With a pneumothorax (PTX), air separates the visceral and parietal pleura layers located on the lung’s outside surface and inner chest wall, respectively. The absence of pleural sliding on ultrasonography can suggest PTX, but when this is found adjacent to a lung point, it’s 100% specific for a PTX.
The lung point shows where the separated pleural layers reapproximate each other – on one side, there is no pleural sliding (where the PTX is), and on the other, there is normal sliding. A lung point may not be discernible with very large PTX because the visceral pleura is completely encapsulated by air and never close to the parietal pleura.
In this lung ultrasound, one can appreciate a transition between the presence and absence of pleural sliding. After placing a chest tube and evacuating the PTX, pleural sliding was observed over the entire lung.
Drop me a comment below with questions!