Tag Archives: imaging

When To Image The Aorta In Blunt Trauma

Blunt injury to the thoracic aorta is one of those potentially devastating ones that you (and your patient) can’t afford to miss. Quite a bit has been written about the findings and mechanisms. But how do you put it all together and decide when to order a screening CT?

There are a number of high risk findings associated with blunt aortic injury. Recognize that they are associated with the injury, but are still not very common. They are:

  • Fractures of the sternum or first rib
  • Wide mediastinum
  • Displacements of mediastinal structures (left mainstem down, trachea right, esophagus right)
  • Loss of the aortopulmonary window
  • Apical cap over the left lung

Here’s a sensible method for screening for blunt aortic injury, using CT scan:

  • Reasonable mechanism (fall from greater than 20 feet, pedestrian struck, motorcycle crash, car crash at “highway speed”) PLUS any one of the high risk findings above.
  • Extreme mechanism alone (e.g. car crash with closing velocity at greater than highway speed, torso crush)

Note on torso crush: I have seen three aortic injuries from torso crush in my career, one from a load of plywood falling onto the patient’s chest, one from dirt crushing someone when the trench they were digging collapsed, and one whose chest was run over by a car.

Related post:

Results – Blunt Trauma Radiographic Imaging Protocol

In my previous post (click here to view) I discussed an imaging protocol that we developed and implemented last year. Today, I’ll detail what it has accomplished in our patients.

We looked at 229 patients who had their imaging performed according to the new protocol during a 3 month period and compared them to 215 patients who were imaged the previous year. Each scan administered to each body area (head, chest, abdomen/pelvis, c-spine, t-spine, l-spine, face, neck angio) were tabulated separately.

We found that the overall number of scans performed decreased significantly. We looked at our data and generated numbers per 100 patients. During the control period, we did 298 CT scans per 100 patients. This decreased to 271 during the study period. The number of head scans remained the same (82 per 100 patients during control, 85 per 100 during the study), as did the cervical spine scans (84 vs 86).

The biggest declines were seen in chest CT (53 per 100 control vs 33 per 100 study) and abdominal CT (57 vs 43).

We did see an increase in conventional xrays of the thoracic and lumbar spines to offset the absence of reformatted spine images that would have been generated from the chest and abdominal CT scans. We also noted small increases in CT of the head, cervical spine, and neck angio. This was likely due to better adherence to specific guidelines.

Bottom line: we believe that our work shows that careful adoption of well thought out guidelines can make a difference in practice and significantly decreases radiation exposure in our blunt trauma patients.

To read the post on this protocol, or to download it, click here.

Click here to download the Blunt Trauma Radiographic Imaging Protocol Worksheet

Blunt Trauma Radiographic Imaging Protocol

Last year, we developed an evidence-based protocol for deciding what radiographic images to order in our blunt trauma patients. For some body regions, there is fairly good literature available for guidance (i.e. Canadian head and cervical spine rules). For other areas, there is not nearly as much.

We convened a small group of people, including trauma surgeons, emergency physicians, radiologists and a radiation physicist to combine the information into a practical tool. 

You can view or download the worksheet we use by clicking the link at the bottom of this post. The protocol has been in use for about 9 months, and has significantly decreased the use of higher radiation dose imaging (CT). As a result, there has been a small increase in the use of lower dose conventional imaging (plain spine studies), but no missed injuries. 

Tomorrow, I’ll write about the specifics of how this protocol has changed our ordering habits. Click here to view it.

Click here to download the Blunt Trauma Radiographic Imaging Protocol Worksheet

Click here to download a bibliography of the literature used to develop the protocol

Clinical Tip: The Flat Vena Cava in Blunt Trauma

Trauma patients who are hypotensive in the Emergency Department can only be transported to one of two places: the operating room or the morgue. With rare exception, they should never be taken outside the department (e.g. CT scan) because of the fear that they may arrest in an area that is not conducive to efficient resuscitation.

Sometimes patients are initially stable but decompensate later. Since most stable blunt trauma patients end up in CT scan, perhaps there is some telltale sign that can predict later deterioration. A recent Japanese paper looked at the “flatness” of the inferior vena cava as seen on the abdominal CT scan as a predictor of hemodynamic decompensation in the first 24 hours.

A small cohort of 114 patients was used in this prospective study. The vena cava was evaluated at the level of the renal veins. The flatness of the IVC was determined by dividing the transverse diameter by the anteroposterior (AP) diameter. A flat IVC was defined as a transverse to AP diameter ratio of more than 4:1. The ratio in normal patients was about 2:1. See the figure for details.

Patients who had a flat IVC required significantly more blood transfusions, crystalloid infusions within 2 hours of admission, and were more likely to proceed to the OR within the first 24 hours of their hospital stay.

Bottom Line: Assuming that you are only taking stable blunt trauma patients to CT, the incidental finding of a flat vena cava should increase your paranoia levels and lower your threshold for ordering blood and getting the trauma surgeons involved. 

Reference: Predictive value of a flat inferior vena cava on initial computed tomography for hemodynamic deteroration in patients with blunt torso trauma. J Trauma 69(6):1398-1402, 2010.