Lung sonography

Lung ultrasound represents an emerging and useful technique in the management of some pulmonary diseases. For many years, sonography of the thorax was limited to the study of pleural effusion and thoracic superficial masses because alveolar air and bones of the thoracic cage limit the propagation of the ultrasound beam. Only recently it has been highlighted that lung ultrasound is highly sensitive to variations of the pulmonary content and balance between air and fluids, like a real lung densitometer. Dynamic and static analysis of a combination of sonographic artifacts and real images makes possible accurate diagnosis of many lung disorders, particularly when lung ultrasound is applied in the emergency and critical care setting. Sonography is useful in the diagnosis of lung diseases where the alveolar air content is impaired and interstitial and alveolar fluids are increased, and also when air or fluids are collected in the pleural space. This article analyzes the basic principles of lung ultrasound and all the supposed limitations to the diagnostic usefulness of the technique. Moreover, the article reviews the three main fields of application for lung ultrasound: interstitial, alveolar and pleural syndromes.