Dangerous In-Flight Blood Clots

(CBS)  "Economy class syndrome" is a term for the risk of blood clots from sitting in cramped airplane seats for long periods of time. As The Early Show reported Monday, it has resulted in lawsuits from some passengers.

New research sheds some light on the risks. The Early Show medical correspondent Dr. Emily Senay reports.

A blood clot known as deep vein thrombosis can develop in the veins of the leg as a result of sitting still in a cramped position for hours. In many cases, these clots dissolve on their own, but Senay says they can be very dangerous if they break away and travel through the bloodstream to the lungs, where they can get stuck and cause a potentially fatal pulmonary embolism.

One illustration of the tragic consequences is the surprise death of Iraq war correspondent David Bloom, who died as a result of a pulmonary embolism attributed to a blood clot that formed as a result of sleeping in a cramped vehicle. Senay explains there is still a lot of controversy about how the health problem might be caused or exacerbated by air travel, but there seems to be enough evidence to cause concern for some travelers.

A number of new studies from the Archives of Internal Medicine link air travel with an increased risk of blood clots. The good news is that the risk of these clots occurring on or just after a flight is shown to be extremely small -- about one in a million. But the research did confirm that the risk of a clot increased on flights over eight hours, and even more for people who already have risk factors for blood clots.

Although most experts agree that sitting still for hours and the cramped seating is the main cause of the syndrome, some theorize that it may also have something to do with the cabin pressure or the dry atmosphere inside a plane.

The studies also show that certain groups were at higher risk. Age, obesity, recent surgery, family history of blood clots, medical conditions or disease that make a person prone to clotting can put a person at higher risk. And women who are pregnant or use contraceptive pills or hormone replacement therapy are also at higher risk of clots.

If any of these conditions are combined with the risk factor of sitting in an immobile, cramped position for a long time, it can put a person at an even higher risk.

Senay says your doctor is the best person to advise you of your personal risk. He or she can prescribe medication to prevent clot formation if necessary. According to the American Heart Association, the following are other simple precautions you can take while flying:

Walk if possible

Drink extra water

Avoid alcohol

Wear tight stockings (you can buy them at medical supply stores)