Inhalation lung injury induced by smoke bombs in children: CT manifestations, dynamic evolution features and quantitative analysis

Smoke bombs are often used in military/fire drills, firefighter training, and on the battlefield as obscurants. Smoke bombs can release a mixed chemical smoke containing zinc chloride, zinc oxide, hexachloroethane and other chemical ingredients after flaring. Smoke inhaling can cause airway and lung injury. Pathological changes of this inhalation lung injury include edema of interstitial and alveolar, an increase of fibroblasts as well as an increase of collagen in the interstitium and alveolus in the early phase, and pulmonary fibrosis in the later phase (1,2). A number of studies have already focused on clinical, radiographic, and pulmonary function of smoke inhalation (3-7). Some studies showed that the chest radiograph is an insensitive indicator of inhalation of airway and parenchymal lung injury (8,9). Therefore, computed tomography (CT) was used by radiologists to diagnose the inhalation lung injury. Compared with the chest radiograph, CT is more reliable for the detection of pulmonary abnormalities at an early stage, as also for the demonstration of pulmonary complications during the follow-up (10). There was a study to evaluate the efficacy of CT scan in assessing the severity of inhalation lung injury with sheep, and the conclusion was that CT scan was potentially useful in gauging the severity of inhalation injury non-invasively (11). In recent years, quantitative CT has been used in the evaluation of lung fibrosis (12-15). Therefore, the authors would like to study whether CT quantitative analysis can be used to further evaluate the severity and longitudinal changes of inhalation lung injury