All posts by TheTraumaPro

Fracture Care Of The Future: Traditional Casts vs 3D-Printed Braces

I’ve been fascinated by 3D printing for at least a decade.  Here are some examples from previous posts:

Unfortunately, practical applications have been relatively limited in the field of trauma.  But a lot has been going on in the background. The trauma research group at Erasmus Medical Center in Rotterdam recently published a systematic review on very practical work using 3D printing to produce casts and splints.

Sounds like a very mundane problem to through high tech at, right? But for those of you who look after patients with fractures that have been casted, you know the problems that can arise. Casts can be too tight. They can be ill-fitting. The patient may have soft tissue injuries that require windows cut into the side of the cast. Additional technology such as electrical stimulators may be indicated to enhance healing.

The old-fashioned way of creating a plaster or fiberglass cast seems crude. It is shaped by hand using skill and a fair amount of guesswork. If it’s just a bit too tight, serious complications may occur. If windows are not cut properly, it can destabilize the entire cast.

The Rotterdam trauma research group performed a systematic review of 12 papers that have been published on the topic of 3D-printed casts used in the treatment of forearm fractures. The authors found that most currently use a technique called fused deposition modeling with a polylactic acid substrate.

Instead of relying on subjective skill and luck to shape the brace, the uninjured forearm is scanned with a 3D scanner. The data is fed to a computer aided design (CAD) workstation and a mirror image is created and further refined. Special features such as soft tissue windows or entry points for bone stimulators can be designed into the brace at that time. Because the strength of polycarbonate exceeds that of plaster and fiberglass, it is possible to create a design with a great deal of open area so the underlying skin can be monitored. And allowances can be made for areas with swelling not present on the control extremity.

The data is then fed to a 3D printer to actually create the cast. Here’s an example:

This design is stronger that a traditional cast, is cool and comfortable, and avoids problems with hidden tissue injury or unrecognized foreign objects dropping into the cast creating major problems.

The use of 3D-printed casts and braces is relatively new and is used in only a few centers. For this reason, we do not have enough numbers to show that it is equivalent to traditional casting. Yet. But as the price continues to drop and use becomes more widespread, it’s only a matter of time before you start seeing these items in your own trauma center.

Reference: Personalize d 3D-printed forearm braces as an alternative for a traditional plaster cast or splint; A systematic review. Injury, in press, July 29, 2022. https://doi.org/10.1016/j.injury.2022.07.020

Whaaat? Stuff You Sterilize Other Stuff With May Not Be Sterile??

When one works in the trauma field, or medicine in general, we deal with the need for sterility all the time. We use equipment and devices that are sterile, and we administer drugs and fluids that are sterile. In surgery, we create sterile fields in which to use this sterile stuff.

In the past few years, we’ve come to the realization that the sterility we take for granted may not always be the case. There have been several cases of contaminated implanted hardware. And a few years ago, supposedly sterile injectable steroids were found to be contaminated with fungus, leading to several fatal cases of meningitis.

An article in the New England Journal of Medicine brings a bizarre problem to light: microbial stowaways in the topical products we use to sterilize things. Most drugs and infused fluids are prepared under sterile conditions. However, due to the antimicrobial activity of topical antiseptics, there is no requirement in the US that they be prepared in this way.

A number of cases of contamination have been reported over the years:

  • Iodophor – contamination with Burkholderia and Pseudomonas occurred during manufacture, leading to dialysis catheter infection and peritonitis
  • Chlorhexidine – contaminated with Serratia, Burkholderia and Ralstonia by end users, leading to wound infections, catheter infections, and death
  • Benzalkonium chloride – contaminated with Burkholderia and Mycobacteria by end users, causing septic arthritis and injection site infections

Bottom line: Nothing is sacred! This problem is scarier than you think, because our most basic assumptions about these products makes it nearly impossible for us to consider them when tracking down infection sources. Furthermore, they are so uncommon that they frequently may go undetected. The one telltale sign is the presence of infection from weird bacteria. If you encounter these bugs, consider this uncommon cause. Regulatory agencies need to get on this and mandate better manufacturing practices for topical antiseptics.

Reference: Microbial stowaways in topical antiseptic products. NEJM 367:2170-2173, Dec 6 2012.

Flash Pulmonary Edema After Chest Tube Insertion

You are seeing a young man in the emergency department who gives a history of falling two days ago. He experienced chest pain at the time which has persisted, but he did not immediately seek medical care. He has noticed that he now gets winded when walking quickly or climbing stairs, and describes pleuritic chest pain.

He presents to your emergency room and on exam has a bruise over his left lateral chest wall. Subcutaneous emphysema is present, and breath sounds are absent. Chest x-ray shows a complete pneumothorax on the left.

You carefully prepare and insert a chest tube in the usual position. A significant rush of air occurs, which tapers off over 15 seconds. Here is the followup image:

About 10 minutes later you are called to his room because he is complaining of dyspnea and his oxygen saturation has decreased to 86%. Breath sounds are somewhat decreased and the tube appears to be functioning properly. You immediately obtain another chest x-ray:

What just happened? This is a classic case of unilateral “flash” pulmonary edema after draining the chest cavity. This phenomenon was first described in 1853 in a patient who had just undergone thoracentesis. It is very uncommon, but seems to occur after rapid drainage of air or fluid from the chest cavity.

Here are some interesting factoids from case reports:

  • It occurs more often in young men
  • It is most common when draining large hemo- or pneumothoraces
  • Rapid drainage seems to increase the incidence
  • It is likely due to increased pulmonary capillary permeability from inflammatory mediators or changes in surfactant
  • Symptoms typically develop within an hour after drainage

What should you do? First, if you are draining a large collection of air or blood, do it slowly. Clamp the back end of the chest tube prior to insertion (you should always do this if you value your shoes) and use it to meter the amount of fluid or air released. I typically let out about 300cc of fluid, then wait a minute and repeat until all the blood has been drained. For air, vent it for 10 seconds, then wait a minute and repeat.

In patients at high risk for this condition, apply pulse oximetry and follow for about an hour. If they still look and feel great, nothing more need be done.

References:

  • Fulminant Unilateral Pulmonary Edema After Insertion of a Chest Tube. Dtsch Arztebl Int 105(50):878-881, 2008.
  • Reexpansion pulmonary edema after chest drainage for pneumothorax: A case report and literature overview. Respir Med Case Rep 14:10-12, 2015.
  • Re-expansion pulmonary edema following thoracentesis, Can Med Assn J 182(18):2000-2002, 2010.

Blame The Trauma Surgeon?

I just finished reading a recent paper published in the Journal of Trauma that purports to examine individual surgeon outcomes after trauma laparotomy. The paper was presented at AAST last year, and is authored by the esteemed trauma group at the University of Alabama at Birmingham. It was also recently discussed in the trauma literature review series that is emailed to members of EAST regularly.

Everyone seems to be giving this paper a pass. I won’t be so easy on it. Let me provide some detail.

The authors observe that the mortality in patients presenting in shock that require emergent laparotomy averages more than 40%, and hasn’t changed significantly in at least 20 years. They also note that this mortality varies widely from 11-46%, and therefore “significant differences must exist at the level of the individual surgeon.” They go on to point out that damage control usage varies between individuals and trauma centers which could lead to the same conclusion.

So the authors designed a retrospective cohort study of results from their hospital to try to look at the impact of individual surgeon performance on survival.

Here are the factoids:

  • Over the 15 month study period, there were over 7,000 trauma activations and 252 emergent laparotomy for hemorrhage control
  • There were 13 different trauma surgeons and the number of laparotomies for each ranged from 7 to 31, with a median of 15
  • There were no differences in [crude, in my opinion] patient demographics, hemodynamics, or lab values preop
  • “Significant” differences in management and outcomes between surgeons were noted:
    • Median total OR time was significantly different, ranging from 120-197 minutes
    • Median operation time was also different, from 75-151 minutes across the cohort of surgeons
    • Some of the surgeons had a higher proportion of patients with ED LOS < 60 minutes and OR time < 120 minutes
    • Resuscitation with red cells and plasma varied “significantly” across the surgeons
  • Mortality rates “varied significantly” across surgeons at all time points (24-hour, and hospital stay)
  • There were no mortality differences based on surgeons’ volume of cases, age, or experience level

The authors acknowledged several limitations, included the study’s retrospective and single-center nature, the limited number of patients, and its limited scope. Yet despite this, they concluded that the study “suggests that differences between individual surgeons appear to affect patient care.” They urge surgeons to openly and honestly evaluated ourselves. And of course, they recommend a large, prospective, multicenter study to further develop this idea.

Bottom line: This study is an example of a good idea gone astray. Although the authors tried to find a way to stratify patient injury (using ISS and individual AIS scores and presence of specific injuries) and intervention times (time in ED, time to OR, time in OR, op time), these variables just don’t cut it. They are just too crude. The ability to meaningfully compare these number across surgeons is also severely limited by low patient numbers. 

The authors found fancy statistical ways to demonstrate a significant difference. But upon closer inspection, many of these differences are not meaningful clinically. Here are some examples:

  • Intraoperative FFP ranged from 0-7 units between surgeons, with a p value of 0.03
  • Postoperative FFP ranged from 0-7 units, with a p value of 0.01
  • Intraoperative RBC usage was 0-6 units with the exception of one surgeon who used 15 in a case, resulting in a p value of 0.04

The claim that mortality rates varied significantly is difficult to understand. Overall p values were > 0.05, but they singled out one surgeon who had a significant difference from the rest in 22 of 25 mortality parameters listed. This surgeon also had the second highest patient volume, at 25.

The authors are claiming that they are able to detect significant variations in surgeon performance which impacts timing, resuscitation, and mortality. I don’t buy it! They believe that they are able to accurately standardize these patients using simple demographic and performance variables. Unfortunately, the variables selected are far too crude to accurately describe what is wrong inside the patient and what the surgeon will have to do to fix it.

Think about your last 10 trauma laparotomies where your patient was truly bleeding to death. How similar were they? Is there no difference between a patient with a mesenteric laceration with bleeding, an injury near the confluence of the superior mesenteric vessels, and a right hepatic vein injury? Of course there is. And this will definitely affect the parameters measured here and crude outcomes. Then add some unfavorable patient variables like obesity or previous laparotomy.

In my estimation, this paper completely misses the point because it’s not possible to retrospectively categorize all the possible variables impacting “surgeon performance.” This is particularly true of the patient variables that could not possibly be captured. The only way to do this right is to analyze each case as prospectively as possible, as close to the time of the procedure and as honestly as possible. And this is exactly what a good trauma M&M process does!

So forget the strained attempts at achieving statistical significance. Individual surgeon performance and variability will come to light at a proper morbidity and mortality conference, and should be evened out using the peer review and mentoring process. It’s not time to start blaming the surgeon!

Reference: It is time to look in the mirror: Individual surgeon outcomes after emergent trauma laparotomy. J Trauma 92(5):769-780, 2022.

By Request: Submental Intubation – The Video!

In my last post, I dusted off an old post that described a novel technique for providing a secure yet short-term airway tailored to patients who can’t have a tube in their mouth or nose. Patients undergoing multiple facial fracture repair are probably the best candidates for this procedure.

A picture may be worth a thousand words, but a video is even better. Please note that it is explicit and shows the blow by blow surgical procedure. Of note, it is a quick and relatively simple advanced airway technique. Note the cool music!

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