Traveller’s thrombosis 2001

66IntroductionBased on an initiative of the German, Swiss and AustrianSocieties for Phlebology and Angiology, an experts meet-ing was organized on June 9, 2001 in Vienna. As a furtherdevelopment of recommendations from 1995 [2], the fol-lowing comment on traveller’s thrombosis was elaborated.Prompted by accumulating reports in the press, more andmore travellers, especially those with far destinations, feelinsecure and consult their physicians.This statement is meant to give some help to the physi-cian but really only presents a framework for recommen-dations to the patient. Currently available data from studiesare not sufficient to formulate more detailed or binding re-commendations.For instance, from the available data, it is not clear whichfactors lead to a traveller’s thrombosis. It may be deducedfrom the common experience concerning development ofthrombosis that immobilization by sitting for several hours,plus additional patient-related risk factors, may be regardedas a trigger. Future studies will determine if additional cir-cumstances, such as lower air pressure, lower humidity, andnarrow seating in airplanes, promote thrombosis.The present knowledge on traveller’s thrombosis issummarized in a WHO report [1] as follows: “A link prob-ably exists between air travel and venous thrombosis; sucha link is likely to be small, and mainly affects passengerswith additional risk factors for venous thromboembolism.The available evidence does not permit an estimation ofthe actual risk.”As a guideline for medical advice concerning the dan-ger of thrombosis after long journeys, the following risk-groups are defined and prophylactic measures are proposedaccordingly.Definition of traveller’s thrombosisOccurrence of deep vein thrombosis of the lower extrem-ities (with/without pulmonary embolism) in connectionwith a journey lasting several hours in the sitting positionin persons who did not have signs of acute venous throm-boembolism when starting the travel.Risk groupsGroup 1: Low risk• Every journey in the sitting position for several hours islinked with a low risk in passengers who do not have per-sonal risk factors as stated in the following risk-groups.Group 2: Medium riskIn addition to travelling for many hours:• Pregnancy/postpartum periodOr if at least two of the following factors are present:• Age over 60• Clinically relevant cardiac disease• Documented thrombophilia/family history of venousthromboembolism• Large varicose veins, chronic venous insufficiency• Oral contraceptives, hormone replacement therapy• Obesity (BMI > 30)• ExsiccosisGroup 3: High riskIn addition to travelling for many hours:• Previous venous thromboembolism independent of thetime interval• Manifest malignant disease or other severe illness• Joint fixation procedure of lower extremity• Recent surgery with high risk for thrombosisPrevention of traveller’s thrombosisThe recommended measures are tailored to the underlyingrisk constellation. The individual decision of the doctormay differ from the recommendations in the table. Thescientific data are insufficient to recommend specific mea-sures except leg exercises during the journey [1], sufficientfluid intake (at least 0.25 l in 2 hours), and compressionstockings class I or higher [4].In particular, in view of recognized side effects, indis-criminate use of pharmacological agents cannot be recom-mended [1]. Aspirin is not expected to exert satisfyingeffects for thrombosis prevention in the venous circulation.Venotonic drugs are not evaluated for this indication. Therecommendation to use antithrombotic medications (main-ly low molecular weight heparin) for the prevention ofthrombosis is not based on clear data but made in analogywith results from other internal medical risk groups.Group 1: Low riskGeneral measures• Leg exercises, e.g., ankle movements, isometric exer-cises. Car-drive: repeated breaks and some walking.• Sufficient fluid intake (restriction of alcohol).• Restricted use of tranquillizers and sleeping pills (caveat:long sitting without any movement).