Blood sputum that suggested lung contusion occurred in 45% of patients, chest X ray on admission could detect lung contusion at 65.8% of patients, the remainders were diagnosed lung contusion by chest CT scan; 24 hours after trauma, lung contusion could be seen on chest X ray at 100% of patients, mean of time from trauma to severe respiratory failure due to ALI / ARDS that needed mechanical ventilation was 18.54 ± 6.17 hours, ALI group was 21.16 ± 5.57 hours and ARDS was 14.02± 4.26 hours (p<0, 001).