UOTW #62

This patient is a 56 year old male smoker who presents with sudden onset of left sided chest pain and shortness of breath.

Answer

 

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:
  1. Lichtenstein DA. Relevance of Lung Ultrasound in the Diagnosis of Acute Respiratory Failure: the BLUE protocol. Chest. 134(1):117-. 2008. [article]
  2. 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]
  3. 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]
  4. Soldati G. Occult Traumatic Pneumothorax . Chest. 133(1):204-. 2008. [article]

  1. Enjoyed the comparison views very much and I get the visible difference. But do not understand the term “‘ lung point'” and its derivation and I figured that I would be looking for air on imaging.
    cheers

    1. Great point. Some would say that technically this scan does not represent a lung point (Lichtenstein included), because there’s clearly not air deep to the pleura. Now we’re just in a semantics argument. The purpose of this UOTW is that one could easily mistake this scan for PTX. I prefer to think of this as a false positive lung point, but you could also call it a pseudo-lung point (thereby protecting the sanctity of the pathognomonic lung point).

  2. clearly from screen left one see the pleura with shimmering and sliding as well as z-lines come into view with inspiration and goes off screen with expiration. What remains is a zone that shows no shimmering or sliding. The lung point is specific for pneumothorax (PTX) IF what is far field to the zone without shimmering or sliding is NOT the heart on the left hemithorax or the liver in the right hemithorax. Absence of shimmering or sliding in the area of interest suggests ptx and presence of a pathological or true lung point, not just a cardiac or liver lung point, rules in the diagnosis. A z-line when it is present is specific for lung sliding. The other concept which warrants mention is the lung pulse. If there was a heart beating behind that pleura one should be able to see the heart beat transmitted to the pleura and chest wall just as one can see that the intercostal muscles were contracting to show respiratory effort. Therefore, the absence of a lung pulse is telling that indeed this is a true lung point in the context of the given clinical scenario.

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