Preventing Traveller's Thrombosis (Economy Class Syndrome)

Causes of and preventive measures for traveller's thrombosis (economy class syndrome)

What causes traveller's thrombosis?

Commentary: Dr. Taketoshi Morimoto (Professor Emeritus, Kyoto Prefectural University of Medicine)

  • *Dr. Takatoshi Morimoto's title shown in the video is as it was in 2002 when the video was recorded.

Traveller's thrombosis (economy class syndrome) occurs when the moisture in the body evaporates, causing blood viscosity to rise. This is especially likely in the dry atmosphere and low pressure of an aircraft cabin. Insufficient rehydration, and the consumption of drinks with a diuretic action, such as alcohol, also leads to dehydration and the risk of a rise in blood viscosity.

When the lower legs continue to be put under pressure from prolonged sitting in such conditions, blood thickens, and a blood clot can form; this is called deep-vein thrombosis. If a blood clot becomes detached when you stand up, it travels through the blood stream, and can get stuck in a narrow blood vessel in a lung, which can cause difficulties in breathing and palpitations. This is called a pulmonary embolism.

People particularly at risk of developing traveller's thrombosis

Factors which can lead to thrombosis formation include; endothelial disorder of the vein (a state in which the blood vessel is injured), hypercoagulability of the blood (a state in which the blood can easily clot), and stagnation of the blood flow of the vein (a state of poor blood flow).
People with the conditions listed below should be extra careful.

Degree of additional risk of developing traveller's thrombosis posed by various factors

Risk Level Risk Factor
  • Obesity
  • Estrogen treatment
  • Varicose veins in legs
  • Old age
  • Prolonged immobility
  • Congestive heart failure
  • Respiratory failure
  • Malignant disease
  • Central venous catheterization
  • Cancer chemotherapy
  • Severe infectious disease
  • Past history of the vein thromboembolism
  • Clot-related factor
  • Paralysis of lower limbs
  • Lower limbs in a cast

Thrombophilic diathesis: Congenital diathesis could be caused by antithrombin deficiency, protein C deficiency, or protein S deficiency etc. Acquired predispositions could be due to antiphospholipid antibody syndrome etc.
Source: Pulmonary thromboembolism / deep vein thrombosis (venous thromboembolism) prevention guideline - abridged version

Preventing Traveller's Thrombosis

Massage your lower legs

Adequate exercise and massage are effective ways of maintaining normal blood flow and preventing bloods clots, especially when focused on the lower leg and feet.
Elastic stockings can also be used in place of foot massages.

Be sure to drink plenty of fluids

Adequate fluid intake is important to prevent dehydration, which causes increased blood viscosity. However, alcoholic drinks or other beverages that have diuretic effects may contribute to body fluid loss.

Otsuka Pharmaceutical conducted a study in which it chartered an airplane and flew 40 volunteer staff members from Japan to the USA in order to research the relationship between pulmonary embolism and rehydration. In the study, subjects were divided into two groups of 20 each: a beverage containing electrolytes and carbohydrates group and a mineral water group. During the nine-hour flight, both groups drank the same amount at the same times. Learn more about this study by following the link below.