Wide Complex Tachycardias

You are dispatched to the report of a sick case.  Upon arrival, you find a 52-year old male patient complaining of palpitations.  When pressed, he complains of very mild chest discomfort that he refuses to describe as “pain,” but is worth a two on the 0-10 scale. He has an irregular pulse rate of 130, a blood pressure of 116/70, and a respiratory rate of 16.  He is warm, pink, and dry and is completely awake and oriented with humor.

His ECG:

I started this post expecting to clear up misconceptions about the differentiation of wide complex tachycardias (WCTs).  I wanted to explain some of the main differentiation algorhythms with their reported sensitivity and specificity.  I was going to include algorhythms from Brugada (1), the American College of Cardiology (2), Verecki (3), and Griffith (4).  I’ve taught 12-lead ECG interpretation for more than 10 years, so this kind of topic is right in my wheelhouse.

I decided not to waste my time or your time.  The lesson is simpler than that: Prehospital and emergency differentiation of WCT is a waste of your time.

There are several issues with the differentiation of WCTs.  First, all of the algorhythms have low specificity.  Specificity is the percentage of cases that are negative for the condition and are found to be negative after applying the test – the true negative rate.  So, low specificity means that the test “pings” when the condition isn’t there.  Think of a radar detector in your windshield that alerts constantly, even when there is no speed trap.  Even the relatively higher sensitivity (true positive) ratings of the WCT algorhythms are only in the high 80% range.  That means you will get a false positive (read: be on the wrong path) about 10% of the time.

The second issue is that the algorhythms are complex - probably too complex for prehospital use, especially in front of a patient who needs your time and full attention.  For example, the ACC algorhythm has four main decisions, plus 13 morphology clues to remember.  How often will you practice using that?  A sub-point of this one is that most of the differentiation algorhythms involve precise measurements of R-wave to peak times, nadirs, and V_i/V_t ratios* that are difficult to measure accurately.

The third reason not to differentiate in the field is that there is no upside.  Every decision you make has a cost-benefit analysis, whether you overtly weigh the two sides or not.  The cost side doesn’t matter in this case because there is no upside to getting the differentiation right - the treatment (cardioversion or amiodarone) is the same for SVT and VT.  And you won’t look as cool as you think you will, like a paramedic Babe Ruth calling his shot.  Anyone that hears your ECG interpretation will assume that you just guessed right through chance, not skill.

The final reason is the most important: It does not matter! 

Cardioversion works for supraventricular tachycardia with aberrancy or with pre-existing bundle branch block.  Cardioversion works for ventricular tachycardia.  Amiodarone works for SVT.  Amiodarone works for ventricular tachycardia.  Adenosine can even convert ventricular tachycardia on occasion! (5)

Simplify!

Your decisions should revolve around whether or not the patient is stable or unstable.  Unstable patients get to ride the lightning – after a benzodiazepine, of course.  For me, the decision to cardiovert someone revolves around their level of responsiveness.  I am very hesitant to weld a patient who is awake, even with midazolam.  But other medics have a lower threshold and include chest pain as a sign of instability. 

If the patient is stable, your next decision is pretty much to think about adenosine, roll your eyes and skip the adenosine, and then start an amiodarone drip.  There are some decisions that revolve around whether the presenting rhythm is regular or irregular, but that decision is in the ACLS treatment algorhythm in order to avoid giving adenosine (or other AV node blockers) to atrial fibrillation with pre-excitation.  You can avoid those problems by just not giving adenosine.

The differentiation of WCTs can be a fun skill to have.  But you have to remember that it is a skill applied after you have dropped the patient off at the hospital.  It is a skill made for debating with your partner at the ED dock or in the front of a bus at post.  Not when you are in front of a patient. 

Instead of studying the ECG that your monitor just printed off, think about what else you could be doing.  Prioritize your actions.  The patient above, at the beginning of this post, has a pretty long list of required actions.  They include oxygen, IV access, possible blood draw, a complete physical exam, a complete history of the present illness, a complete health history, at least one 12-lead ECG, aspirin, consideration of nitrates, a phone call to the receiving hospital so that they are ready, considering/prepping an amiodarone infusion, repeat vital signs, constant monitoring, and extrication from wherever they are to the ambulance.  Pretty much all of those would take higher priority than ten minutes of studying a field ECG with a magnifying glass and a pair of calipers.

My heart-felt advice is to treat all wide complex tachycardias as wide complex tachycardias, rather than trying to differentiate whether it is a ventricular or supraventricular origin.

*V_i is the height/depth of the QRS after 40 milliseconds; V_t is the height/depth of the terminal 40 milliseconds.  Want to measure those while bouncing down the road, do you?

1. Brugada P, Brugada J, Mont L, Smeets J, Andries EW. A new approach to the differential diagnosis of a regular tachycardia with a wide QRS complex. Circulation. 1991; 83(5): 1649-1659.

2. Blomström-Lundqvist C, Scheinman MM, Aliot EM, Calkins H, Camm AJ, et al. ACC/AHA/ESC guidelines for the management of patients with supraventricular arrhythmias… J Am Coll Cardiol. 2003; 42(8): 1493-1531.

3. Vereckei A, Duray G, Szénási G, Altemose GT, Miller JM. Application of a new algorhythm in the differential diagnosis of wide QRS tachycardia. Eur Heart J. 2007; 28(5): 589-600.

4. Griffith MJ, Garratt CJ, Mounsey P, Camm AJ. Ventricular tachycardia as default diagnosis in broad complex tachycardia. Lancet. 1994; 343(8894): 386-388.
5. Marill KA, Wolfram S, Desouza IS, Nishijima DK, Kay D, Setnik GS, et al. Adenosine for wide-complex tachycardia: efficacy and safety. Crit Care Med. 2009; 37(9): 2512-2518.

The Power of Why

There are two big complaints from students and trainees that I hear fairly often.  The first is that their preceptor/trainers are inconsistent between each other.  One trainer says one thing and another says exactly the opposite.  The other complaint is that trainers are just plum mean – they seem to be trying to berate and belittle a student, rather than to teach them.  This happened to me, as well, until I figured out the answer.

When I started with my current employer, a part of the new hire academy was a day spent running scenarios at the SWAT team’s training house.  The house is a building that is made up to look like an apartment complex inside an old hangar.  The scenarios were fairly realistic, and were set up to give specific lessons that were important before your first day on the street.  All in all, it was a pretty fun day.  We no longer do it, but I was lucky enough to take part.

One of the scenarios was a narcotic overdose.  There was a bystander who was a friend of the victim who was mostly getting in the way.  Long story short, I pushed 0.5 milligrams of pretend Narcan and the preceptor said, “Nothing happened.”  Another half milligram: “Nothing happened.”  Another half milligram: “Okay, Greg, get him.”

Oh, damn.  Not words you want to hear.  The victim and bystander ganged up to put a whoopin’ into me.  I still have a faint scar on my arm.

The lesson from the scenario was to be able to make the right decision as to where to initiate treatment.  It was the lion cage theory: A lion tamer never enters the lion’s cage, where the cats eat and sleep.  The lion feels comfortable there and will eat the trainer.  Instead, the tamer moves the lion to the less familiar surroundings in the ring where the trainer is “at home” and more comfortable.  The lions are less comfortable and will perform the act.

A week or two later, when I was on the street working with a field trainer, I ran a narcotic overdose in an apartment.  I know! I know! Move him to the ambulance to wake him up!  It may have been the first thing on a call that I thought I knew the answer to.

After I voiced my move-to-the-ambulance plan, my field trainer said disgustedly, “What’s the matter with you?  Wake him up here!  Why would we move to the bus*?”  So I administered Narcan and woke the patient up in the apartment.  Huh.  Apparently the trainers in the academy were not in touch with the “real” way paramedicine was done.

The next narcotic overdose was a few weeks later.  When I asked for an IV line and Narcan, my field trainer was flabbergasted: “Are you crazy?  Move him to the bus and wake him up there!”

The third narcotic overdose was in the bathroom of a convenience store.  The unconscious patient still had a burnt spoon in his hand and a needle in his arm.  At this point, I had no idea where I was supposed to wake up junkies.  I did a mental coin flip and it apparently landed on its edge.  I split the difference: “Let me bag him up, I will get the line here, and we will give Narcan in the bus.”

My field trainer blew my mind: “Why would you go through all that work?  Just mainline the Narcan.”

“Mainline it?” I said.

“It’s Narcan.  It works IV, sub-q, IM, sublingual, whatever.  A blown mainline IV is just IM, right?  Mainline it and wake him up.” 

[Whatever you do, don’t do this.  We have other, safer ways to administer medications.  This was a long, long time ago.  As a matter of fact, on this call I pulled the Narcan needle out of the heroin addict’s vein and accidently stuck it directly into a firefighter’s leg.  You can’t do that with the intranasal atomizer.  Trust me, you don’t want to look down at the needle swinging from where it is buried in a thigh, look up to make horrified eye contact with an enraged firefighter, and then have to make the etiquette decision as to who should pull it out.  That’s one Miss Manners has never had to answer.]

See what I mean?  Inconsistency between field trainers and an apparent ability to make me feel small and stupid. 

Photo courtesy Intropin, Creative Commons License

What I discovered is that I was too unsophisticated to see what was obvious to experienced medics.  On the first street call, the patient was in a sixth story walk-up apartment.  My trainer wanted to wake him up and let him walk down, rather than carry him while he wasn’t breathing.  It is hard to bag someone being manhandled on stairs.  The second scene was unsafe, like the scenario house.  There were bystanders who would be likely to jump in on the patient’s behalf.  The third call: I have no idea why you would mainline Narcan.  It would be best if trainers and instructors could explain what the trainee is missing clearly without being asked.  But sometimes they don’t.

The answer to this problem is the ability to ask “Why?”  It has to be done in a collegial, non-argumentative way, however.  I have found that the best way is to compliment the trainer: “It seems to me that your experience is giving you clues that I don’t have.  What influenced you to make that decision?” 

You could even explain flat out what you are doing: “I don’t understand.  When I ask this, I am only trying to get the information so I can make the right decision later.  I mean no disrespect.  Why did you decide to do that?”

Usually the answer will enlighten you.  That is what you are being trained for, right?  In rare cases, the trainer will give you a flat wrong answer (mainlining Narcan).  But at least you know how he/she came to that decision.  Sometimes you will get two contrary answers and have to research which answer is right. 

Researching conflicting answers is important.  Research can mean asking people with more education than you have (your medical director or another physician), reviewing literature, or just thinking through the pathophysiology.  It is your practice.  You will have to make the choice when the situation repeats itself.  You will own that choice – your trainer won’t know all of the background you’ve been through.  You have to do what you think is right.  Wouldn’t you rather get in trouble for doing the right thing, rather than some guess as to what your trainer would want?  Do what you would be proud to defend.

One way or the other, it is important to ask “Why?” and get the information.  You are responsible for the choices that are made on a call.  So it is important to understand the factors that influence that decision.  There are no easy answers in EMS.  Everything is a grey area.  How can you expect yourself to operate in the grey if you don’t even know that influencing factors exist?

*Every system has its own vernacular.  Here, an ambulance is called the bus.  Not a rig, not a truck, not an ambo – a bus.

Referees Are Infuriating

I’m not really a team sport kind of guy.  I am much more likely to spend my time with solo endurance athletics like cycling, running and climbing.  But I do like to watch football on a Sunday afternoon when I have time.  My problem is that I get all fired up.  A referee will make a boneheaded call and I find myself on my feet bellowing at the incomprehensible idiocy displayed. 

What's that yellow thing?
Dude. That fell out of your pocket.  Now you have to make something up.
(Picture courtesy Jeramey Jannene, Creative Commons license)

I admit it.  I don’t like referees.  I’m not sure a lot of players (or fans, or ex-players, or coaches) do.  You can call them officials, referees, or umpires and I still don't like them.  I played baseball from tee ball through high school.  One of my favorite things to shout at an umpire was, “Hey, Blue!  If you had one more eye, you’d be a cyclops!”  I love seeing a baseball manager scream at an ump face-to-face, kick dirt on their shoes, and throw third base.  Awesome stuff.  I think most people would admit that a ref’s job is demanding in its own right.  But I don’t understand why anyone would want to be a referee.  Why wouldn’t you play if you could play? 

No call that goes against my team is fair, sensible, or warranted.  All flags thrown against my team are the result of pure idiocy or a nefarious plot by “the man” to bring my team to ruin.

“That wasn’t holding! His hand got accidentally tangled in his shirt!” 

“That call was obviously because the ref was out to get me!  What, are they being paid off?!?” 

Good calls, or good non-calls, absolutely go unrecognized.  I mean, that’s the referee’s job – getting it right is what you are paid for.

Remember the Seattle-Green Bay game from 2012?  One ref is signaling touchdown, the other is signaling time out.  The crew decided on simultaneous possession and the Seahawks won.  The replay showed pass interference and the Packers should have won.  Nice work, boys.

Refs are important for game efficiency, but aren’t really a necessity. There are thousands of pick-up basketball games, touch football games in the park, and informal baseball games on an empty diamond every day.  All without referees tilting the balance in favor of one team or another.

But none of that is really a reasonable point of view, is it?

Peter King, from the Monday Morning Quarterback website, was recently allowed unprecedented access to an NFL officiating crew for the first time ever.  That resulted in three incredibly interesting articles (one, two, three – if you’re a football fan, follow the links and read the articles) that help to tell the story of how professional football referees work.  I was surprised at how much preparation goes into their job.  I was also surprised at how much scrutiny they are under from the NFL office.  It was enlightening to find out that their orders (e.g. what to emphasize, what to look for, what rules to enforce more stringently) come directly from the NFL.  Their decisions look arbitrary (even spiteful), but are the result of the NFL planning changes to the game to improve the product.  I suppose that makes sense, but the players, coaches, and teams have almost no say in the matter.  The NFL says to pay more attention to hits involving helmets and the officiating crew pays more attention to hits involving helmets.  Refs are graded by the NFL, not the players or fans.  So the refs go with what the NFL wants, not what the players or fans want.  I’m sure that Major League Baseball, the NBA, the Premier League, La Liga, etc., are all set up the same way.

I didn’t realize the work, knowledge, and discipline required of a referee.  I didn’t realize the scrutiny they were under.  Did you know that every play is watched repeatedly by multiple experts who don’t just look for bad calls, but bad non-calls too?  Did you know that each NFL official watches three or four players on each play, dependent on the formation, and the assignments change when the formation changes but the refs don’t verbalize or otherwise coordinate who is watching whom?  They just know their job.  They are as coordinated as the players in a lot of respects.

Referees get no respect. 

Damn.  I hate it when reading opens my mind.

Fast decisions in the “heat of battle” made at full speed can have a huge effect on the game.  It is a massive responsibility.  It is entirely too easy to second-guess a ref’s decision with instant replay and slow motion when I’m half in the bag at home.  In my calmer moments I will admit that I probably would do a much worse job than the professional officials do.  (‘Calamitous debacle’ is the description that comes to mind if you put me in stripes).  And when it gets down to it, I can see that there is a big difference between a pickup game of football in the park on Thanksgiving afternoon and Monday Night Football in front of a national audience.  The officiating crew can be almost perfect, but I only notice the one or two plays that they drop the ball on.  (They do screw up – they are human).

I still don’t like refs.  I still get all fired up at boneheaded calls that I can see were bad calls.  I still shout and complain to nobody.  But after learning about their point of view, expertise, knowledge base, and job pressures, I think I respect refs a little more.

It struck me: I feel the same way about EMS dispatchers as I do referees.  Replace NFL with command staff, game with EMS system, team with ambulance, referee with dispatch, and player with paramedics and it is almost exactly the same situation.

Weird.

Four Eyes are Good

What do blood, pus, fingers, sweat, vomit, dental plaque, urine, feces, dust, dirt, phlegm, saliva, snot, medications, dust bunnies, little parasitic bugs, amniotic fluid, meconium, dandruff, and those little seeds from dandelions that float on the breeze have in common?

They are all stuff that can be heading toward my eyes at high velocity on a “normal” day.  They are also all things that I do not want to get into my eyes.

Patients don't always cover their mouth. (CDC, Public domain image)

I always wear splatter glasses on calls.  They are pretty cheap, are easy to forget that you have them on, and are good protection.  Easily one of the most common workplace injuries in EMS is “Boss, I got potentially infectious filth in my eyes.”  And it is stupidly easy to prevent.

Splatter glasses block intentional spitting, unintentional bleeding, coughing and sneezing, ejecta from intubations, dust, and fingers. They are pretty important if you are a bike medic, as well.

We do a poor job of estimating risks in EMS.  Many, if not most, paramedics in my agency drop $300 on  body armor but not $50 on splatter glasses.  It makes no sense to me.  The most common injuries are the most easily prevented – funk in your eyes (wear splatter glasses), injuries from ambulance crashes (put on your seatbelt), and lifting injuries to the back (lose your false sense of “I got this” pride and ask for lifting help).  EMS has a tendency to focus on rare event safety – is the scene safe, do we enter into an active shooter scene, and those kinds of things.  We tell ourselves platitudes like, “I want to go home in the same condition that I arrived to work” and “Scene safety is our primary concern.”  But the simplest safety devices that can make a huge impact are generally ignored.

I understand that nobody wants to wear the flimsy disposable glasses that are usually provided by an EMS agency.  Me neither.  My choice is photochromic safety glasses.  Photochromic means that light forces a color change.  They are clear in dim light and smoked like sunglasses in bright light.  I don’t have to swap out sunglasses when I am outdoors for safety glasses in the back of the ambulance.

I wear these glasses.  They are a little on the expensive side, but I want them to last, have good lenses, and look good enough to actually wear.  Other good choices include these Spits (great name), and these.  I got mine at a local bicycle shop, but search “photochromic safety glasses” on Amazon to get a bunch of choices.

Splatter glasses: Just put ‘em on and leave ‘em on. 

Why wouldn’t you wear them?  Are there any good reasons to not wear splatter glasses?

Speed is a Silly Question

Imagine one of the most common calls that you will run in EMS – a motor vehicle accident.  Your patient is the restrained driver of a mid-sized sedan who was involved in a frontal impact crash and is complaining of mild dizziness and midline neck pain.  So you take her to the hospital.  After you arrive there, you give your verbal report to the accepting nurse:
“This is the 43 year old restrained driver of a frontal impact crash complaining of dizziness and midline neck pain in a general sense, from about C3 to C7.  She is neurologically intact, was ambulatory prior to my arrival, and remembers the event.  She has a heart rate of 120, a blood pressure of 100/60, and a respiratory rate of…”

“How fast was the crash?” the nurse asks.

“I don’t know, but there was 8-12 inches of frontal damage and the airbags deployed.  The steering wheel, windshield and dash…”

“But how fast was the crash?”

Speed is a dumb question.

There are a few reasons that I feel this way.  First, police don’t take people’s word for the speed of impact.  Why would medical providers?  Police and insurance accident investigators have extensive training in how to estimate the speed of a crash based on skid mark length, road conditions, vehicle damage, passenger injury patterns, and such.  They don't come up with a number by looking at the results for a few seconds.  It makes no sense for me to ask the driver how fast he was going, especially when he is probably worried about what it will do to his insurance rates if he is found to be at fault.

Next, people don’t really know how fast they are going.  For the most part, people kind of just go along with traffic in a way that makes them feel safe.  They certainly don’t realize that a grinder is imminent, take unsuccessful evasive action, and then look at the speedometer right at the time of impact.  When pressed, they quickly try to recall which road they were driving on, try to guess the speed limit on that road, and maybe take off a few miles per hour to decrease the chances of them getting in legal trouble.  Any braking before the crash is not usually included in speed estimates.  Even if it was, it is almost impossible to guess whether their speed went from 55 to 30 at impact or from 55 to 52.  

In addition, the orientation of the impact isn’t included in speed estimates.  What we’re really interested in is the change in velocity.  Hitting a stopped car at an angle and glancing off is completely different than plowing into a bridge abutment at a perpendicular angle.  In the first case, the impact doesn’t take their speed all the way down to zero.  Was what they hit movable?  Were there other factors such as spinning, rollover, or ejection?  What part of the car was hit – there are big differences between taking an impact on the front bumper, getting your hood under a tall vehicle so the impact is on the A-posts, or taking the hit in the driver’s door. 

Finally, the type and age of vehicle matters.  There is a big difference in crashing a 1976 cast iron land yacht and a brand new SUV with all of the modern safety features.  Crumple zones, air bags, and such matter.  Think of really high speed crashes in auto racing – car parts go flying as the race car pirouettes through the infield, but the driver gets out and throws his helmet at the other racer that caused the crash.

Who cares about the reported number?  What if the accident was reported to be a 2 mph crash, but the patient has chest pain, pallor, JVD, and a really narrow pulse pressure indicative of pericardial tamponade?  What if the crash was reported to be 100 mph, but the only damage is that the license plate is sort of bent and the patient is completely uninjured?  The problem is that a 2 mph crash is unlikely to cause severe injury and a 100 mph crash is likely to result in life-threatening injury.  Most crashes we see, though, fall in between where anything can happen.  A person can walk away from a 40 mph crash, or they can be killed.

Quick, what was the speed of this crash?
(Elvert Barnes, Creative Commons)

To me, an accurate description of the crash events and a complete description of the damage to the patient and vehicle is what matters.  The major vehicle factors that should be reported are damage, intrusion, airbags, windshield, steering wheel, and dashboard findings. 

Damage is the amount of external damage.  How deep was the dent?  Where is the damage located on the car?  Is the vehicle drivable?  Could the doors open?  Was heavy extrication required to extricate the patient?  Intrusion, in contrast, is the depth of damage that made it into the passenger compartment (along with its location, etc).  Damage is how the shape of the car changed and intrusion speaks to how the shape of the passenger compartment space changed.  The difference is important, and I hate to hear people mix up the vocabulary. 

Whether or not airbags deployed and their location is important information.  The shape and integrity of the steering wheel, along with any dash damage is important data, as well.  Windshield damage should be reported with any caveats.  By caveats, I mean that a broken windshield can be caused by the airbag, the driver’s hand (as it is blown upwards by the airbag), by the impact itself, or by passenger body parts (read: face) impacting it.  Each of those results in a different mechanism of potential injury and a different index of suspicion. 

Finally, injury patterns on the patient’s body matter.  To say that the airbag deployed and seatbelts were reported to be used is great, but it is also a good idea to point out that the patient’s chest says “DROF”.  Whether or not the patient self-extricated and was ambulatory on scene matters.  So does their position in the car in relation to the impact site.

So I wish that hospital providers focused on the tale that I am trying to tell them, based on all of that damage pattern description.  I think that the importance of speed comes from trauma center requirements, but I don’t know for sure.  There is usually a list of trauma criteria that result in team activations of different levels.  Speed of a car wreck is one of them.  So the hospital is sort-of forced to document the speed findings.  That doesn’t make it any less of a silly question to me.  But there is no need to get into some passive-aggressive pissing contest over it.  I try a few times to point out that I wasn’t there and which road it happened on so they can recall how fast that road moves, but I usually end up estimating that the speed was X mph based on the reported damage/injury patterns.  Move on.