Résumé
Background: chest trauma may modify thoracic stiffness and chest wall elastance, which makes airway pressures unreliable to reflect lung status. This study aimed to describe respiratory mechanics of chest wall and its influence on respiratory system elastance in severe chest trauma patients under mechanical ventilation within first days following trauma. Methods: a monocentric prospective physiological study was carried out in the Montpellier Lapeyronie University Hospital from January 2019 to May 2021. Patients hospitalized with a severe chest trauma (AIS ≥3) and requiring a prolonged mechanical ventilation were included. An esophageal pressure monitoring was placed to distinguish chest wall and lung mechanical properties under mechanical ventilation and their evolution within 5 days. The chest wall /respiratory system elastance ratio (ECW/ERS) was specifically studied. Results: forty-two patients with mechanical ventilation requirement were enrolled. Seventy-nine percent were male and the median age was 52 years [32− 60 years]. Fifty-five percent had chest flails and 36% had pulmonary contusions involving 3 lobes or more. Mean respiratory system driving pressure (ΔPRS) on admission was 10±2 cmH2O with a respiratory system elastance (ERS) of 22 (SD 5) cmH2O/L. Chest wall driving pressure (ΔPCW) on admission was 4 cmH2O (IQR 4−5 cmH2O), chest wall elastance (ECW) 10 cmH2O/L (IQR 8−13 cmH2O/L) and ECW/ERS ratio 0.48 (IQR 0.34−0.60). No significant evolution was found in respiratory system and lung parameters. ΔPCW was found significantly increased over the first 5 days following trauma (P<0.01), while keeping physiological values. ECW and ECW/ERS did not significantly vary in contrast (P=0.25 and P=0.31, respectively). Conclusion: chest wall mechanical properties and ECW remained stable and close to physiological ranges during first days following severe chest trauma with unmodified contribution to the total respiratory system elastance.