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Why do they tell people to get up and walk around on long airline flights?

April 8, 2008

Matthew Vasey, MD

The reason for this is what is termed pulmonary embolism or PE. When blood is stagnant, its natural tendency is to clot. Most often a clot or thrombus will form in the veins of someone's legs called a deep venous thrombosis or DVT. Deep venous thromboses are ticking time bombs, not literally of course otherwise one would not make it through security. In all seriousness, these DVT's can kill in the event one of these clots becomes dislodged or breaks free into the blood circulation. The clot now termed and embolus travels up your body passing through the right side of your heart and lodging in your lungs. The creates an emergent often life-threatening traffic jam so to speak in your lungs preventing your body from being able to provide enough oxygen from the air you breath to the cells in your body.

Eight to Ten percent of people who experience a pulmonary embolism will die within the first hour. (2) While prolonged immobility is not by any means the only cause for DVT and PE it is certainly one of the most preventable causes. Even eThrombosis has been described in people spending extended periods of time in front of their computer (1) ... (excuse me I'll be right back)... Other causes or risk factors are things like being old (still working on a cure for that), recent surgeries particularly orthopedic surgeries, cancers, estrogen-containing birth control pills, pregnancy, obesity, hypercoagulable blood disorders (diseases that make people more prone to blood clots), to name a few. (2) Unfortunately, the exact degree and duration of reduced mobility that would guarantee prevention is not known (3).

An incomplete list of some things to look out for either in yourself, or someone you care about would be leg pain, warmth, swelling and fever as a tip off there might DVT cooking in a leg vein. Worrisome symptoms concerning for a clot that has broken free and gotten stuck in a lung would be immediate shortness of breath, chest pain often worsened with cough or deep breath, a fast pulse, bloody cough and even passing out in massive PE's. Call 911! Getting care in a hospital is very important. There are drugs that can be used to break up these clots both in the immediate setting as well as over the course of a few months. In some cases, invasive procedures are required. On that note, I think it's time for a walk.

1. Beasley R, Raymond N, Hill S, Nowitz M, Hughes R. eThrombosis: the 21st century variant of venous thromboembolism associated with immobility. Eur Respir J 2003;21:374-376.
2. Ferri, F. Clinical Advisor. Mosby-Elsevier, Philadephia, PA. 2008
3. Tapson VF Acute Pulmonary Embolism Volume 358:1037-1052 on Social Media