Changes of biochemical markers and functional tests for clot formation during long-haul flights

Introduction: Long-haul flights have been suggested to be associated with an increased risk for thromboembolic events. Until now, changes in the coagulation system during an actual flight have not been investigated. Materials and methods: To explore whether any changes occur in the coagulation system during a real long-haul flight molecular markers for coagulation and fibrinolysis were measured in 20 volunteers (10 subjects with a low and 10 with a moderate risk for venous thromboembolism (VTE)) during and after a return flight from Vienna to Washington. In addition, functional measurements of coagulation were performed using activated thrombelastography. Results: Thrombelastographic measurements revealed activation of coagulation in all passengers, who showed an increased activity of FVII and FVIII as well as suppressed fibrinolysis. There was no evidence of a pronounced thrombin and fibrin formation. We did not find any differences between both groups concerning coagulation changes. Conclusion: Long-haul flights induce a certain activation of the coagulation system. This activated coagulation could be a risk factor for VTE during long-haul flights mainly when other risk factors are present.