Deep Vein Thrombosis

Deep Vein Thrombosis (DVT) is a condition in which a small blood clot forms, mainly in the deep veins of the legs, as a result of a slowing down of blood flow in the legs back to the heart. DVT may occur as a result of inactivity and can result in blood clots forming in the calves.

Such clots can be present without signs or symptom, but may give rise to swelling of the infected leg, at such times accompanied by pain (particularly when the foot is flexed hard upwards) and local tenderness.

Deep vein thrombosis is not dangerous in itself, but complications arising from it may be occasionally life threatening. Complications occur when a thrombus breaks away from the wall of the vein to which it is attached and is carried along with the flow of blood, this is termed an embolus.

If the embolus reaches a blood vessel through which it cannot pass, it bocks the vessel. The consequence of such a blockage is called an embolism. The most serious of these occurs in the lungs (a pulmonary embolism) giving rise to chest pain and breathing difficulties and, in worst cases, death from respiratory failure.

Specific risk factors associated with long distance travel

• Increasing frequency & duration of travel.

• Immobility elected or enforced.

• Seating constraints, particularly leg room.

• Seating posture, including when asleep.

• Wearing of tight undergarments or restrictive clothing.

• Reduced oxygen or pressure leading to increased blood clotting tendencies.

• Low humidity affecting body fluid content.

• Excessive consumption of alcohol and coffee leading to dehydration.

There is a small risk of deep vein thrombosis in the general population, however within the highest risk group the risk factors can be categorised as follows:

Low risk group

Aged over 40, very tall, very short or obese. Previous or current leg swelling from any cause. Recent minor leg injury or minor body surgery. Extensive varicose veins.

Medium risk group (and any of the above)

Recent heart disease, or pregnant or on any hormone medication (contraceptive pill and HRT). Recent major leg injury or leg surgery. Family history of deep vein thrombosis.

Highest risk group (and any of the above)

Previous or current deep vein thrombosis, with known clotting tendency. Recent major surgery or stroke. Current malignant disease or undergoing chemotherapy. Paralysed lower limb(s).

The highest risk group should consider avoiding or postponing their flight or take medical advice if unsure.

It is important to begin wearing hosiery at the start of the journey and for as long as it is practical at the end. There is a small risk that even after the journey a small DVT may form in the vein.

When prescribing hosiery to prevent DVTs it is important to assess if patients are at increased risk of a DVT. A DVT can develop during periods of immobility not just on planes but on coaches, trains etc.

The Activa Class 1 is suitable for traveler at low risk of a DVT; medium risk patients should wear a class 2 but would need a full assessment to ensure they are suitable for compression. Travelers in the high risk category should consult their GP/Specialist on their suitability to travel.

Lower Risk Rating

• Aged over 40

• Very tall, very short or obese

• Previous or current leg swelling from any cause

• Recent minor leg injury or minor body surgery

• Extensive varicose veins

Medium Risk Rating

• Recent heart disease

• Pregnant or on any hormone medication particularly the contraceptive pill and HRT

• Recent major leg injury or leg surgery

• Family history of DVT

Higher Risk Rating

• Previous or current DVT

• Known clotting tendency

• Recent major surgery or stroke

• Current malignant disease or chemotherapy

• Paralysed lower limb(s)

The highest risk group should consider avoiding or postponing their flight or take medical advice if unsure.

Measuring for Activa Unisex sock 14-17mmHg

Patients need to be measured at the calf, ankle and foot for Activa Activa Unisex sock 14-17mmHg. Foot size alone does not give an accurate guide to the size required. E.g. A large foot may indicate large but as the leg is very slim a medium is needed to give required compression.