Hypoxia-reoxygenation contributes to increased frequency of venous thromboembolism in air travellers.

Commercial air travel is widespread, with close to 2 billion people traveling each year. The association between venous thromboembolism (VTE) and confined sitting has been established and a correlation between the distance traveled and its incidence had been documented. Most studies underscore stasis caused by immobility as the cause of VTE and ignore the possible contribution of additional factors including coagulation and the blood vessel wall. Recent studies indicate that hypobaric hypoxia may contribute to blood vessel wall alteration and activation of coagulation. We suggest that air travel associated hypobaric hypoxia may lead to endothelial injury and initiation of a pro-coagulatory response, effects which are augmented by the reoxygenation upon landing, thus culminating in thrombosis. Prevention of air travel associated hypoxia and reoxygenation injury may decrease the incidence of flight associated VTE.