DVT is a topical issue for passengers (not for flight deck crew who stay awake!) and there is an increasing amount of information available.
For the best overview, an article by Dr Mike Bagshaw written for the Aerospace Medical Association is the most helpful and this can be found at www.aeromedical.org . Go to 'Home' and then to 'Articles' and it is one of the most recent additions.
The UK Department of Health published some advice on the subject on the 30th November 2001 which is a reasonable contribution. Go to www.doh.gov.uk/dvt/index.htm to see it.
There is a technical site that has considerable detail in it and is run by the Thrombosis Research Institute in London. It is being updated and so may not be online at present. It should be at www.tri-london.ac.uk.
Finally, Dr Stanley Mohler(an eminent and respected aviation medicine expert in the USA) had a short summary article published in the British Airways Safety Magazine in Spring 2001 and this is reproduced below for easy access.
If you are a passenger, follow the advice offered!
What is a Deep Venous Thrombosis (DVT)?
As well as the veins we can see on our hands and arms, we also have deep veins. Sometimes when we cannot take normal exercise, for example on a long flight, after an operation or during pregnancy, the blood in these deep veins flows so slowly that it actually clots solid. This process is called thrombosis, hence Deep Venous Thrombosis.
What is phlebitis?
Clotting can also occur in veins we can see, e.g. varicose veins. When we can see and feel the inflammation on the surface it is called phlebitis.
How would I know if I had DVT or phlebitis?
Usually one leg (rarely both legs) swells fairly suddenly, over a period of hours, and usually becomes painful. In the case of phlebitis, you can often feel the tender area on the surface.
What should I do?
If you suspect you have a problem, you need to see your GP urgently. If he/she diagnoses a DVT or phlebitis you will probably be sent immediately into hospital for a test.
This is usually carried out with an ultrasound (Duplex) scanner - it's a bit like a baby scan. Jelly is placed on the leg, to improve the contact between the scanning instrument and the skin, and sound waves check out the veins. It is a simple out-patient procedure, does not hurt and will take about thirty minutes. In cases of doubt, an x-ray called a venogram is used; during this procedure a dye is injected into the suspect veins and x-rays are taken to check the flow of blood.
Can it be treated?
Yes. In mild cases like phlebitis the affected leg usually needs only a support bandage and painkillers. In the case of DVT, patients usually have their blood thinned, either with tablets or a fluid called Heparin. One such tablet (Warfarin) is often continued for three months, whilst the blood in the circulation finds an alternative route around the blocked vein.
Are DVT's and phlebitis dangerous?
Phlebitis, no - DVT's, sometimes, yes, even fatal. Occasionally, clots drift from the legs to the lungs causing what is known as a pulmonary embolus. The treatment is then more complicated and prolonged.
Can DVT's be prevented? Can I help myself?
Yes, many can. Exercise, even if it is simply moving your legs in bed after an operation (if at all possible) helps keep the blood flowing and stops the formation of clots. Similarly, on long coach or air journeys, it is important to wear support stockings and, whenever possible, make use of comfort stops, or periodic strolls round the plane, (see below) to exercise. This is especially important if you have suffered with leg problems before.
Despite recent press interest the risk of a serious problem when flying or going on long journeys is still small. The following advice issued by British Airways seems to us sensible:-
British Airways offers this advice to avoid the development of DVT:
Recent published research suggests that wearing light support (travel) stockings also helps.
Airport Medical Services Limited