Blood Clots and Air Travel

Just another thing to worry about before departure: lower leg, deep vein blood clots from long distance air travel. Although recent publicity regarding the relationship of lengthy air travel (prolonged sitting and immobility) and blood clots (thrombosis) forming in the deep veins of the lower legs is fashionable, the association remains more circumstantial than scientific. The World Health Organization, after an exhaustive review in March 2001, stated, "a link probably exists between air travel and venous thrombosis."

"Economy-class syndrome" or "travelers' thrombosis" are just a few of the names given to this condition of deep vein thrombosis (DVT) occurring in travelers on long air flights. The term travelers' thrombosis is preferred because the condition may also occur in first class air passengers as well as travelers using other forms of long distance transportation, e.g. buses or automobiles.

Travelers' thrombosis may occur in long-haul travelers because the legs are too dependent (low), too inactive, and the blood flow is too slow. When seated, the veins are cramped at the knees and pelvis and the backs of the knees may be pressed against the seat. Also, the oxygen in an airplane cabin may be reduced and dehydration may occur when traveling more than 6 hours. In a worse case scenario, a blood clot forms in the deep veins of the leg and moves through the venous system to the lungs causing serious, acute heart and lung disease (pulmonary embolism) and possible death. Symptoms of leg thrombosis (e.g., calf pain) typically occur 2-3 days after a long journey, but may occur as long as several weeks later.

Who is at risk? The person most at risk is a female, over 40 years of age, with a prior history of deep vein thrombosis. Others at risk include the following: older travelers, obese travelers, pregnant women, anyone with varicose veins or a prior history of venous thrombosis, women taking birth control pills or estrogen, and travelers with a history of a major operation, cancer, heart failure, or recent leg surgery.

What can you do to prevent blood clots? Dress in loose-fitting clothes and shoes. No socks or garments should have banded constriction. Stay well hydrated, but avoid alcohol. Exercise your legs and feet every chance you can (e.g. every 20 minutes). Consider fitted, compression stockings - compression of 20 mm. Hg or more is best. It is not certain taking aspirin to avoid thrombosis is helpful, but if you are at risk, it seems prudent (and safe) to take a single aspirin tablet daily, starting a day before departure and continuing for a day after the flight terminates. You might try to sit in an aisle seat - you will have more room and it is easier to stand up and move around in the airplane.

There are several resources you can turn to for advice (but remember, they are frequently selling something and should not be considered sources of scientific information). Jobst Hosiery, a manufacturer of fitted compression stockings, may be contacted at www.economyclasssyndrome.com. Another helpful source is www.airhealth.org, a Web site monitored by an individual, Michael Reynolds. The site contains significant educational material and describes beneficial exercises to prevent thrombosis as well as a description of the signs and symptoms of DVT and pulmonary embolism. Sockwise, Inc., produces a high-quality compression sock called TravelSox® that was designed specifically for travelers. They can be ordered at www.travelsox.com.

Travelers' thrombosis, DVT, and pulmonary embolism are all treatable conditions. If you develop unexplained leg swelling, leg tenderness, leg warmth, leg pain deep in either calf or unexplained shortness of breath, particularly within a few months after a long flight, see your doctor immediately!