You gave adensoine for THAT? (part 3)

To recap - the paramedic had a patient who was throwing off long segments of both narrow-complex tachycardias, and wide-complex tachycardias. An initial dose of adenosine managed to transiently establish a sinus rhythm.

Sinus rhythm for 3 whole beats! *Pumps fist in air*

So what was converted; SVT or VT?
It's tempting to think that, beacause it was converted by adenosine, it must have been a SVT with aberrant conduction. A few things suggest that this was, instead, true VT.

Playing the odds...
First, a wide-complex rhythm in an older patient is far more likely to be VT than SVT - if you're betting, that's where yo should put your money. 

Your instructor was right - axis is important!
Second, you could be tempted to call this a left bundle branch block, but the axis is unusual. A LBBB usually points off towards the left.

Note the large R waves in I and aVL (Source)

Our patient, on the other hand, shows an axis oriented a bit to the right.

Note the large R waves in II, III, and aVF

Fusion beats
Third, the patient keeps kicking out fusion beats, or QRS complexes that show features of both a supraventricular beat, and a simultaneous ventricular beat. They usually look like an "average" of a PAC and a PVC. Here's an example from Life in the Fast Lane:

Not wide, not narrow, just ... average.
(source)

 When we look at the initial rhythm strip we see a bunch of sorta wide/sorta narrow beats.

Another ECG, done in the ED, also shows multiple fusion beats, indicated by the arrows.

Such a finding strongly suggests that this patient had ventricular tachycardia that was converted by adenosine. Crazy, right?

Well, it turns out that not everything that converts with adenosine is SVT!  One infrequent kind of VT can convert with adenosine - right ventricular outflow tachycardia.

RVOT
A fairly uncommon kind of VT is know as RVOT, named for the location of the problem. It basically looks like a LBBB, but with an inferior, rather than a left-oriented axis. A great example comes courtesy of Dr. Ken Grauer. Compare it with the initial 12-lead we have.

RVOT - from Dr Gauer's collection.

I'm not going to go on further about this rhythm, since it's pretty uncommon, but if you want to know more go check out Dr Grauer's blog.

(I'll note again that my cardiology education started when I read the 1993 edition of his ACLS textbook. He has a 2014 update, available on a variety of e-readers. Buy it!)

Uh, so there's this rare RVOT thing. Why should I care?
As I mentioned in Part 2, there are two important things to know about giving adenosine for a WCT:

1. Adenosine is relatively safe in regular, monomorphic WCT.
2. However, it can convert certain types of VT.

Since the publication of the 2010 ACLS Guidelines, a large number of EMS agencies have adopted adenosine as the first agent to administer in the treatment of a stable, regular, and monomorphic wide-complex tachycardia. I don't have any hard numbers on how common this protocol is, but instead of a study, I can give you a collage! 

I makes it for u.

Despite the popularity of this protocol, many clinicians have reservations about the wisdom
of this approach, since there are a number of potential pitfalls. One of the big ones would be to assume that adenosine is a reliable test for supraventricular rhythms. Keep in mind that he ACLS guidelines only state that "adenosine is relatively safe for both treatment and diagnosis."  

Safe, not accurate!

The Bottom Line
The SHCGB protocols allow for the use adenosine when the etiology of a WCT isn't clear. Keep in mind that, even if adenosine is successful, the etiology may still be unclear!

You gave adenosine for THAT?! (part 2)

In a prior post, I looked at whether you could give adenosine to a patient with a history of WPW (see "Can you give adenosine to a patient with WPW"). The answer was "Yes, but..."

I want to look at another adenosine issue today - can (or should) you give adenosine to a patient with a wide-complex tachycardia (WCT)?  

Spoiler: The answer to this questions is...

Or, more specifically:

1. Adenosine is relatively safe in regular, monomorphic WCT.
2. However, it can convert certain types of VT.

A case of WCT treated with adenosine by EMS
Our paramedic was just "minding his own business" when he was called for a patient with palpitations. He was an older person, with no history of any cardiac problems, and was hemodynamically stable. His rhythm strip, however, looked like:

Wut.

Okay, that's a data-rich ECG!  Taking a closer look at two different segments, we see evidence of both a regular monomorphic WCT...

So it's VT, right?
... as well as a regular narrow-complex tachycardia.

Tell me if you see P waves. I didn't.

VT with episodes of PSVT?
The full 12-lead ECG looked wide and scarey:

So, what to do?
Our intrepid medic decided that adenosine would be appropriate, and gave a slug, right as the patient was going through a spell of WCT.

At first it seemed to work ....

... aaaand right back into the WCT, after a brief period of apparent sinus rhythm.

Wait, what the heck - the adenosine converted a VT? Or was it aberrant SVT? What should the next drug be? How much does the response to adenosine change our impression?

To be continued...
Tell me what you think, and I'll be back with the follow-up, as well as how lessons from this case should affect your assessment and treatment in the field.

"We had a LUCAS save!" - No, you didn't.

I don't get it.

More and more, I'm seeing Facebook posts, newspaper articles, and personal testimony that excitedly describe a "LUCAS save." That is, a successful resuscitation is credited to the use of a mechanical compression device made by Physio-Control. For example:

"Saves man's life!"

Source

"More residents survived thanks to LUCAS!"

Source

"Life-saving CPR technology!"

Source

"Life-saving technology!" "Saves local man!" "Thanks to LUCAS!" Why hasn't this news of Lazarus-like success swept the country? Why are we still doing CPR with our hands?

Doing CPR with our muscles... like a sucker!

 Well, there is one teensy fact that the press releases leave out...

The LUCAS doesn't save lives.
And no, I don't mean this in the clever "guns don't kill people..." sense. 
I mean this in the "proven by science" sense.

Source

This study, published in January, describes the use of the LUCAS in out-of-hospital cardiac arrest. 

 - Methods
The study looked at patients who had a cardiac arrest treated by EMS. They enrolled adults, who had suffered a non-traumatic arrest, and were neither too small, nor too large, to fit in the LUCAS. They randomized patients to either get manual CPR according to 2005 European ACLS guidelines, or to get chest compressions delivered by a LUCAS device.

The teams were well-trained - not only was there initial preparation for the teams with both usual and mechanical techniques, but team members had twice-yearly re-training, as well as random "spot checks" of individual participants using a manikin. Pretty rigorous!

The primary outcome was maintaining survival for 4 hours after ROSC. You can quibble that this isn't as important as, say, neurologically-intact discharge from the hospital, but it's a reasonable goal, and likely easier to achieve.

 - Results
This should have been a slam-dunk for the machine. Mechanical CPR is consistently high-quality, does not fatigue, and frees up EMS workers for other tasks. One more bonus for the machine - the protocol called for defibrillations to be given during the mechanical compressions, something that humans are not usually able to do! In theory, this elimination of the peri-shock pause should have increased survival in the LUCAS-treated patients.

LINC trial protocol

However, after 2500 patients were enrolled, they found squat for differences between manual CPR and the LUCAS. Nothing. No matter what outcome you picked, there was no advantage to using the LUCAS. None.

LINC trial results

 - Interpretation
So that's the end of the LUCAS for routine management of cardiac arrest by EMS, right? We did the research, it was negative, and we took the expensive machines off the rigs. The EMS services that haven't bought them have expressed relief that they didn't lay out the cheddar.

"But the LUCAS..."

But regardless of these completely negative results, people are protesting. They point out that, yeah, maybe this study didn't show a difference. "But the LUCAS..., " they point out...

• "...delivers better CPR!" 
• "...can shock during CPR!"
• "...can do better CPR during transport!"
• "...doesn't get tired!"

Despite all that, which is likely true, no difference was found in a high-quality trial where the researchers has every opportunity to demonstrate these . This is how clinical research goes - the slaying of appealing theories by means of ugly facts.

The graph is explained HERE, if you're into that sort of thing.

Don't give credit to a piece of plastic!
A recent article over at JEMS describes a successful cardiac arrest resuscitation. The authors write about the myriad contributing factors:

The integrated training between EMS responders and the CPR/AED-equipped police officers; the multilayered, coordinated response and resuscitation effort by police and EMS familiar with the pit-crew approach to resuscitation and use of a mechanical CPR device; and the rapid response and time-to-care by the rescuers—particularly at such a large gathering—were all key factors in this successful resuscitation.

But the authors then go on to emphasize in the last paragraph that the LUCAS "was clearly a part of this successful resuscitation," and that "they’d never seen this type of response in all of their years of managing cardiac arrest cases." 

In other words; "We did okay, but we're pretty sure that this inanimate object should get the lion's share of the glory." 

You know, I think I've seen this before...

"Simpsons already did it!"

The Bottom Line: 
You know what saves lives? 

You. 

You, and your well-trained team, utilizing the proven techniques that save lives. Believe me, if the LUCAS was able to generate these sorts of results...

 Source

... you would have heard about it by now!

(For another analysis of this trial, plus some interesting comments, read the post Man vs Machine: A CPR Battle to the... over at Ryan Radecki's excellent blog.)