What is a pulmonary embolism? We hear about them occurring on airplanes--some airlines have started handing out exercise tips to prevent them on long-haul flights--and they're a potential side effect of birth-control pills and hormone therapy. In fact, says Dr. Victor Tapson of Duke University in Durham, North Carolina, we should all learn more about them. In the United States, they kill more people than breast cancer and traffic accidents combined. The condition occurs when a blood clot, usually in a vessel deep inside the leg, breaks off and travels to the lung, cutting off arteries that carry oxygen and causing heart failure. Among the risk factors: inactivity, dehydration, age (over 40), pregnancy, hospitalization, heart attack, obesity and prior clots. As many as 5 percent of the population also have a defective clotting gene that makes them more susceptible. (Doctors rarely test for the defect, since there's no consensus on what to do if you have it.) If you have a risk factor and you'll be traveling in a plane or car for more than eight hours, consult your doctor. It might make sense to take a long-acting blood thinner as a preventive measure.
Pay attention to warning signs: leg pain or swelling, shortness of breath, lightheadedness and chest pain. And when traveling, remember to get up, flex your calves and have a big drink of water.