Usefulness of transthoracic lung ultrasound for the diagnosis of mild pneumothorax.

The aim of the present study was to investigate the diagnostic accuracy of ultrasonography in the detection of mild pneumothorax using computed tomography (CT) in dogs. Nine adult healthy beagles were included in the study. A thoracic tube was inserted into pleural space at the left thoracic wall, and each dog underwent the examinations in the order of CT, lung ultrasonography, and radiography before the infusion of room air into the pleural space. Two, 3, and 5 mL/kg infusions of room air were sequentially introduced into the pleural space and CT, lung ultrasound, and radiography examinations were performed. Sonographic signs included A-lines, stratosphere, lung sliding, lung point, lung pulse, and reverse sliding signs. Radiographs were evaluated for the absence or presence of a pneumothorax. Lung ultrasound results were more accurate than radiography results for the detection of mild pneumothorax. The overall sensitivity of the sonographic reverse sliding sign was higher than that of other sonographic signs, and its specificity was 100% for detection of mild pneumothorax. Thus, the reverse sliding sign is useful when using lung ultrasonography for diagnosis of mild pneumothorax.