No really, snakes can hurt you after they’re dead

Even though we have all (hopefully) been taught that dead snakes can still envenomate people, apparently it hasn’t been reported much in the literature. I say this because this case report is in press as of 18 Nov 2016.
Southern Copperhead
In this instance a young man killed a copperhead by cutting it into three pieces. While holding the piece containing the snake’s head, “his right index finger brushed against the fang and was inadvertently punctured.” I’m sure all of us think that is exactly how this happened. Pain and swelling followed, so the patient went to his local hospital where he received 4 vials of antivenom.
There was further progression of the swelling and ecchymosis, so another 4 vials were administered. The patient was then transferred to a tertiary center “with concern for compartment syndrome of his hand.” Another 2 vials were given and the hand was elevated, and no operative intervention was done. Of note, his labs showed he did not have a bleeding diathesis, but readers of this blog already knew that.
I wish I didn’t have to say it, but sadly some people out there still believe that fasciotomies are required after snake bites. Truthfully, based on the evidence, the best treatment is antivenom and elevation, not surgeries that can cause complications and haven’t been shown to give benefit.
This paper does note that there have been multiple case reports of envenomations by dead rattlesnakes or rattlesnake heads. One even had been freeze-dried, bought at a gift shop, and used as a tie tack. Almost all of those required antivenom. This is an interesting thought, as recently deceased snakes likely retain the ability for the venom gland to contract reflexively. Envenomation from a freeze-dried snake has to be retained protein on the fang itself, as the ducts aren’t functioning anymore. This particular episode is the first documented case involving a copperhead that required antivenom.
So it is more than just an old wives tale. Dead snakes can still evenomate you, even if they’ve been dead for quite a while. So stay away from the pointy ends of snakes, and stop killing them for crying out loud.

Clinically Significant Envenomation From Postmortem Copperhead (Agkistrodon contortrix)
http://www.wemjournal.org/article/S1080-6032(16)30225-3/abstract

So maybe you can use that for a wilderness airway

We’re going to have to talk about the improvised wilderness airway. Caveat: this post is not exactly evidence based. It’s literally an anecdote. But an amazingly good and peer-reviewed anecdote at that. And there is a smattering of evidence thrown in at the end. Typical wilderness airway tool

The case report starts like this: Three firefighters were climbing as part of a team in California when they saw a man falling ~1500ft down a rocky slope. They descended to offer help, and when they got there they removed his helmet, checked ABCs, and maintained his C-spine. Neurologically he was unresponsive. Two emergency doctors with a separate climbing team arrived 15 minutes later. By this time his respirations were irregular and they noted significant facial trauma. Due to gurgling respirations, they decided to perform a cricothyrotomy.

All the physicians had for supplies were climbing equipment and a small first aid kid. They used a pocket knife to make the incision (vertical first, then horizontal), and tubing from a hydration pack as a makeshift ETT. Suture from the first aid kit was used to secure the tube. Since respirations were spontaneous, they did not perform positive pressure ventilations initually.

His pelvis was bound with a pair of pants, and extra clothes were used to prevent hypothermia. After 30 minutes though, his respirations became irregular again. Blood was noted in the tube, so the team decided to create a makeshift positive pressure bag using the rest of the hydration pack. One of the team would blow into hydration bladder to inflate it, and close it off using pliers as a valve of sorts. They would then deliver breaths by squeezing the bladder, similar to commercial products. They used this for another 30 minutes successfully.

Helicopter transport eventually was able to evacuate the man, and it turns out that a 6.5 ETT adapter fit into the makeshift tube easily. A bougie did confirm airway placement, and etCO2 readings were monitored. Unfortunately the patient went into V fib, got ROSC, then went into it again shortly after. The patient never regained pulses after that, and was pronounced dead prior to landing at the hospital.

The most important point of this case report isn’t the cool factor of Macgyvering other equipment into functional airway tools. It’s making the hard decision to perform the cric in the first place. Making that call, even in a low resource setting, is critical. Sadly this patient didn’t survive the injury, but it wasn’t due to lack of an airway. The fact that these physicians were able to also devise and then produce something that gives some form of PEEP is icing on the cake. However, it would be nice if someone took this device and measured what kind of pressures they could obtain with it.

And remember, if you’re going to perform a makeshift cricothyrotomy as your wilderness airway, make sure to use something of proper diameter. Ballpoint pens have too much resistance, but sports bottle and hydration bladder straws will work in a pinch.

Improvised Cricothyrotomy on a Mountain Using Hiking Gear
http://www.wemjournal.org/article/S1080-6032(16)30208-3/abstract

SteriPEN, convenient or worthless?


Clean water is of utmost importance, whether you’re backcountry hiking, camping, or travelling abroad. And there are many ways to disinfect water, including chemical tablets, mechanical filters, simply boiling, and ultraviolet light. And while we know that UV light from the sun works with enough contact time, does a handheld UV light work well enough to be safe?

They’ve been around since the late 90s, but decreases in size and cost have made them more popular recently. They are lighter than ceramic filters, don’t require heating and then cooling the water, and they don’t leave a funky taste in the water after use. And while you can go to SteriPENs’s website and see a bunch of articles they sponsored showing how awesome they are, it’s nice that an independent group has finally looked into their effectiveness.

One of the things the article points out is that UV light is bacteriostatic, not bacteriocidal. Their DNA is damaged, so they can’t reproduce or cause infection (probably), but the water is disinfected, not sterile. Also, while still effectively treated by UV light, viruses and spores require much higher doses to be inactivated.

They tested the function against of the SteriPEN against water bottles contaminated with Escherichia coli, Staphylococcus aureus, and the spore of Geobacillus stearothermophilus. Using 1 L bottles in 3 different styles (wide mouth reusable, narrow mouth reusable, and disposable narrow mouth bottles), they either agitated as per the instructions for the device, or let the water remain calm. For wide mouth containers, you can stir. With narrow mouth bottles, you need to plug the mouth with the pen and invert and shake. However, knowing that many people don’t do this, they also did a test by simply stirring the narrow mouth bottle as well. They also measured the spectrum emitted by the device during use.

Used correctly the SteriPEN works pretty well. Bacteria counts were reduced more than 99.99%, but spores were only reduced 99.57% on average. If you don’t agitate the water, this drops to 94.2% on average. The SteriPEN does emit its maximal intensity of UV at 254nm, which is the most efficient wavelength for bacterial DNA. And in a bottle made of glass, PET, or metal, there’s no risk of UV injury to the user, as it’s all blocked. However, in a big open-topped pot, there’s a risk of UV emission that could be hazardous to the eyes. Thankfully, the device won’t turn on if not immersed in water.

Therefore it is ok to use a SteriPEN to disinfect your water, as long as you’re doing it right. You’ve got to agitate the water, not just put it in and let it sit there. These authors also didn’t test against viruses, but the manufacturer does have data, and since this paper replicates some of their other results, it’s not unreasonable to state that it likely works against those as well.

Downsides are a few. 4 AA batteries only gives you 100 cycles and the bulb is pretty fragile, so pack extras. It doesn’t filter out toxins, and turbid water decreases efficacy, so you might night a filter anyway. This particular device has 2 settings, 90s of light for 1L containers, 48s for 0.5L ones, so you’ll need to make sure you have it set for the correct size as well. Finally, it doesn’t keep the water disinfected forever, so be aware that the water can become contaminated again and require re-treatment.

Drinking water treatment with ultraviolet light for travelers – Evaluation of a mobile lightweight system
http://www.travelmedicinejournal.com/article/S1477-8939(15)00174-X/abstract
And it’s FOAMed!

Dislocations? Put your shoulder into it!

Shoulder dislocations. Few procedures are more fulfilling in the emergency department. A little intra-articular lidocaine, some ketamine (always the answer), some propofol, and you’ve nearly instantaneously fixed a painful condition. Thankfully we’ve moved on from the barbaric techniques pictured below.

But this blog isn’t about reducing a shoulder in the emergency department using procedural sedation. It’s about the wilderness. So what are you supposed to do when it happens to someone on your trip, or heaven forbid, yourself? Between skiing, climbing, kayaking, mountain biking, and Pokemon Go, there are lots of activities that can result in shoulder dislocations at a scene distant from advanced medical care.

There are a few options other than openly cursing. At least one doesn’t have a name yet, and another is the Davos Technique, which was brought to my attention by none other than Tim Horeczko (@EMtogether). There are more, but I’m only going to talk about these two today.

First is the sin nombre technique, which I will refer to as the German technique after the location of the authors. It involves the following steps:

1.The practitioner holds the patient’s wrist with the left hand (in the case of a left shoulder dislocation) and the patient’s elbow with the right hand.
2.With the elbow in 90° of flexion, the glenohumeral joint is flexed forward to 90°.
3.While still in flexion, the glenohumeral joint is adducted until the elbow reaches the midline of the body; it is important to continue this movement until this landmark is completely reached.
4.Then, internal rotation of the shoulder is performed. During this step, the patient’s elbow must stay at the landmark described above. At 25° to 30° of rotation, a mild resistance is usually encountered.
5.The last step of the maneuver consists of applying a constant internal rotation pressure to overcome this mild resistance without pain. Reduction is usually achieved at approximately 30° of internal rotation.

For the visual learners, it is demonstrated in the video below.


The authors published their paper after a 50 month prospective observational trial that enrolled 39 patients older than 16. Of note, no pre-reduction xrays were performed, diagnosis was made clinically by deformation, pain, and decreased range of motion. All reductions were made without sedation, analgesia, or anesthesia, including alcohol.
Of the 39 dislocations, reduction was 95% successful on first attempt, and success was 100% on the second attempt on the 2 that failed the first. Mean dislocation time was nearly 4 hours, and reduction time was 6 minutes. Pain on a visual analog scale was low, and at least according to their followups, there was no need for surgery after reduction, nor were there any complications.
100% success without medications puts this at the top of list of possible techniques, tied with scapular manipulation. The downside to this technique (and many others) as far as wilderness medicine goes is that it pretty much requires a second participant. The arm movements would be nearly impossible to perform on yourself.

The Davos Technique is pretty trendy, as it just came out in JEM. However, it has been around awhile first described in 1993 by Boss, Holzach, and Matter. They worked at Davos Hospital. Their reduction rate was 60%, and further descriptions of this maneuver had similar rates. It is performed by following these steps:

The patient is sitting on his bed holding his injured extremity with his other hand. He is asked to flex his ipsilateral knee as much as possible and, with a little help, he passes both hands in front of the flexed knee. The hands are then tied together using an elastic band, preferably at the level of the wrist joint and not at the fingers, as this way the patient doesn’t have to concentrate on keeping the fingers crossed, and thus, can be more relaxed. Another important point is that the elbows should be kept close to the thigh, as this way the shoulders can be more relaxed. The two wrists can either be tied on the proximal tibia or simply held in place by whoever is treating the patient. At that point the physician can sit on the patient’s foot and instruct the patient to lean his head back, let his shoulders roll forward, extending the arms and relaxing all the muscles. By extending the neck, the patient exerts a constant traction on the injured shoulder and the dislocation is reduced without any need for additional maneuvers on the physician’s part. Once the shoulder is reduced, it is immobilized in a sling, and postreduction x-ray studies can be obtained.

Or, again, watch the video.


This paper retrospectively evaluated 100 patients with shoulder dislocations who had the Davos Technique performed on them over a period of 18 months. 82% of them had received analgesia prior to reduction, with morphine given nearly 40% of the time. Reduction was only successful in 86 patients, and they don’t list the number of attempts of the Davos Technique. 4 of them were reduced using a different technique, and the last 10 went under general anesthesia.
However, 8 of the 14 failures had psychiatric problems or dementia, and for a technique that requires patient effort, this could drastically decrease success rate. Of note, the 18 patients who didn’t get pain medications were all successful with Davos. Their complication rate was zero, just as with the German technique. It seems that this could be successful as an auto-reduction by interlocking your fingers, but some people may not have the strength to keep their hands together. The new authors recommend against it specifically. If you use the band, it again requires a second participant. I can’t read in German, so if anyone wants to pull the original Boss et al paper, let me know what their thoughts were on the matter.
In the end, it looks like both techniques are suited for wilderness reduction of shoulder dislocations because they are well tolerated, have minimal apparent complications, and don’t require the use of medications.

You’ll note that I recommend either of these techniques over the Riggs method, demonstrated below.


And should you think this will never happen, think again.

Reduction of Acute Shoulder Dislocations in a Remote Environment: A Prospective Multicenter Observational Study.
http://www.ncbi.nlm.nih.gov/pubmed/25823603
Also available as FOAMed!
http://www.wemjournal.org/article/S1080-6032(15)00006-X/fulltext
Reducing a Shoulder Dislocation Without Sweating. The Davos Technique and its Results. Evaluation of a Nontraumatic, Safe, and Simple Technique for Reducing Anterior Shoulder Dislocations.
http://www.ncbi.nlm.nih.gov/pubmed/26899512

Komodo dragons: Myth vs Reality

The Komodo dragon is a creature that inspires fear and mysticism in many. It’s got all the characteristics of a good monster movie: only found on rare tropical islands, large, and possessing magical saliva that can kill. First identified by the west in 1910 by Dutch sailors, they reported the lizards could spit fire and reached 7m in length. In reality the lizard can only get up to 3m and can weigh 70kg, and none have been identified as either breathing or spitting fire.

Komodo dragon (Varanus komodoensis), Komodo National Park, Indonesia

This review comes after a zoo worker was bitten on the hand by a small Komodo dragon. She had transient hypotension, and a retained tooth on xray. This was not removed, and after loose approximation (Ed. note: never do this), she was discharged on antibiotics. Thankfully the tooth came out on its own, and she did not develop a deep space infection. After this case report, the authors decided to do a literature review, knowing that it would help them get published.

Many of us are taught in school that Komodo dragon saliva is a possibly venomous, potentially fatal concoction of particularly virulent bacteria, including E. Coli, Staphylococcus, Streptococcus, and Pasteurella. These bacteria live in the rotting flesh that they leave in their mouth. But what is that based on?

It turns out, not much. The “facts” we have in textbooks, zoos, and medical literature are based on one guy’s book written in 1981. While Walter Auffenberg was the Jane Goodall of Komodo dragons, moving to the island and studying them in their natural habitat, his results haven’t been widely reproducible. And, more importantly, komodos don’t carry rotting flesh in their mouth. They fastidiously clean their teeth and gums. Now, perhaps the water buffalo does die of sepsis after being bitten, but if it does, it’s because it runs into murky water with fresh wounds, and not from bacteria in the mouth of the lizard. So, the “bacteria as venom” concept is just as dead in the water as the buffaloes.

So what about the venom aspect? The author of that study (Fry) was able to identify glands in the lower jaw that could potentially be venom glands. Furthermore, the extract of those glands does in fact contain proteins that inhibit blood clotting similar to snake venom. However, there isn’t any evidence that the venom actually affects the prey or is secreted in any significant amount during bites. The teeth lack venom grooves present in every other venomous animal (including the shrew). On the plus side, the author did come up with the “grip, rip, and drip” model of lethality from komodos.

Then why do animals die after being bitten by a large, reptilian predator? For the same reasons they die after being bitten by any large animal. Direct trauma, blood loss, and hypovolemic shock (and by eating).

Our findings are also in accord with the view that the killing technique of V. komodoensis is broadly similar to that of some sharks and Smilodon fatalis (saber cat). Despite obvious anatomical differences, these unrelated predators kill or are thought to have killed (respectively) large prey by using relatively weak bite forces amplified by sharp teeth and postcranial input.

They have strong neck muscles and serrated teeth, so after they bite they pull away, tearing holes in the prey that then bleeds to death. Is it possible that venom can increase this bleeding? Sure, but it’s also possible that it doesn’t.

So then why did this patient become hypotensive? Likely a vasovagal response. And given that the bite was on the hand, it’s appropriate to put the patient on antibiotics. But maybe we can finally stop propagating the magical thinking associated with komodo dragons.

Bitten by a Dragon
http://www.wemjournal.org/article/S1080-6032(16)00100-9/abstract

Further enjoyable reading
National Geographic
http://phenomena.nationalgeographic.com/2013/06/27/the-myth-of-the-komodo-dragons-dirty-mouth/
A central role for venom in predation by Varanus komodoensis (Komodo Dragon) and the extinct giant Varanus (Megalania) priscus
http://www.pnas.org/content/106/22/8969.full

Don’t use compression-only CPR for drowning victims

Vasily Perov: The drowned, 1867

Compression-only CPR has improved bystander participation and patient survival for OOCA. Advertisements on television and in print media have done a good job of increasing layperson awareness of this modality. And for many patients, it’s the right thing to do. But only if the etiology of their cardiac arrest is cardiac in nature. As is explained in this short little “article in press” that’s actually a letter to the editor, this can ignore the true cause of arrest in drowning victims and decrease their chance of survival.

In drowning victims, it’s primarily respiratory in nature, and they absolutely need ventilations. But how many of the ads for CCPR are that nuanced? I certainly haven’t seen any, and I would imagine many of the rest of you haven’t either. The major societies (ECR and AHA) are certainly aware of it, as their guidelines strongly urge proper use of respiratory support.

European Resuscitation Council Guidelines for Resuscitation 2015. Section 2 and 4.

“Most cardiac arrests of non-cardiac origin have respiratory causes, such as drowning (among them many children) and asphyxia. Rescue breaths as well as chest compressions are critical for successful resuscitation of these victims.”

“Most drowning victims will have sustained cardiac arrest secondary to hypoxia. In these patients, compression-only CPR is likely to be ineffective and should be avoided.”

American Heart Association (AHA) 2010

“CPR for drowning victims should use the traditional A-B-C approach in view of the hypoxic nature of the arrest”

“The first and most important treatment of the drowning victim is the immediate provision of ventilation.”

And since preventable drowning deaths can be due to improperly or not-at-all performed bystander CPR, this gap between the guidelines and the layperson needs to be closed by education. Anticipatory guidance for parents with pools, people who take part in watersports, and lifeguards can help, but really there needs to be a public campaign for CPR for drowning that’s similar to that of cardiac arrest of coronary artery disease. Specifically, any instructional materials need to address the dreaded mouth foam that can appear during resuscitation, as this is a major deterrent for anyone performing mouth to mouth.

So yeah, maybe we can dial back on the CCPR a bit, and focus on getting patients the best care available specific to their process.

A call for the proper action on drowning resuscitation
http://www.resuscitationjournal.com/article/S0300-9572(16)30043-0/fulltext

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.

About that New Year’s resolution

Many of us make New Year’s resolutions. And we’ve done it for a long time, with resolutions having been recorded since the time of the Babylonians. And while some of them involve repaying old debts, most are attempts at bettering ourselves (losing weight, blogging more often, quitting smoking, etc).

As medical professionals, we all see the people who set out to become more healthy magically on Jan 1, and often we tell them that moderation is the key. We don’t want people to set goals too lofty that they then cannot meet, causing setbacks or ultimately failures. People shouldn’t expect 1 trip to the gym, or even 1 month to see hugely measurable goals. If you want 1 excursion to make that much of a difference, it has to be of the sort in this case report of a nearly 4 month-long backpacking trip. That is, the nearly ludicrous type.

Of course, the study participant (and investigator, natch) wasn’t a couch potato before his trip. He was an experienced backpacker, at 49. However, he wasn’t an elite athlete either, having a BMI of 29.37 before the trip. He also had Stage I hypertension at 132/98.

True to a resolution, he started out on the Appalachian Trail on Jan 3, finishing on May 1. In total, he hiked from Georgia to New Hampshire, completing 2669km. Anyone who has hiked part or all the AT knows that this is not an insignificant amount of work, even if he wasn’t quite Scott Jurek. In doing so, he lost only 11kg, totaling 13% TBW. However, he went from 25% body fat to 14.3% based on hydrostatic weighing, or 23.8% to 11.6% based on skinfold measuring. These were 43 and 51% changes, respectively. His BMI went down to 25.46, and all of his waist measurements also improved by a fair amount. He even improved his blood pressure to normal (124/78).

This all happened without changing the diet to a large degree. The total amount of calories was remarkably similar at the nearly halfway point as it was pre hike, and at the 100 day mark the hiker was gorging on a resupply visit, consuming nearly 15% more calories. More remarkable was that a diet containing nearly 50% of the calories from fat (at times) still resulted in significant improvement in all lipid levels, including triglycerides, HDL, LDL, and total cholesterol.

So there you have it. All you have to tell your patients (or do yourself), is walk almost 23km per day. In the woods. With snow and rain. Add in another 120km of elevation change (give or take)* over the entirety of the trip and you’ve got a pretty good understanding of the difficulty of pulling this off.

A Long-Duration (118-day) Backpacking Trip (2669 km) Normalizes Lipids Without Medication: A Case Study
http://www.ncbi.nlm.nih.gov/pubmed/20030443

*Based on total distance is 76% of the entire AT, and 120km is 76% of the total elevation change of 156km.

Animals attacks aren’t really that bad, after all

At least, not according to the CDC WONDER database. When you take 9 years of data from said database, you get a whopping 1802 deaths. That comes out to just a hair over 200 deaths per year. Now, the article says they used ICD-10 codes W53-59 and X20-29 as their inclusion criteria, so take from that what you will.

Of the 1802 deaths, 1088 (60%) were from nonvenomous species, and specifically, 655 (36% of the total) were from farm animals. Thus, farm animals account for nearly as many deaths as venomous animals. Guess which one we spend more time on with teaching. When’s the last time you saw a board question that involved cattle?

The authors also break down the statistics by gender, race, age, and regional geography. The gender and race of the most commonly injured shouldn’t surprise anyone (white, male), but the ages might. We are taught that often it is young, intoxicated men are on the receiving end of most bites, but this data shows the overwhelming majority of those killed are >35 years old. The only group with more deaths at a young age(<9) is those killed by dogs, sadly. Children under 9 make up 46% of dog related deaths, despite making up only 10% of the total deaths.

Now, the question is, is this an example of the problems with ICD-10, or just a problem with reporting in general? Clearly more than 200 people are killed per year by animals, so how do we accurately assess the true risks? Based on this data we should put as much emphasis on agricultural education as we do on venomous species. Now, a significant majority of the farm animal injuries occur in rural areas, but so do most of the venomous animal injuries that don’t involve hymenoptera (~28% of the total). And yet we clearly devote a larger proportion of our teaching towards exotic, venomous animals. This even differs from the perceived over-emphasis on critical care, as knowing the exact thing to do in a time stressed situation can have a mortality benefit. Rarely is that true in the case of a venomous species, apart from anaphylaxis.

As the authors propose, we should as a specialty spend more effort on teaching agricultural safety as well as dog safety in homes with children. We already do a fair amount of teaching and community outreach with regards to anaphylaxis and hymenoptera, which is another significant cause of mortality. However, we could always do more with regards to preventable deaths.

Fatalities from venomous and nonvenomous animals in the United States (1999-2007)
http://www.ncbi.nlm.nih.gov/pubmed/22656661

You can overdo heat stroke treatment

Heat stroke can kill. This isn’t debatable. And mortality is linked to duration of hyperthermia. Thus, prehospital treatment of heat stroke improves mortality. Due to this, many EMS agencies will start with cooling patients using low-tech methods such as ice packs and ice water laden towels or sheets. The problem with these methods is that many agencies do not have the ability to continuously monitor core temperatures.

This case report has an example of just such a problem. Their patient was found ataxic and confused during a 17km march in the mild climate of the Texas hill country. His rectal temperature was 42.3°C. They correctly undressed him and placed ice in the axillae and groin. He also got 1L of saline that was room temperature. The issue comes from the extended travel time to the hospital, at 34 minutes. No further temperatures were checked en route. When the patient arrived at the ED, his temperature was 38.1°C.

Now it gets weird. Not many of use would have much of a problem with that temperature, but the astute physician was concerned about afterdrop from rapid cooling. All of the ice was removed, and the patient was placed under a forced air warming blanked and received 43.0°C normal saline. Even with all of this, the temperature continued to drop, hitting a nadir of 36.0°C.

I know what you’re saying. The patient didn’t actually even become hypothermic. And true, we don’t know how cold the patient would have gotten if they had simply stopped cooling and not initiated active rewarming. But clearly if the transport time had been longer or they had failed to check the temperature early on, the patient could have developed a degree of hypothermia. Whether or not the patient would be harmed by this (at best) mild hypothermia is also undetermined.

Take home points should be that you should be continuously monitoring the core temperature of any patient, whether you’re cooling them or warming them, and also the endpoint at which you should cease active cooling is 38.9°C. They do offer a good point that in the absence of ability to measure temperatures, such as the austere or prehospital environments, use shivering as your endpoint or only do any measure for 15 minutes at a time.

Dangers of Prehospital Cooling: A Case Report of Afterdrop in a Patient with Exertional Heat Stroke
http://www.jem-journal.com/article/S0736-4679(15)00615-0/abstract