The Role of Chest Ultrasound in Differentiating Lung Congestion and Pneumonia in Adult Critically-ill Patients and Its Prognostic Impact

Lung ultrasound (LUS) is used at the bedside in emergency and critical care settings. It is a rapid and low-cost approach that can direct patient care without the use of harmful radiation. The success of this technique depends on its simplicity to discover the sonographic signs which indicate certain lung pathology. These signs include a hyperechoic and sliding line, moving forward and back with ventilation seen 0.5 cm below the rib line and is called the pleural line. The A-profile associates anterior lung sliding with A lines. A lines are horizontal repetition artifacts of the pleural line. The B-profile associates anterior lung sliding with B lines. B lines appear as shining vertical lines arising from the pleural line and reach the edge of the screen.

Several pathological etiologies can fill the alveolar spaces, with fluid (heart failure), pus (pneumonia which is the commonest), blood (pulmonary hemorrhage), and cells (lung cancer).

Other causes of lung consolidation may include atelectasis, pulmonary edema, infarction, and lung cancer. Chest imaging with CT is regarded as the gold standard modality allowing for the diagnosis of pneumonia in earlier stage and with higher sensitivity and specificity. On the contrary, cardiogenic pulmonary edema (CPE) is defined as alveolar transudation caused by elevated pulmonary capillary hydrostatic pressure secondary to increased pulmonary venous pressure with low-protein content in the interstitial tissue of lung as a result of cardiac dysfunction