Other Traumatic Chest Injuries

In the era of the pan scan, it is not really important to use US to diagnose the small area of aspiration, the small patch of contusion associated with rib fractures. But when the patient is hypoxic with sats of 50% on oxygen, too unstable to move to CT and the CXR just shows a whiteout, bedside US can help you differentiate the cause and initiate management to improve oxygentation. For example, aspiration with lung collapse would benefit from bronchoscopy and suction, significant areas of contusion may benefit from improved ventilator settings. 

CONTUSIONS

Contusions to the lungs are common with blunt chest trauma. They are often under-diagnosed on supine CXR (1). On lung US they appear as a slightly ragged, thin pleural line with attached B lines (2). The more confluent the B lines, the greater the area of injured lung. Sometimes you may also see a small localised pleural effusion seen as a quad sign. With time, the area may show subpleural consolidations.

Lung contusion on US: note the inverted pleura and the B lines originating from this area of injured pleura: typical of contusion, 

ASPIRATION

Aspiration into small bronchioles may cause localised atelectasis and an area of B lines with normal pleura. However, a large area of bronchial obstruction will look like unventilated lung on US: Absent pleural sliding + lung pulse. There is not much literature on the US appearence of acute aspiration. Studies in children with FB aspiration shows localised B lines and pleural effusions or a convex appearence to the pleura due to hyperinflation (3). Anecdotally, I have found significant aspiration causing hypoxia looks like unventilated lung. 

Unventilated lung: absent pleural sliding. B lines on the right of screen exclude a pneumothorax. Usually the tachycardia associated with hypoxia with significan aspiration causes a more prominent lung pulse to the lung which can be seen in 2D.

REFERENCES

1. Pape HC, Remmers D, Rice J et al (2000) Appraisal of early evaluation of blunt chest trauma: development of a standardized scoring system for initial clinical decision making. J Trauma 49:496–504

2. Soldati G, Testa A, Silva FR, Carbone L, Portale G, Silveri NG. Chest ultrasonography in lung contusion. Chest. 2006 Aug;130(2):533-8.

3. Aydin O, Birbilen AZ, User IR, Turer OB, Teksam O. Lung ultrasound findings in children with foreign body aspiration. J Clin Ultrasound. 2023 Mar;51(3):447-451.