Lung Ultrasonography

Lung ultrasound (LUS) is a repeatable, cost-free, and non-invasive technique that allows diagnosing and closely monitoring several lung conditions at the bedside due to its ability to detect alterations in lung parenchyma and pleural cavity. Whereas lung parenchyma disorders rely primarily on the interpretation of multiple sonographic artifacts, some pleural pathologies, such as effusion, are detectable on the ultrasound screen as real images. Ultrasound is considered a lung densitometer: its accuracy in detecting air loss proportional to the increase of pulmonary tissue density has been widely demonstrated. Variable degrees of air loss in the lung parenchyma, from mild to severe stage, relate to different sonographic patterns, ranging from interstitial syndrome to consolidation. Analysis of the ultrasound signs of pulmonary edema, pneumonia, and other lung pathologies allows an initial estimation, monitoring, and patient follow-up. LUS applications for pleural imaging are mainly directed to pneumothorax and effusion. Given its high accuracy, LUS has been fully integrated into the standard trauma assessment to enhance the clinical decision-making process and to select those patients that might need further investigations. In the presence of effusion, by direct visualization of a transonic fluid window, LUS can define fluid characteristics and guide thoracentesis, improving the success rate and safety. This chapter reviews applications of bedside LUS for focal and diffuse disorders of pulmonary interstitium and pleura, providing some clinical scenarios and target questions for a case-based discussion on LUS advantages and pitfalls. Increasing awareness of LUS in critical care settings will strongly encourage its incorporation into routine clinical practice.