It’s been a while, but PrehospitalFOAM is back after a brief(ish) hiatus. Med School applications had to take precedent, and luckily it was a successful endeavor, so now we can concentrate on finding good FOAM for those in the world of prehospital medicine!
With brand-new EMT students riding with me, I like to take a moment to explain why many of our “shortness of breath” patients are likely to receive a nasal canula instead of a NRB cranked to 15lpm. We talk about baroreceptors and chemoreceptors and the hypoxic drive and how they’re likely to see a question about COPD patients and oxygen administration somewhere along the line.
Turns out that’s all wrong.
LifeInTheFastLane sent an email with their most-viewed articles of 2015, and this one, Oxygen and CO2 Retention in COPD, was right at the top. And for a good reason.
The gist of it: increased O2 administration causes vasodilation of normally constricted vessels leading to poorly ventilated alveoli. This causes a V/Q mismatch. Also, the Haldane Effect.
The next time you have a student or are oxygenating a COPD patient, consider why, and get that hypoxic drive stuff out of your head.
In the prehospital setting, when you’re obligated to be both treating (mostly) fully-clothed patients and moving them through various public spaces, the logistics of the ECG are slightly more complicated than in the hospital setting.
Although the anatomical landmarks of the precordial leads are known and usually utilized by prehospital providers, there is significantly greater variation in the placement of the limb leads; whether driven by circumstance or preference, the limb leads (RA, RL, LA, LL) may be placed in a number of places ranging from the anterior chest wall and abdomen to distal wrists and ankles. BLS providers seeking to help their paramedic partner frequently ask their preference; however, there is a clinically correct answer.
The Question: Where should the limb leads be placed for a standard 12-lead?
The Short Answer: Limb leads should be placed on the limbs, distal to the shoulders and hips but not necessarily on the wrists and ankles.
The Long Answer: A 2007 article in Circulation outlines the AHA’s recommendations for standardization of the ECGs. The authors reference a 1975 statement released by the AHA that recommends limb lead placement “on the arms and legs distal to the shoulders and hips, and thus not necessarily on the wrists and ankles” as the leads had been placed traditionally. **Note– despite my best efforts, including a thorough search of the Circulation archives, I cannot find this original reference; the closest thing I can find is a 1967 recommendation on the standardization of ECGs, in there is no discussion of lead placement.**
The authors continue to explain that one study found variations in limb lead placement (on a given limb) can alter the ECG, specifically the amplitude and duration. They go on to explain that, because there isn’t great evidence surrounding the question, we don’t know if the differences are significant enough to alter diagnostic criteria.
Then there is the more important question of limb lead placement on the torso, which is also called the Mason-Likar lead position. (Lead positioning in this system has the arm electrodes placed in the infraclavicular fossae medial to the deltoid insertions with the left leg electrode placed midway between the costal margin and iliac crest in the left anterior axillary).
While the AHA acknowledges that rhythm diagnosis is not adversely affected by lead placement on the torso, tracings that use this position differ significantly from the standard 12-lead ECG. Specifically, “electrodes placed on the trunk do not provide standard limb leads, and distortion of the central terminal alters the augmented limb leads and the precordial leads.” Differences in QRS morphology and repolarization may then lead to false-negative and/or false-positive infarction criteria.
So despite the fact that placement on the torso may reduce artifact, “ECGs recorded with torso placement of the extremity electrodes cannot be considered equivalent to standard ECGs for all purposes and should not be used interchangeably with standard ECGs for serial comparison.”
The Takeaway: If, as a prehospital provider, you place your electrodes on the patient’s limbs distal to the shoulders and hips, your prehospital tracings can be considered a part of the serial-ECG monitoring of patients with ACS. The same is not true with torso limb lead placement.
BONUS QUESTION: Should precordial electrodes be placed above or underneath the breast of a large-breasted woman?
AHA Answer: Despite one study that said that “reproducibility of ECG measurements is slightly increased when electrodes are positioned on top of the breast,” the under-breast placement leads to more intuitive lead placement and would reduce amplitude attenuation caused by torso impedance. So, until further studies say otherwise, under-boob placement it is.
“Contentment is the refuge of the boring and the uninspired” -Ralph Waldo Emerson
Prehospital providers have always been particularly prone to complacency. Once the novelty of running code-3 wears off, routine transports and inglorious 911 responses threaten to demoralize providers and make them content with only the knowledge and skills needed for “the everyday.”
So let’s examine the extraordinary and apply it to the ordinary. Here are three incredible examples of prehospital FOAM that should get your blood flowing once again. Be inspired, share it with others, and bring your game face to each and every call
1) The First Prehospital REBOA— EMCrit chats with the first provider (registrar Jonny Price from London HEMS) to have performed a prehospital REBOA. What is REBOA? Essentially it inflates a balloon that occludes the aorta to stop bleeding at non-compressible points of hemorrhage. Why should you get excited? They did prehospitally what once only a full resuscitative thoracotomy and aortic clamp would. And a paramedic assisted with the procedure.
2) Making the Call— Again via EMCrit, Michael Lauria (@resuspadawan)–formerly of USAF Pararescue and then Dartmouth-Hitchcock Advanced Rescue Team (DART)–applies techniques and lessons learned during his time in the Special Forces to working as a prehospital provider. Why should you get excited? Mike speaks authoritatively on how providers can apply techniques used by Special Forces to improve their cognitive decision making under stress and keep a cool head in the inevitable cluster-call.
3) Motobike Mayhem— Dr. John Hinds (@DocJohnHinds) gives an incredible lecture outlining some of the traumatic injuries that result from high-speed motorcycle crashes. Listen to it and flip through the slides at the same time. No part of you will be disappointed. Why should you get excited? This team treats injuries similar to those that could be seen by any prehospital provider and have spectacular resuscitations. And it’s motobike EMS. Need I say more?
I recognize that not all of this is directly applicable to everyday-American-EMS, but that doesn’t mean that we discount it as irrelevant. All of these things are being done outside of the hospital by those who aren’t complacent with their everyday medicine. And I don’t see any reason why we can’t work our way there too.
**We’re back after an extended, biochem-organic-chem-induced hiatus!**
I’ve already extolled the virtues of Dr. Scott Weingart enough, but his latest post provides a one-stop-shop to learn the best and latest about cricothyrotomy. On this page, you’ll find a number of resources from how to make a cric trainer to an in-depth look at surgical airway anatomy. And, of course, Weingart’s SMACC lecture bringing it all together.
Feeling a little anxious about the thought of performing a prehospital cric? Stay on the EMCrit site to check out former Air Force PJ Mike Lauria’s (@resuspadawan) lecture on Acute Care Cognition. His lecture brings together a wealth of experience and study all geared towards critical-thinking and decision making in high-stress situations. (I’ll be doing a post soon about my own attempt at a lecture/workshop regarding Responder Conditioning).
The hope is that giving these resources a little more attention can bring the idea of actually performing cricothyrotomy back into the mind of paramedics. One of my current services does annual proficiencies, which requires medics to touch the cric-kit and go through the steps exactly once each year. Clearly that is not enough, and I would love to hear how other prehospital providers incorporate such training on low-frequency procedures into their practice.
Last year around this time, the National Association of EMS Physicians (NAEMSP) released a position statement on the prehospital use of the “long backboard” as an immobilization device. In their statement, the NAEMSP outlines the type of patients that should be immobilized with a backboard; however, they also outline who should not be immobilized AND they make a potentially game-changing statement:
-Spinal precautions can be maintained by application of a rigid cervical collar and securing the patient firmly to the EMS stretcher [emphasis added], and may be most appropriate for: patients who are found to be ambulatory on scene; patients who must be transported for a protracted time, particularly prior to interfacility transfer; patients for whom a backboard is not otherwise indicated.
That was a year ago. Last month they released a resource document providing more background and research supporting the position statement. In the article, they provide supporting evidence for each of the points in the position statement.
If you can get your hands on it, it’s actually a pretty good read; they start at the beginning with the 1966 report by Geisler et al. that attributed “delayed onset of paraplegia” in hospitalized patients with spinal fractures to the “failure to recognize the injury and protect the patient from the consequences of his unstable spine.” They touch on the study that took pain-free volunteers, strapped them to a backboard for an hour, and then had pain persisting for 24 hours afterwards, as well as the myriad studies showing just how rare unstable spinal fractures are (o.o1% of patients in one study had incomplete, unstable spinal injuries requiring operative fixation).
Finally, they get to the part that matters–what we can do differently. To summarize: they recommend selective spinal immobilization protocols, they recommend (for appropriate patients) using a cervical collar and the stretcher as spinal precautions, and they recommend considering protocols that allow providers to consider removing patients from backboards if appropriate. Very cool.
Some services have even started implementing these recommendations: the article mentions an Ohio fire department with protocols to transport with only a c-collar and stretcher as well as the State of Maryland, which recently changed its statewide protocols and will be eliminating the use of backboards for penetrating trauma.
As always, the change will be slow, but more supporting research is already on the way. Currently in the “Early Online” section of Prehospital Emergency Care is a study that looks at Spinal Motion Reduction training program, and I’m sure other studies are on the way.
For now we’ll just have to keep following protocols, but this seems like a decently obvious change to make. Are your systems taking steps in this direction? And is anyone aware of additional recent studies? This resource document may be the tipping point in taking more definitive action against the widespread use of backboards in the field, and I would encourage having that conversation with your peers and medical directors.
**RougeMedic did a post on the original position statement, which goes into details a little more than I do here. I also borrowed his picture…
In my quest to make a “pocket brain” to keep with me on the truck, I’ve been looking at any
pocket or student reference I can find. One medical student reference I stumbled across is from the University of Washington’s Alpha Omega Alpha Medical Honor Society, and they call it The Turkey Book. I have no idea why, but it’s pretty fantastic.
Medics and EMTs certainly don’t need to know about screening for cervical cancer; however, the internal medicine portion includes very useful information about electrolyte imbalances and acid-base balances, and the emergency medicine portion takes you into the mind of a ED physician conducting an exam AND provides a a cheat sheet for common ED presentations.
If sorting through the different sections and finding the most useful bits isn’t enough, a new App called AgileMD will let you download the whole thing for $20 in a nice digital format (LitFL just reviewed the app here, and the App website is here).
I highly recommend checking out this guide, even if you don’t incorporate it into your daily-reference-library; I’ll be putting the link under the Resources section as well, so you’ll always know how to find it!