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Matt Freed, Post-Gazette
Allegheny General Hospital's Dr. Satish Muluk is an expert on DVT, a dangerous ailment air travelers can get.
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In June of last year, Steve Ayer of Mount Lebanon flew to Phoenix to visit his mother. He stayed a lot longer than he had intended.
"I had a window seat," Mr. Ayer, 57, said, recalling the Sunday flight. "There was an elderly woman in the middle seat. She didn't get up (during the flight), so I didn't get up, so as not to bother her. That was my first mistake."
That evening he felt "a bit of a cramp," but attributed it to the 38 miles he'd cycled the day before he boarded the plane.
"By Tuesday, the cramp had gotten worse, and I had a warm feeling down my ankle," he said. "Being out in Arizona, I thought I might have been stung by something."
The next morning, he went to a local pharmacy.
"As I started to describe the swelling in my ankle and the cramping feeling in my calf, the pharmacist said, 'That sounds like DVT. You should go to a hospital.' "
DVT stands for deep venous thrombosis, a blood clot which typically forms in the deep veins of the leg. A primary cause is having a limb or limbs immobile for a prolonged period of time. A DVT is dangerous primarily because if the blood clot travels, it can lead to a pulmonary embolism, a blockage of the artery that supplies blood to the lungs. According to the American Heart Association, about 6 percent of patients diagnosed with DVT die within a month.
DVT is one of the leading causes of hospital mortality, said Dr. Satish Muluk, a vascular surgeon at Allegheny General Hospital. Pulmonary theobosism, a complication from DVT, kills around 200,000 people a year in the U.S. -- more than AIDS and breast cancer combined.
"It can lead to long-term problems with the function of the leg," Dr. Muluk said. "It can damage the valves in the veins (of the leg). This can present (itself) years after the DVT episode."
Those most likely to suffer a DVT are the elderly, the sedentary and the obese. For men and women ages 30-49, there are only two to three cases of DVT per 10,000 people, according to the American Heart Association. That rises to 20 per 10,000 people at ages 70-79.
When the pharmacist told Mr. Ayer he should go to the emergency room, his first reaction was denial.
"I'm healthy and fit," he said. "I can't have a blood clot."
He called his primary care physician in Pittsburgh.
"His nurse called back and said I should go to the emergency room. I shouldn't get on a plane until this is checked out," Mr. Ayer said.
At the hospital, a sonogram confirmed he had a DVT behind his left knee. He was in the hospital for three days, and was restricted from flying for three more.
Immobility for a prolonged period of time, is a reason the clots tend to occur after flights of 11 hours or longer, and extended car trips. But DVT also can occur on shorter trips; Mr. Ayer's flight to Phoenix was 4 1/2 hours.
Dr. Muluk said there is little difference in risk factors of a long car trip vs. a long plane flight, other than passengers in coach tend to have their movements constricted more than car passengers.
Limb immobility increases the risk of blood clots because it slows the blood's circulation, increasing the likelihood it will pool. A static pool of blood offers an ideal environment for clot formation.
Stasis is one of the three principal risk factors for DVT, Dr. Muluk said. The other two are trauma, such as an injury to a limb, and thicker than normal blood, which can be due either to genetic factors or certain medications.
A patient who has had or is facing major surgery, especially for a cancer-related ailment, may be at greatest risk. The surgery is a trauma. A post-surgery bedridden patient typically doesn't move around much. And some cancer medications thicken the blood.
Dehydration also thickens the blood, which is why it is not a good idea for an endurance athlete to board a plane shortly after a strenuous workout or competitive event. The effects of dehydration are amplified somewhat by low cabin pressure in a plane.
A study by the World Health Organization released June 29 indicated that the risks of developing a DVT roughly double after four hours in a plane. But the risk is still relatively low, the study noted. Even if a person is completely immobile throughout the flight, the odds of developing a blood clot are only one in 6,000.
DVTs typically are treated with blood thinners. Mr. Ayer was prescribed Lovenox and Coumadin. Dr. Muluk said Heparin is the blood thinner most commonly prescribed. But people who are not normally at risk for DVTs should not take blood thinners before a flight as a preventive measure.
The best way to prevent a DVT is motion, Dr. Muluk said.
"One of the things we try to do is to get our patients up and walking," he said. "It's important to maintain some level of mobility."
The key to avoiding a DVT on a long flight is to move around as much as possible. Walk in the aisle. If that's not possible, just wiggling your feet and pumping your legs while sitting can help. So can massaging your calves. It's a good idea to drink water while airborne and avoid coffee and alcohol, which increase dehydration. And wear loose clothing when flying, as tight clothes can restrict circulation.
First Published: July 24, 2007, 7:00 p.m.