DVT and Travel

People have become concerned about the risk of deep vein thrombosis (DVT) during long air flights or long journeys by bus, car or train following the press reports about occasional deaths due to fatal pulmonary embolism. The below information explains about DVT and pulmonary embolism (PE) risk, identify people who may be at increased risk and advise how to reduce the risk.

What are DVT and PE?
DVT means clotting of blood in deep veins of the legs causing usually swelling and pain in the leg, but often occurs without any symptoms (silent DVT). DVT may either settle completely, as thrombosis is dissolved by natural process or extends up the deep veins and get carried through main veins and heart to lodge in the lungs. This condition is called a pulmonary embolism and may cause chest pain, sometimes coughing up of blood and shortness of breath. A large pulmonary embolus (dislodged thrombosis) which blocks the main blood vessels to the lungs can be usually fatal. The chronic or untreated thrombosis can cause blockage in the deep veins or damage valves leading to disabling or long term selling and skin changes.

Why does deep vein thrombosis occur?
All veins in the leg have valves which should direct blood flow from feet upwards towards the heart. The venous system is passive and muscular activity such as moving the legs, walking, jogging or any leg exercises helps to pump the blood up these veins. When the legs become inactive, and particularly when sitting or standing, blood tends to stagnate in the deep veins eventually leading to thrombosis. The longer period of stagnation, the more likely thrombosis will occur. If blood is unusually thick or sticky then the risk of thrombosis is greater. These conditions can be triggered by dehydration or some diseases. 

Who is at risk of DVT and how large is the risk?

  • Individuals who had DVT or PE before
  • Pregnant women
  • Women who takes contraceptive pills or hormonal replacement therapy (HRT)
  • Cancer patients
  • Obese and overweight people
  • Some blood diseases
  • Varicose veins in legs
  • Individuals who underwent a recent major operation

The risks of DVT are highest for people with more than one of these risk factors and who take no precautions against thrombosis. In these cases the risk is as high as 1/20 on long haul flights but many of these conditions are minor and cause no problems.

How to reduce the risk of DVT during travelling?
Based on what is well known about the causes of DVT and successful methods of prevention used in health care units, the following are recommended precautions on long haul flights or journeys lasting several hours:

  • Move your legs.  Avoid sitting with your legs crossed for hours, try to stretch your legs out from time to time and move your feet up and down at the ankles. Stretching and moving the legs stops blood stagnating in the deep veins of calf, and it is simplest and most effective thing you can do. Go for a walk up and down the aisle.
  • Wear compression stockings. Below knee graduate compression stockings reduce the risk of DVT. They also help prevent the ankle swelling which many people experience during long journeys. Medical graduated compression stockings are supplied in three classes and can be prescribed by a doctor if there is medical need.
  • Avoid dehydration.  Drink plenty of fluid before and during long journeys – water is ideal. Avoid drinking excessive amount of alcohol which tends to cause dehydration.
  • Anticoagulants . Heparin injections or warfarin by mouth may be advisable for a few people who have medical conditions with particular high risk of DVT. This kind of treatment will always be at the discretion of a doctor.
  • Aspirin.  Taking an aspirin tablet either 75mg or 300mg a few hours before a long journey may provide a small amount of extra protection against DVT

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