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Your Health

Long journeys, heat trigger blood-clot warning

For travelers flying the skies on long journeys to distant lands for the vacation of a lifetime, there are more hidden costs than the high price of jet fuel and fees for extra baggage. And those costs are too high.

Nearly 214 million people traveled on domestic airlines last summer, according to the federal Bureau of Transportation Statistics. Anyone sitting in place for an extended period of time is at risk for developing deep vein thrombosis (DVT), a potentially fatal condition where a blood clot develops in the deep vein(s) of a muscle, most often the legs.

But it's another set of statistics that concerns Dr. Tej Singh, clinical director of the Heart and Vascular Center at El Camino Hospital and director of the Vascular Center at the Palo Alto Foundation Medical Group.

Besides blocking the flow of blood to the immediate area where a clot (thrombus) has formed, the clot or a portion of that clot (emboli) can break off and travel to the lung, blocking the pulmonary artery or its branches, causing a pulmonary embolism. Of the nearly 2 million Americans affected by deep vein thrombosis each year, 600,000 will suffer a pulmonary embolism, according to the American Heart Association, and 10 percent of those will die.

With the summertime heat, proclivity to dehydration and travel plans often resulting in hours of sitting and immobility, Singh sees a marked increase in DVT during the hottest months of the year.

"I see four each month at El Camino and at the (center) 10 to 15," Singh said. "Those are big numbers. These are monthly averages for DVT. (The) numbers do go up slightly during the summer."

Singh said blood clots can cause leg pain and swelling. Other symptoms include tenderness, discoloration or redness. However, warning signs that alert people they have developed clots in their bodies are often absent.

"DVT is silent but deadly," said Linda Anderson, a clinical nurse specialist at the Heart and Vascular Center. "But precautionary steps – and I mean that quite literally – can reduce your risk while traveling. First and foremost, get up and walk around."

This can be a difficult task when a plane's aisle space limits passenger traffic.

"It's a safety issue for the airlines," Singh said. "They need people sitting and not standing up in the aisles."

Long periods of sitting increase the odds of developing deep vein thrombosis because blood flow to the legs is restricted, allowing the blood in stasis to pool and form clots. Often referred to as "economy-class syndrome" because the seats in that section of planes have less leg room and passengers have even less freedom to move about, a Federal Aviation Administration newsletter identifies DVT as a threat to any passenger.

"Recent research, however, has found that passengers in any seating class of the aircraft may develop a DVT," the newsletter reports. "… any situation where one's activity is limited for long periods … may contribute to a DVT. For this reason, the term Traveler's Thrombosis is more appropriate."

Immobility during journeys via train, bus or auto can also trigger clot formation, as can their associated occupations – plane pilots, bus drivers and long-haul truck drivers whose paychecks often depend on the number of miles they drive.

Office workers are at risk, too. A May 9, 2006, article in The Guardian magazine warned those working at computer screens to take frequent breaks. The warning was issued after a computer programmer in England collapsed from e-thrombosis, (different name, same problem) after 12 uninterrupted hours at his workstation. The term e-thrombosis was coined in New Zealand, when a 32-year-old man who sat at his computer for 12 hours daily suffered a pulmonary embolism.

"Walking around allows the leg muscles to squeeze the veins and move blood to the heart," Anderson said. "It's the most important thing you can do to prevent DVT."

But any obvious signs of DVT usually show up well after the plane has landed.

"One reason DVT is so dangerous is because it often goes unrecognized," Singh said. "Travelers who develop the condition might not experience a symptom until they've been home a few days."

A moving clot can trigger chest pain, the symptom of a heart attack or a pulmonary embolism, Singh said.

"A pulmonary embolism also can cause shortness of breath and coughing up blood," he said. "When such symptoms appear, it's important to get to an emergency room quickly and let the doctor know you recently completed a long trip."

Timing is critical.

"Most people who die from a pulmonary embolism do so within 30 to 60 minutes after symptoms start," Singh said.

But immobility isn't the only risk factor in developing clots or embolisms, Singh said.

Trauma to the lower leg, recent surgery or hospitalization are factors that can contribute to developing deep vein thrombosis. Cancer treatments, a family history of clots or a genetic predisposition to DVT alone or in combination aid in the propensity to clot formation.

In his two-and-a-half years in practice at the foundation clinic and the Heart and Vascular Center, Singh has noticed two demographic spikes for embolisms.

Women 25 to 40 with family histories of blood clots, who are taking birth control pills or hormone replacement therapies, are at high risk; and anyone 50-70 undergoing cancer therapy, who has had surgery, is inactive and/or dehydrated is in danger, also.

Deep vein thrombosis is usually diagnosed using ultrasound, Singh said. Clots and emboli are normally treated with blood thinners such as Coumaden or Heparin. But Singh urges people to be proactive and prevent DVT and its consequences.

"Stay active, hydrated and know your family history," Singh said. "Perhaps it's worth it to give up the idea of sleeping through that long, boring flight to Europe in order to take steps – and avoid DVT."

Contact Mary Beth Hislop at This email address is being protected from spambots. You need JavaScript enabled to view it. .

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