[Pathophysiology, Diagnostics and Therapy of Pulmonary Contusion - Recommendations of the Interdisciplinary Group on Thoracic Trauma of the Section NIS of the German Society for Trauma Surgery (DGU) and the German Society for Thoracic Surgery (DGT)]

Improved Discriminability of Severe Lung Injury and Atelectasis in Thoracic Trauma at Low keV Virtual Monoenergetic Images from Photon-Counting Detector CT

Objectives: To evaluate the value of virtual monoenergetic images (VMI) from photon-counting detector CT (PCD-CT) for discriminability of severe lung injury and atelectasis in polytraumatized patients. Materials & Methods: Contrast-enhanced PCD-CT examinations of 20 polytraumatized patients with severe thoracic trauma were included in this retrospective study. Spectral PCD-CT data were reconstructed using a noise-optimized virtual monoenergetic imaging (VMI) algorithm with calculated VMIs ranging from 40 to 120 keV at 10 keV increments. Injury-to-atelectasis contrast-to-noise ratio (CNR) was calculated and compared at each energy level based on CT number measurements in severely injured as well as atelectatic lung areas. Three radiologists assessed subjective discriminability, noise perception, and overall image quality. Results: CT values for atelectasis decreased as photon energy increased from 40 keV to 120 keV (mean Hounsfield units (HU): 69 at 40 keV; 342 at 120 keV), whereas CT values for severe lung injury remained near-constant from 40 keV to 120 keV (mean HU: 42 at 40 keV; 44 at 120 keV) with significant differences at each keV level (p < 0.001). The optimal injury-to-atelectasis CNR was observed at 40 keV in comparison with the remaining energy levels (p < 0.001) except for 50 keV (p > 0.05). In line with this, VMIs at 40 keV were rated best regarding subjective discriminability. VMIs at 60-70 keV, however, provided the highest subjective observer parameters regarding subjective image noise as well as image quality. Conclusions: Discriminability between severely injured and atelectatic lung areas after thoracic trauma can be substantially improved by virtual monoenergetic imaging from PCD-CT with superior contrast and visual discriminability at 40-50 keV.

Classification methods of pulmonary contusion based on chest CT and the association with in-hospital outcomes: a systematic review of literature

INTRODUCTION

Patients sustaining pulmonary contusion (PC) have a higher risk of complications and long-term respiratory difficulty. Computed tomography (CT) scans have a high sensitivity for PC. However, since PC develops over time, CT scans made directly post-trauma may underestimate the full extent of PC. This creates a need to better define in which PC-patients complications are more likely. The aim of this systematic review was to identify different classification systems of PC, and investigate the association between amount of PC and in-hospital outcomes.

METHODS

A systematic review was conducted in accordance with PRISMA guidelines. Studies reporting a classification system for PC after blunt thoracic trauma based on a CT scan were included. Outcomes were classification method of PC and the relation between classification and pulmonary complications and in-hospital outcomes.

RESULTS

Twenty studies were included. Total number of patients ranged from 49 to 148,140 patients. The most common classification system used was calculating the percentage of contused lung volume. Other classification methods were based on Blunt Pulmonary Contusion score-6 and -18, Abbreviated Injury Score and Thoracic Trauma Severity scores. Worse outcomes were generally associated with between > 18 to > 24% contusion volume.

DISCUSSION

The heterogeneity of currently available literature makes comparing classification methods challenging. The most common classification of PC was based on volumetric analysis. Calculating a percentage of PC as part of the total volume allows for the highest level of segmentation of lung parenchyma as compared to using BPC-6, BPC-18, or AIS. Contusion volume exceeding 18-24% was generally associated with worse outcomes.

[Complications after conservative vs. operative treatment of severe thoracic trauma]

BACKGROUND

Thoracic trauma is a frequent injury in the routine treatment of injured patients. Due to the increasing demographic changes a further increase is to be expected, especially after low-energy trauma.

OBJECTIVE

Expected complications after conservative vs. operative treatment of various injury patterns of thoracic trauma.

MATERIAL AND METHODS

Evaluation of a selective literature search regarding possible complications after thoracic trauma and formulation of instructions for action as expert recommendations.

CONCLUSION

Both conservative and operative treatment of thoracic trauma have their specific complications, which have to be known to the treating physician. Lung contusions are often underestimated in the initial radiological diagnostics but often lead to relevant problems during the further course of treatment. After conservative treatment of rib fractures persistent pain, functional limitations or even relevant deformities due to secondary dislocation, can remain. There is a significant risk of overlooking or underestimating relevant injuries during the initial diagnostics which then leads to secondary complications. By far the most frequent risk of surgical treatment is an incorrect positioning of chest tubes. Overall, postoperative infections after chest trauma are relatively rare.

[Treatment of Persistent Parenchymal Lung Injuries in Thoracic Trauma: Lung Laceration, Pleural Fistula and Pneumothorax]

Thoracic trauma is a frequent injury pattern with high patient morbidity and mortality. Preclinical and clinical emergency treatment is consented in a national S3-guideline. Following emergency therapy one third of patients may develop lung lacerations, pleural fistulation and persisting pneumothorax. An interdisciplinary working group of the German Society for Thoracic Surgery and the German Society for Traumatology reviewed the published medical literature on treatment of those injuries and assessed the existing evidence according to consensus recommendations. An inconsistent classification of those subsequent lung injuries was found. Evidence for diagnostic and therapeutic recommendations is small.