Deep vein thrombosis occurs when a blood clot forms in the deep veins of the leg and obstructs the flow of blood back to the heart. This can lead to swelling of the leg and pain in the calf muscle, although sometimes there are no symptoms. Pulmonary embolism occurs when blood clots leave the veins where they developed, travel through the right side of the heart, and lodge in the small or large branches of the blood vessels going to the lung (pulmonary arteries). This can cause symptoms such as chest pain, difficulty breathing, or coughing up blood. In severe cases, it may result in collapse and sudden death. Long airplane flights or multiple flights in a short period can be associated with deep vein thrombosis and pulmonary embolism. Any situation in which the leg is bent at the knee for prolonged periods without much active motion may lead to a reduction of blood flow and increase the risk of blood clots. Other factors can increase this risk, such as recent surgery, taking oral contraceptives or hormone therapy, pregnancy, cancer, heart problems, and older age. Inherited genetic factors may also play a role.
Properly fitted graduated compression stockings have been shown to be of some value.
For people at high risk, such as those who have had a previous episode of thrombosis, low-molecular-weight heparin can be prescribed by a primary care physician and can be self-administered by injection beneath the skin just prior to a flight.
Getting up frequently and walking in the aisle of the plane increases blood flow and may reduce the risk of clots forming but is not always practical or safe.
The simplest preventive measure is to frequently “pump your feet” while sitting in your seat. Alternately lifting the toes and then lifting the heels increases blood flow in the calf veins and reduces the risk of forming blood clots.
World Health Organization Research Into Global Hazards of Travel (WRIGHT) Project www.who.int/cardiovascular _diseases/wright_project/phase1_report/WRIGHT REPORT.pdf
The Surgeon General's Call to Action to Prevent Deep Vein Thrombosis and Pulmonary Embolism www.surgeongeneral.gov/library/calls/deepvein/call-to-action -on-dvt-2008.pdf
To find this and previous JAMA Patient Pages, go to the Patient Page link on JAMA’ s website at www.jama.com. Many are available in English and Spanish. A Patient Page on thrombophlebitis was published in the April 6, 2011, issue of JAMA and one on pulmonary embolism in the January 11, 2006, issue.
Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.
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Topic: VASCULAR DISEASE
This article was corrected for errors on March 8, 2013.
Sugerman HJ, Eklöf BG, Toff WD, Burke AE, Livingston EH. Air Travel–Related Deep Vein Thrombosis and Pulmonary Embolism. JAMA. 2012;308(23):2531. doi:10.1001/jama.2012.4098