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Tips on Deep Vein Thrombosis (Economy Class Syndrome)

Recently there has been a huge upsurge of articles in the press on Deep Vein Thrombosis in travelers. This subject was sparked off by recent deaths of travelers from a clot in the lungs shortly after she had completed a journey.

The dramatic term "economy class syndrome" is often coined in the lay press but "travelers thrombosis" is a more accurate description of the association between long distance travel and the possibility of deep vein thrombosis.

Deep Vein Thrombosis (DVT) refers to the formation of a clot or thrombosis in the deep veins of the calf or other non superficial vein. Deep Vein Thrombosis symptoms can vary from a mildly uncomfortable ache and swelling to nothing at all. The real concern about DVT is that in a small number of people a piece of the clot can break off and travel in the circulation to the lungs – the medical term is pulmonary embolism – with a reaction that is sometimes fatal.

As long ago as 1940 one of England’s greatest forensic scientists Dr Keith Simpson recorded an increase in cases of pulmonary embolism in people who had sat for a long time in air raid shelters during the London Blitz. He attributed this to people sitting immobile in a cramped position for long periods. Certainly such a description can apply to modern passengers on long haul flights where, to quote Stacy Greg writing in the Sunday Times "aircrafts serve as a flying cattle-pen for the cramped, miserable masses…" and indeed applies just as much to long road or rail journeys.

The question of how much does travel contribute to the development of DVT still remains to be answered.

DVT is not a rare condition. The average overall rate of around 1 in 10 000 people per year.

The fundamental question yet to be answered is whether this number [of travelers who get thrombosis] is greater than the number from an equivalent population who would have developed DVT if they had not recently flown’. The British Medical Journal states: "current evidence indicates that any association between symptomatic deep vein thrombosis and air flights is weak and its incidence much less than the impression given by the recent publicity."

Nevertheless many vascular surgeons seem to be convinced and the theoretical reasons why long haul travel could predispose to clot formation make sense.

What should travelers make of the current discussion?

In the first place it must be emphasized that what is thought to be the main underlying cause for DVT is prolonged immobility in the sitting position, so long haul bus or train travel is as much a risk as plane travel. Undoubtedly there are medical conditions which predispose to clot formation and nothing replaces pre-travel medical advice.

Travelers can be placed into four groups:

1. Those with no known predisposing factors:

   • Move around as much as possible
   • Exercise calf muscles whilst seated with half hourly flexing and rotating of ankles
   • Avoid excessive alcohol and caffeine containing drinks, both before and during the flight
   • Drink only water or juices when thirsty

2. Those at minor risk (aged over 40, very tall,obese, extensive varicose veins, recent minor leg surgery or minor body surgery, previous or current leg swelling from any cause):

   As above, plus:

   • Take only short periods of sleep, unless you can lie down
   • Avoid sleeping pills
   • Consider wearing support stockings

3. Those at moderate risk (recent heart disease, pregnant or on any hormone medication, recent major leg injury or leg surgery, family history of DVT)

   As above, plus:

   • Take professional advice about risk involved
   • Take professional advice about the need to wear compression stockings

4. Those at substantial risk (previous DVT, known clotting tendency, recent major surgery, current malignant disease, paralyzed lower limbs)

   • All the above plus a blood thinner injection called low molecular weight heparin. This product is given before take off and will protect for over 12 hours. Travelers at risk can be taught to self administer LMH.

A word or two about aspirin

Many travelers are already taking aspirin in an attempt to prevent thrombosis. A couple of studies have been published that showed a very small advantage in taking aspirin after hip replacement surgery – a totally different group of patients from the average traveler. If this group of patients at high risk showed such a small decrease in incidence of DVT one would expect the effect in travelers to be minute. Taking aspirin could lead to a false sense of security ie that you would think you are doing something to prevent thrombosis when in fact you are probably doing nothing. Aspirin could increase any tendency to nose bleeding at altitude and of course must not be used in the presence of any digestive disorders. Additionally, as aspirin is an anti-inflammatory it may mask the symptoms of Deep Vein Thrombosis and subsequently result in a delayed diagnosis. Those that fit into higher risk categories will do better to get advice on compression stockings or the possibility of heparin injections.

Compression Stockings

Proper compression stockings are designed to transmit graduated pressure and should be individually fitted. They are not cheap but the expense is small in the total context of travel expenses and in high risk cases could be the difference between health and illness. Ask the clinic staff for a list of suppliers in the area.