Background and methods: The paper reviews air travel and venous thrombosis. The risk of venous thrombosis increases with distance flown. The mechanisms that cause thrombosis are unknown, but may be related to hypobaric hypoxia, i.e. reduced air pressure inside the aeroplane, stasis of the lower limbs, often referred to as economy class syndrome (ECS), and dehydration.
Results: Symptomless deep venous thrombosis may occur in 10% of healthy long-haul airline travellers over 50 years of age, and up to 4.5% of passengers under 50 at high risk of thrombosis. Wearing of elastic compression stockings during the flight is associated with reduced risk of deep venous thrombosis.
Interpretation: Passengers should be encouraged to use the muscle-vein pump regularly, ensure adequate hydration, and in some cases wear elastic compression stockings. A majority of passengers will not need any thromboprophylaxis. Aspirin may have a protective role, but its efficacy in preventing venous thrombosis is much smaller than that of low molecular weight heparins. A high prophylactic dose of a low molecular weight heparin should be considered in passengers at high risk of thrombosis.