Lung Sonography

Lung sonography 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 has it been highlighted that lung sonography 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 accurate diagnosis of many lung disorders possible, particularly when lung sonography is applied in the emergency and critical care settings. Sonography is useful in the diagnosis of lung diseases in which 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 ultrasonography and all of the supposed limitations to its diagnostic usefulness. Moreover, the article reviews the three main fields of lung sonography application: interstitial, alveolar, and pleural syndromes.