Many people have heard of deep vein thrombosis or DVT as it is commonly referred to. But most people are unaware of the full story behind this condition, pulmonary embolism and the link to long periods of sedentary behaviors such as during extended car trips or airline travel.
What is a DVT?
A DVT is a blood clot within the venous system, usually in the lower extremities. While these blood clots most commonly occur in one of the veins of the calf area, they can occur at any point of the leg. The biggest danger from a clot in one of these veins is not from obstruction of the vessel. While obstruction of vascular flow can be a limb threatening emergency in the arteries of the legs, which bring blood to the tissues, the urgency of a blood clot in the veins is very different.
How does a DVT lead to a pulmonary embolism?
The veins of the lower extremities bring blood back from the legs to the lungs for oxygenation. The danger of a DVT or blood clot in the legs is that this clot or thrombosis has the potential to break off and travel in the bloodstream up to the lungs, where it lodges in the smaller blood vessels. When this happens, the clot becomes what is called a pulmonary embolism. This is an emergent condition, which is often fatal, even with immediate medical attention. A pulmonary embolism (or PE) obstructs the vessel(s) bringing blood to the lungs; causing hypoxia and ischemia to the affected lung tissue. This can rapidly lead to death depending on the size of the clot and the blood vessel it becomes lodged in. The bigger the blocked blood vessel, the more likely the clot will be fatal.
Who is at risk?
While there are medical conditions such as cancer, clotting disorders or recent orthopedic surgery that predispose people to developing blood clots, these clots can also develop in otherwise healthy people. One of these risks that may affect healthy individuals is prolonged immobility. While people often think of this as pertaining to bedridden or otherwise ill people, the immobility has been linked to DVT in travelers. So much so, that episodes of deep vein thrombosis or pulmonary embolism after recent travel has been nicknamed, ‘coach-class syndrome’. This condition received this moniker after this phenomena was observed more frequently in passengers traveling in more cramped conditions.
How to prevent DVT
Bartholomew and Schaffer published a paper in the Cleveland Clinic Journal of Medicine which discusses these risk factors and ways for potential passengers to reduce their risk of developing ‘coach-class syndrome’. Many of these preventative measures are easy to implement; such as avoiding the use of constrictive clothing during travel and taking routine rest stops to get out and stretch during extended road trips. Several airlines now include information on other measures, such as periodic exercises such as walks in the aisles during long flights along with foot pump and calf stretches to prevent pooling of blood in the lower extremities. Other strategies include avoiding lengthy travel after surgical procedures and staying well hydrated. The longer the flight or driving period, the greater the risk, particularly in transatlantic or international flights longer than 8 hours.
Philbrick et al. (2007) conducted a meta-analysis of 24 studies looking at deep vein thrombosis in travelers and concluded that in higher risk individuals, with a personal of family history or clotting disorders, recent surgery, obesity or oral contraceptive use, more aggressive measures may include the use of compression socks or anti-thrombotic medications such as enoxaparin. However, the use of aspirin has not been shown as effective in preventing deep vein thrombosis.
If you or your loved ones have any of these risk factors, or are planning a trip involving a flight longer than eight hours, contact your healthcare provider to discuss your risk, and whether you need anti-coagulation prior to travel.