Part 11: Travel | What measures can be taken to prevent
blood clots during travel?
Air travel increases the risk of thrombosis. Besides immobility, other factors may play into this increased risk (See Question 45); nevertheless, immobility is probably the single most important factor in travel-related thrombosis. Immobility— that is, lack of movement—can result in slow, sluggish, or nonexistent blood flow, which increases a person’s risk of a blood clot. Therefore, the most important measure to prevent blood clots during travel is to move around for at least five minutes every two hours. Even when passengers are confined to their seats in a plane, they can still move their feet and legs. Passengers can move their feet back and forth as if stepping on and off of a gas pedal and can move their legs back and forth by bending at their knees.
Dehydration can increase the concentration of clotting factors in the blood, so staying hydrated is also important. Drinking water is recommended. (Alcohol has a dehydrating—rather than hydrating—effect.)
Fitted elastic compression stockings may also help reduce the risk of a blood clot. In one study, volunteers who were taking a flight of more than eight hours’ duration were randomly assigned to one of two groups. Members of one group wore knee-high fitted elastic compression stockings; members of the other group did not. After returning from their trips, the volunteers had an ultrasound examination of their legs even though they had no symptoms of DVT. Ten percent of the group who did not wear stockings had asymptomatic DVT (DVT without any symptoms) in the calf, whereas none of the group who wore fitted elastic stockings developed DVT.
Individuals who have had DVT or PE in the past, have thrombophilia, have had recent surgery, or have other medical conditions that place them at risk such as heart failure, but who are not currently taking warfarin, should consult their physician or anticoagulation clinic for recommendations prior to travel. Some physicians or anticoagulation clinics may recommend taking a single dose of a LMWH prior to flights that will last six hours or longer.
Long automobile or train trips may pose similar risks to air travel. The same precautions as for air travel should be considered when planning long trips in the car or on the train. Taking a brief, five minute walk every two hours is advised.