Sunday 30 July 2017

Prevalence and Clinical Import of Thoracic Injury Identified by Chest CT but not Chest X-ray in Blunt Trauma: Multicentre Descriptive Study

Uuuggggh… this paper was hard to digest. The writing and presentation of the manuscript was more complicated than playing Twister in a hot-tub. 

Case in point; the abstract alone has 629 words.  Screw the Annals of Emergency Medicine limit of 250 words in their instructions to authors.

I’ll try to distil it for you…
  • In patients with blunt trauma, how many more injuries does a chest CT find over a plain film?
  • Are these injuries clinically significant?
  • Does finding these occult injuries result in major intervention?

This was a secondary analysis of data collected for NEXUS chest and chest CT studies collected at 10 level 1 trauma centres in the USA. (So, good data in...)

Inclusion criteria were patients >14 years old with blunt trauma who had both a chest x-ray and chest CT. (98% of the time, the chest x-rays were portable supine films.)

Occult injury was defined as those seen on CT but not on plain film. These included pneumothorax, hemothorax, sternal or scapula fracture, >2 rib fractures, pulmonary contusion, T-spine fracture, diaphragm injury.


Of 14,553 patients in the NEXUS database, 5,912 met inclusion getting both plain film and chest CT. Of these, 2048 had chest injury.

What was the rate of occult injury?


What proportion of occult injuries required major intervention? (as defined by surgery, chest tube, or mechanical ventilation for pulmonary contusion).


This sounds rather impressive until you realize the great majority of these interventions were chest tubes for occult injury! 

In the end, 48 patients (08%) out of 5912 had major intervention (excluding chest tubes). A few of these were clearly nasty injuries including diaphragm rupture and major vessel injury.

Could many of these interventions been of no patient benefit and/or harmful? Could these injuries have been detected after a period of observation?

Of course.

Did over-diagnosis with CT cause harm with increased downstream intervention and resource utilization?

Quite possible.

What about the addition of point-of-care ultrasound? We know that portable supine chest x-rays are awful at finding pneumothorax and haemothorax.

This was ignored.

What are we to make of all of this?

The biggest caution is the interpretation.

You will probably hear it quoted that chest x-ray misses 70% of all injuries compared to CT without mention of the details above.


Also, remember the included patients got both plain film and CT at the discretion of the ED doctors. So, this is not all comers with blunt trauma… This was a sicker group that the doctors were worried about.

In the end, I think this paper provides more questions than answers. If you use a bigger microscope, you will find more injury. But does this help or harm patients?

The answer is still uncertain.

I think I need a dip in that hot-tub.


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