No Link Shown Between Long-Distance Flights, Blood Clots
WebMD News Archive
"These results do not lend support to the widely accepted
assumption that long traveling time is a risk factor for [DVT]," writes
study author Roderik Kraaijenhagen. "Even for journeys lasting more than
five hours, no association was apparent."
Kim tells WebMD that because this condition is relatively rare
and difficult to diagnose, a study involving 700 people may not have been large
enough to disprove a connection between blood clot formation and long
Clifford C. Dacso, MD, MPH, a professor of medicine and chief
of general medicine at Baylor College of Medicine in Houston, agrees that the
study may be too small to be significant. "But I don't even think it is
relevant. It probably does occur, but it may not. Even if it doesn't, the
remedy we know is harmless. I think it is pretty nontoxic to tell people to get
up every hour and walk around, flex their calf muscles 10 or 20 times an
hour," says Dacso.
Patricia M. Young, MD, medical director of the International
Travel Clinic at the Medical College of Wisconsin in Milwaukee, tells WebMD it
is unclear whether the British woman who died had medical problems or previous
injuries that might have caused her fatal blood clot. "Other risk factors
for DVT are major surgery in recent weeks, certain types of cancer, heart
failure, and varicose veins," says Young.
She says she agrees with the Lancet study conclusion
that there is probably no association between flying itself and the development
"Most travelers are healthy enough that they will be moving
around somewhat, which stimulates blood flow by causing contracting muscles to
pump the blood onward," says Young, who was not involved in the study but
reviewed it for WebMD. "The travel itself is not necessarily the cause of
DVT, but the immobilization that many passengers undergo during a flight,
perhaps combined with tight fitting clothes that impede blood flow, can
increase risk of stagnating blood in lower leg veins."
Young suggests taking an aspirin the day of travel to help thin
the blood. "I would continue to encourage travelers to wear comfortable
clothing for travel, walk about frequently, clench their toes or rotate their
ankles to stimulate blood flow, as well as stay hydrated, so the blood is
thinner during their long periods of sitting," she says. "Airlines may
need to lead the way in educating people about immobilization risks and perhaps
return to more leg room so that passengers can move around easier."