What Is Deep Vein Thrombosis?

This condition is defined as: “a plug or clot in a deep blood vessel, formed by coagulation of the blood, and remaining at the point of its formation”. This condition is not life-threatening UNLESS a small piece of the clot (called an embolus) travels in the bloodstream to become lodged in a vital blood vessel, blocking the blood supply. Death can then result.

What Causes Deep Vein Thrombosis?

Swollen ankles and thrombosis can develop during long periods of sitting — in particular long plane flights, as well as bus and train excursions. This inactivity of the legs causes the blood circulation to slow to a minimum. The blood stagnates due to the effect of gravity. It can also be aggravated by the low pressure in an aircraft cabin of around 11 pounds per square inch (psi). Normal atmospheric pressure at sea level is 14.7 psi. Therefore, because of this reduced cabin pressure in the aircraft, it is easier for swelling to develop. You may be more prone to develop deep vein thrombosis if you:

  • are overweight
  • have a history of heart failure
  • are of advanced age
  • have varicose veins
  • have an occupation where you sit for long periods of time
  • are unfit
  • take oral contraceptives
  • have high levels of cholesterol
  • smoke

Reduce the risk of Deep Vein Thrombosis

By following some simple rules, you may reduce the risk considerably if you:

  • wear knee high, low compression stockings/socks
  • do leg exercises such as knee raises, bending the feet up and down and exercise the toes by flexing
  • drink plenty of water (not alcohol)
  • carry out deep breathing exercises
  • wear loose, non-constricting clothing
  • sit with legs straight, not crossed.

If travelling, seek medical advice before taking anti-coagulants (blood thinners), such as aspirin.

Support socks

For active people, travelling by plane, train and bus, special socks are advisable. These are a support sock graded to give firmer pressure at the ankle and lighter pressure at the top. By indicating 15-20mm of Hg at the ankle, this is equivalent to 15-20mm of mercury at the ankle joint — the scientific way that blood pressure is measured. The top should measure about 8mm Hg. The socks must be soft, have no elastic tops and be fitted by a podiatrist or doctor.