By Duke Medicine News and Communications

With summer vacation season just around the corner, many long-distance air travelers will face an increased risk of developing DVT, sometimes called "economy-class syndrome." DVT, or deep-vein thrombosis, is a circulatory condition in which blood clots form deep in the legs, often after lengthy periods of immobilization.

Victor Tapson, M.D., associate professor in the division of pulmonary and critical care medicine at Duke University Medical Center, says these clots in the legs can lead to serious trouble elsewhere in the body.

"Sometimes these blood clots can break off and go to the lung, causing what's known as pulmonary embolism," says Tapson. In some circumstances, this may result in serious illness or even death. Deep-vein thrombosis may also contribute to other serious medical problems such as heart attack and stroke.

"The death rate from pulmonary embolism is probably in the range of 100,000 to 200,000 per year in the U.S," he adds.

Tapson recommends that anyone on a long flight should follow some travel tips to help prevent problems from DVT.

"Traveling a lot, I realize that if you're in economy class for trips longer than five hours, the risk is probably there," he says. "The airlines nowadays are advertising on transatlantic flights, for example, that patients flex their legs, move around at least hourly, stand up when possible and not just sit in the same place."

Other recommendations include: drinking adequate fluids, at least one liter per five hours of flight time; avoiding alcohol; wearing loose-fitting clothing; and avoiding crossing your legs or remaining in a prolonged uncomfortable position while seated.

"Millions of people travel," he says, "and not everybody gets blood clots. It may be that patients who get blood clots also have other risk factors."

Among the common risk factors for DVT are being overweight or obese, having high blood pressure, being pregnant, taking estrogen replacement therapy or having been immobilized for a prolonged period within 30 days of flying, for example after surgery.

Tapson says if a physician feels a patient is at particularly high risk, administration of preventive therapy, such as a shot of low molecular weight heparin, may be appropriate before the flight, and prior to return.

He also believes more attention should be given to DVT preventive care, as well as increased DVT screening in hospitals. "Any patient who's admitted to the hospital ought to be at least considered for preventive therapy with anticoagulants such as heparin, low molecular weight heparin or mechanical devices. Perhaps everyone coming in doesn't need prevention, but everyone ought to be considered."