All posts by TheTraumaPro

How Much Radiation Exposure In Imaging Studies?

Everyone knows that CT scans deliver more radiation than conventional x-ray. But how much does each test really deliver? And how significant is that?

Let me try to put it all into perspective. First, how much radiation are we exposed to just living outside the hospital? Background radiation is everywhere. It consists of radioactive gases (argon) in the air we breathe, radiation from the rocks and other things around us, and cosmic rays blasting through us from space.

In the United States, the average background radiation each of us is exposed to is about 3.1 milliSieverts (mSv). I’ve compiled a table to show the approximate dose delivered by some of the common radiographic studies ordered by trauma professionals. And to keep it real, I’ve calculated how much extra background radiation we would have to absorb, in units of time, to have an equivalent exposure.

Read and enjoy! Remember, doses may vary by scanner, settings, and dose reduction measures used.

Test Dose (mSv) Equivalent background
Chest x-ray 0.1 10 days
Pelvis x-ray 0.1 10 days
CT head 2 8 months
CT cervical spine 3 1 year
Plain c-spine 0.2 3 weeks
CT chest 7 2 years
CT abdomen/pelvis 10 3 years
CT T&L spine 7 2 years
Plain T&L spine 3 1 year
Millimeter wave
scanner (that hands
in the air TSA thing at
the airport)
0.0001 15 minutes
Scatter from a chest
x-ray in trauma bay
when standing one 
meter from the
0.0002 45 minutes
Scatter from a chest
x-ray in trauma bay
when standing three 
meters from the
0.000022 6 minutes

Cognitive Rest? What Is It?

One of the more commonplace recommendations for recovery from mild traumatic brain injury (TBI) is “cognitive rest.” Sports medicine professionals recommend it, physiatrists recommend it, and trauma professionals talk about it.

First, what is it, exactly? I’ve seen a number of descriptions, and they vary quite a bit. The main concept is to avoid all activities that involve mental exertion. This includes using a computer, watching TV, talking on a cell phone, reading, playing video games, and listening to loud music. Huh?

What good does this allegedly do? Most articles that I’ve read theorize that cognitive activity somehow increases the metabolic activity of the brain and that this is bad. One of the more interesting papers I read (from 2010!) says it best: “It is now well-accepted that excessive neurometabolic activity can interfere with recovery from a concussion and that physical rest is needed.”

Read carefully. Well-accepted. The paper cites unpublished data on children by one of the authors, 2 meta-analyses and 2 consensus opinions. In other words, no data at all. Yet somehow the concept has caught on.

First of all, I don’t think it’s possible for most people to realistically practice cognitive rest. Who knows if there is really any difference in metabolism and energy use by the brain if you are engaging in any of the banned activities above? And let’s go to the other extreme: if one lies quietly in bed meditating, shouldn’t this be the ultimate cognitive rest? Yet fMRI and PET studies suggest (also limited data) that cerebral flow in specific areas of the brain increases during this state.

Maybe a modest increase in activity is good. Physical activity (within limits) has been shown to be very beneficial to physical and psychological well being time and time again. And the only paper I could find on the topic with respect to TBI showed that randomization to bedrest vs normal physical activity had no difference in post-concussive syndrome incidence or severity. However, the active group recovered with significantly less dizziness.

Bottom line: There is no data to support the concept of cognitive rest. Any type of activity, either mental or physical, can cause fatigue in a variable amount of time in people with mild TBI. It is probably best to interpret this as a signal to take it easy and recover for a while before exerting oneself again. But so far there is no objective data to show that cognitive activity either helps or hinders recovery.


  • Cognitive rest: the often neglected aspect of concussion management. Athletic Therapy Today, March 2010, pg 1-3.
  • Effectiveness of bed rest after mild traumatic brain injury: a randomised trial of no versus six days of bed rest. J Neurol Neurosurg Psychiatry 73:167-172, 2002.

The ACS “Gang Of 6” Trauma Activation Criteria

For more than 10 years, all trauma centers verified by the American College of Surgeons (ACS) have been required to have a group of mandatory criteria for their highest level of trauma activation. I call these the gang of 6 (ACS-6). They are:

  1. Hypotension (systolic < 90 torr for adults, age specific for children)
  2. Gunshot to neck, chest, abdomen or extremities proximal to elbow or knee
  3. GCS < 9 from trauma
  4. Transfer patients receiving blood to maintain vital signs
  5. Intubated patients from scene or patients with respiratory compromise transferred in (may already be intubated but still having compromise)
  6. Emergency physician discretion

For the most part, it seems obvious that any one of these criteria would indicate a seriously injured patient needing rapid trauma team evaluation. But do all centers use these criteria?

The answer, detailed in a recently published paper, would seem to be no! Researchers at the Universities of Minnesota and Michigan looked at the Trauma Quality Improvement Program database for all Level I and II centers in Michigan over a three year period. They specifically analyzed the data to determine how many centers used all 6 criteria, and any differences in mortality between those that did and those that didn’t. They reviewed records for adults with blunt and penetrating trauma with an ISS > 5.

Here are the factoids:

  • More than 50,000 patient records were reviewed, and 12% met at least one of the ACS-6
  • Only 66% of patients with at least one ACS-6 criterion were full trauma activations (!!)
  • Compliance was poorest with hypotension (only half activated), compared to intubation (75%), central gunshot (75%), and coma (82%)
  • 79% of patients meeting any ACS-6 criterion needed an intervention, with a third going emergently to the OR
  • Undertriaged patients (ACS-6 with no high level activation) were significantly more likely to die (30% vs 21%), and this was most pronounced in the coma group (47% vs 40%)

Bottom line: Physiologic trauma activation criteria are important, as is the central gunshot one! Although this is a database review subject to the usual flaws (retrospective, data accuracy), the numbers are large and the statistics are sound. And remember, this is an association study, so we don’t really know why the mortality numbers were different, just that they were.

Nevertheless, there is a lot to learn from it. Why don’t all centers use the ACS-6? They certainly have them in their criteria list, or they would have failed their verification visit. It’s because of undertriage! How does this happen? Two ways: either the information in the field is incorrect (GCS may be incorrectly estimated, hypotension may be transient), or personnel in the ED failed to activate properly.

This study shows the importance of rigidly adhering to the criteria. It found a 20% mortality reduction if all of the ACS-6 were applied properly. So make sure that your own trauma program regularly monitors for undertriage, especially with respect to the “gang of 6”!

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Reference: Noncompliance with American College of Surgeons Committee on Trauma recommended criteria for full trauma team activation is associated with undertriage deaths. J Trauma 84(2):287-294, 2018.

What You Need To Know About Frontal Sinus Fractures

Fracture of the frontal sinus is less common than other facial injuries, but can be more complex to deal with, both in the shorter and longer terms. These are generally high energy injuries, and facial impact in car crashes is the most common mechanism. Fists generally can’t cause the injury, but blunt objects like baseball bats can.

Here’s the normal anatomy:




There are two “tables”, the anterior and the posterior. The anterior is covered with skin and a small amount of subcutaneous tissue. The posterior table is separated from the brain by the meninges.

Here’s an image of an open fracture involving both tables. Note the underlying pneumocephalus.


A third of injuries violate the anterior table, and two thirds violate both. Posterior table fractures are very rare. A third of all patients will develop a CSF leak, typically from their nose.

These fractures may be (rarely) identified on physical exam if deformity and flattening is noted over the forehead. Most of the time, these patients undergo imaging for brain injury and the fracture is found incidentally. Once identified, go back and specifically look for a CSF leak. Clear fluid in the nose is, by definition, CSF. Don’t waste time on a beta-2 transferring (see below).

If a laceration is clearly visible over the fracture, or if a CSF leak was identified, notify your maxillofacial specialist immediately. If more than a little pneumocephalus is present, let your neurosurgeon know. Otherwise, your consults can wait until the next morning.

In general, these patients frequently require surgery for the fracture, either to restore cosmetic contours or to avoid mucocele formation. However, these are seldom needed urgently unless the fracture is an open fracture with contamination or there is a significant CSF leak. If in doubt, though, consult your specialist.

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Keeping Patients Warm In Your Trauma Bay

Hypothermia is the enemy of all trauma patients. It takes their potential bleeding problems and makes them exponentially worse. From the time you strip off their clothes in the trauma resuscitation room, they begin to cool down. And if you live in Minnesota like me (or some similar fun place), they start chilling even before that.

What can you do in the trauma bay to help avoid this potential complication? Here are some of the possibilities, and what I think of them. And I’ll also provide a practical tip to help keep your patient warm  while you can still do a full exam.


– Warming lights in the ambulance unloading area. I know lots of people look at this area and recommend them. Unfortunately, they don’t do a lot. Consider that your patient will move through this space quickly. While it may be cold, they’ll only spend a minute or so getting to the back door to the ED.

– How about the path from the helipad? If this is mostly outside, it can be a problem. If it’s wide open, there aren’t really a lot of options. Cover and heat it? Lots of $$$. Typically, flight crews working in winter climates have bundled up their patient very well, and this is the patient’s primary source of protection from the elements. If the pad is far away from the ED, consider a fancy golf cart to move them quickly, and perhaps get an even fancier one that has a heated enclosure.


– Heat the room! This only works on a moment’s notice if you have a smaller room or a really good heating system. Otherwise, you must keep it cranked it up at all times.

– Close the door! You will not be able to keep the room toasty unless you make sure the door is closed as much as possible. No doors? Then consider the next tips.

– Use radiant heating systems. Some EDs have lights in the ceiling, others have portable units that can be rolled over to your patient.

– Use hot fluids, especially in the winter. At a minimum, all blood products must be administered through a warmer, since they are only a few degrees above freezing. If it’s winter outside, or your patient is already cool, give all IV fluids through the warmer, too.

– Cover your patient. Keep a blanket warmer nearby, and pull several out at the beginning of each resuscitation.

– What about those fancy air blankets? Unfortunately, they are unwieldy. They’re all one piece, they try to fall of the patient all the time, and they limit access for your exam. But there is a solution!

Here’s a clever way to deal with this problem. Use my two-blanket trick. Don’t use just one warm sheet or blanket. Use two! Fold each one in half, so they are each half-length. Place one on the top half of the patient, the other at the bottom, overlapping slightly at the waist. Your whole patient is now covered and toasty. If you need to look at an extremity, fold the blanket that covers it over from right to left (or left to right) to uncover just the area of interest. To insert a urinary catheter, just open the area at the waist, moving the top sheet up a little, the bottom down a little. Voila!