Blood clots can strike at 10,000 feet - the dangers of deep vein thrombosis

Andrew Dunn, the chief of the Division of Hospital Medicine at Mount Sinai, specializes in blood clots, anti-coagulation and deep vein thrombosis (DVT). During his 15-year career, he's seen hundreds of patients with DVT.

Who's at risk

Flying is more dangerous than you think. But it's got nothing to do with the pilot. "Between one and six Americans per 1,000 are affected by deep vein thrombosis each year," says Dunn.

One of the triggers of the blood clots that form in the veins of the body, specifically in the legs, is long flights. "Prolonged air travel is a rare but potential cause," says Dunn. That's because sitting for long periods of time in one position can contribute to poor blood flow — a condition called statis.

A much more prevalent risk factor is surgery. "Stasis can result from being severely ill, surgery, fracture, heart failure, stroke and obesity," says Dunn. "Stasis in the setting of illness and inflammation are really the tipoff to this disease," says Dunn.

"Active cancer and other severe ­medical illness resulting in inflammation and hospitalization all put you at risk," adds Dunn.

Other risk factors include taking birth-control pills or hormone replacement therapy, especially when paired with smoking. There's also a genetic component in some cases. "Some people have a predisposition to clot," says Dunn, "so DVT can run in families."

DVT strikes men and women of all races and ages, though the risk does increase with age. "Everybody is at risk of this, and once you've had one clot you're at high risk," he explains, adding that about a third of patients have a recurrence.

Signs and symptoms

The textbook symptoms of DVT are pain and swelling. "It usually presents in the legs, just on one side," says Dunn. "It can happen in the arms, but that's almost always in the setting of an IV."
Cancer patients and patients who go home with a PICC (a type of catheter) line are at particularly elevated risk of DVT in the arms.

One specific form of clot is a pulmonary embolism, in which the blood clots break off from the legs and travel to the lungs — sometimes with fatal results.

"The hallmark of pulmonary embolism is the sudden onset of severe shortness of breath and chest pain," says Dunn. "Often the chest pain gets worse when you take a deep breath."

While many people take a week to see a doctor about DVT in the legs, pulmonary embolisms are abrupt enough that people usually go to the ER within a day. Patients often describe the experience of pulmonary embolism as similar to a cardiac event, such as in, "I couldn't catch my breath, and it hurt every time I took a deep breath." Other symptoms are pain when coughing, heaviness in the legs and a dull persistent ache.

Traditional treatment

The primary treatment for DVT is medical. "We treat it with blood-thinning medication — anti-coagulants," says Dunn. "The drug Warfarin is a pill that takes five to seven days to kick in, and you need a medicine that works immediately, so it has to be injection therapy first, followed by pills for the long term." Some patients continue taking Warfarin for a lifetime, while others can stop after three to six months.

The good news is that Warfarin is highly effective. "This is a treatable, curable condition," says Dunn. "The blood thinner works extremely well, but it does take a lot of diligence and monitoring."

Warfarin also can cause serious drug and food interactions, so treating patients with related problems, like severe heart failure, emphysema, kidney or liver disease or bleeding disorders requires extra precautions and sometimes longer hospital stays.

Doctors are now able to treat more patients with DVT in their legs at home. "It takes some organization and oversight, because someone has to be monitoring the pill level at home," says Dunn. "Often people who end up in the ER for DVT in the legs go home the same day or after a short hospital stay of about 24 hours."

Clots in the lungs are very dangerous and more likely to be fatal than clots in the legs, so these patients often need hospital stays. "With pulmonary embolism, if you miss a few doses, you could die," says Dunn. "Surgery is an option for major embolism in the lungs, but is rarely necessary."

The recovery period for DVT is about a month plus.

"Most patients have their symptoms resolve slowly," says Dunn. "They start feeling better in a week or so, and they recover in about one to three months."

About a quarter of patients with leg clots have long-term symptoms like pain, swelling or ulceration that don't go away.

"Elastic stockings can help reduce the risk of long-term symptoms,"says Dunn.

Research breakthroughs

Doctors are excited about the next generation of drugs that may come to replace Warfarin. "The new pills provide immediate blood thinning, eliminating the need for the temporary injections and intense monitoring of Warfarin," says Dunn. "They also have few food or drug interactions, so it's a very exciting moment in DVT care."

Questions for your doctor
If you're hospitalized, ask your doctor, "Are you giving me a medicine to prevent clots?" Once you've gone on medication to prevent DVT, you should track your INR level, a measurement that reads for how fast your blood clots in comparison to someone who's not
on Warfarin. Ask, "What's my INR — and what's my target?"

What you can do

Get moving after surgery or illness.

"If you are sick, try to get mobile as soon as you can,” says Dr. Andrew Dunn. “The doctors and nurses should be pushing this."

Do exercises on long-haul flights.

Deep vein thrombosis is usually only a problem on flights of more than six hours. Dunn recommends doing calf exercises every hour by pushing up on the balls and then the heels of your feet and squeezing.

Don’t smoke if you take birth-control pills.

"The combination multiplies the risk," says Dunn.

Get informed.

A reliable patient advocacy group is the Coalition to Prevent Deep Vein Thrombosis (preventdvt.org), which has patient-friendly FAQs and tools to help you assess your risk.

nydailynews.com