Pediatric ultrasound of the respiratory tract: Clinical applications

<p>Ultrasound for the respiratory tract has been considered useful in various settings of pediatric practice. Important findings include A lines (linear high-echogenicity lines parallel to the pleura), B lines (lines perpendicular to the pleura), and lung sliding (movement of the pleural line in synchrony with breathing).</p><p>Appropriate tracheal intubation is confirmed using the snowstorm/bullet signs and the absence of the double tract sign. Pneumothorax is characterized by the disappearance of lung sliding and B lines, and the presence of a lung point.</p><p>Even a small amount of pleural fluid is also detectable. Effusion presents as anechoic fluid in the pleural cavity, while in contrast, empyema has higher echogenicity.</p><p>Ultrasound further allows for direct observation of pulmonary parenchyma adjacent to the parietal pleura, enabling detection of conditions such as pneumonia, abscess, tumors, and malformations. Indirect findings such as B lines may also be helpful for the diagnosis of bronchiolitis and pulmonary edema. In transient tachypnea of the newborn, delayed absorption of lung fluid is demonstrated as the presence of B lines. In respiratory distress syndrome, an admixture of A lines and B lines is found in mild cases and a white lung pattern without A lines is found in severe cases. These observations can be applied to determination of the need for surfactant administration.</p>