Capabilities of radiation imaging methods in detecting symptoms of behind-armor blunt trauma of the chest organs

Abstract

Background. Russia’s full-scale invasion of Ukraine caused a significant increase in the number of the wounded with surgical combat trauma. According to the literature data, chest injuries account for 10–12% of all mechanical injuries. Some of them are associated with the invention of personal body armor vests that effectively convert penetrating traumas into closed ones. Such type of trauma is called a «behind-armor blunt trauma». Sudden powerful compression is the main mechanism of lung injuries (contusion and parenchymal lacerations) in a behind-armor blunt trauma. In a combat thoracic trauma, imaging plays a key role in detecting and properly characterizing injuries and their complications. The purpose of the work is to determine characteristics of symptoms of a behindarmor blunt trauma of the chest in radiation imaging examination. Materials and methods. Our study involved the wounded with a behind-armor blunt trauma of the chest who underwent treatment at the Military Medical Clinical Center of the Northern Region, Kharkiv, over the period from September to December 2023. Imaging examination included a conventional chest X-ray, which was performed in all patients, an ultrasound examination according to FAST (Focused Assessment with Sonography in Trauma) and BLUE (Bedside Lung Ultrasound in Emergency) protocols, which was performed in 75% of patients, and computed tomography which was performed in 45% of patients. From the viewpoint of evidence-based medicine, the format of this study is a case series. Results. Lung contusion accounts for the overwhelming majority of injuries (51,2%) in a behind-armor blunt trauma. We distinguished three degrees of lung contusion, depending on the size of the injured area, severity of X-ray symptoms, and the injury course over time. The main radiological features of lung contusion were areas of reduced transparency (from mild to severe intensity) with unclear contours that did not correspond to anatomical borders of segments. X-ray symptoms of lung contusion can be delayed. A significant increase in contusion size after 24–48 hours is a negative prognostic factor for pneumonia, aspiration, or fat embolism. The isolated lung contusion was observed in a small number of cases (11,5%), because most patients had multiple trauma. Emergence of pneumothorax and hemothorax is closely associated with rib fractures and lung lacerations. The latter can look like lung contusion, therefore they are difficult to detect on a conventional X-ray image. Thus, CT is required to establish a final diagnosis. Not only lung contusion but also rib fractures caused pneumothorax which was categorized into small, moderate, and big according to air volume in the pleural cavity. In 18,3% of cases, besides traumatic changes in the lung parenchyma and ribs, we observed intramuscular emphysema of the soft tissues, which was mainly caused by laceration of the parietal pleura by a piece of rib. As a result of the wounds accompanied with the injury of the lung parenchyma or intrapleural vessels, there is a risk of development of hemothorax, which was observed in 23,2% of patients with a behind-armor blunt trauma of the chest and categorized into small, moderate, big, and total depending on blood volume in the pleural cavity. FAST ultrasound examination was essential for detecting hemothorax. In addition, BLUE ultrasound examination allowed us to also study changes in the lung parenchyma, primarily in subpleural areas, and observe these changes in the process of treatment over time. Conclusions. The most frequent symptom of a behind-armor blunt trauma of the chest is lung contusion (51,2%), the course of which depends on complications: lung laceration, pneumothorax, hemothorax, fractures of the chest bones. However, it should be noted that in a behind-armor blunt trauma, we observed more frequently a first-degree contusion (67,4%), a first-degree hemothorax (16,3%), and a first-degree pneumothorax (9,3%). X-ray examination remains a standard radiation imaging method for a behind-armor blunt trauma of the chest organs, and the use of FAST and BLUE ultrasound examination makes it possible to examine soft tissues of the chest, detect pneumoand/or hemothorax, posttraumatic changes in the subpleural lung regions. The use of spiral CT in a combat trauma of the chest organs should be considered a key radiation imaging method, which, at this stage, allowed us to comprehensively determine the extent and nature of chest injuries in 45% of patients, compared to X-ray examination, and also accurately assess these changes over time. The use of spiral CT is essential in absence of life-threatening injuries and complications, or after their elimination. In the article, we present clinical cases of patients with various symptoms of a behind-armor blunt combat trauma of the chest.