FAA Brochure - Deep Vein Thrombosis

Summary

1. A Deep Vein Thrombosis (DVT) is a clot that

forms in a leg vein.

2. A DVT can cause harm by obstructing blood

flow to a limb or if a part of the clot flows to the

heart or lungs.

3. A DVT can be caused by some medical

problems, medications, and long periods

of inactivity.

4. The risk of developing a DVT can be

reduced by:

• Occasional muscular activity

• Maintaining hydration

• Limiting alcohol and caffeine intake

• And, if indicated by a physician:

— Support socks or stockings

— Blood-thinning medications Deep Vein

Thrombosis

and Travel

Provided by

Aerospace Medical Education Division,

AAM-400

To obtain copies of this brochure online:

https://www.faa.gov/pilots/safety/

pilotsafetybrochures/

or contact:

Federal Aviation Administration

Civil Aerospace Medical Institute

AAM-400

P.O. Box 25082

Oklahoma City, OK 73125

(405) 954-4831

OK-24-0000 9/12/2024

Introduction

Deep Vein Thrombosis (DVT) is a condition in which a

clot, or thrombus, typically forms in a deep vein. An area

with a DVT may notice pain and swelling in the leg where

the clot has formed, though smaller clots may not cause any symptoms. The major problem occurs when a part of

the clot breaks off and flows to the lungs. This condition,

called a Pulmonary Embolus (PE), can cause severe injury or death. DVT’s are known to occur in about 1.8

cases per 1000 people in the general population from all causes.

Traveler’s Thrombosis

The condition has been erroneously dubbed Economy Class Syndrome by some people because of the perception that passengers in the more restrictive coach or economy class of the aircraft are more likely to develop DVTs. Recent research, however, has found

that passengers in any seating class of the aircraft may develop a DVT. Research indicates that any situation in which a person’s activity is restricted for long periods

-such as a long car ride or train trip - may contribute

to the development of a DVT. For this reason, the term Traveler’s Thrombosis is more appropriate.

Cause

The precise cause of Traveler’s Thrombosis, while

currently not clear, appears to be related in part to long periods of sitting and inactivity. The decrease in activity may lead to inadequate circulation of the blood in the legs. In addition, the veins may be slightly constricted,

which could also impair circulation in the legs.

Other conditions that alter blood flow or normal clotting

mechanisms may make some people more likely to develop a DVT. Some of these risk factors include a prior DVT, certain heart diseases, cancer, pregnancy, smoking, older age, and some blood clotting disorders. Recent major surgery or trauma is also a risk factor.

Certain medications may also contribute to formation of

the thrombus. Birth control pills and related hormones have been found to make some people slightly more susceptible to forming DVTs.

Symptoms

Not all DVTs cause noticeable symptoms, but the most common are swelling and redness in the affected leg,

often associated with some pain in

the same area. Severe chest pain or problems breathing may indicate a pulmonary embolus and should be evaluated immediately.

Treatment

If you suspect that you may have developed a DVT, you should immediately contact your physician or go to an emergency room. Be sure to mention that you have recently completed a long journey, as that information may aid in making the correct diagnosis. Different procedures will be used to check for the presence of a

DVT and to evaluate a possible pulmonary embolus, if indicated. If a DVT or PE is found, then you will usually

be started on a blood thinner to help prevent the clot from becoming larger while it slowly resolves.

Prevention

Since it has not been scientifically established that

there is a direct relationship between DVT and

flying, there may be no need for specific preventive

methods. However, some practices may be found to be

beneficial:

• Increasing leg muscle activity during long periods

of sitting improves blood flow in the legs. This may

include walking around the cabin or exercising your

lower legs and ankles while seated.

• Drinking adequate fluids, and avoiding alcohol and

caffeine, may also help by preventing dehydration.

• Loose-fitting clothing may be beneficial in avoiding

constriction of veins.

• Some recommend taking short naps, instead of long ones, to avoid prolonged inactivity.

If you have any of the risk factors for DVT, consult your physician before long trips. If indicated by a physician, special support socks or stockings can reduce blood pooling in the legs and blood thinning medications may be prescribed.

For more information, we encourage you to read

“Traveller’s Thrombosis: A Review of Deep Vein

Thrombosis Associated With Travel,” published in

Aviation, Space, and Environmental Medicine, Vol. 7 , No. 9, September 2001.