Pre-existing pulmonary thromboembolic disease in passengers with the "economy class syndrome"

Background: Pulmonary emboli, which have occurred in association with air t ravel, in the past have been thought to have arisen from deep venous thromb oses (DVT) which formed during the flight. Hypothesis: This study was perfo rmed to test the idea that not all pulmonary emboli which occur following a ir travel are the result of inflight DVT formation. Methods. Fourteen cases of fatal "economy class syndrome" were examined histologically to determin e the age of the fatal thromboemboli. Results: In 5 of the cases, evidence of pre-existing pulmonary thromboembolic disease was present and in 4 of th ese cases the fatal thromboemboli observed in the lung tissue pre-dated the flight. Fresh perimortem thrombus without evidence of organization or hemo siderin deposition was observed in 9 cases. Conclusions, The commonly held pathological mechanism that the conditions of the flight lead to DVT format ion and subsequent pulmonary embolism are not applicable in all cases of,ec onomy class syndrome" and thus other pathophysiological mechanisms must be entertained.