January 11, 2001
Airlines urged to issue health warnings
November 22, 2000
Snacking, moving can decrease risk of flight-related blood clots
November 21, 2000
Woman dies from blood clot after long-haul flight
October 23, 2000

WHO - World Health Organization
CDC - Travelers' Health
The Lancet
International Air Transport Association
International Civil Aviation Organization
The European Commission

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