Prolonged Air Travel and Blood Clotting Disorder
Long airline flights increase the risk of developing a potentially fatal blood clot in the deep veins of the legs, according to a new study in British Medical Journal (2003;327:1072). A blood clot in the legs is more than four times more likely to develop within two weeks of arriving from a long-haul flight than it is in someone who has not flown at all.
Blood clots that develop in the deep part of the legs (deep vein thrombosis or DVT) may be due to prolonged immobilization, poor circulation, dehydration, or low atmospheric pressure. Genetic factors render some people more susceptible than others to developing DVT. DVT may cause calf pain, leg swelling and tenderness, or skin discoloration, although some people do not experience any symptoms at all. Some DVTs resolve on their own without treatment, but it is also possible the clot could dislodge from the vein and enter the lungs, causing a pulmonary embolism. Pulmonary embolism can be fatal if not identified and treated in time. Approximately 1 to 2% of those with DVT die from related complications. Treatment to prevent the development of DVT is only given to those who have a known disorder that causes them to form spontaneous blood clots or to those who have a history of DVT. This treatment may include aspirin, heparin, or warfarin (Coumadin®).
In the new study, travel data from 5,408 Australian citizens admitted to the hospital for treatment of DVT was compared with travel data from healthy individuals who had traveled during the same time period.
The findings showed that the risk of developing DVT was more than four times higher within two weeks of completing long-distance air travel than it was after that two-week period. Based on the data, the annual risk of DVT is increased by 12% in those taking one long flight a year. Although the authors of the new study do not define what constitutes "long-haul flight," other studies suggest these are flights lasting more than seven to eight hours.
While there are currently no prescription treatments for preventing DVT in healthy adults, some natural substances may help reduce the risk. Nattokinase, an enzyme derived from fermented soybeans, is a potent compound than breaks down blood clots. A recent study found that 150 mg of nattokinase was significantly more effective than placebo in reducing the risk of developing DVT in high-risk adults taking long-haul flights. Another enzyme, called lumbrokinase, may also be effective, but specific studies on long-distance travel have not been performed. Walking around frequently during long flights may also be beneficial. Some physicians recommend taking high amounts of vitamin E and fish oil to prevent blood clotting.
People prone to forming blood clots, such as those with atrial fibrillation or with chronic venous insufficiency, should consult their physician before taking any type of substance that may thin the blood.
Darin Ingels, ND, MT (ASCP), received his bachelor’s degree from Purdue University and his Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. Dr. Ingels is the author of The Natural Pharmacist: Lowering Cholesterol (Prima, 1999) and Natural Treatments for High Cholesterol (Prima, 2000). He currently is in private practice at New England Family Health Associates located in Southport, CT, where he specializes in environmental medicine and allergies. Dr. Ingels is a regular contributor to Healthnotes and Healthnotes Newswire.
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