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Deep Vein Thrombosis


Long distance travel is a risk factor in the development of blood clots. The risk is not confined to air travel; it increases with the duration of travel and is more common in those with pre-existing risk factors.

Prolonged periods of immobility can lead to slow blood flow in the veins which increases the risk of developing a blood clot within a deep vein in the body; this is called deep vein thrombosis (DVT). Blood clots most commonly form in the legs; parts of the clot can break off and travel to the lungs, this can block blood vessels and is called pulmonary embolism (PE) which is a potentially life threatening condition.

Although the absolute risk of developing DVT or PE after a long haul flight is very small, the risk is increased where the individual has pre-existing risk factors.

Pre-Existing Risk Factors

If you have any of the following conditions you may be at greater risk of DVT or PE and should be assessed by your GP prior to travel:

  • a history of DVT or PE
  • Cancer, whether untreated or currently on treatment
  • chronic debilitating illness especially those causing mobility problems
  • recent surgery
  • recent serious injury or trauma
  • pregnancy or less than 6 weeks after delivery
  • heart or lung disease
  • taking combined oral contraceptives and/or hormone replacement therapy
  • varicose veins
  • obesity
  • thrombophilia, a condition where the blood has an increased tendency to form clots.

Preventive Measures

General advice

  • Mobilise as much as possible.
  • Choose an aisle seating where feasible, this is known to encourage mobilisation.
  • Carry out calf muscle exercises, flex and extend ankles to encourage blood flow.
  • Avoid excessive alcohol consumption, this may discourage mobilisation.
  • Keep well hydrated, this can encourage mobilisation to toilet.
  • Seek urgent medical attention if you develop:
    • swollen, painful legs especially if one is more so than the other
    • breathing difficulties.

Aspirin therapy

  • It is now generally accepted that there is no place for aspirin in the prevention of travel related DVT or PE.

Anti-embolism stockings

The use of anti-embolismĀ stockings (AES) may reduce the risk of DVT and PE:

  • ensure you buy the correct type and size of stocking and know how to wear them correctly
  • if you have varicose veins wearing AES can slightly increase your risk of an inflamed vein near the surface of the skin, this is called Superficial thrombophlebitis
  • if you require a higher level of compression than basic AES provide, you must have them measured and fitted by a trained individual:
    • incorrectly fitting AES can increase your risk of DVT or PE.

Low molecular weight heparin

Low molecular weight heparin can be considered for those at higher risk of developing DVT (see above). This treatment is administered by injection andĀ must be prescribed by your GP or hospital specialist and used under their direction.

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