Background Among the deaths due to trauma,about one half of the patients suffer from road traffic injury(RTI).Most of RTI patients complicate acute respiratory distress syndrome(ARDS)and severe multiple injuries.ARDS is a major contributor to morbidity and mortality in trauma patients.Although many injuries and conditions are believed to be associated with ARDS independent risk factors in trauma patients.their relative importance in development of the syndrome are undefined.We hypothesize that not all of the traditionaI risk factors impacting mortality are independently associated with patients strictly identified by traffic injury.This study aimed to sieve distinctive risk factors in our RTI population,meanwhile,we also hypothesize that there may exist significantly different risk factors in these patients.Methods This was a retrospective cohort study regarding RTI as a single cause for emergency intensive care unit (EICU)admission.Patients identified as severe RTI with post-traumatic ARDS were enrolled in a prospectively maintained database between May 2002 and April 2007 and observed.Twenty-three items of potential risk impacting mortality were calculated by univariate and multivariate Logistic analyses in order to find distinctive iterns in these severe RTI patients.Results There were 247 RTI patients with post-traumatic ARDS admitted to EICU during the study period.The unadjusted odds ratio(OR)and 95％ confidence intervals(CI) of mortality were associated with six risk factors out of 23:APACHE Ⅱ score,duration of trauma factor,pulmonary contusion,aspiration of gastric contents,sepsis and duration of mechanical ventilation.The adjusted ORs with 95％ CI were denoted with respect to surviving beyond 96 hours EICU admission(APACHE Ⅱ score,duration of trauma factor,aspiration of gastric contents),APACHE Ⅱ score beyond 20 EICU admission(duration of trauma factor,sepsis,duration of mechanical ventilation)and mechanicaI ventilation beyond 7 days EICU admission fduration of trauma factor and sepsis).Conclusions We have retrospectively demonstrated an adverse effect of six different risk factors out of 23 items in mortality of post-traumatic ARDS within severe RTI patients and,moreover,gained distinct outcomes in stratified patients under real emergency trauma circumstance.An impact of APACHE Ⅱ score and pulmonary contusion contributing to prediction of mortality may exist in prophase after traffic injury.Sepsis is still a vital risk factor referring to systemic inflammatory response syndrome,infection,and secondary multiple organs dysfunction.Eliminating trauma factors as early as possible becomes the critical therapeutic measure.Aspiration of gastric contents could lead to incremental mortality due to severe ventilation associated pneumonia.Long-standing mechanical ventilation should be constrained on account of severe refractory complications.