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.
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