Risk Factors for Venous Thromboembolism Following Prolonged Air Travel: A “Prospective” Study

Abstract

The aim of this study was to analyze patients with air-travel-related venous leg thromboembolism (VTE) concerning the occurrence of patient-related and cabin-related risk factors. Twenty-five patients, still in hospital, with deep-vein thrombosis (DVT) and/or pulmonary embolism (PE) with onset of symptoms during or after air travel were questioned according to a study protocol. There were 14 women and 11 men with an age range of 36-79 years. Flight times were 5-18 hours. All patients had DVT, and nine (36%) had PE as well. The proximal extensions of the thrombus were in tibial vein, five patients; popliteal vein, two patients; superficial femoral vein, three patients; common femoral vein, four patients; greater saphenous vein, four patients; and iliac vein, seven patients. All but two patients (92%) had one or more patient-related risk factors; the mean was three. Overweight was present in 76% of the patients; chronic heart disease in 44%; hormone medication in 40%; chronic disease, except chronic heart disease and malignancy in 32%; history of previous VTE in 28%; malignancy in 28%; smoking in 20%; recent lower limb injury in 16%; and recent surgery in 12%. Only two patients had no known patient-related risk factor. The flight travel itself does not seem to be an important risk factor in healthy individuals. However, when patient-related risk factors are superimposed, there is increasing evidence that cabin-related risk factors, such as immobilization, cramped “coach” position, insufficient fluid intake, low humidity, and hypoxia contribute to development of VTE. Improved information is required so that passengers can prepare their travel in good time. Active precautions are recommended.