9. Case of the month: PoCUS in pneumomediastinum

Images Chris Fox

A 14 year old boy presents to ED with throat and neck pain after persistent vomiting. He states he vomited > 30 times over the previous 8 hours.

On examination:  oxygen saturation 98% on RA, BP 128/89, HR 66/min. No obvious crepitaions to the neck.

A chest Xray was ordered

What can you see?

  • There is an extensive pneumomediastinum and a possible pneumopericardium
  • There is subcutaneus emphysema in the right supraclavicular fossa

This is his ultrasound from the area on the right side of the neck. How would you interpret this clip?

The air in the tissues of the neck is causing reverberation artifacts. These look like B lines but are not B lines per se as this is a term used when  describing the reverberation artifacts which arise from the pleural line. Here the same artifact is produced from air in the tissues. Note that there is some movement of these artifacts as the chest wall of the patient moves whilst he is talking and breathing.

This is his PLAX view . How do you interpret this clip?

There is air overlying the heart and the air could be in the mediastinum or in the pericardial space. The air moves freely with each cardiac pulsation and seems to be “attached ” to the pericardium which suggests there is indeed a pneumopericardium.  The air is obscuring the view of the heart. It is not possible to “see” through the thin layer of air. The air creates a “dirty shadow”.

This is his subcostal view. What is your conclusion?

It is possible to get a very good view of the heart from the subcostal view.  This suggests that there is little air in the pericardial space and that this is seen only in the PLAX view when the patient is supine as air rises to the most anterior part of the chest. There is no evidence of tamponade.

A pneumomediastinum is visible in 90% of cases on Chest Xray so why use ultrasound?

There are few reports for the need for ultrasound in the context of possible Borrhaave’s syndrome or a pneumomediastinum, however ultrasound has been found to be useful in the following situations:

  • To  exclude a significant pneumopericardium which would cause the heart to be obscured in all windows in the context of blunt trauma. (1)
  • When a  chest Xray is not readily available (2) such as in rural settings
  • When patients are obese and crepitus is not palpable but subcutaneous emphysema is suspected. Note that crepitus was not palpable in our patient. The ease of diagnosis of subcutaneous emphysema quickly leads to the suspicion of either  a  pneumomediastinum or Borrhaave’s syndrome.
  • To exclude tamponade as a cause of hypotension which may occur in cases of malignant pneumomediastinum.
  • To rapidly diagnose a pneumothorax as 40% of cases of pneumomediastinum are associated with pneumothorax. Note that this is possible only if there isn’t  overlying subcutaneous emphysema


  1. Perm J. 2015 Summer; 19(3): e122–e124.
    doi: 10.7812/TPP/14-232
    PMCID: PMC4500492
    PMID: 26176579
    Pneumomediastinum Diagnosed on Ultrasound in the Emergency Department: A Case Report
  2. J Thorac Dis. 2015 Feb; 7(Suppl 1): S44–S49.
    doi: 10.3978/j.issn.2072-1439.2015.01.11
    PMCID: PMC4332083
    PMID: 25774307
  3. Pneumopericardium diagnosis by point-of-care ultrasonography
    Xavier Bobbia MD, Pierre Géraud Claret MD, Laurent Muller MD, Jean Emmanuel de La Coussaye PhD


1 thought on “9. Case of the month: PoCUS in pneumomediastinum

  • Very nice! I’ve been a fan of lung ultrasound, though sadly this isn’t so popular as the cardiac ECHO. Assessing for predominance of A lines or B lines in lung USG, giving an idea of the underlying pathology in a hypoxic, shocked patient prior to a CT scan, is very helpful if done appropriately. FALLS protocol (from Prof. Lichtenstein) is also helpful in fluid challenges.

    Even free gas under the diaphragm is something that can be picked up bed side USG though not easy and uncommon. If you come across any, please share the educational videos. Many thanks for the above educational videos with adequate explanations – these are amazing!

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