OBJECTIVE: The aim of this study was to assess the performance of Forced Vital Capacity (FVC) for prediction of secondary respiratory complications in blunt chest trauma patients. METHODS: During a 15-month period, all consecutive blunt chest trauma patients admitted in our emergency intensive care unit with more than 3 rib fractures were eligible, unless they required mechanical ventilation in the prehospital or emergency settings. FVC was measured at admission and at emergency discharge after therapeutic interventions. The main outcome was the occurrence of secondary respiratory complications defined by hospital-acquired pulmonary infection, secondary admission in the intensive care unit or mechanical ventilation for respiratory failure or death. The performance of FVC for prediction of secondary respiratory complications was assessed by receiver operating characteristic (ROC) curve and multivariate analysis after logistic regression. RESULTS: Sixty-two consecutive patients were included and 13 (21%) presented secondary respiratory complications. Only FVC measured at emergency discharge - not FCV at admission - was significantly lower in patients who developed secondary respiratory complications (44+/-15 vs. 61+/-20%, P=0.002). The area under the ROC curves for FCV in predicting secondary pulmonary complications was 0.79 [95% CI: 0.66-0.88], P=0.0001. An FVC at discharge</=50% was independently associated with the occurrence of secondary complications with an OR at 7.9 [1.9-42.1], P=0.004. CONCLUSION: The non-improvement of FVC</=50% at emergency discharge is associated with secondary respiratory complications and should prevent the under-triage of patients with no sign of respiratory failure at admission.Read less <