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Deep Vein Thrombosis 

Frequently Asked Questions

  What is Deep Vein Thrombosis.?

  What happens.?

  Why does it happen.?

  Why does that cause a clot.?

  Who is at risk.?

  What are the symptoms.?

  What should you do.?

  How Serious is it.?

  Is it always fatal.?

  Some Do's and Don'ts

  New Drug (for use following orthopaedic surgery)

NB: The contents of this page are meant as a guide only. If at anytime you think
you are suffering from DVT or are likely to suffer from it you should seek medical
advice without delay. 

Question: What is Deep Vein Thrombosis.?

Answer: DVT is the name given to a blood clot that forms
in a vein, most commonly in the calf. On a plane, DVT
can be caused partly by dehydration - it gets very dry
in planes and the blood becomes thicker than usual - and
by not moving about.

Long-haul, direct flights may carry the biggest risk
because there is less opportunity to move around.

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Question: What happens.?

Answer: A combination of inactivity, sluggish 
circulation and thicker blood results in a clot forming
on the side wall of a vein.

Platelets in the blood stick to each other and to the 
wall.

The clot gets slowly bigger and obstructs the vein,
although it is rare for the whole vein to become blocked.

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Question: Why does it happen.?

Answer: Because it is a long way from the bottom of the
leg back to the heart, the calf muscle acts as a vein pump
to send the blood back up. The problem is it only works
when the muscle is working, so if you are sitting in a
chair or lying for a long time the calf muscle takes time
out.

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Question: Why does that cause a clot.?

Answer: The blood is thicker, both because of dehydration
and because it is not moving about, and as a result there
is a tendency for it to become sluggish and clot.

When you eventually stand up, the muscle gets going and
the clot or a bit of it may break off and head up towards
the heart along with a tail of debris which has built up
behind and may be several inches long. It arrives in the
right side of the heart and is pumped into the lungs,
becoming a pulmonary embolism. If it is big enough to clog
up vessel it can have a big impact on breathing. The whole
functioning of the lung can be compromised.

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Question: Who is at risk?.

Answer: Factors include being over 40, although there have 
been younger victims. Others include being on the Pill,
smoking, overweight or having a previous DVT or recent
major surgery.

Also more susceptible are those suffering from the gene
mutation known as Factor V Leidan, found in one in twenty
of the population. It affects the clotting performance
of the blood, increasing sevenfold the sufferers
vulnerability to flight related DVT.

Few are unaware that they suffer from the mutation and 
while it can be picked up in tests they are too expensive
to allow for mass screening. It is also believed that
passengers are at risk of DVT if they become dehydrated
through drinking alcohol and if they use sleeping pills.
The deep sleep induced by some knock-out drugs leads to
a long period of inactivity and lowers oxygen in the blood,
increasing stickiness.

DVT can also occur during pregnancy, because there is an 
increased tendency for the blood to form clots, a natural
mechanism to prevent bleeding during childbirth.

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Question: What are the symptoms?.

Answer: Early signs are swelling of the ankle. But remember
that many people get swollen ankles during flight.
However an indication that it might be DVT is when one 
ankle swells much more than the other.

There may also be localised redness and some pain. More 
serious symptoms are a cough, breathlessness, a rapid
heartbeat, and palpitations.

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Question: What should you do?.

Answer: Seek medical advice quickly.

Question: How Serious is it?.

Answer: A pulmonary embolism can be life-threatening and
needs immediate medical attention. If it blocks a major
artery feeding the lung it can cause death from respiratory
or cardiac failure because the heart cannot get the blood
through the system.

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Question: Is it always fatal?.

Answer: No. Many people get DVT and never realise it. The
clot can just sit there and not turn into an embolism. It
can be a smaller clot which goes into the lung and causes
respiratory problems but not catastrophic failure.

Or sometimes a pulmonary embolism can go unnoticed by the
victim because it is not a major part of the lung which
becomes clogged up.

Sometimes the clot does not break off at all and simply 
remains as a deep vein thrombosis.

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Some Do's and Don'ts

DO: Always have a glass of water in front of you. Make 
sure drink plenty of water (or juice) both during and 
before the flight. Carbonated (Seltzer) Ginger drinks
are particularly beneficial.

DO: Get up and walk up and down the aisle when you get
a chance.

DO: Take an aspirin before the flight to thin the blood.
But check with your GP, aspirin is not advisable with
conditions such as stomach ulcers.

DO: Try elastic stoking, particularly if you have varicose
veins. They apply constant pressure down the leg and aid
the blood flow.

DON'T: Drink alcohol, it dehydrates you.

DON'T: Drink too much coffee or tea; like alcohol they
can dehydrate you.

DON'T: Have any kind of obstruction near or around the
calves when seated.

DON'T: Go to sleep with any constriction on lower legs.

DON'T: Wear tight socks, though you can wear the airline
versions which are not constricting.

DON'T: Smoke. even assuming the airline allows it.

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NEW DRUG - Information only.

A new generation drug has been launched which can
dramatically reduce the serious risk of potentially fatal blood
clots following orthopaedic surgery.

Deep vein thrombosis - blood clots in the legs - caused by
"economy class syndrome" on long-haul flights has
attracted much publicity.

But a much bigger cause of clots both in the legs and the
lungs is orthopaedic operations such as hip replacement,
repair of hip fractures and major knee surgery.

With no preventative treatment, an estimated 50% of the
180,000 UK patients undergoing surgery to lower limbs
each year will develop deep vein thrombosis.

DVT often occurs without the patient or doctors knowing,
and may lead to a blood clot in the lung, or pulmonary
embolism, which can be fatal.

Current treatments reduce the hazard, but a 15% to 30%
risk remains that a patient will develop either DVT or PE.

In 2000-2001 there were in excess of 45,000 NHS hospital
admissions resulting from DVT or PE, of which more than
80% were emergencies.

The new drug, fondaparinux sodium, sold under the brand
name Arixtra, is said to reduce the risk by a further 50% - a
massive improvement.

John Skinner, consultant orthopaedic surgeon at the Royal
National Orthopaedic Hospital in Stanmore, Middlesex,
said: "There remains a need for an effective, well-tolerated
agent that will help to prevent venous thromboembolism
(blood clots). Such a therapy could save lives and reduce
the pressure on the NHS when it has to cope with this
dangerous yet difficult to diagnose condition."

Arixtra is the first of a new class of drug which targets a
particular protein called activated factor X that plays a key
role in clotting blood. Trials have shown it to be more than
50% more effective than the currently most widely
prescribed anti-clotting agent, enoxaparin. Unlike
enoxaparin, however, Arixtra does not affect the blood
platelets which help prevent bleeding.


Acknowledgements: Daily Mail, Ananova and Joe Curry

NB: The contents of this page are meant as a guide only. If at anytime you think you are suffering from DVT or are likely to suffer from it you should seek medical advice without delay.
 

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