Injury to the thorax is a dominant contributor to post-traumatic neutrophil mediated inflammatory response

PURPOSE: Traumatic injury induces a neutrophil associated inflammatory response mediated by the release of damage-associated molecular patterns (DAMPs). This response can be maladaptive, increasing risk of infection. Since blunt thoracic injuries are associated with high infection rates, we hypothesized that these injuries elicit a stronger neutrophil associated inflammatory response than injuries to other body regions. METHODS: A cohort study was conducted in adult patients presenting at the trauma bay of a level 1 trauma center between March 2020 and November 2022. These patients underwent routine analysis of their neutrophil associated inflammatory response by phenotyping blood neutrophils using automated flow cytometry. Injury per body region was counted when the Abbreviated Injury Severity (AIS) scores were ≥3 to focus on substantial injuries. The primary outcome was an extensive post-traumatic inflammatory neutrophil response. RESULTS: 861 patients were included. Blunt internal thoracic injuries showed the strongest association with severe neutrophil associated inflammation (OR 5.7), followed by abdominal (OR 2.6), pelvis (OR 2.5) and lower extremities (OR 2.3), even when corrected for ISS, age and hemodynamic instability. In multivariable analysis, only thoracic internal injuries remained a statistically significant contributor to excessive neutrophil associated inflammation (OR 5.4). CONCLUSION: Injuries to internal thoracic organs elicit a more pronounced post-traumatic neutrophil associated inflammatory response than injuries of similar severity in other body regions. This might be due to greater release of DAMPs from the soft tissue of the lungs. Understanding the body region-specific activation of neutrophil associated inflammation may support more patient-tailored surgical strategies to lower the infection risk.