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

Abstract

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. 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. 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. 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.