“Economy class syndrome” is an old concept that sitting in tight, cramped seats in the back of an airplane can lead to DVTs or blood clots in the legs. The idea of travelers and blood clots/DVTs is an important concept and all travelers need to know about this illness along with how to prevent it. Before we look at a new piece of medical literature on the subject, I think it is important to define a few terms.
DVT = Deep Vein Thrombosis which is basically a blood clot in the larger veins of the legs or pelvis and rarely the arms or torso. Signs of this condition include swelling of the leg compared to the other, a history of immobility and pain in the calf.
PE = Pulmonary Embolism or a blood clot in the lungs. This occurs when the DVT migrates through the veins up to the lungs. This can causes chest pain, shortness of breath and be a life threatening emergency!
Hypercoagulatory state = A condition that makes your blood clot more than normal and some of these conditions include cancer, pregnancy using birth control pills or genetic disorders that change how your blood clots
DVTs and Travelers
The concept of DVTs and travelers began to be linked years ago by noticing travelers on “long-haul” intercontinental flights, who were previously healthy and began developing blood clots. Some of these young and healthy travelers even died from the PEs. Researchers began to link together what they had in common and immobility was the common link. Basically, sitting still for hours and hours caused the blood to pool in the legs and sludge a bit resulting in clots. Although extremely rare the condition is possible and not just limited to airline travel. Minimizing risk is what doctors began to focus on.
Generally, travel medicine doctors have generally avoided the concept of giving “blood thinners” to protect people from DVTs on long flights, car rides, etc. unless they were at very high risk. A good guideline for this comes from the CDC Yellow Book and their chapter on DVT/PE in Travelers. Educating travelers on the importance of in-flight exercises, walking around the plane every few hours and in-chair exercises every few hours has been the mainstay of prevention for most travelers. The CDC article heavily references the wonderful work done by the American College of Chest Physicians and their reports on DVT prevention. The College has recently published a new article specifically aimed at travelers. http://www.chestnet.org/accp/article/new-dvt-guidelines-no-evidence-support-economy-class-syndrome
The following conditions are considered risk factors for long distance travelers
- Previous DVT/PE or known thrombophilic disorder
- Recent surgery or trauma
- Advanced age
- Estrogen use, including oral contraceptives
- Sitting in a window seat
Old vs. New Data
What is new about this article is the data now shows there is no increased risk from alcohol intake, flying in economy class versus business class or being dehydrated. These conditions were all previously considered to be risks and things to be avoided by travelers on flights or sitting for greater than 4 hours. In fact, the new guidelines have upgraded a long-haul flight to be 6 hours or longer and most DVT/PE are associated with flights 10 hours or longer. Compression stockings continue to be advised only for patients at high risk and to be avoided for “normal risk” travelers. As expected, stretching and exercises involving the calf muscles are first line for prevention.
Overall, the American College of Chest Physicians continues to lead the world in research and advice on DVT/PE prevention and treatment. This article should be read by all travelers and especially those who travel long-distances!