Anyone can get economy-class syndrome; you don’t need to be in economy-class at all. People in business and first-class have also developed it, because it’s related to low cabin pressure, low humidity and dehydration. Relative humidity is 20 to 25% in the Arabian deserts, while optimum comfort is found at around 50% humidity. In-flight cabin humidity gradually falls on long-distance flights and in many cases can get as low as one per cent. That’s pretty dry and is also the reason why people don’t urinate much on a long flight, unless they’ve drunk plenty of liquids. This low humidity causes thicker blood and vein constriction because of dehydration, which combined with a slower heart rate and reduced cabin pressure, can cause blood to pool in the legs. Couple this with the effects of gravity and lack of exercise, and the result can be a DVT. You can also get DVT’s from prolonged train or car travel, so it’s more common than was initially thought.

London’s Heathrow airport has reported one passenger death a month. In Australia, a law firm has filed 1,000 DVT claims against six airlines in one year. Narita airport’s records show that on average, 100 to 150 passengers are treated for DVT, immediately upon arrival each year, of which three to five per cent die. Even former Vice President Dan Quayle nearly died from a DVT during a 1994 flight, and we see quite a few cases, in travellers arriving here in Phuket.

In DVT, blood clots form in the deep veins of the legs, usually between the ankle and upper calf. They can occur in a matter of only a few hours. Problems really start when the clot breaks off, usually as the ’plane descends or when it decompresses, and the clot then travels through the bloodstream and obstructs a vessel in the lungs, restricting blood flow. This condition is called pulmonary embolism which seriously damages lung tissues and causes poor lung function, and can be fatal. The time taken for the clot to travel from the legs to the lungs may be days, even weeks. This time frame leads researchers to believe that even more people die from DVT than the current statistics suggest.

If you’re going to be in a position where your legs are cramped for several hours, you’re at risk. The risk increases if you’re obese or tall. Smokers and anyone with a history of leg clots or recent leg or pelvic surgery, are also more prone to developing a DVT, as are the elderly. If you’ve varicose veins or a history of venous problems, the chances of developing a DVT continue to escalate.

If you’re planning to travel and your legs are going to be cramped, exercise. Those funny cartoons that are shown with the little man or the air hostess stretching their legs will get you started. Better still, get up out of your seat and walk around for a few minutes every hour. When flying, drink lots of liquids to avoid dehydration, which causes the blood to thicken and the vessels to constrict. Avoid alcohol and coffee, as this will contribute to the dehydration.

You can also take an aspirin before the flight and every six hours during the flight. If you’ve multiple risk factors, discuss this with your doctor, who may give you a shot of Heparin before the flight. Heparin is an anticoagulant which stops the blood from clotting. Researchers also recommend wearing compression stockings, particularly for those at risk. These garments, which help put pressure on the leg muscles and assist in returning blood to the heart have been shown to help minimise the risk significantly.

Usually, the development of a DVT will not be obvious. There may be pain and warmth in the lower legs or a prickly sensation in the legs. Swelling of the feet or legs may occur, but this happens with most people on long flights who are sedentary. Swelling of the legs, feet and ankles can be a normal response to the low humidity, dehydration, and just being inactive for a long period of time. If you develop shortness of breath during, or up to a week after a flight, this could be an indication that a clot has moved to the lungs and a pulmonary embolism has developed. If shortness of breath occurs, don’t delay seeking emergency medical assistance.

Peter Davison is the Manager International Services
at Phuket International Hospital.
Tel: +66 (0)76 249400. Email: info@phuketinternationalhospital.com.