Deep vein thrombosis (DVT), better known as "economy-class syndrome", is a potentially life-threatening condition. Before traveling, it is a good idea to know exactly what it is and how to avoid it.

DVT develops when blood coagulates and slows down, particularly in the lower legs, after long periods of immobility when traveling. It usually occurs after longer periods of 4 hours or more. About 3-5% of air travelers develop these clots. They are usually painless, but they can cause pain and swelling.

If the clot breaks off, it can travel through the bloodstream and obstruct blood vessels in the lungs and heart, restricting blood flow. This can cause various problems to include damaged lung tissues, stroke and sometimes death.

Besides immobility, factors that cause DVT include dehydration, low humidity and low cabin pressure. While it is most common on planes, it can occur during any type of travel and even when simply sitting in a restricted area for longer periods.

While those who have previously had DVT, the elderly, pregnant women, people with serious medical conditions such as cancer and those who have had recent orthopedic surgery are most at risk, DVT can affect anyone to include serious athletes. Also, in spite of the economy-class syndrome nickname, it is possible for people in business class to get it too.

The following are some ways to avoid DVT:

1. Get up and move about whenever practical. Also, avoid sitting at window seats since window seat passengers are much more likely to develop DVT.

2. Keep hydrated and avoid alcohol and caffeine consumption when traveling.

3. Wear compression socks. These keep pressure on the feet and push blood out of the feet and towards the heart and lungs.

4. Stretch and move your feet and legs even while sitting.

Being aware of DVT and taking simple precautions can greatly reduce the risks of suffering from it.