By Prof Charles McCollum, MB ChB, FRCS, MD, Head of Academic Surgery and Professor of Vascular Surgery in the Institute of Cardio-Vascular Research, University of Manchester. Expert in Deep Vein Thrombosis (DVT) and Pulmonary Embolism (PE).
Elite sportsmen and women who travel frequently or on long-haul flights are at particular risk of suffering deep vein thrombosis (DVT) or pulmonary embolism (PE). A DVT may destroy their carer in sport. A third of all PEs are fatal.
Many people develop small calf vein DVTs following a long haul trip abroad (Scurr et al, 2001). Sitting still for over four hours or repeated flights in a month allows small DVT to grow and spread into the major deep veins. Once a DVT is large enough to cause symptoms, there will have been permanent damage to the valves in the deep veins of the leg. The result may be long-term swelling with pain on standing, walking and running.
For elite athletes at their peak, this vein damage would normally ruin their careers. This risk is higher following a sporting event or strenuous training session as the calf muscle may be swollen and inflamed following vigorous exercise making DVT more likely.
Falling asleep on the plane after a sporting event or a strenuous training session increases this risk markedly as it causes profound venous stasis in the leg increasing the risk further. Athletes who do this take an unacceptable risk with their future career. A third of PEs are fatal, depriving the family of their principle bread winner.
Research shows higher levels of risk
Asymptomatic calf vein DVT (diagnosed by ultrasound but not big enough to cause symptoms) can be detected in 10% of people completing two 8 hour flights within a month (The Lancet 2001).
Elite athletes have larger calves with big veins to carry the high blood flows of peak exercise, but which cause slow blood flow on sitting still (venous stasis). I have seen many athletes with large calves who developed disabling DVT during coach or aeroplane journeys or simply after falling asleep in a chair.
In a much larger study, symptomatic larger DVTs developed in 1% of people travelling 4+ hours by aircraft (Hughes et al 2003). These patients are likely to have permanent disabilities as a result of these more extensive DVTs.
Repeated flying encourages small asymptomatic calf DVTs to develop into major clots throughout the veins of the leg. In a very large study recruiting thousands of patients, flying for more than 4 hours twice in 8 weeks more than doubled the risk of symptomatic or damaging DVT compared to a single flight (Kuipers et al 2007, McCallum et al 2011). Flying 3 or 4 times in 8 weeks increases the risk more than fourfold; 5 times or more increases the risk more than seven fold.
NHS advises wearing compression that fits
The NHS offers the following advice for long-haul travellers: “It's vital that compression stockings are measured and worn correctly. Ill-fitting stockings could further increase the risk of DVT” (NHS Choices. Prevent DVT when you travel).
It is important to note that independent research shows that standard ‘off-the-shelf’ elastic stockings often do not fit and, in some cases, create a bigger risk.
- 54% failed to achieve an acceptable pressure gradient
- 20% had reversed gradients – increasing the risk of DVT
- High-pressure bands cause swelling of the foot and ankle, frequent when flying (K Bowling et al 2015 and A. J. Best et al 2000).
Isobar Compression works with Olympic athletes, professional rugby teams and US colleges and professional teams to offer custom-fit compression for travel.