Blood Clots: A Long-Distance Danger

Millions of people travel long distances each year and some face a very serious threat.  Those travelers sitting for long periods of time (four hours or more) could be at risk for blood clots or deep vein thrombosis (DVT) in the legs.

“Probably the most significant contributor to DVT is immobility,” said Mark Iafrati, MD, Chief of Vascular Surgery and the Vascular Center at Tufts Medical Center.

While DVT can occur in people riding in cars, trains or buses for hours at a time, Dr. Iafrati explained the higher risk for these blood clots tends to be with long-haul flights of seven hours or more.  The cramped quarters with limited ability to move, reduced pressurization, lower oxygen levels, plus a higher tendency to dehydrate, as contributors to the risk.

How dangerous is deep vein thrombosis?  “DVT can, if untreated, have a high risk of serious complications,” said Dr. Iafrati.  “Those could be, in the long term, destroying the veins in your legs, resulting in all sorts of problems.  But also, if the clot breaks free, it could go to the lungs, resulting in pulmonary embolism (PE), which can actually be fatal.”

Increased Risk

Clotting is a normal function of blood, which prevents excessive bleeding when a vessel is injured or damaged.  Clots are always being made and removed by your body.  The problem comes when the fine balance is disturbed and excessive clot formation occurs.  Deep vein thrombosis is a blood clot in a deep vein, usually in the legs.  The abnormal clot blocks the return of blood to the heart through these veins.

How common is DVT?  “In the long-haul flights, if you are not taking any special precautions, in the average population, it is probably up to about ten percent,” said Dr. Iafrati.  He points out that some of the risk factors may include:

  • Age (65+)
  • History of blood clots
  • Genetic disposition
  • Overall health
  • Limited mobility
  • Dehydration

Any combination of these factors could put a long distance traveler at a higher risk, explained Dr. Iafrati.

Symptoms of DVT and PE

For some travelers in whom DVT occurs, there may be no symptoms at all.  But Dr. Iafrati urges people to watch out for swelling in the legs, unusual leg pain or tenderness, and redness of the skin or skin that is warm to the touch.  Sometime a firm “cord” can be felt in the back of the calf or inner portion of the leg when a superficial vein is clotted.

“It is very common to be tender and achy and swollen from an airplane trip,” said Dr. Iafrati. “The biggest clue that there is something to worry about would be asymmetry.  If one leg is worse than the other, that’s a real trigger that something is going on, like a DVT.” 

And if DVT becomes a pulmonary embolism, symptoms tend to come on suddenly.  Watch for problems breathing, chest pain, and coughing.  Don’t wait.  Get medical attention immediately.  A pulmonary embolism could be fatal.

Treating DVT

There are several ways to diagnose DVT. A physician might use a screening test called a D-Dimer. 

“This test is very sensitive and if there is a DVT, this test will almost always be positive,” he said.  “However, it is not very specific so you might have a positive test and not have a clot.”

Dr. Iafrati pointed out, that ultrasound is the gold standard diagnostic exam, however, it is not always readily available.

Treatment for deep vein thrombosis involves blood thinners and fortunately, advancements have made the treatment easier. For years, blood thinners were given intravenously for several days while an oral blood thinner was administered overlapping for typically three to five days in the hospital. 

Dr. Iafrati explained things changed dramatically about a decade ago when an injectable therapy, low molecular heparin, became available, which allowed the use of twice-daily injections to replace IV infusions for the initial management of DVT or PE.  Even more recently, novel oral anti-coagulants (NOACS) have been developed which allow effective and rapid blood thinning with pills alone and no injections or IVs in most patients.

Reducing the Risk

Education about DVT is the best way to reduce the risk during long-distance travel.  Know the symptoms and talk to your doctor ahead of time. 

The key to lowering your risk of DVT, Dr. Iafrati emphasized, is to move!   Get up and walk around or, at least, extend your legs or keep your feet up to improve blood flow.  You can also work your calf muscles to keep the blood flowing just by flapping your ankles like you’re stepping on an accelerator.  Also, avoid crossing your legs. 

Another tip is to wear compression stockings. These special socks put pressure on your legs to keep blood moving.  Compression stockings can reduce your risk of DVT on long-haul flights by up to ten-fold.  Dr. Iafrati said even he wears these special stockings on long distance flights and he has no risk factors.

Finally, it’s critical to stay hydrated. Dehydration causes blood vessels to narrow and blood to thicken.  Avoid alcohol or caffeine.

Whether for business or pleasure, knowing how to avoid your risk for a blood clot during long-distance travel, can make for a safer, more pleasant trip.

Updated November 2018. The above content is provided for educational purposes by Tufts Medical Center. It is free for educational use. For information about your own health, contact your physician.

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