Travellers thrombosis (economy class syndrome) has had a lot of  coverage recently due to a  number of highly publicised deaths .It is estimated that over 2000 flyers each year die from the condition. This page hopes to explain what this condition is and also give you some practical advice to prevent it when undertaking a long haul flight.

It has been known for many years that immobilisation can lead to the development of deep vein thrombosis (DVT) .This is a clot of blood that forms in the leg veins, when blood in the lower leg stops flowing when the calf muscle is not exercised. Long periods of immobilisation and the dehydrated atmosphere on board are thought to contribute to the problem.

Symptoms include a swollen and painful calf or thigh, an increase in skin temperature and skin discoloration (faint blue-red) at the site of the pain.

DVT is not dangerous in itself, but complications arising from it can be life threatening. If the clot breaks free from the veins and pass through the blood stream into the lungs (a condition called "pulmonary embolus") you could suffer from pain in the chest, which is worsened by breathing. Pulmonary embolus can also cause shortness of breath and the coughing up of small amounts of blood. If  the blood clot is large enough, it can cause sudden death by travelling to the heart and lungs and interrupting the blood flow,

Research  has brought peoples attention  to the fact  that air travel could increase the risk of developing DVT. Although more studies need to be carried out involving larger numbers of people, it is now believed that air travel can increase the risk of developing DVT if only because it increases both  immobilisation and dehydration as mentioned above.

The blood oscillates between a fine balance of bleeding and clotting. Flying pushes this balance in favour of clotting. Whilst for the majority of passengers this does not cause a problem, it could for some groups, including older passengers and those with coexisting diseases. The real problem is that people with genetic predispositions are not easily identified and such defects probably account for the small number of cases of DVT in young people.

Risk Factors

 It is important to remember that even if people have no apparent risk factors they are not immune from the possibility of developing DVT. Therefore, all travellers should take some basic precautions against DVT and those with known risk factors should take additional ones.

 Advice for travellers 

People at very high risk of DVT should consider either postponing their flight or the use of anticoagulation therapy .

General advice

All travellers should take some basic precautions against developing DVT. This includes simple exercise such as  circling the ankles, pumping the feet, lifting the knees and neck and shoulder rolls also keeping well hydrated 
  It is easy to become dehydrated on aeroplanes because of the low humidity in cabins and because of eating and drinking patterns people often adopt when flying. Dehydration increases blood viscosity and hence the risk of DVT. To avoid dehydration, travellers should be advised to drink plenty of water and to minimise intake of alcohol, caffeinated drinks and salty snacks. Some airlines are now including this type of advice in in-flight magazines. Make sure you have good medical insurance for your trip. U.K citizens I travelling within the European Economic Area, you may be eligible for an E111 form. This is available from Post Offices or using the application form in the Department of Health leaflet, Health Advice for Travellers. This entitles you to free or reduced-cost emergency treatment only, and therefore you must also be insured.

Aspirin

Many experts  advocate the use of preflight aspirin due to its antiplatelet effect. A House of Lords report recommends the use of pre-flight aspirin for people at moderate risk of developing DVT, including people who take the contraceptive pill or hormone replacement therapy.

The lack of clinical trial evidence for aspirin for prevention of travel-related DVT meant that it was unclear exactly what dose should be used. It has been suggested that the dose should be between 75 and 150mg. One dose was sufficient for all flight durations.
However, the Medicines Control Agency cautions that DVT is an unlicensed indication for aspirin and it should be used with caution in many patient groups including those with an active peptic ulcer, asthma or on anticoagulation therapy. People with known aspirin intolerance could ask their general practitioner for clopidogrel. The use of heparin is probably less suitable because of the practicalities of patients administering it by injection just before a flight.

Compression hosiery

Below the knee compression stockings e.g. Scholl, Activa are available for preventing travel DVT. They offer the equivalent of class I compression. . Class II stockings give an unnecessary amount of compression for most people but could be useful for people who fall in one of the risk groups.  Support tights are unlikely to be  beneficial. 
 People with arterial pathogenesis should not use compression hosiery. In addition, people are occasionally allergic to the components of stockings; this can be overcome by wearing a cotton inner sock. 

Scholl Flight Socks should be worn in place of normal socks throughout the flight. Always wear both socks and ensure that they are pulled up to just below the knee. The pack  leaflet explains correct fitting and care of the socks. Scholl Flight Socks can also be worn at any time to improve leg comfort.

 Not to be used if you have serious circulatory problems such as active arterial or venous disease. 

- If you have a previous history of arterial or venous disease.

- lf you suffer from diabetes.

- lf you are currently using prescribed compression hosiery.

Three measurements are needed to ensure correct fitting:

1. Around the fullest part of the calf (B)

2. Around the ankle, just above the ankle bone (C)

3. The length of the foot (D)

Now use the table below to choose the size you need:

Activa Flight Socks

Ultrafine Tactel Micro filaments with Lycra Soft for smooth stretching.

Three measurements are needed to ensure correct fitting:

1. Around the fullest part of the calf (B)

2. Around the ankle, just above the ankle bone (C)

3. The length of the foot (D)

Now use the table below to choose the size you need:

 The Lancet Volume 358, Number 9284     08 September 2001 Deep-vein thrombosis in long-haul flights

 Department of health online site http://www.doh.gov.uk/dvt/

 British Airways travel health online http://www.britishairways.com/health/docs/during/travellers_thrombosis.shtml

page last updated  15th March 2002