Special stockings that put pressure on leg muscles or an injection of the blood-thinning drug heparin can help prevent potentially deadly leg blood clots in travelers taking long airplane flights, researchers said on Tuesday.
Doctors have known for years that long periods of immobility, such as sitting, increase the chances for the formation of dangerous blood clots. That is why travelers are often encouraged to stand up or walk around during long overseas flights.
Those with a history of heart disease are considered most vulnerable to such clots, which form in the body’s deep veins such as in the legs, although even healthy people have a very small chance of developing a clot while on a long plane ride.
Deep vein clots can be life threatening because they can break free and cause strokes or lung blockages.
About 4% to 5% of high-risk individuals may suffer such clotting, known as deep vein thrombosis, on flights of 10 hours or longer, according to researcher Gianni Belcaro of the University of Chieti in Chieti, Italy.
“Immobility is the cause, but low pressure in the cabin, low humidity and dehydration may also contribute” to clotting risk, Belcaro said at a meeting of the American Heart Association being held in Anaheim, California.
Belcaro and researchers from England and Australia first tested a control group of men and women who used no stockings or clot-prevention drugs before taking flights lasting an average of 12.4 hours.
They included 355 travelers with no history of cardiovascular disease and taking no medications, among whom no clots were detected after the flights by ultrasound scans. But among 389 travelers in the control group with previous histories of clotting and related problems, 13 developed deep vein clots.
The researchers then tested 833 healthy travelers to see whether compression stockings could prevent deep vein clots, with half wearing the below-the-knee garments and half going without during their 12-hour flights.
About 4.5% of the group not equipped with the stockings developed deep vein clots, almost 19 times as many as those who wore the leg-squeezing garments.
In a final trial involving 249 high-risk travelers, one third took no medications, one third took daily 400-milligram doses of aspirin for three days starting 12 hours before their flights and one third received injections of low-molecular weight heparin several hours before flying.
Of the medicine-free group, 4.8% developed deep vein clots, compared with 3.6% among the aspirin takers. But no cases were seen in the heparin group.
“These findings suggest that deep vein thrombosis prevention with stockings is useful for low- to medium-risk patients (as is) a single dose of heparin for high-risk subjects,” said Belcaro, who added that heparin injections were “easy” and should be prescribed for long-distance travelers with clotting histories.