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 labored. I also had nagging pain in my calves. The discomfort had been with me since I landed in the Philippines four days earlier.
Back in Washington a few days later, I again was out of breath. But this time, I had just walked up two flights of stairs. I Googled "shortness of breath + calf pain + long flight," and found a possible cause: deep vein thrombosis (DVT), or blood clotting, that could travel up to my lung and cause a pulmonary embolism, a sudden blockage in a lung artery that could kill me.
I drove to the hospital and told the admitting nurse why I believed I had DVT. Fifteen 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. A nurse quickly gave me anticlotting 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 anticlotting 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 for observation.
So began my education on deep vein thrombosis. I returned to Google and learned that 350,000 to 600,0000 Americans get DVT every year, and up to 100,000 die from it.
I found that the biggest risk factors for DVT include surgery, immobilization, smoking, obesity, genetic tendencies to form clots (see related box) — and long-haul flights.
I reached a Web-based clearinghouse of information on DVT, ClotCare. The founder, Dr. Henry Bussey, said that the few studies on DVT showed that long-distance flying could be a "substantial risk." He also said those with a tendency toward 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.
After I'm off my anticlotting medicine, my doctor will test my blood to see if I have a genetic disorder. And when I need to fly, I'll take precautions and be observant (see box).
John Donnelly is the author of "A Twist of Faith: An American Christian's Quest to Help Orphans in Africa.''