How to Avoid Deep-Vein Thrombosis on Long Flights

February 27, 2012

New guidelines for travelers published by the American College of Chest Physicians recommend using below-knee compression stockings on long airline flights for people at higher risk for deep vein thrombosis -– but only if travelers have a risk factor for blood clotting.
Those risk factors include the use of oral contraceptives, advanced age, pregnancy, severe obesity, limited mobility, recent surgery or trauma and cancer. Because it can be harder for window-seat passengers to get up and move around, the guidelines identify window seats as a risk factor and suggested sitting in an aisle seat is a wise choice for people at risk.
The guidelines come from a team of physicians who studied 14 previous DVT research reports from around the world. They found no definitive evidence to support that dehydration and alcohol intake in-flight increase risk, and they recommended against the use of aspirin as a preventive measure.
DVT is a serious condition that can lead to a potentially fatal blockage in the lungs known as a pulmonary embolism. DVT with symptoms is rare among travelers, but the highest frequency comes among people who sit on flights longer than eight to 10 hours. Most passengers who do develop a thrombosis or embolism after long-distance travel have one or more risk factors, said guideline co-author Mark Crowther of McMaster University in Hamilton, Ontario.
While medical literature decades ago labeled DVT as “economy-class syndrome” because cramped seating was thought to exacerbate the problem, the guidelines agree with previous studies that first-class and business-class passengers are also at risk. The issue is immobility, not tight quarters. If you don’t move and exercise legs while sitting in a big seat, you can face heightened DVT risk.
As with previous DVT advice, the guidelines suggest frequent ambulation on long flights and calf-muscle exercises. Despite finding no evidence that dehydration can raise the risk of blood clots, the guidelines suggest avoiding dehydration anyway. In the arid air of an airplane cabin, drinking fluids is frequently recommended.
Based on previous studies, the researchers concluded that the use of various brands of below-knee compression stockings reduced the rate of asymptomatic DVT detected by screening study participants after flights from 3.6% (47 of 1,323 control subjects) to 0.2% (three of 1,314 stocking users). The recommendations say stockings used should provide 15-30 mm Hg compression at the ankle and need to be fitted properly -– not too tight up near the knee. Researchers suggested travelers wear them around the house a few days prior to a long trip to ensure a good comfortable fit.
The guidelines stressed, however, that people without risk factors shouldn’t wear compression stockings as a DVT preventive measure.

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