Today's POTD came as a request from the Maimonides Attending Group Chat! This was a request after the Pitt, so taking a play out of Dr. Dan Ye's book to talk about case that is described in the latest episode.
So without further adue lets look at some pneumomediastium specifically pneumomediastium causing tamponade.
Pneumomediastium: air present in the mediastinum, usually this occurs from air extravastaing from within the airways/lungs or esophagus and migrates into the mediastium. This air then dissects the cervical subcutanous tissues, epidural space, pericardium, and/or peritoneal cavity.
Pneumomediastium is either typically spontaneous, rare, and typically self limited. Consider risk factors including smoking/tobacco use, recreational drug inhalation. Other causes include intrinsic lung and airway causes including asthma, COPD, bronchiectasis, COPD, ILDz, lung cancer, foreign body, increased intrathoracic pressure (forceful sneezing), increased intravagal tone (such as with childbirth, excessive vomiting, or strenous physical activities). Other iatrogenic cauases include: endoscopy, intubation, central line placement, thoracostomy, or chest/abdominal surgeries, and probably most commonly: traumatic causes: blunt trauma, penetrating trauma, or blast injuries.
In the Pitt, **SPOILER ALERT**, the patient was shot in the chest and had a penetrating trauma.
Spontaneous pneumomediastum can also present with younger males of tall structure with low body mass. This spontaneous pneumomediastium occurs because of Macklin phenomenon: increased intra-aveolar pressure --> alveolar rupture --> air dissects into peribronchial and perivascular sheaths --> air progresses itno mediastium and surrounding tissues.
Presentation:
Most of the time this occurs with retrosternal chest apin that may radiate into the back or neck.
On physical exam, these patients present with subcutaneous emphysema
Other signs and symptoms include: rhinolalia (nasal tone of speech), dysphonia, neck swelling, hoarsness, tachycardia or tachypnea
Diagnosis:
Diagnosis is made usually on xray, and clinical diagnosis.
On CXR you may see subcutaneous emphysema, elevated thymus (in peds patients), air around the pulmonary arteries, V shape between the descending aorta and left hemidiaphragm, double bronchial wall, or pleural effusion.
In pneumomediastium causing tamponade, these patients may have explained hypotension. Normally when we think about tamponade, we are able to be clused in with ultrasound findings, pneumomediastium on ultrasound may be seen as the "air gap" sign which would appear as sonographic echos, usually seen with M mode, that obsecure the cardiac structures underneath. If you have ever tried to place an ultrasound probe on a patient's chest with subq emphysema, you see nearly nothing, so this is definitiely more a clinical diagnosis to consider with unexplained hypotension in someone with subq emphysema.
Tension pneumomediastinum/tamponade leads to compression of great vessels and compromises venous return --> hypotension and hypoxemia
Management of tension pneumomediastinum that causes tamponade physiology:
In the show, the patient got bilateral "blowholes": performed by a 2 cm incision infraclavicular through the skin and prepectoral fascia
Other methods described include b/l chest tubes, placement of penrose drains into the neck
Otherwise pneumomediastium is treated with supportive care and usually resolves on its own.
Until next time friends!
Fleming AM, Zambetti BR, Valaulikar GS. Bedside Mediastinotomy for Tension Pneumomediastinum With Tamponade in COVID-19. Ann Thorac Surg. 2021 Oct;112(4):e265-e266. doi: 10.1016/j.athoracsur.2021.01.032. Epub 2021 Jan 30. PMID: 33529601; PMCID: PMC8402946
Iteen AJ, Bianchi W, Sharman T. Pneumomediastinum. [Updated 2023 May 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557440/
Sciortino CM, Mundinger GS, Kuwayama DP, Yang SC, Sussman MS. Case report: treatment of severe subcutaneous emphysema with a negative pressure wound therapy dressing. Eplasty. 2009;9:e1. Epub 2009 Jan 7. PMID: 19198645; PMCID: PMC2627309.