Category Archives: General

Pop Quiz: Part 1

Okay, this one’s tough! This is by far the hardest one I have posted. I don’t think anyone has a clue! It’s so hard, I’m going to post another image as a hint tomorrow. Then on Friday, I’ll show the after photo so you can tell me what the final problem was. Answer Monday!

Have a look at the image below and tell me what you think. Seems simple, right? How did it happen? What other injuries might be present? Comment below or tweet or email your thoughts!

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FAST Cardiac Ultrasound And Traumatic Arrest

Cardiac arrest in trauma patients is bad. Really bad. There are few survivors, mainly those who have some signs of life when they roll into the resuscitation room. One of the signs we look for is cardiac electrical activity, especially a narrow complex rhythm. But most of the time these patients don’t survive either. Could there be a way to fine tune the use of pulseless electrical activity (PEA) to better determine when further care is futile?

The trauma group at UCSF-East Bay did a nice, retrospective review on the use of the cardiac portion of the FAST exam to assess patients arriving in PEA arrest after either blunt or penetrating trauma. The numbers were a bit thin, but they were able to study 162 patients who had both FAST and EKG upon arrival. Of those patients, 71 had electrical activity, but only 17 had cardiac motion. However, 4 of these 17 survived (24%) vs only 1 of the 54 who did not have cardiac motion.

About a third of these 71 patients suffered blunt trauma, the remainder had penetrating injury. Of the 17 with cardiac activity, 14 were penetrating and 3 were blunt. And of the 4 survivors mentioned above, 3 were penetrating.

Only 1 of the 71 patients with PEA and no cardiac activity survived, and this was a blunt arrest(!).

Bottom line: Traumatic arrest is a generally fatal problem. However, it appears that use of the cardiac portion of the FAST exam in penetrating or blunt trauma can help fine tune the aggressiveness of resuscitation. PEA without cardiac activity is uniformly fatal (although there was one blunt survivor, the authors did specify the quality of this survival). It may be wise to forego further resuscitative efforts in PEA patients without cardiac activity because they will not survive, even as an organ donor.

Reference: The heart of the matter: Utility of ultrasound of cardiac activity during traumatic arrest. J Trauma 73(1):103-110, 2012.

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How Much Radiation is the Trauma Team Really Exposed To?

Okay, so you’ve seen “other people” wearing perfectly good lead aprons lifting them up to their chin during portable xrays in the trauma bay. Is that really necessary, or is it just an urban legend?

After hitting the medical radiation physics books (really light reading, I must say), I’ve finally got an answer. Let’s say that the xray is taken in the “usual fashion”:

  • Tube is approximately 5 feet above the xray plate
  • Typical chest settings of 85kVp, 2mAs, 3mm Al filtration
  • Xray plate is 35x43cm

The calculated exposure to the patient is 52 microGrays. Most of the radiation goes through the patient onto the plate. A very small amount reflects off their bones and the table itself. This is the scatter we worry about.

So let’s assume that the closest person to the patient is 3 feet away. Remember that radiation intensity diminishes as the square of the distance. So if the distance doubles, the intensity decreases to one fourth. By calculating the intensity of the small amount of scatter at 3 feet from the patient, we come up with a whopping 0.2 microGrays. Since most people are even further away, the dose is much, much less for them.

Let’s put it perspective now. The background radiation we are exposed to every day (from cosmic rays, brick buildings, etc) amounts to about 2400 microGrays per year. So 0.2 microGrays from chest xray scatter is less than the radiation we are exposed to naturally every hour!

The bottom line: unless you need to work out you shoulders and pecs, don’t bother to lift your lead apron every time the portable xray unit beeps. It’s a waste of time and effort!

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How To: Flexion / Extension Views of the Cervical Spine

Clearance of the cervical spine can often be done using clinical criteria alone (see this video at If this is not possible, a combination of radiologic and clinical evaluation is usually carried out. 

In some cases, radiographic studies (usually CT) are normal, but there is pain on clinical exam. Our next step is to send the patient to xray for flexion and extension views. This exam is performed by removing the collar while the patient is sitting, so the thoracic and lumbar spines must be clear before ordering this. The patient then gently flexes and extends the neck to their limits of comfort. Images are then obtained at the limits of flexion and extension. The premise is that a normal, awake patient cannot and will not move their neck beyond their comfort level to the point where they could cause themselves neurologic injury. 

It is very important that you look at the images yourself. The radiologist may review the images and will report that “there is no evidence of subluxation at the limits of flexion and extension.” But the patient may have barely moved their neck!

The question is: how much flexion and extension do you need to have to clear the spine?

The answer is not easy to find, and is buried in literature from the 1980s and 90s. According to the EAST guidelines, the ideal amount is 30 degrees from neutral for both flexion and extension. This is not always achievable in elderly patients, so in those cases you must use your judgment. Talk to the patient to find out if they stopped moving their neck forward or backward due to pain, or because they just can’t move it that far.

Trouble signs to look for are:

  • Subluxation of more that 2mm at any level
  • Angulation of more than 11 degrees

Any abnormality should prompt a spine consult.

If the study is not abnormal but the amount of flexion and/or extension is not adequate, there are two options. First, just leave the collar in place and try again in a week or so and try again. This will allow any soft tissue injuries to get better and may allow a successful repeat study. The alternative is a more costly and less well-tolerated MRI.


  1. EAST Practice Guidelines, Identifying Cervical Spine Injuries Following Trauma – Update (2000).
  2. Defining radiographic criteria for flexion-extension studies of the cervical spine. Robert Knopp et al. Ann Emerg Med. 2001 Jul;38(1):31-5.
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