Yesterday I talked about the most common chest xray finding in patients with a thoracic aortic injury, the wide mediastinum. There are several lesser known (and less common) findings that may also occur. These can be divided into three broad categories: associated fractures, displacements, and other weird findings.
The associated fractures indicate that a lot of energy has passed into the chest and generally involve bones that are difficult to break. They consist of:
- First rib (or second). These are flattened with a pronounced curve and are very difficult to break.
- Scapula. Also irregular, and thick in some areas.
The displacements are shifts in other mediastinal structures causes by a hematoma near the aortic arch. They generally involve the bronchial tree and esophagus.
- Left mainstem bronchus is pushed down, since it is nestled under the arch.
- Trachea is angled to the right as the whole bronchial tree on the left side is pushed down
- Esophagus is shifted to the right. This can only be seen if an NG is in place.
Weird stuff are just miscellaneous things that people have found to be associated with this injury:
- Apical cap. This is blood that has dissected away from the aorta and is extrapleural. Think of it as an epidural hematoma of the pleura, so it pushes in from the outside making it somewhat lenticular (lens-shaped). It is only significant if seen on the left, since the hematoma can’t dissect all the way over to the right. (see image below)
- Loss of the aortopulmonary window. This is a small space seen between the shadows of the aorta and pulmonary artery on chest x-ray. It is best seen on the lateral view, which we don’t get in trauma patients.
Tomorrow, I’ll talk about what kind of mechanism is needed to tear the aorta, and finish up with some guidelines on when to image people for this injury.
A. The apical cap. Note how it bows inward
B. Blood along the spine dissecting up from the arch.