Prediction of respiratory complications by quantifying lung contusion volume using chest computed tomography in patients with chest trauma

www.nature.com/scientificreports OPEN Prediction of respiratory complications by quantifying lung contusion volume using chest computed tomography in patients with chest trauma Na Hyeon Lee 1, Seon Hee Kim 1*, Sang‑hyup Seo 2, Byeong‑Jun Kim 3, Chi‑Seung Lee 3, Gil Hwan Kim 1, Sung Jin Park 1, Seon Hyun Kim 1, Dong Yeon Ryu 1, Ho Hyun Kim 1, Sang Bong Lee 1, Chan Ik Park 1 & Jae Hun Kim 1 Pulmonary contusion is an important risk factor for respiratory complications in trauma patients. Hence, we aimed to determine the relationship between the ratio of pulmonary contusion volume to the total lung volume and patient outcomes and the predictability of respiratory complications. We retrospectively included 73 patients with a pulmonary contusion on chest computed tomography (CT) from 800 patients with chest trauma admitted to our facility between January 2019 and January 2020. Chest injury severity was expressed as the ratio of pulmonary contusion volume to total lung volume by quantifying pulmonary contusion volume on chest CT. The cut-off value was 80%. Among the 73 patients with pulmonary contusion (77% males, mean age: 45.3 years), 28 patients had pneumonia, and five had acute respiratory distress syndrome. The number of patients in the severe risk group with > 20% of pulmonary contusion volume was 38, among whom 23 had pneumonia. For predicting pneumonia, the area under the receiver operating characteristic curves for the ratio of pulmonary contusion volume was 0.85 (95% confidence interval 0.76–0.95, p = 0.008); the optimal threshold was 70.4%. Quantifying pulmonary contusion volume using initial CT enables identifying patients with chest trauma at high risk of delayed respiratory complications. Pulmonary contusion is an important risk factor for respiratory complications, including pneumonia and acute respiratory distress syndrome (ARDS), in trauma patients. In addition, pulmonary contusions, which account for approximately 25% of all deaths, are an independent risk factor for m ortality1. A pulmonary contusion can occur due to any mechanism, such as crushing and penetrating injuries and blunt trauma. These mechanisms damage the alveolar capillaries, causing blood and other body fluids to accumulate in the lung tissue, thereby interfering with gas exchange and leading to hypoxia2. It is also related to the activation of inflammatory response via innate immunity following t rauma3. Patients are treated with adequate oxygen supplementation, and mechanical ventilation may be required in severe cases. Pulmonary contusions usually resolve spontaneously with supportive care; however, they may progress to respiratory complications during treatment in intensive care units (ICUs). The scoring systems for evaluating injury severity in patients with pulmonary contusions include the chest abbreviated injury scale (AIS) and injury severity score (ISS). However, because these scoring systems are obtained through anatomical abnormalities, they have limitations in representing functional impairment or predicting prognosis. Therefore, it is necessary to introduce a method for measuring the injury severity that reflects pulmonary function better. Hypoxemia is induced by ventilation-perfusion mismatch and an increase in shunt in areas with pulmonary contusion; hence, the wider the pulmonary contusion area, the more severe the degree of hypoxemia2. Pulmonary contusions may be an important risk factor for the progression of respiratory 1 Department of Trauma Surgery, School of Medicine, Pusan National University, Biomedical Research Institute, Pusan National University Hospital, 179 Gudeok‑Ro, Seo‑Gu, Busan 49241, Republic of Korea. 2Busan Center for Medical Mathematics, National Institute for Mathematical Sciences, Daejeon, Republic of Korea. 3Department of Convergence Medicine and Biomedical Engineering, School of Medicine, Pusan National University, Biomedical Research Institute, Pusan National University Hospital, Busan, Republic of Korea. *email: Scientific Reports | (2023) 13:6387 | https://doi.org/10.1038/s41598-023-33275-z 1 Vol.:(0123456789) www.nature.com/scientificreports/ Figure 1.  Study design flow chart. CT computed tomography. complications. Chest radiography has limitations in confirming the pulmonary contusion volume. However, it is easier to visualize pulmonary contusions and measure their area through chest computed tomography (CT). Contrast-enhanced CT is a good tool to identify bleeding and ground-glass opacity (GGO) due to parenchymal damage more clearly in chest CT. Recently, studies have been conducted using lung segmentation technology for chest CT. Ultimately, it is important to extract the total lung and contusion volumes using CT. Automated lung segmentation algorithms are limited in handling routine data because they are developed for limited datasets of specific diseases or cases. According to a study by Hofmanninger et al.4, models trained with routine data were more effective in lung segmentation than public datasets in generalizability to a wide spectrum of pathologies4. Including or excluding pathologies, such as effusion or pneumothorax, when using these trained models is a matter of definition and application. To determine the Hounsfield units (HU) range for segmenting the entire lung area and the area expected to have normal lung function in trauma patients, we used a three-dimensional (3D) slicer and hand labeling data as a reference. Therefore, this study aimed to determine the relationship between patients and the ratio of the pulmonary contusion volume caused by all mechanisms of trauma to the total lung volume. We also aimed to determine whether respiratory complications can be predicted. Methods Informed consent was obtained from all participants or their legal guardians. All methods were conducted in accordance with the relevant guidelines and regulations. This study was approved by the ethics committee of Pusan National University Hospital (IRB No. 2011-017-097, date of IRB approval: November 12, 2020). Study design and patients. Among 800 patients with chest trauma admitted to our level I trauma center between January 2019 and January 2020, we retrospectively analyzed 73 patients diagnosed with pulmonary contusion based on chest CT. The following patients were included: (1) Patients injured because of trauma, (2) those diagnosed with pulmonary contusion by chest CT, and (3) those with a chest AIS score of one or higher. The exclusion criteria were as follow: (1) absence of chest CT at the time of admission and (2) death within the first 48 h of admission (Fig. 1). Data collection. The data collected included patient demographics, mechanism of injury, injury severity, mechanical ventilator application period, length of hospital stay, length of ICU stay, pneumonia, and ARDS. Data were obtained through medical records. Injury severity included ISS, chest AIS, head and neck AIS, initial Glasgow coma scale (GCS) score, transfusi (...truncated)