Pneumothorax is a serious potential consequence of blunt thoracic trauma and, if misdiagnosed, it may quickly become life-threatening.
For a discussion on epidemiology, clinical presentation, pathology, and treatment and prognosis please see the main pneumothorax article.
CT is considered the gold-standard in the diagnosis of pneumothorax. Thoracic ultrasound has more sensitivity than a supine chest radiograph (see: supine pneumothorax) for the identification of pneumothorax after blunt trauma. The other advantage of ultrasound is that it can be used at point-of-care.
The normal lung interface with pleura shows lung sliding with vertical comet tails running down from the pleural surface. In pneumothorax, this sliding is absent and so are the comet tail artifacts from the pleura. This is due to air in between the parietal and visceral pleura, preventing lung from sliding.
Visualising the junction between sliding lung and absent sliding is known as the lung point sign and is near 100% specific for pneumothorax and also gives an indication of pneumothorax size by its location. It is not able to be found in all pneumothorax cases (sensitivity is around 65%) especially large pneumothoraces where the lung is collapsed and there is globally absent sliding.
On M mode, classical signs for the gray scale imaging are seen:
- seashore sign: normal lung sliding
- barcode/stratosphere sign: pneumothorax
History and etymology
The use of ultrasound to diagnose pneumothorax was first described in a veterinary medical journal in 1986 4.
- 1. Husain LF, Hagopian L, Wayman D et-al. Sonographic diagnosis of pneumothorax. J Emerg Trauma Shock. 2012;5 (1): 76-81. doi:10.4103/0974-2700.93116 - Free text at pubmed - Pubmed citation
- 2. Stone MB. Ultrasound diagnosis of traumatic pneumothorax. J Emerg Trauma Shock. 2008;1 (1): 19-20. doi:10.4103/0974-2700.41788 - Free text at pubmed - Pubmed citation
- 3. Lichtenstein DA, Mezière G, Lascols N et-al. Ultrasound diagnosis of occult pneumothorax. Crit. Care Med. 2005;33 (6): 1231-8. Pubmed citation
- 4. Rantanen NW. Diseases of the Thorax. Vet Clin N Am. 1986; 2:49–66. Pubmed citation