First recognised in 1946, travel related DVT is an additional potential problem for 'at risk' travellers who are immobile for extended periods of time. While the problem is often associated by the media with air travel, the risk is equally reported among those travelling by car, coach and train.
A deep vein thrombosis (DVT) is a blood clot that forms in a deep leg vein. These are blood vessels which go through the muscles (they are not the veins which you can see just below the skin). A calf vein is the common site for a DVT. A thigh vein is less commonly affected.
A DVT can occur some days or even weeks after a trip. Most cases have at least 3 predisposing risk factors - the risk increases as the number of risk factors increase. Very little established research exists in relation to travel. However we do have a wealth of information from hospital research specific to DVT.
Blood normally flows quickly through veins, and does not usually clot. Sometimes a DVT occurs for no apparent reason. However, the following increase the risk of having a DVT.
Immobility which causes blood flow in the veins to be slow. Slow flowing blood is more likely to clot than normal flowing blood.
A surgical operation which lasts more than 30 minutes is the most common cause of a DVT. The legs become still when you are under anaesthetic. Blood flow in the leg veins can become very slow.
Any illness or injury that causes immobility increases the risk of a DVT.
Long journeys by plane, train, etc are thought to cause a slightly increased risk of DVT. This is probably due to sitting cramped for long periods.
Faulty blood clotting is an uncommon cause. One example is an inherited condition that causes the blood to clot more easily than normal (factor V leiden).
The contraceptive pill and hormone replacement therapy (HRT) which contain oestrogen can cause the blood to clot slightly more easily. Women taking 'the pill' or 'HRT' have a small increased risk of DVT.
Damage to the inside lining of the vein increases the risk of a blood clot forming. For example, a DVT may damage the lining of the vein. So, if you have already had a DVT, then you have a higher than average risk of having another one sometime in the future.
Older people are more likely to have a DVT, particularly if you have poor mobility or have a serious illness such as cancer.
Pregnancy increases the risk. About 1 in 1000 pregnant women have a DVT.
Obesity also increases the risk of having a DVT.
Dehydration
How can I reduce my risk?
Those in a high-risk categories should see their travel health advisor before they travel and discuss prevention.
Those at risk should try to exercise at least every hour on long journeys. Exercise the calf muscles by rotating your ankles, or making use of the commercially available exercise equipment. The risk applies to any form of travel where you are routed to one place for hours at the time.
Good hosiery will encourage circulation. However it is important that you do not wear clothing that will cause a restriction of circulation. Any hosiery should be measured properly to ensure a suitable fit.
For long flights wear loose clothing. Due to the change in atmospheric pressure in a plane, parts of your body can expand due to increased gas! In the dry environment of a plane, it is a well-documented fact that too much alcohol, tea and coffee on flights can add to the problem of dehydration. It is therefore very important to remain hydrated during a long flight by drinking plenty of water and fruit juices.
What are the symptoms of a deep vein thrombosis?
The typical symptoms are pain, tenderness, and swelling of the calf. Blood that would normally go through the blocked vein is diverted to outer veins. The calf may then become warm and red. Sometimes there are no symptoms, and a DVT is only diagnosed if a complication occurs.
Sometimes it is difficult for a doctor to be sure of the diagnosis as there are other causes of a painful and swollen calf. For example, a muscle strain or infection. You will normally be seen urgently at hospital if you have a suspected DVT. Tests may be done to confirm the diagnosis.
In-Flight Stockings and Socks
With much attention given over the potential risks associated with Travel Related Deep Vein Thrombosis, it is not surprising that many people are looking for products, which will offer protection. Research has shown that correctly fitting anti-thrombosis stockings increase blood flow, thus lowering the risk of DVT in those at risk. Advice related to stocking/socks should apply to all forms of travel when a passenger is sitting still for a long period of time.
Before buying any products it is essential that you are able to assess your personal risk factors and obtain advice from your own doctor regarding fitness to fly if you are in any doubt. If you are in a very high-risk category you should seek advice from your doctor and consider postponing your travel plans.
It is important that any stocking/sock purchased is fitted properly. A stocking that is too tight and worn by a traveller with existing circulation problems can do more harm than good -- cutting into the skin on a long flight and potentially causing ulceration and increased risk of DVT.
Never guess the size stocking or sock you require. A good stocking/sock will come in a variety of sizes allowing for measurement from the knee to the ankle as well as the foot size. If a stocking is too tight around the knee it will prevent essential venous return causing the blood to pool around the knee.
When buying your stockings/socks make sure they are comfortable with your chosen footwear for travelling. Some stockings can be slightly thicker than normal leg covering and can be potentially restrictive with tight foot wear.
Do not think that if you wear tight knee-highs during a flight you will save some money. Any clothing or tight shoes cutting into the skin around will prevent normal blood flow and increase the risk of travel related DVT.
Wear your stockings around the house prior to travel to ensure you have a good, comfortable fitting. On the morning of your travel put them on when you get dressed, especially if you are travelling a distance to the airport. Hurriedly put on stockings in the airport lounge can cause no end of travel related anxiety!
Stockings are just one-way to help
prevent travel related DVT - take advice from your doctor as well
as preventative advice related to travel
Note: This information is designed to complement and not replace the relationship that exists with your existing family doctor or travel health professional. Please discuss your travel health requirements with your regular family doctor or practice nurse.
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