(The real reason) Why COPD patients get low-flow O2

nasalcannula_dummyWith 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.

Advertisements

Settling an Argument: Prehospital Limb Lead Placement

Early commercial ECG machine and electrodesIn 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.

Three reasons why you should get excited to be a prehospital provider

“Contentment is the refuge of the boring and the uninspired” -Ralph Waldo Emerson

Screen Shot 2014-10-30 at 9.19.06 AM

Dr. John Hinds responding. (via Twitter)

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.

LIT. ALERT–“EMS Spinal Precautions and the Use of the Long Backboard…”

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…

The importance of pre-hospital ECGs

The last issue of Prehospital Emergency Care (PEC) published a couple of articles about prehospital ECGs, including this one: A Prospective Evaluation of the Utility of the Prehospital 12-lead Electrocardiogram to Change Patient Management in the Emergency Department.  (If you have access to this journal or article, please let me know–I can’t find any way to access it, even after trying several hospital databases).

This article discusses how prehospital ECGs can capture clinically significant abnormalities that aren’t always found in the first ED ECG, and that these prehospital ECGs influence the physician’s treatment plan roughly 20% of the time.

Two questions came to mind after reading that abstract.  First, how good are paramedics at interpreting ECGs (specifically those that change the clinical course of a patient), and second, what about lead placement?

The first question is less pertinent to the article, but if the prehospital ECG is the deciding factor in a patient’s clinical course, paramedic providers should also recognize this sign.  A quick PubMed search, however, suggests that this might not always be the case.  An article from PEC last year concluded that, despite extensive training and a high level of confidence, ED physicians cannot rely solely on paramedic providers to activate the cath lab.  That stings a little bit.  But that’s a conversation for another time.

More concerning is if prehospital ECGs are truly capturing the “clinically significant” ECG abnormalities that influence physicians’ treatments.  One 2012 study looked at how the displacement of electrodes by one intercostal space can affect the ECG interpretation about 20% of the time. Another found that precordial lead displacement significantly affects ECG morphology; however, it did not extrapolate to clinical significance.  (This study also commented on the classic over-breast/under-breast dilemma faced with precordial lead placement! Skip to the discussion to see what they say).

Not only does lead placement affect the accuracy of the ECG, but lead displacement is common even in the hospital setting and when done by clinical ‘experts’ identifying correct sites for placement.

Perhaps then, we should put a little more consideration into our ECG skills and lead placement.  It’s easy slap some leads on in roughly the right places, but that really isn’t good enough.  So here’s some FOAM incase you (or your partner[s]) need a refresher on correct lead placement!

EMS 12-Lead’s Lead Placement Diagrams

LitFL’s Lead Positioning 

CPR Score Sheets

Clinical Scoring_Fotor

I’m working on a CPR improvement program for my agency.  The goal, more than anything else, is simply to practice skills we don’t perform very often.  More specifically though, we want to work on both the clinical aspects as well as the leadership and management aspects of running a resuscitation (you might be noticing a theme with some of my interests).

So another medic and I (you know who you are) have been working on the logistics of it.  It took a little bit of time and consideration, but using the High-Performance CPR Toolkit and a number of CPR leadership studies, we developed these score sheets to quantify, evaluate, and track the quality of simulations in our company.

Leadership Scoring_Fotor

My question to you is, do you have something similar at your company or training institution?  What do you think of the scales on the clinical sheet?  I feel as though those are hard to develop until you actually see a scenario or two.  Any feedback would be greatly appreciated.

*I found the tense discrepancies in the leadership scoring sheet and fixed it on the original

**the clinical evaluation includes QCPR data that allows us to look at compression depth, rate, etc.

Resuscitation Management Guidelines

As a new paramedic, I’ve spent a lot of time thinking about my new role as a leader and manager.  As myriad recent studies have shown, effective leadership during CPR events leads to better outcomes.  That’s to be expected.

My question is, can we create evidence-based resuscitation management guidelines that can be considered in all resuscitation events.

Using the Incident Command System as a point of inspiration, is there a process that prehospital providers can use to manage every call they take, from a nursing home fall to a traumatic code.  The goal is to have a mental checklist of sorts that is a formalization of the thought process that occurs fluently in experienced medical providers in order to create a structure that considers the steps for effective team-building.

With this as my springboard and using evidence-based medicine as my backboard, this is what I’ve come up with:

1) Pre-Plan— With very few exceptions, prehospital providers have some period of time in which they can preplan their approach to a call based on dispatch information.  This window of opportunity, even if only brief, is crucial for the provider moderating their own thought process and for communicating with their partner(s) about the way in which they want to handle the call.

One simulator-based study of physicians in CPR scenarios found that clinical outcomes are negatively affected by shortcomings in the process of ad-hoc team-building and deficits in leadership.  Establishing some sort of team unit, initiating a structure, and mentally preparing for the scenario ahead may be the largest luxury (regarding resuscitation management) afforded to pre-hospital providers responding to emergencies.

2) Establish Yourself as the Leader— This point encompasses a couple of points.  First of all, the lack of a defined leader  leads to poorer outcomes when there is any question of hierarchy during a resuscitation.  As noted in the above study, establishing a structure eases information flow, which is obviously crucial in resuscitation situations.

Having a clear leader on a scene also allows for structure to develop more fluently.  On any fire scene, everyone knows to look for the white helmet talking on the radio (he might even be wearing an “Incident Commander” vest if the scene is large enough).  On an EMS call, the paramedic patch on your arm might clue others in to the fact you’re in charge, but it’s never that simple.  Having a calm, confident presence and presenting yourself as the head-cheese-in-charge facilitates a more fluid resuscitation.

3) Assign Roles– The driving force behind these guidelines is, if you couldn’t guess, structure.  Structure primarily provides some semblance of comfort in chaos but also allows each member of the team to be effective.  When the leader of a resuscitation assigns roles or tasks, it leaves no doubt as to what each team-member should be doing, and (perhaps most importantly) it helps the leader focus on leading.

One of the most cited studies in the resuscitation management literature (that I’ve come across) is from a the European Resuscitation Council, which found that the absence of leadership behavior and explicit task distribution were associated with poor team performance (emphasis my own).

Another most-important piece of literature is the “Lighthouse Leadership” study, also from Resuscitation.  This paper found not only that building a structure in the resuscitation is essential to performing effectively but also that leaders were more effective when “hands-off.”  Those who do so can prioritize treatments, plan the resuscitation, and are more inclined to make changes when needed.  I won’t dwell on it much longer, but this may very well be the most important step in a well-lead resuscitation.

4) Verbalize and Continue Communication Again, it may sound like common sense and/or something that is already regularly done, but explicitly verbalizing treatment plans, exam findings, and changes in patient condition invariably leads to better outcomes.  A formally verbalized treatment plan/plan of attack prior to arrival on scene may be the closest thing pre-hospital providers have to the checklists and time-outs that have made such drastic improvements in the OR setting.  (I don’t have a citation for this one; just start reading everything Atul Gawande ever wrote).

As for continued communication, we all know about the closed-loop communication of the ACLS class room–and I think that certainly is important–but members of the team should not just be a confirmatory echo.  An interesting (but rather limited) simulator study found that unsolicited team-member contributions may prevent critical errors from occurring.  One example of this that comes to mind is the Resuscitation Academy’s suggestion that “EMTs Own CPR.”  This means that even the lowliest, greenest, most wet-behind-the-ears EMT-B should be able to point out that nobody is doing compressions, or that compressions are being performed poorly.  Obviously there are many issues inherent in individuals other than the leader speaking up in those situations, but the idea is to foster the environment where everyone is comfortable contributing to a successful patient outcome.

————————————————————————————————————

I would just like to emphasize again that these are my own musings as I work on becoming a more effective leader, and I welcome any comments/suggestions/ideas that you might have related to creating a framework that could be used for managing any given patient encounter.  Such guidelines could be used for training and teaching, which is a whole other (but important) topic of conversation.