Category Archives: General

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 http://youtu.be/NhjF9kDOcjE). 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.

References:

  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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How To: Stop Scalp Bleeding

Bleeding from scalp wounds may seem like a trivial problem, but I have personally seen someone die from unrecognized hemorrhage over time from one. All too often, these are covered up with a crude dressing when the patient arrives in the ED and is not looked at for some time.

Here are some tips to stop scalp bleeding:

  • Use direct pressure. This seems obvious but is frequently done incorrectly. Direct pressure involves a small diameter piece of gauze (stack of 2x2s or double folded 4×4) and only one or two fingers. Larger dressings or the palm of the hand do not provide enough pressure to stop all the bleeding. Direct pressure for 5 minutes (no peeking) will stop all bleeding that doesn’t need more advanced techniques.
  • Inject local anesthetic with epinephrine. This increases vasoconstriction and helps the direct pressure work even better. Be cautious if there is a large skin flap that does not have a nice pink color. Degloved skin has been crushed and small vessel vascular injury has occurred. Further reducing blood flow with epinephrine may kill the skin flap in this type of injury.
  • Apply Raney clips. Neurosurgeons use these to stop scalp bleeding during brain procedures. Caution! Only apply to unconscious patients, and only to the scalp (not face)! These hurt!
    Raney clips
  • Oversew the scalp. Use a large silk or nylon suture and insert a large running stitch to close the wound. This will stop all bleeding from the skin edges. However, any arterial bleeders underneath will continue to be a problem.
  • Ligate individual bleeders. Use a small absorbable suture and attack each small arterial bleeder with a figure of 8 stitch. Don’t suture large chunks of tissue; make sure that you are attacking just the artery and not any adjacent nerves.
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Trauma Patient Stability

EMS in the field and physicians in the ED are faced with rapidly assigning some degree of stability to the patients they treat. What exactly are the shades of stability, and what considerations are there for each degree?

In my mind, there are three levels of “stability”:

  • Unstable – this one is easy to figure out. The patient has obvious physiologic compromise, which may be objective (low blood pressure, low GCS or poor neuro exam, etc) or subjective (just plain looks bad). 
    EMS: These patients need transport to an appropriate level trauma center (I or II) immediately. If they need airway control or IV access that can’t be obtained in the field, stop at the nearest Level III or IV for assist, then continue on your way FAST. 
    ED: These patient must be a trauma activation. If not activated as your top-tier trauma, activate or upgrade now! These patients must be seen by a trauma surgeon immediately, and can only go to the OR. No diagnostics outside the resuscitation room are allowed unless they can be converted into one of the two stability levels below.
  • Stable – this one is usually easy to figure out, too. These patients look good, have good vitals, and a low to moderate energy mechanism for their trauma. Look out for those few patients that may be hiding something like moderate bleeding into some body cavity.
    EMS: Follow your usual transport protocols to select the closest, appropriate hospital.
    ED: Follow your standard protocols for trauma activation if needed. Transport for standard imaging is fine.
  •  Metastable – this is a term I invented. It describes patients who have evidence of ongoing volume loss that can be controlled with infusion of crystalloid and/or blood products. It is possible to maintain a certainly level of stability using higher than normal volume infusions. This allows physicians to consider diagnostics or interventions outside of an OR.
    EMS: Ensure adequate IV access and give fluids and/or blood per your local protocols. Transport to a Level I or II trauma center as quickly as possible.
    ED: Activate or upgrade to your highest level of trauma activation. The trauma surgeon needs to be present to help direct diagnostics or interventions. These patients may go to CT, IR or other appropriate areas with nurse and physician accompaniment to diagnose and possibly treat bleeding. If the patient changes to unstable at any point, they must immediately be taken to the OR.
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