In lung ultrasound, air bronchograms (indicated by yellow arrows in the video) occur when segments of the bronchial tree remain patent (filled with anechoic air) amid the surrounding consolidated, echogenic lung tissue. These adjacent alveoli could be collapsed as in atelectasis, filled with inflammatory exudates as in pneumonia, damaged in ARDS, etc. Air bronchograms can be linear (ultrasound parallel to bronchi as in this video) or punctiform (cross-section of bronchi) depending on the ultrasound probe’s orientation.
Moreover, the motion of air bronchograms can provide insights into pathology. Static bronchograms, usually immobile, often signify trapped air, such as in cases of atelectasis. On the other hand, dynamic bronchograms move in sync with the respiratory cycle, indicating air mobility but compromised alveoli, as seen in pneumonia. The video showcases a scenario where pleural effusion compression, actively relieved during a thoracentesis, has led to right lower lobe atelectasis, manifested by visible static, linear bronchograms.