Medical professionals are concerned about the increased connection between long-haul travel and developing potentially fatal deep vein thromboses (DVT), which is the formation of blood clots in the veins. This is not a new concern. The first case was reported in 1954 in the New England Journal of Medicine, which occurred in a doctor after a 14-hour flight.



Air travel has been linked with DVT since the 1950s, with a number of plausible explanations. However, the risk of DVT might have been overlooked or underemphasized, with incidences that could happen up to several weeks after air travel. In a recent study published in British Journal of Medicine, the risk of DVT was reported to be highest within two weeks of a long-haul flight. The study concluded that the annual risk of DVT increased by 12 percent if a single long-haul flight (traveling more than 6,200 miles) is taken yearly.

The lack of mobility while traveling long distances already has been established as a contributor to DVT. There are also a number of factors travelers can experience in aircraft cabins that can increase the risk of developing DVT or pulmonary embolism (clots passing to the lungs where they may block blood flow and could result in death). These include immobility due to cramped seating positions, dehydration due to consumption of alcoholic drinks as well as tea and coffee, low humidity of the aircraft cabin, hypoxia, which is an inadequacy in the oxygen reaching the body's tissues, and reduced barometric pressure.

The overall risk of DVT after a long-haul flight is about one in 2,000. For people with known risk factors, the risk may be higher, but for those without other risk factors, it is likely to be very low though the possibility is always there. The combination of immobility and increased risk factors could be the reason for long-haul travel DVT in some individuals, but not in all.

Recent studies show that anywhere from 6 to 20 percent of the total population is believed to have a certain degree of increased clotting tendency, or increased risk factors for developing DVT. This shows that there might be a "natural" tendency for some individuals toward DVT that's associated with their personal factors, putting them at higher risk.

There is good news though. There are preventative measures that potentially could reduce this risk. Movement and exercise, which counteract one of the major contributing factors to DVT immobility, can help while traveling.

Physical therapists and movement experts have been guiding and providing movement interventions and exercises to prevent this potentially killer condition.

Individuals considered at risk for DVT including those:

-- Over 40 years old.

-- Who have already experienced blood clots.

-- With a family history of blood clots.

-- Who have/had cancer.

-- With certain blood diseases.

-- Being treated for circulation problems or heart failure.

-- Recovering from recent surgery (especially hips or knees).

-- With an inherited clotting tendency.

-- Who are pregnant.

-- Who are new mothers.

-- Taking the contraceptive pill.

-- On hormone replacement therapy (HRT).

While many airlines offer some onboard tips to help avoid DVT, here are other risk-reduction strategies to consider before traveling:

-- Wear loose clothing.

-- Find a comfortable position in your seat and recline if possible.

-- Don't cross your legs when sitting because doing so compresses blood vessels.

-- At stopovers and refueling points, leave the aircraft and walk around.

-- Move at regular intervals to increase blood flow through the veins.

-- Walk around on long flights (when permitted).

-- Drink plenty of water.

-- Avoid the dehydrating effects of alcohol.

-- Postpone long-haul flights for three months after hip or knee replacement surgery.

-- Learn and apply in-seat exercises to ensure proper circulation.

-- Wear elastic/compression stockings.

-- Women taking contraceptive pills or hormone replacement therapy should perform regular exercises, as well as consider wearing elastic/compression stockings.

-- Get more information from your physical therapist or gynecologist, if pregnant or nursing.

-- Take current prescriptions.

-- Make sure your health insurance covers you on your trip.