 |
Why people die suddenly of blood clots on
planes |
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Economy class syndrome -
deep vein thrombosis (DVT) and how to avoid it |
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Do anti embolus stockings save lives
by preventing deep vein thrombosis? |
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Health risks of business travel from blood
clots / DVTs |
The so-called "economy class syndrome",
DVTs, deep vein thrombosis, blood clots, clotting and all the rest
- no matter what you call it, flying in planes seems to make the
blood clot faster.
Deep vein thrombosis happens in economy, business,
and first class seats - perhaps in up to 5% of long-haul passengers
depending on their age, sex, weight, medication, if women are pregnant,
or on the pill, dehydration, length of flight and altitude.
No one really knows.
Dehydration makes the blood thicker and alcohol, tea
or coffee all make it worse and blood clots more frequent.
Humidity levels can be near zero in a pressurized airline cabin
at 35,000 feet.
But there is another effect which adds to the risk
of DVT and clots in the legs passing into the lungs (pulmonary embolus)
and that is the altitude factor itself. An aircraft is only
partly pressurized. As it ascends, the pressure falls in the
cabin so that by the time you are at cruising altitude, the cabin
pressure is as low as it would be if you were 8,000 feet up a mountain.
This altitude problem stresses the body, and the blood reacts so
that clots form more easily.
So deep vein thrombosis is for this reason far more
common than you would expect in people confined in the same way
for the same length of time on - say - a train or a bus.
And what about the evidence for "economy class
syndrome"?
If the "economy class syndrome" exists then
airlines will come under immediate irresistable pressures to abandon
crowding of people into narrow pitch seats. They will fear
being sued. But what is the actual evidence? There are
not enough studies to be certain that cramped seats are particularly
to blame though common sense suggests that of people cannot move
around for hours at a time then they are more likely to be at risk
from deep vein thrombosis. Lack of movement promotes blood
clot formation.
Symptoms of a deep vein thrombosis are very variable
and often there are none at all. It is impossible for a doctor
to tell on examination whether someone has a blood clot in their
legs. A phsyician will look for the following:
- Pain or swelling in a limb
- Fever
- Rapid heart beat
- Sudden, unexplained cough
- Joint pain and soreness
The diagnosis of DVT can only be confirmed by specialist
centres with blood flow tests and other diagnostics designed especially
to detect deep vein thrombosis.
Deep vein thrombosis is not actually a great risk
to health in itself, compared to it's major complication which
is when a piece of clot breaks off and enters the heart, before
being pumped into the lungs. This can happen in up to 10%
of cases but usually far less often. When clots like this land up
in the lungs the result is often severe pain and breathlessness,
caused by blockage of one of the main arteries into the lungs.
This is called a pulmonary embolus and is a frequent cause of sudden
death in people who walk off planes after a long haul flight, feeling
tired but otherwise perfectly well.
The most important ways to prevent deep vein thrombosis
in flight are the following:
- Drink plenty of non-alcoholic fluids before flight and during
- Make sure you get out of your seat every hour and walk around
- Don't take sedatives to help you sleep during a flight
- Make sure the seat is not pressing into the back of your legs
and your feet can rest on the ground or on a foot rest
- Don't cross feet when sitting
- Do stretching exercises of thighs and lower leg / feet regularly
- Avoid alcohol during flight
- Use anti-thrombosis stockings
- Take low dose aspirin 12 hours before flight - but not if
you have a tendency to ulcers or indigestion
Treatment involves thinning the blood with warfarin
or heparin or both, and bed rest to discourage pieces of clot from
moving around the body.
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