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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