Answer: Normal Lung at level of diaphragm
This scan demonstrates normal lung sliding of the pleura that appears to be going in and out of the frame.
- Movement of pleural line in and out of the frame is described as a lung point sign, and is commonly quoted as being pathognomonic for pneumothorax.1,2
- If you scan too low on the thorax3 or too close to the pericardium,4 however, you can get a scan that looks remarkably similar to a lung point. This is a pitfall for diagnosing pneumothorax.
- To avoid this problem, make sure that you are well away from the diaphragm and heart, and make sure you can tell the difference between an actual lung point and a false positive lung point.
- Visually, the key is to look at the image deep to the non-sliding pleural line. If you see movement or tissue and absence of a-lines, your scan does not represent a true positive lung point:
- Lichtenstein DA. Relevance of Lung Ultrasound in the Diagnosis of Acute Respiratory Failure: the BLUE protocol. Chest. 134(1):117-. 2008. [article]
- Lichtenstein D, Mezière G, Biderman P, Gepner A. The “lung point”: an ultrasound sign specific to pneumothorax. Intensive care medicine. 26(10):1434-40. 2000. [pubmed]
- Gillman LM, Alkadi A, Kirkpatrick AW. The “pseudo-lung point” sign: all focal respiratory coupled alternating pleural patterns are not diagnostic of a pneumothorax. The Journal of trauma. 67(3):672-3. 2009. [pubmed]
- Soldati G. Occult Traumatic Pneumothorax . Chest. 133(1):204-. 2008. [article]