Category Archives: gear

Is there anything a SAM splint can’t do?

Deciding what to carry in your medical kit on an expedition is hard. You don’t want to leave anything out, but you can’t carry an entire hospital on your back. I mean, the wheels on the slit lamp really suck at crossing rough terrain. So you have to decide what goes and what doesn’t. Thus the reason for much of the improvisation inherent in wilderness medicine. An item that only does one job had better be the only item that can do that job, or it is extra weight.

C collars are one of those items. Now, ignoring the fact that many of them aren’t good at their job to begin with, they really aren’t good for much else. Sure, you could maybe improvise a pressure dressing out of it, but what else are you going to do? And while some of them do lay flat, they’re still pretty long and take up space that could be used for something else.

Enter the SAM splint®*. Waterproof, moldable, and able to be cut to size, it can be used pretty much anywhere on the body. And everyone has seen the picture of one being used to immobilize the cervical spine. But does it work well in that role?

Improvised C Collar in Auckland

These authors put it to the test against a Philadelphia collar using 13 EM resident “volunteers”. I’m sure they were paid well for their time. Using a goniometer they measured maximal extension, rotation, and lateral flexion. They found that no statistically significant difference in any one measurement, but looking at the results the SAM does appear to allow slightly more rotation and extension, while doing a better job of limiting lateral flexion. This likely is due to the bulkiness of the SAM laterally.

While the method of measuring falls short of a radiographic gold standards, and the number of subjects is low (but powered to an 11° difference per the authors), it looks like the SAM splint, in fact, is just as good as a Philly collar at immobilizing the C spine. I am OK with it in an awake patient, but would add more reinforcement to an unconscious patient.

Comparison of a SAM Splint-Molded Cervical Collar with a Philadelphia Cervical Collar
http://www.ncbi.nlm.nih.gov/pubmed/19594206

*I’m using SAM splint to cover all the moldable splints out there, similar to how Xerox is used to cover all photocopiers. I do not receive any money from SAM Medical Products® for using their name here. You are welcome to use other splints, but this article only used the SAM.

Venom extraction kits. Seriously, just don’t.

I learned from a speaker at this years Wilderness Medical Society conference that while we as clinicians mostly know about venom extractors and why they don’t work, this hasn’t trickled down to the lay public unfortunately. All you have to do is look at their ratings on  their respective Wal-Mart pages for the Sawyer and Coghlan devices. Even more frightening, there are still some wilderness providers out there that use and recommend these devices.

Seriously though, this is one of those things in medicine that got started because it’s a good idea, made logical sense, had plenty of anecdotal evidence, and one apocryphal article that showed some success. Due to this, it was recommended by many agencies. This success was short-lived, as future research showed that it didn’t actually remove much venom, and might actually cause harm.

Based on the plurality of case reports that were all over the map, Sean Bush (of Venom ER fame), decided to study this using pig models. His was the first RCT looking at outcomes for this device. Because actual snake venom varies by each bite, they used a simulated model by injecting a standardized amount (25mg) of venom. Of note, this was because 50mg resulted in mortality, and as the pigs were used as their own control, they needed a non-lethal dose.

They of course found no difference in local tissue swelling using the extractor, and did have two instances of necrosis in the extractor group. Thus, based on their paper, no benefit, possible harm, so don’t use them.

Effects of a negative pressure venom extraction device (Extractor) on local tissue injury after artificial rattlesnake envenomation in a porcine model
http://www.ncbi.nlm.nih.gov/pubmed/11055564

This wasn’t enough for many people, as people clearly report seeing fluid in the pump after using it. It had to be doing something, so later a group from UCSF led by Michael Alberts set out to determine what actually is sucked out using the extractor. Deciding that pigs weren’t suitable for this, they instead injected a proteinaceous fluid tagged with radioactive technetium, as they would be able to measure exactly what was removed, and what was left. This was injected using a curved needle into people’s legs.

They of course succeeded in obtaining serosanguinous fluid into the pump. Even with applying the extraction device a scant 3 minutes post injection, as recommended by the instructions, when they put the counter on that fluid, they found it contained a whopping ~0.04% of the total load. Counting what was left in the body found that, on average, most people had ~98% of their venom load still present, with the maximum of 7% in one. Comically, the radioactive counts of the fluid that spontaneously “oozed” from the fluid actually measured higher than that in the extractor, with an average of 0.7%.

Thus, what it removes isn’t venom, it’s interstitial fluid.

Suction for Venomous Snakebite: A Study of “Mock Venom” Extraction in a Human Model
http://www.ncbi.nlm.nih.gov/pubmed/14747805

So really, just don’t do it. Tell everyone you can to get rid of the kit. It doesn’t help, and probably hurts, and will likely delay what medical treatments actually would do anything.
Also, feel free to review any website that sells this device. Write the editors of websites that offer medical advice (see here) and tell them to correct their errors. We have a duty to protect the public, and preventing them from buying harmful devices is included in this.

Necessity is the mother of tourniquet invention

A lot of wilderness medicine teaching is geared towards bringing the right tools for the circumstances, but sometimes you end up in a situation where you don’t have the best tool for the job. Thus,  quite a bit of preparing for austere environments is making improvised devices out of whatever is lying around.

This article discusses one of those macgyvered lifesaving tools. While there are many commercially available tourniquets out there, there are still times when you have to create one out of something else. As the article points out, you might simply run out of tourniquets at a mass casualty incident. When the situation arises that you have to create a tourniquet, what items should you use to make one?

The authors chose to test the band and windlass design. They mention that this was based on a paucity of non-military literature about various improvised tourniquets. The band was always cotton cloth folded into shape, and they tested 3 items common to the urban environment as windlasses. While pencils, chopsticks, and popsicle sticks might not exist in the wilderness, they’re a reasonable idea for testing. It’s not like you can ensure quality control with broken twigs.

Using a computerized above-the-knee amputation simulator, they then attempted to stop bleeding using the improvised tourniquet and one of the potential windlasses. If 1 pencil, popsicle stick, or chopstick was insufficient to stop bleeding (or broke), the test would be repeated with 2, 3, or 4 until 100% effectiveness was reached.

Granted, this study only looked at occluding arterial flow instead of venous, and had a very narrow scope of windlasses. In the end, the take-home message is as follows:

  • Popsicle sticks suck as windlasses, and you shouldn’t use them. They often broke on the first turn.
  • Pencils are better, but still pretty terrible.
  • Strangely enough, chopsticks work best of those tested.
  • 2, or better yet 3, is always better than 1 when it comes to windlasses
  • Maybe use something other than flimsy wood objects when you make an improvised windlass, such as plastic or metal
  • Use a commercial device if you can find one

Which Improvised Tourniquet Windlasses Work Well and Which Ones Won’t?
http://www.ncbi.nlm.nih.gov/pubmed/25771027

Femoral traction splints, helpful or not?

It’s been awhile since the FOAM twitter community got together and discussed the utility of femoral traction splints. Thus, forgive me for not remembering all the finer details of everyone’s points of view. The gist of that discussion was similar to many other twitter-based medical discussion. Many anecdotal accounts of benefits of an intervention (in this case, traction splints), vs the utter lack of data showing benefit. Knowing that absence of data does not equal absence of benefit, we all left likely doing the same thing we were doing before. And that discussion was mostly directed at commercial devices used in inter-facility transport or in-hospital use.

In wilderness medicine, the situation is even worse. Poor or completely nonexistent data, and even fewer premanufactured devices are available. Therefore, many “traction” splints are make-shift devices that are macgyvered out of available materials. After all, make-shift devices are the essence of austere medicine.

But do we need to be doing them at all, and more importantly, should we be teaching the next generation of wilderness medical professionals to do it ad infinitum? Let’s face it, the devices we concoct out of ski poles, webbing, carabiners, and the like, often aren’t very good at providing traction to begin with. They simply aren’t robust enough compared to commercial products. Not only that, but the usually involve some poor soul being left without a shirt, poles, a jacket, and maybe their backpack. If there’s real benefit to doing it, that’s a reasonable sacrifice. But if there isn’t, is it time to stop?

This article investigated the use of femoral traction splints by Mountain Rescue England and Wales, as well as did a literature review to see if there is any definitive data for or against the use of traction splints. The authors also surveyed rescue teams to assess their use and opinions of traction splints.

They found that suspected femur fractures were fairly uncommon in their cohort, occurring at a rate of less than 10 per year. This likely overestimates actual fractures by a decent margin as well. Of these, only 13% were treated with traction splints, 17% with non-traction splints, and a whopping 70%(!) without any splinting at all. This data flies in the face of what was reported by the responding rescuers. Fully 68% reported that they used a traction splint for every suspected femur fracture, and the other 32% said they selectively used them. Generally they felt the devices to be useful and not problematic in the survey as well. Then why aren’t they using them? This isn’t answered by this survey, but I bet a few medical directors out there would like to know why their medics are saying one thing, and doing another.

What did the literature say about traction splinting? Of the 141 they found using Boolean operators, only 5 were ultimately included in the review. The rest were historical, single case reports, too low level of evidence, or not pertaining to the issue at hand. And of those 5 (see references below), all were level of evidence 4. Shockingly, there aren’t a lot of double blinded RCTs on this topic.

Of those articles, they also found that splints were often applied to patients with contraindications, are rarely used, take up space, and don’t have much evidence for their benefit. Specifically, the often theorized benefits of pain reduction, bleeding, and nerve injury are not shown in any recent literature. There is a book from 1919 (Gray, H. The Early Treatment of War Wounds. H Frowde, Hodder and Stoughton, London; 1919) that argues a reduction of death from 80% to 15% for femoral gunshot injuries, but this can’t be used realistically today as evidence.There is a teaser at the end of the article though. Susanne Spano at UCSF-Fresno presented a poster at SAEM with some good data that showed no statistical difference in mortality or complications of actual femur fractures treated with either traction splinting or no traction splinting.

The main problem in prehospital or wilderness care is that the person with the femur fracture also needs extraction. Traction splints interfere with many litters, are by design only useable for 1 type of injury, and require a significant amount of highly specific training. In the end, I’m not saying that traction splinting isn’t without benefits. In the pre-hospital or austere setting, these benefits are much smaller and have a higher risk associated as well. And certainly I don’t advocate not immobilizing the limb, as this clearly has benefit. But creating a make-shift splint needs to stop being taught as the best or only way to treat femur injuries. And simple splinting should be used until we have clear data showing a benefit to traction splinting.

Femoral Traction Splints in Mountain Rescue Prehospital Care: To Use or Not to Use? That Is the Question
http://www.wemjournal.org/article/S1080-6032(15)00075-7/abstract

Referenced Articles

Agrawal, Y., Karwa, J., Shah, N., and Clayson, A. Traction splint: to use or not to use. J Perioper Pract. 2009; 19: 295–298
Wood, S.P., Vrahas, M., and Wedel, S.K. Femur fracture immobilization with traction splints in multisystem trauma patients. Prehosp Emerg Care. 2003; 7: 241–243
Abarbanell, N.R. Prehospital midthigh trauma and traction splint use: recommendations for treatment protocols. Am J Emerg Med. 2001; 19: 137–140
Bledsoe, B. and Barnes, D. Traction splints: an EMS relic?. JEMS. 2004; 29: 64–69
Ellerton, J., Tomazin, I., Brugger, H., and Paal, P. International Commission for Mountain Emergency Medicine. Immobilization and splinting in mountain rescue. High Alt Med Biol. 2009; 10: 337–342