When I travel abroad, which I do frequently for work, I try to run every day for an hour. It gives me energy and a great look at my new surroundings. After starting a run in Manila recently, I stopped three minutes into it. My breathing was shallow and laboured. I also had a nagging pain in my calves. The discomfort had been with me since I had landed in the Philippines four days earlier. So that morning I ran, walked, ran and walked for 30 minutes. I was confused, but I dismissed it as lingering jet lag and a by-product of the intense heat. I decided to stop running for the rest of my trip, and wrote later in my running blog about how I was pushing myself perhaps too much. Indeed, I was. Back in Washington a few days later, I was out of breath again. But this time I had just walked up two flights of stairs at home. Something was wrong. I opened my laptop, connected to Google, typed in \"shortness of breath + calf pain + long flight\", and found a possible cause that turned me cold: deep-vein thrombosis (DVT), or blood clotting, that could travel up to my lung and cause a pulmonary embolism, a blockage in a lung artery. And that, I read, could kill me. A half-hour later, I drove to the hospital. There I told the admitting nurse that I believed I had DVT and cited my conditions. She checked off a box on the form for \"urgent\", and 15 minutes later an ultrasound technician was looking at the veins inside my right calf. \"Oh, my god,\" she said in a whisper. \"You found a clot?\" I asked. \"Don\'t move,\" she said. She had found two, one a large clot just below my knee. She was worried that if I moved, the clot could travel up to my lungs. An orderly wheeled me back to the emergency room, where a nurse quickly gave me anti-clotting medicines. A doctor came a few minutes later and said that based on my story, I had almost surely had a pulmonary embolism in Manila and again in Washington. And at that moment, he said, I probably had several clots in my veins. He told me that the anti-clotting drugs would not break apart the clots — medications to do that can cause serious bleeding and generally are used only in life-or-death moments in the emergency room. Instead, he said, I would start a regimen of two medicines — Coumadin orally and daily shots of heparin — to prevent my clots from getting bigger and further clots from developing. I was not yet out of danger, and so I would be kept in the hospital for a few days to make sure everything was OK, he said. \"You\'re lucky,\" he said. So began my education in deep-vein thrombosis. From Google I learnt that 350,000 to 600,0000 Americans get DVT every year, and up to 100,000 die from it. I found out that the biggest risk factors for DVT include surgery, immobilisation, smoking, obesity, genetic tendencies to form clots and ... long-haul flights. DVT is frequently called \"economy-class syndrome\" because of the number of people who get it after sitting immobilised in cramped seats on long flights. Phyllis Kanki, an infectious-diseases professor at the Harvard School of Public Health, told me she travelled business class in part because of the ability to elevate her legs, a way to lessen the risk of DVT. \"The trouble with diagnosing DVT after long trips is that so many things are going on. You\'re fatigued, so it\'s really easy to not get the right cues. If you were at home, you would pick up on them immediately.\" Several people told me about the physician John LaMontagne, deputy director of the National Institute of Allergy and Infectious Diseases, who died suddenly in 2004 from a pulmonary embolism after leaving an aircraft in Mexico City. I called his former boss, Anthony Fauci, to learn more about what happened. \"It was tragic,\" said Fauci, who is also a physician. \"John was sitting at the very back of a crowded flight going into Mexico City. He was doing fine, and as he was going through the passport line, he had a pulmonary embolism, and it killed him right then and there.\" Fauci, one of the country\'s premier Aids scientists, said he walks a lot on flights, even if he clogs the aisles. He explained how sitting in a cramped aircraft seat for a long time could cause clotting: \"If you are sitting down and the under part of your knee is constricted, when you bend the femoral vein, it creates more blood statis\", or stagnation, which causes blood platelets to clump up and form clots, he said. But Victoria Day, a spokesperson for Airlines for America, a trade association, said there is \"no specific link between air travel and DVT. The risk of developing a DVT during air travel is about the same as being seated for the same period of time at a desk, in a film theatre, on a bus or in a car.\" I decided to reach out to a web-based clearinghouse of information on DVT called ClotCare. The doctor who founded the organisation, Henry Bussey, said that the few studies on DVT showed that long-distance flying could be a \"substantial risk\". But he also said that those who had a tendency towards clotting were older people with poor circulation, women who were on hormonal medicine and people with a genetic condition that allows clots to form more easily, not necessarily people who frequently travel long distances. He suggested that my DVT could have been caused by a genetic disorder that made me predisposed to clotting. So what does this mean for me? I can\'t say just yet. After I\'m off my anticlotting medicine, my doctor will test my blood to see if I have a genetic disorder. The result matters. And what will I do when I need to fly to Manila or Addis Ababa or some other distant city? I will probably shoot myself up with an anti-clotting medicine before each flight that is longer than six hours. I will wear knee-high compression socks to prevent my blood from pooling in my legs. And I will walk up and down the aisles, drink lots of water and avoid beverages that dehydrate me. I dodged a bullet twice. No need to do it again. From gulfnews