Category Archives: General

Targeted Hypernatremia In Trauma Brain Injury

Traumatic brain injury (TBI) frightens and confuses most trauma professionals. The brain and its workings are a mystery, and there is very little real science behind a lot of what we do for TBI. One thing that we do know is that intracranial hypertension is bad. And another is that we do have some potent drugs (mannitol, hypertonic saline) to treat it emergently. 

So if we can “dry out” the brain tissue on a moment’s notice and drop the ICP a bit with a hit of sodium, doesn’t it stand to reason that elevating the sodium level constantly might keep the brain from becoming edematous in the first place? Many neurosurgeons buy into this, and have developed protocols to maintain serum sodium levels in the mid-140s and higher. But what about the science?

A nice review was published in Neurocritical care which identified the 3 (!) papers that have promoted this practice in humans with TBI. In general, there was a decrease in ICP in the patients in the cited papers. Unfortunately, there were also a number of serious and sometimes fatal complications, including pulmonary edema and renal failure requiring hemodialysis. These complications generally correlated with the degree of hypernatremia induced. Papers were also reviewed that involved patients with other brain injury, not caused by trauma. Results were similar. 

Bottom line: There is no good literature support, standard of care, or even consensus opinion for prophylactically inducing hypernatremia in patients with TBI. The little literature there is involves patients with severe TBI and ICP monitors in place. There is nothing written yet that justifies the expense (ICU level care) and patient discomfort (frequent blood draws) of using this therapy in patients with milder brain injury and a reliable physical exam. If you want to try out this relatively untried therapy, do us all a favor and design a nice study to show that the benefits truly outweigh the risks. 

And if you can point me to some supportive literature that I’ve missed, please do so!

Related posts:

References:

  • Induced and sustained hypernatremia for the prevention and treatment of cerebral edema following brain injury. Neurocrit Care 19:222-231, 2013.
  • Continuous hyperosmolar therapy for traumatic brain injury-induced cerebral edema: as good as it gets, or an iatrogenic secondary insult? J Clin Neurosci 20:30-31, 2013.
  • Continuous hypertonic saline therapy and the occurrence of complications in neurocritically ill patients. Crit Care Med 37(4):1433-1441, 2009. -> Letter to the editor Crit Care Med 37(8):2490-2491, 2009.
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January Newsletter Released To Subscribers Tonight!

The JanuaryTrauma MedEd Newsletter will be released to subscribers tonight. I’ll be covering shock. Articles include:

  • Thoughts on trauma patient stability
  • Does initial hematocrit predict shock?
  • Not all plasma is created equal
  • Can I take a hypotensive patient to CT?
  • Pelvic fractures: OR vs angio in the unstable patient

Anyone on the subscriber list as of 8 PM (CST) will receive it tonight, February 4. I’ll release it to everyone else next Monday via the blog. So sign up for early delivery now by clicking here!

Pick up back issues here!

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Cool Device: Noninvasive Spot Check Hemoglobin

I always tell my trainees that “your patient is bleeding to death until you can prove otherwise.” Sometimes bleeding is obvious in our trauma patients and sometimes it isn’t. The usual routine for assessing major trauma patients involves a blood draw, with a high priority on obtaining a specimen for the blood bank. But most centers also get standard analyses on the blood, including CBC, lytes, etc.

But remember, a blood draw is a snapshot. And it’s a snapshot of values that change relatively slowly. This means that you can get suckered into believing that your patient is okay because one set of labs looked pretty normal. And it’s impractical (and uncomfortable) to get labs frequently with repeated needle sticks.

Masimo, a medical equipment manufacturer, has added something extra to the pulse oximeter that you are already familiar with. Using the usual clip-on finger probe, it measures arterial oxygen saturation, pulse rate, perfusion index, and total hemoglobin.

I wrote about this device a year ago after an abstract was presented at EAST. The final paper from the University of Arizona – Tucson has now been published,  and here are the updated factoids:

  • 525 patients were spot-checked, with a success rate of 86% 
  • Spot-check failures were due to nail polish or soot on the nails, sensor fit problems (only one size was available in the study), placement problems due to other imaging equipment, or patient agitation
  • 173 (38%) of patients had a Hgb <= 8
  • The mean difference between spot-check and blood draw results was only 0.3 g/dL (!)
  • Sensitivity was 95%, accuracy 76%

Bottom line: This is an interesting new tool for acute trauma care. The only downside that I see is that we may lose sight of the fact that hemoglobin values lag behind as an indicator of true blood volume in rapidly bleeding patients. We mustn’t be fooled into thinking that everything is fine just because a number is normal. There’s still room for common sense! And don’t start monitoring serial hemoglobins willy nilly in solid organ injury just because you can. You still don’t need it!

Related posts:

Reference: Transforming hemoglobin measurement in trauma patients: noninvasive spot check hemoglobin. J Am Col Surg 220(1):93-98, 2015.

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The Two-Sheet Trauma Trick

Hypothermia is always a concern in trauma patients. Even the simple act of completely exposing your patient in the trauma room facilitates it. How do trauma professionals balance the need to see everything with the equally important need to keep the patient warm?

The natural reaction is to cover them up. Sheets and warm blankets are the usual tools. But I always marvel that, as soon as the blanket goes on, there’s always a need to examine something or do some procedure. Look at a wound. Insert a urinary catheter. And every time this happens, the blanket comes off.

Here’s a clever way to deal with this problem. Don’t use just one 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. 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.

Bottom line: Keep your patient toasty! Use the two-sheet (or warm blanket) trick to avoid hypothermia. Remember, patient temperature begins to drop as soon as the clothes come off! And I don’t recommend the use of one-piece inflatable warming blankets (e.g. Bair Hugger) until the work in the ED is complete, because the whole thing has to be removed every time you need meaningful access to the patient.

Related posts:

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New Technology: 3-D Printed Casts For Fractures

I’ve written quite a lot about the promise of medical applications for 3-D printers. Here’s another one for use by trauma professionals.

Look at the good, old-fashioned plaster cast. It’s been around for decades, and serves its purpose well. It’s easy to apply, inexpensive, and reasonably durable.

Then, along came fiberglass. It’s lighter, more durable, and a bit more water-resistant. And not a whole lot more expensive.

But both of these items have drawbacks. They are heavy. It’s best not to get them wet. Their application is very operator dependent. And probably most importantly, they are opaque. This masks any wounds or skin conditions under it for an extended period of time.

Deniz Karasahin, a Turkish student, won a design award for the development of a 3-D printed cast. It used the appearance of cancellous bone as a model, and is aesthetically very cool. A body scanner is used to scan the affected extremity so that the cast can be customized to the patient. The actual cast is printed from plastic, and can be rendered in a variety of colors. It is hinged, and locks together with a simple pin mechanism.

Bottom line: This is an interesting development in 3-D printing. However, it is not for everybody. Cheap plaster and fiberglass casts are very suitable for many patients. But for some, having the ability to inspect the underlying skin or deal with wounds will make this item much more desirable. And keep in mind, this product was developed for aesthetics. The holes can be much larger and still maintain strength and rigidity. So the cast of the future could be mostly holes, making it very light and shower compatible. Many people might be willing to pay a little more for this convenience.

Note: Ignore the LIPUS ultrasound units that can be incorporated into the one in the article. This is still unproven technology and I don’t recommend it.

Reference / photo credit: A’Design Award Competition

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