Visual anatomical lung CT scan assessment of lung recruitability

Abstract

Purpose: The computation of lung recruitability in acute respiratory distress syndrome (ARDS) is advocated to set positive end-expiratory pressure (PEEP) for preventing lung collapse. The quantitative lung CT scan, obtained by manual image processing, is the reference method but it is time consuming. The aim of this study was to evaluate the accuracy of a visual anatomical analysis compared with a quantitative lung CT scan analysis in assessing lung recruitability. Methods: Fifty sets of two complete lung CT scans of ALI/ARDS patients computing lung recruitment were analyzed. Lung recruitability computed at an airway pressure of 5 and 45 cmH 2 O was defined as the percentage decrease in the collapsed/ consolidated lung parenchyma assessed by two expert radiologists using a visual anatomical analysis and as the decrease in not aerated lung regions using a quantitative analysis computed by dedicated software.Results: Lung recruitability was 11.3 % (interquartile range 7.39-16.41) and 15.5 % (interquartile range 8.18-21.43) with the visual anatomical and quantitative analysis, respectively. In the Bland-Altman analysis, the bias and agreement bands between the visual anatomical and quantitative analysis were -2.9 % (-11.8 to ?5.9 %). The ROC curve showed that the optimal cutoff values for the visual anatomical analysis in predicting high versus low lung recruitability was 8.9 % (area under the ROC curve 0.9248, 95 % CI 0.8550-0.9946). Considering this cutoff, the sensitivity, specificity, and diagnostic accuracy were 0.96, 0.76, and 0.86, respectively. Conclusions: Visual anatomical analysis can classify patients into those with high and low lung recruitability allowing more intensivists to get access to lung recruitability assessment.

Detection of Fibroproliferation by Chest High-Resolution CT Scan in Resolving ARDS

“…This work is distinct from previous investigations in which chest CT imaging has been used to assess lung recruitability in the setting of ARDS to adjust the application of PEEP. 21,24,25 Our fi ndings suggest the potential of early HRCT scan evaluation in patients with ARDS with the poorest lung compliance to identify individuals who may be at risk for complications related to excessive fi broproliferation. 6 Emerging evidence suggests that HRCT scan scores measured very early (within days) aft er ARDS diagnosis using validated methods 7,8 may be helpful in prognosticating short-term outcomes, illustrated in a prospective observational study 9 in which evidence for chest HRCT scan fi broproliferation present on the fi rst day of ARDS diagnosis was associated with 60-day mortality.…”

Recruitment Maneuvers and PEEP Titration

“…[88][89][90][91] CT imaging has long been the accepted standard for assessments of alveolar recruitment and overdistention. Digital chest radiography done at the bedside with PEEP of 5 and 15 cm H 2 O might also be useful to detect recruited lung volume.…”

Lung imaging: how to get better look inside the lung

“…For the purpose to reduce the workload to estimate lung aeration two methods have been proposed: extrapolation of a sub-set of ten slices from a whole-chest CT scan (25), and visual instead of computer-based image assessment (21). Concerning dose exposure reduction, lowdose spiral CT protocols with a reduced tube current have been tested (26), while more recently a protocol tried to combine low current tube with prospective acquisition of a reduced number of thin slices (27).…”

“…All these strategies showed good concordance with the aeration assessment performed with conventional whole-chest CT scan, and could be useful to widen the clinical and research application of CT, especially when multiple scans are required, as is the case when recruitment is assessed performing the CT scan at two levels of PEEP. Table 1 (21,22,(25)(26)(27)(28)(29)(30) compares the main characteristics of these experimental protocols.…”