The Importance of Normocapnia in Patients With Severe Traumatic Brain Injury in Prehospital Emergency Medicine

Objectives: Severe traumatic brain injury (TBI) is a leading cause of mortality and morbidity worldwide. Optimal management of cerebral perfusion and intracranial pressure already at the prehospital setting can have a positive influence on the outcome of these patients. Both target values are influenced by the arterial PaCO2. We investigated the association between PaCO2 immediately on hospital admission and mortality of patients with severe TBI. Methods: This study conducted a retrospective analysis of prospectively collected data from trauma patients who were admitted to 2 Swiss level 1 trauma centers with severe TBI between 2017 and 2022 that were selected from the hospitals' databases. Relationship between PaCO2 obtained from arterial blood gas analysis (aBGA) immediately on hospital admission and 28-day mortality was examined by multivariable logistic regression analysis. Results: Of the 866 eligible patients, we observed an association between PaCO2 and 28-day mortality, with mortality increasing at values above 35 mm Hg. Conclusion: A target PaCO2 in the lower normal range as early as in the prehospital phase of treatment of patients with severe TBI seems to be associated with a reduced overall 28-day mortality. Our results support the need for a randomized controlled trial of aBGA-guided ventilation in TBI patients in the prehospital setting.