Introduction: Non-life-threatening blunt chest trauma (BCT) admitted in emergency department (ED) are at risk of acute respiratory failure (ARF) and respiratory complications during their intensive care unit (ICU) follow-up. They may require a special focus to adopt specific prophylactic strategies and proper orientation. The aim of this study was to identify different risk factors for ARF in mild BCT.Methods: This retrospective, monocentric study from January 2015 to December 2020 included all patients with mild BCT admitted to the ED and managed in ICU for at least 48 hours with spontaneous breathing at admission. Occurrence of ARF was defined by PaO2/FiO2 ratio (PaFI) under 200 and need of ventilator support in the first 72 hours after admission. Using univariate and multivariate analysis, the risk factors of ARF incidence after BCT were investigated. We also studied the global ability of the TTS score to predict ARF occurrence by a ROC curve. Finally, we assessed the most significant and sensitive TTS score threshold. Results: A total of 190 BCT patients was included and 23.7% of them developed an ARF. A TTS score greater than 8 was independently associated with early ARF. A TTS score threshold of 6 significantly predicted the ARF incidence with a sensitivity (91%) and negative predictor value (94%) in mild BCT. The others risk factors independently associated with ARF were chronic respiratory disease, high score SOFA and loco regional analgesia.Conclusion: A significant amount of risk factors of ARF following mild BCT were highlighted in our study and must be considered for the proper management of those patient. It is the first study to enhance that a low TTS score threshold could help the mass screening and proper orientation of mild BCT. This study provides the basis for the development of a new risk stratification tool (TTS score) for mild BCT patients who may develop respiratory complications.