Category Archives: General

General

How Much Radiation is the Trauma Team Really Exposed To?

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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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General

Thoracic Aortic Injury in Very Young Children

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Trauma professionals routinely worry about the thoracic aorta when evaluating adults after major blunt trauma. The question is, how much do we have to worry about blunt thoracic aortic injury in children?

Younger children are more elastic, and their organs tend to withstand more punishment than adults. After reviewing the literature, I’ve come to the conclusion that this injury is very rare in children in the single digit age range. It’s difficult to find a good paper that addresses this question. The majority include kids up to age 16 or 18, which really skews the results. These patients are most commonly involved in motor vehicle crashes, although a significant number are also pedestrians struck by cars. 

The National Trauma Data Bank (NTDB) was queried for all children <18 years old sustaining blunt injury with at least 1 diagnosis code. There were nearly 27,000 records matching these criteria. Of these, only 34 had an injury to the thoracic aorta. And in the age range under 10, there were only 2! Both of these children were in very high energy car crashes.

The bottom line: Injury to the thoracic aorta practically never happens in children in the single digit age range. As they get closer to adolescence, they behave more like adults and become more susceptible. The diagnosis should be only be entertained in small children who are involved in very high-energy car crashes. Falls from the usual heights (2-3 stories) are probably not significant enough to cause it. A chest xray may show a full mediastinum, but this will most likely be due to a normal thymus. If investigation is warranted, the standard is to obtain a helical CT of the chest. This study would most likely be obtained anyway to evaluate the torso in a high-energy mechanism. Aortorgraphy is no longer used.

Reference: Trooskin, et al. Risk factors for blunt thoracic injury in children. J Pediatric Surg 40(1):98, 2005. 

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General

The Value of Trauma Center Care

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The cost of care in a trauma center is high. When anything is expensive, it is natural to wonder about its cost-effectiveness. A group of biostatisticians recently looked at the treatment costs and cost-effectiveness of treating trauma patients in a trauma center vs an nontrauma hospital. They were very comprehensive in looking at costs, including costs for transportation, treatment at a transferring hospital, rehospitalization for acute care if needed, inpatient rehab, stays in longterm care or skilled nursing care facilities, outpatient care and informal care given by family members.

Treatment at a trauma center saved 3.4 lives per 100 patients treated. The overall added cost for treatment at a trauma center was about $36,000 per life year gained. However, in order to gauge cost-effectiveness we need to know what a year of life is worth. As you can imagine, this is tough to figure out. A number of researchers have looked at this, and it typically ranges from $50,000 to $200,000 per year. Thus, trauma center care is overall cost-effective.

The data was more closely analyzed, and it appears that the cost-effectiveness is greater for patients with more severe injuries. Unfortunately, cost-effectiveness is not as clear for patients who are 55 years or older.

The bottom line: Trauma is a leading cause of death in this country. The concept of treating more severely injured patients at trauma centers is both effective and cost-effective. Trauma systems need to be fine-tuned so that they get the right patient to the right hospital and so care for elderly patients continue to improve.

Reference: Nathens et al. The Value of Trauma Care. J Trauma 69(1):1-10, 2010.

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