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Travel related deep vein thrombosis | |||||
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The link between cramped conditions and deep vein thrombosis (DVT) has been recognised since World War II, when people sitting for hours at a time in air raid shelters(1) developed the condition. However, the most common situation in which humans now find themselves with limited mobility for prolonged periods is on flights. Whether the flight is long haul or short haul(2), business class or economy and whatever the passenger’s age or sex they could potentially develop a DVT. Although the relationship between DVT and flights was identified half a century ago(3), the condition has increasingly been in the public eye in recent years after media attention focused on a number of cases of people suffering a DVT after flights. Recent research(4) has also suggested long journeys by other forms of travel can also contribute to the development of DVT. What is deep vein thrombosis and how is it caused? Put simply, deep vein thrombosis is a blood clot which forms deep in the leg veins. When blood flows around the body it is helped to travel against gravity through the veins by the leg muscles, which act as a pump when walking around. Problems arise when there is limited movement, as blood can then pool in the veins potentially causing blood clots. While these clots are not dangerous, if they break free and travel to the lungs they can cause pulmonary embolism, which is a much more serious condition and can be fatal. Limited seat pitch on commercial flights results in passengers sitting in cramped conditions, making leg movement difficult. This, combined with the temptation to drink alcohol and caffeine - which dehydrate the body - makes passengers at increased risk of developing a blood clot. What are the symptoms of deep vein thrombosis? Although in some instances DVT has no symptoms, typically the thrombosis will cause pain in the calf, especially when walking, and can cause swelling and redness. The pain is often worsened when the foot is bent towards the knee. If the blood clot breaks free and travels toward the heart and lungs, chest pain, breathlessness and coughing may occur. If any of these side effects is experienced, medical attention should be sought immediately. The side effects may take a while to present themselves so people should remain vigilant for a few days after travelling. Who is at risk of developing deep vein thrombosis? The following should be considered as risk factors in developing DVT: Risk factors for deep vein thrombosis (5)
However, there has been a number of incidences of airline passengers developing DVT after a flight that did not fall into any of the recognised at risk groups. Everyone planning to go on a journey which will involve prolonged periods of immobility (whether it is in a coach, car or train) should take precautions.
There are a number of simple and effective measures passengers can take when going on a journey that will require limited mobility: Precautions (6)
Who should consult a doctor or healthcare professional
Recent research (8) has shown that in medium and high-risk passengers, blood clots form in the first two to three hours of a journey, putting people on short flights at risk. The international study examined more than 500 passengers flying from London to Italy and found blood clots in 4.3% of high-risk subjects after their flight. Many experts believe time spent sitting in airport waiting rooms can also contribute to the development of blood clots. Equally, prolonged periods of immobility in other forms of transport, such as cars and coaches, can also lead to DVT. A study(4) in Nice, France, showed people suffering from DVT were four times more likely to have taken a journey, by either plane, train or car, lasting four or more hours.
While everyone who goes on a flight could potentially develop DVT, if passengers take simple precautions, such as those listed above, journeys should be more comfortable and safer, regardless of the length or type of travel. | |||||
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References (1) Simpson K. Shelter deaths from pulmonary embolism. Lancet 1940; ii:744. (2) Belcaro G. Short haul study SHAPSS preliminary results. VF-E Web Journal 16.10.03 (3) Homans J. Thrombosis of the deep leg veins due to prolonged sitting. New England Journal of Medicine 1954:250:148-149. (4) Ferrari E, Chevallier T, Chapelier A et al. Travel as a risk factor for venous thromboembolic disease. Chest1999; 115:440-444 (5) World Health Organisation (6) House of Lords Select Committee on Science and Technology 5th Report on Air Travel and Health (7) Arya R, Cohen A T. Long haul flights and deep vein thrombosis: who is at risk? Br J of Haematology 2003, 120: 367-368 (8) Belcaro G. Short haul study SHAPSS preliminary results. VF-E Web Journal 16.10.03 | |||||
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Previous history of venous thrombosis (blood clots) and pulmonary embolism
Individuals with a history of venous thrombosis should consult their doctor before flying 