Travel-related Thromboembolism: Mechanisms and Avoidance

Wolfgang Schobersberger; Beatrix Schobersberger; Hugo Partsch

Disclosures

Expert Rev Cardiovasc Ther. 2009;7(12):1559-1567. 

In This Article

Abstract and Introduction

Abstract

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.

Introduction

Long-distance travel is an accepted part of business and vacation for millions of individuals. According to the Annual Review of Civil Aviation, more than 2 billion passengers fly annually, and it is estimated that over 300 million passengers travel on long-haul flights each year.[1] Since Homan's early descriptions of the existence of venous thrombosis after prolonged sitting in a plane, car or theatre many studies have focused on the incidence of travel-related deep venous thrombosis (DVT) and pulmonary embolism (PE).[2] Most studies have related to DVT and PE after long-haul flights, although DVT and PE have also been described after long-distance travel by car, train and bus.[3,4] Recently, an international expert meeting defined 'traveler's thrombosis' as venous thromboembolism that occurs during or within 4 weeks after long-haul travel. 'Air-travel thrombosis' refers to thrombosis that occurs when the main part of the journey was undertaken by plane.[5] At present, long-haul air travel is an accepted risk factor for DVT and PE. Evidence suggests this form of travel may raise risks by two- to four-fold for all travelers.[6,7,8,9,10,11,12,13] However, the capacity to calculate and predict absolute risks is limited, given the quality of study designs and the different limitations of trials conducted to date (e.g., the small number of cases, unavoidable bias, inclusion of asymptomatic and/or symptomatic DVT, different travel duration and time points of duplex sonography). It is suggested that the absolute risk for travel-related thrombosis may be rather low, but that the existence of additional risk factors significantly increases the risk of developing DVT and PE in travelers.

This review focuses on two specific aspects of travel-related thrombosis: the role of additional risk factors (traveler related vs ambient related) and its pathophysiological mechanisms of DVT and PE, and recommendations for avoiding travel-related thrombosis.

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