A Morphological and Quantitative Analysis of Lung CT Scan in Patients With Acute Respiratory Distress Syndrome and in Cardiogenic Pulmonary Edema

Background: The acute respiratory distress syndrome (ARDS) and cardiogenic pulmonary edema (CPE) are both characterized by an increase in lung edema that can be measured by computed tomography (CT). The aim of this study was to compare possible differences between patients with ARDS and CPE in the morphologic pattern, the aeration, and the amount and distribution of edema within the lung. Methods: Lung CT was performed at a mean positive end-expiratory pressure level of 5 cm H2O in both groups. The morphological evaluation was performed by two radiologists, while the quantitative evaluation was performed by a dedicated software. Results: A total of 60 patients with ARDS (20 mild, 20 moderate, 20 severe) and 20 patients with CPE were enrolled. The ground-glass attenuation regions were similarly present among the groups, 8 (40%), 8 (40%), 14 (70%), and 10 (50%), while the airspace consolidations were significantly more present in ARDS. The lung gas volume was significantly lower in severe ARDS compared to CPE (830 [462] vs 1120 [832] mL). Moving from the nondependent to the dependent lung regions, the not inflated lung tissue significantly increased, while the well inflated tissue decreased (ρ = 0.96-1.00, P <.0001). Significant differences were found between ARDS and CPE mostly in dependent regions. In severe ARDS, the estimated edema was significantly higher, compared to CPE (757 [740] vs 532 [637] g). Conclusions: Both ARDS and CPE are characterized by a similar presence of ground-glass attenuation and different airspace consolidation regions. Acute respiratory distress syndrome has a higher amount of not inflated tissue and lower amount of well inflated tissue. However, the overall regional distribution is similar within the lung.