Compression Stockings Cut Fliers' DVT
Deep Vein Thrombosis Is Rare, but Compression Stockings May Help
April 20, 2006 -- Wearing compression stockings on long flights may help avoid deep vein thrombosis (DVT) -- clots that form in legs' deep veins.
Researchers recently reviewed 10 studies of compression stockings for DVT prevention in long-distance flights. The studies included a combined total of more than 2,800 people, all of whom flew for at least seven straight hours.
Compression stockings cover the lower leg, stretching up to the knee. They apply gentle pressure (especially at the ankle) to encourage blood flow in order to cut clotting risk in deep veins.
The review, published in The Cochrane Database of Systematic Reviews, shows a "substantial reduction" in symptomless DVT and leg swelling (edema) in passengers who wore the stockings.
The researchers who wrote the review included Mike Clarke, director of the U.K. Cochrane Center. They note that DVT was rare in the studies and even rarer in participants wearing compression stockings.
About the Studies
Roughly half of the participants were randomly chosen to wear compression stockings on their flights. In one study, 35 participants wore a compression stocking on one leg on their departure flight and on the other leg on their return flight.
In the reviewed studies, participants were carefully checked after their flights for any circulation problems in their legs, even if they felt fine, write Clarke and colleagues.
The point was to look for DVT after long flights and to see if the stockings affected DVT risk.
None of the participants in any of the studies had DVT with obvious symptoms, but 50 had DVT without symptoms. No serious events -- such as blood clots in the lungs (pulmonary embolismpulmonary embolism) -- were seen in any fliers.
Pulmonary embolism is a potentially fatal consequence of DVT. But DVT doesn't always lead to pulmonary embolism.
"There was a big difference in symptomless DVT between the two groups, equivalent to a reduction in the risk from a few tens per thousand passengers to two or three per thousand," write Clarke and colleagues.
"Not all trials reported on possible problems with wearing stockings but in those that did, the researchers said that the stockings were well tolerated, without any problems," Clarke's team adds.