Flying and Thrombosis – It’s Not Just the Inactivity . . .

Airlines have (quite rightly) introduced measures to encourage passengers to move their legs about, to help avoid getting a deep vein thrombosis, or DVT. Wearing compressive stockings on long flights and flexing the calves from time to time reduces the risk considerably. But a new publication suggests that inactivity is not the only risk factor for developing DVT while flying.

Dutch researchers writing in the Lancet used 70 volunteers compared the effects of an 8-hour flight with an 8-hour movie marathon on blood coagulation tests. Blood was drawn before, during and immediately after the 8 hours. After the flight average concentrations of thrombin-antithrombin complex were increased by about a third, but they were decreased very slightly after the movie marathon. Clearly, not just relative immobilization is guilty. The researchers suggest that low cabin pressure and the low-oxygen environment probably affect clotting mechanisms. Temperature changes, poor air quality, excess noise and vibration are hardly likely to help matters.

The answer is to know if you are at risk – and take appropriate action. Risk factors include being older, taking oral contraceptives, and a previous history of venous thrombosis; if you have had a prior DVT, get your doctor to have you tested for a particular gene mutation (Factor V Leiden) – it’s quite common. If you are at high risk, you could be given an injection (low-molecular weight heparin). Anyway, use compression stockings and do calf exercises, if you can; every little helps.