Travel-related thromboembolism: mechanisms and avoidance.

Evidence regarding the existence of travel-related venous thrombosis and pulmonary embolism is building. Research suggests that travel of all kinds increases the risk by two- to four-fold. Risks are not restricted to air travel alone. For travelers without any known risk factors, the risk of experiencing venous thromboembolism is likely to be very low. However, risks increase significantly in the presence of known risk factors, such as age over 60 years, thrombophilic disorders, varicose veins, history of thromboembolism, obesity, women taking oral contraceptives and travel duration over 12 h. A combination of one or more of these risk factors raises the probability of developing travel-related thromboembolism. Possible contributing factors, such as cramped sitting (with suppressed leg venous flow), moderate hypoxia, low humidity in the aircraft and dehydration, are discussed. Depending on the risk profile of individuals, the use of graduated compression stockings and/or pharmacological interventions (low-molecular-weight heparins are preferred) may be recommended.