Air: subcutaneous emphysema vs pneumothorax

Images and text Genevieve Carbonatto

A 66  year old presents to the Emergency Department after a fall onto her right chest wall. She had slipped in her bedroom and landed backwards onto a cabinet in her bedroom . She is in great pain on arrival to ED.

This is her ultrasound where there is clinically subcutaneous emphysema

There is no pleural line nor rib shadows visible because the subcutaneous air is deflecting sound waves before they reach the deeper tissues (pleura and ribs) .The dirty shadow is due to the presence of air in the subcutaneous tissues.

This is her lung ultrasound taken close to the sternum at the highest point of her chest

Note that one rib shadow is visible, but there is no lung sliding. This is the pneumothorax. The pleural line is visible.

Just lateral to the area of pneumothorax, this is her lung ultrasound.

Here the ribs and their shadows are visible, and there is decreased lung sliding, but lung sliding does occur. There is shimmering below the pleural line. M mode through this shows a “lung pulse” first described by Lichtenstein in 2003 (1) showing transmission of the cardiac pulsations to the pleural line. The presence of the lung pulse safely rules out pneumothorax in 93% of cases of patients with absent lung sliding. (1)

This is her Xray

Teaching point: Lung ultrasound should be formalised. Always examine the lungs with the probe in the longitudinal position, in this way the rib shadows and pleural line are always visible. If you are not seeing lung sliding then do an M mode. If a lung pulse is present then you can say with 93% confidence that a pneumothorax is not present. 


  1. Lichtenstein DA, Lascols N, Prin S, Mezière G. The “lung pulse”: An early ultrasound sign of complete atelectasis. Intensive Care Med 2003;29:2187-92.
  2. J Anaesth Clin Pharmacology REVIEW ARTICLE Year : 2016 | Volume : 32 | Issue : 3 | Page : 288-297 Intraoperative lung ultrasound: A clinicodynamic perspective ; Amit Kumar Mittal, Namrata Gupta



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