Risk factors for prolonged mechanical ventilation in patients with severe multiple injuries and blunt chest trauma: a single center retrospective case–control study

Aim: Blunt chest trauma is common and is associated with morbidity and mortality in patients with multiple injuries, frequently requiring invasive mechanical ventilation. The aim of this study was to elucidate risk factors for prolonged mechanical ventilation (PMV). Methods: Consecutive adult patients with multiple severe injuries and blunt chest trauma who treated in Chiba Emergency Medical Center (Chiba, Japan) between January 2008 and December 2015 were enrolled in this retrospective chart-review study. According to ventilatory time, the patients were divided into PMV (≥7 days) and shortened mechanical ventilation (SMV; <7 days) groups. Thoracic Trauma Severity Score (TTSS) was calculated. To identify risk factors for PMV, univariate and multivariate logistic analyses and receiver operating characteristic analysis were carried out. Results: Eighty-four and 49 patients were assigned to PMV and SMV groups, respectively. Compared with the SMV group, the PMV group had a significantly larger number of fractured ribs (P < 0.01), higher rate of severe Glasgow Coma Scale (GCS ≤8) (P < 0.05) and flail chest (P < 0.001), higher TTSS (P < 0.001), or longer intensive care unit and hospital stay (both P < 0.001). Logistic analysis showed that severe GCS (odds ratio [OR] = 4.6, P < 0.01), flail chest (OR = 3.0, P < 0.05), and TTSS (OR = 1.2; P < 0.01) were independent significant risk factors. Receiver operating characteristic analyses showed that the area under the curves for TTSS, flail chest, and severe GCS were 0.74, 0.70, and 0.58, respectively. When the three factors were combined, the area under the curve increased to 0.8. Conclusion: Severe GCS (≤8), flail chest, or TTSS may be independent risk factors. Combining the three risk factors could provide high predictive performance for PMV.