The World Health Organization warns the risk of developing potentially life-threatening deep-vein thrombosis doubles after plane and other forms of travel lasting four hours or more. But, it says the risks remain relatively low. Lisa Schlein reports for VOA from Geneva where WHO has just released a study based on extensive examinations of tens of thousands of travelers.
The World Health Organization says travelers who remain immobile for four or more hours are at greater risk of developing blood clots in their veins, which could lead to death.
It says those taking multiple flights over a short period of time are also at higher risk. It says the risk does not go away completely after a flight is over, but remains elevated for about four weeks.
But, WHO Assistant Director-General for Communicable Diseases, Catherine Le Gales-Camus says the chance of developing deep vein thrombosis is only one in 6,000
"The risk increases due to a stagnation of blood in the veins caused by prolonged immobility, which can promote blood clot formation," said Catherine Le Gales-Camus. "The risk is higher not only after flights, but also in any mode of transport where the passenger is seated and immobile for long periods of time."
Dr. Gales-Camus says air travelers are not the only ones at risk. She says people who remain seated and immobile in a car, a bus or a train for more than four hours also are flirting with danger.
Deep vein thrombosis is a condition in which a blood clot develops in a deep vein. Problems set in when a blood clot in a vein breaks off, travels to the lung where it becomes lodged and blocks blood flow. Symptoms of what is known as pulmonary embolism include chest pain and breathing difficulties. If left untreated, it can lead to death.
The report shows people who are very fat, very tall or very short are at increased risk of getting deep vein thrombosis during travel. WHO explains people who are very tall and travel in a confined space do not have enough legroom. And, very short people, it says may not be able to reach the floor and exercise their legs.
Other factors that can increase the risk, says WHO, include the use of oral contraceptives and inherited blood disorders leading to increased clotting tendency.
WHO Senior Adviser in Cardiovascular Diseases, Shanthi Mendis says to decrease the risks, people have to move.
"We know that exercises at the ankle depend on movement of the feet and will improve the blood circulation in the calves," said Shanthi Mendis. "Other commonsense measures would be, for example, you would want people to wear not very tight clothing and also people should not be taking sedative drugs and too much alcohol because that could promote immobility and not promote movement."
The study also cautions long-haul travelers not to take anti-thrombotic medicines, such as aspirin, because they can have side effects and lead to hemorrhaging.