DVT

Deep Vein Thrombosis (DVT) is a condition, which is also known as
"travellers' thrombosis" and "economy class syndrome", has recently
received much publicity in the media.

It is not uncommon for adult passengers, particularly the elderly, to
develop swollen ankles after a long distance flight. This swelling reduces
without any treatment after a few days. However, a more serious
complication of long distance travelling by air is a thrombosis, or blood
clot, which usually develops in a leg vein, resulting in localised pain,
tenderness, swelling and sometimes a fever. This thrombosis is not life
threatening unless a small piece of the clot, called an embolus, breaks
off and travels in the blood stream to become lodged in a blood vessel,
often the pulmonary artery, blocking off the blood supply, thus causing
death.

A study conducted at London Heathrow Airport has shown that every
fifth sudden death following a long distance flight is caused by a
pulmonary embolus, secondary to DVT. It is believed that the swollen
ankles and the thrombosis develop during the flight from the prolonged
period of sitting. The inactivity of the legs causes the blood circulation
to slow down to a minimum, resulting in stagnation of blood in the lower
legs due to the effect of gravity thereby encouraging the formation of a
blood clot, usually in a deep vein in the calf.

Other causative factors are:

* the low cabin pressure of 11 pounds per square inch (psi) (compared
with the normal atmospheric pressure of 14.7psi at sea level) which
makes it easier for the swelling to develop

* dehydration of the body through an excessive intake of alcohol

* the taking of sleeping tablets (which increases the period of
inactivity)

* wearing tight clothing.

Although anyone can develop a thrombosis in theory, passengers may be
divided into a high or low risk category. Travellers who exhibit two or
more of the following causative factors are placed in the high-risk
group, the more factors that apply, the higher the risk. These factors
are those who:

* are over the age of 40 years who have a history of heart failure,
thrombosis or varicose veins or whose ankles have swollen previously
when flying

* are overweight

* have a sedentary occupation and are unfit

* take oral contraceptives

* have a high cholesterol level

* smoke.

Those in the low risk category are under the age of 40 years who have
none or only one of the causative factors in the high-risk group above.

Probably the two most effective ways to reduce the risk are to wear low
compression stockings up to the knees and to practise leg exercises
while seated. Leg exercises, such as the following, assist in pumping the
blood back towards the heart:

* move your feet and toes up and down

* straighten and bend your knees

* press your legs together

* lift alternate feet off the floor

* stand up, have a stretch and walk up and down the aisle.

These exercises are most effective if practised on a "little and often"
basis, rather than "a lot occasionally".

Compression stockings also assist in returning venous blood to the
heart, increase the effectiveness of the exercises and overcome the
adverse effect of the reduced cabin pressure, thus reducing the risk of
swelling developing. Compression stockings of 30-40mm Hg are
considered to be necessary for most passengers in the high-risk group
while stockings of 20-30mm Hg are suitable for the low-risk group.
These garments are usually referred to as calf or knee-high stockings
and should be of the closed toe variety like socks. They are available in
a variety of colours, fabrics and sizes and should be fitted by a suitably
qualified person who is able to accurately measure the limb. It is
recommended that the stockings be put on before passengers leave their
homes/hotels on the way to the airport and be removed only on reaching
their destination, unless the journey is broken by an overnight stopover
in a hotel.

The Adelaide Lymphoedema Clinic carries a full range of suitable styles
of socks and stockings for flying. Call the clinic to be supplied and fitted.
Contact the Clinic

Other measures which may be taken to reduce the risk during the flight
include:

* elevating the feet by resting them on the seat foot-rest, if provided,
or cabin baggage

* drinking a reduced amount of alcohol and plenty of water

* practising deep breathing exercises

* wearing loose clothing

* avoiding sitting with legs crossed.

Medical advice should be sought before taking anti-coagulants.