Air travel and Venous Thrombosis

Air travel may increase the risk of developing venous thrombosis due to several factors:

Immobilization: airline passengers are often seated in a cramped position for several hours.

Dehydration: due to the low humidity in aircrafts, passengers may dehydrate, especially if they take alcohol or caffein-containing beverages.

Hypobaric hypoxia: at high altitudes, the air contains less oxygen and air pressure is reduced. This may cause hypercoagulability.

Up to now, the exact magnitude of the risk of developing venous thrombosis after air travel is not known. Due to the large number of flights made each year, even a small risk increase may have a major impact on the number of cases. On the other hand, an overestimation of the risk associated with air travel can lead to excessive use of potentially dangerous precautions, such as use of aspirins and anticoagulants (risk of bleeding). This is why it is very important to get a more accurate estimation of the risk of developing venous thrombosis after air travel.

Until better data are available, passengers can reduce the risk of venous thrombosis with some simple precautions:

• Avoid immobilization by doing exercises and getting out of the chair several times.
  
• Avoid dehydration by having frequent non-alcoholic drinks and avoid drinking too much coffee and tea.
  

Use of elastic compression stockings, aspirin, oral anticoagulation or low molecular weight heparin is generally not advised for people without other risk factors for venous thrombosis. Passengers that are at higher risk for developing venous thrombosis (for example people who suffered from venous thrombosis before or people who recently had a major operation) should ask their physician for advice on the use of prophylactic measures.