Why is pulseless SVT considered PEA?

[Markhk]

This is a question I have been confused about for a while, so I'm hoping you ACLS studs might shed some light on this. I honestly have no idea how often you might have a pulseless SVT in a clinical setting, but this question has come up in training.

Question: Why do we treat a SVT, without a pulse, as a PEA rhythm instead of attempting to shock it?

I guess I get confused on the issue since, to me, a pulseless SVT is the ultimate "unstable" tachycardia. If electrical therapy is indicated in unstable SVT, why isn't it indicated for SVT without a pulse?

Thanks for any of your thoughts out there.

 

[bstone]

As I recall the treatment would be 1mg Atropine. Wait a minute and then shock.

Then again, I am an Intermediate and we do our own weird version of ACLS.

 

[Markhk]

I think atropine would be contraindicated in Pulseless SVT since the heart rate is above 60...

 

[bstone]

The electrical rate is above 60 but the heart isn't actually pumping.

I know what my protocols tells us to shock for SVT.

 

[medic755]

Mark, i'm on the same route as you here, but i think that you should rephrase 60 beats, as the electrical rate. Regardless, in our system, so long as the electrical rate is above 60, your withhold atropine. (as per ACLS as well, atropine is only for 'slow PEA rate')

But what it seems to me (again, I'm comparatively new at this whole medic thing), is that the key word in this whole scenario is "pulseless". If your patient is without a pulse, but in a rhythm not defined as VF/VT, thats pulseless electrical activity, regardless of what rhythm it appears to be. The key would seem to be associating the electrical action with the mechanical action - we cant have one without the other.

Now, as a side note, oft-times a rapid SVT rate will make the pulse extremely difficult to detect, due to the rapid rate and poor perfusion status, even at the carotid. Now, THIS would be a perfect time to cardiovert!

Wise medic once said:

Does the patient look like :censored::censored::censored::censored:? -----> NO ------> calm down (chemical)
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YES
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Freak out (electrical)

 

[medic001918]

The electrical rate is above 60 but the heart isn't actually pumping.

I know what my protocols tells us to shock for SVT.

Atropine is a parasympathetic blocking agent that increases conduction across the atrioventricular (AV) node. Giving atropine to a patient in a PEA with a rate greater than 60 is going to have little effect, other than to potentially increase the electrical rate. If you have a tachycardic PEA, the problem isn't electrical but more mechanical in nature.

Most PEA's tend to be bradycardic and the treatment includes other medications other than atropine, but that's not the topic here. Atropine has it's place in this presentation. If it's a fast "PEA," is it possible that the patient doesn't have a sufficient blood pressure to be palpable? That could cause the lack of a pulse. This would be a great time to cardiovert. See if that brings back any perfusing rhythm. Epi or Vasopressin would be a good option in this case. Vasopression would help to increase return to the heart due it's strictly alpha effects while epi would provide the alpha effect as well as an increased electrical effect which may or may not be desired depending on the presentation.

I'm a little puzzled as to why your protocol includes atropine for any kind of accelerated electrical activity. Obviously you have to practice what's in your protocol, but it just seems wrong to me. Has anyone ever explained why to you? Maybe it would help shed light on why the protocol is the way it is.

Shane
NREMT-P

 

[bstone]

I am going to check the protocols and get back to you. I am a little murky on this area.

 

[ccfems540]

The goal of synchronized cardioversion is to break a re-entry rhythm. If you were to cardiovert pulseless SVT the result would be PEA at a slower rate. You have not fixed the problem which is a mechanical one, not an electrical one. Your ultimate goal is to get the heart pumping again. Atropine is absolutely contraindicated in PEA at a rate above 60. Hope this helps.

 

[Ridryder911]

Any rhythm nor matter SVT, Bradycardia, Junctional or idioventricular, etc.. does not matter what the rhythm is, PEA is a condition or syndrome caused by electrical mechanical dissociation (EMD) hence the original name for PEA before 1988. The firing is still coming from the pacemaker, but is not conducting through and connecting with the mechanical end of muscle contractions.

Hence the reason to determine the cause is much more emphasized than just treating the rhythm. Epinephrine is given to maintain the catecholamine level, and atropine is ONLY given in the evidence of bradycardiac rhythms. Atropine has no effect in the causing a connection of the mechanical and electrical functions. And yes, Atropine is strictly contraindicated in SVT.

Determination of the cause can of course by the H's and T's, such poor acid base, hypoxia, poor RBC's ( low HgB ) secondary to hypovolemia, or pericarditis from inability for perfusion or damage to the myocardium.

Until the 80's calcium chloride was administered and was pretty successful in treating but post arrest seizures was common and caused severe cerebral edema.

 

[Anomalous]

I am going to check the protocols and get back to you. I am a little murky on this area.

Me too. I had to look it up to be sure. Defib, Epi, then after second Epi, Lidocaine 1.5 mg/kg

 

[Ridryder911]

Me too. I had to look it up to be sure. Defib, Epi, then after second Epi, Lidocaine 1.5 mg/kg

Defib? Not cardioverting? Lidocaine?.. Wow! Knock out any rythm?

 

[Ridryder911]

I misread the scenario.. sorry, pulseless SVT is usually assumed to be truly pulsless V-tach or V-Fib.

R/r 911

 

[Markhk]

Thanks Ridryder911...I really wish AHA would put a statement out about that so people stop looking at me all crazy. :wacko:

 

[Emtgirl21]

I'm just a silly medic student and too tired to go back and ready what everyone said. However I would say it prob just reached the point that either it is no longer prefusioning and the heart is basicly is quivering or its so fast you just cant feel it. Either way. Cardiovert that bad boy quickly before they go to the light! Or maybe some Adensine???

The older medics tell me " if you look at the monitor and it scares you either
(a) wait until it changes to something you can know and can treat or (b) turn it off and treat the patient.

 

[Ridryder911]

I'm just a silly medic student and too tired to go back and ready what everyone said. However I would say it prob just reached the point that either it is no longer prefusioning and the heart is basicly is quivering or its so fast you just cant feel it. Either way. Cardiovert that bad boy quickly before they go to the light! Or maybe some Adensine???

The older medics tell me " if you look at the monitor and it scares you either
(a) wait until it changes to something you can know and can treat or (b) turn it off and treat the patient.

Actually, if it is PEA/EMD the heart would not be "quivering" because it is all electrical activity not muscle activity, the "quivering" heart would be V-fib. Adenocard has no mechanism of correlating the two mechanisms.

Defibrillation is recommended in certain situations, when the SVT can be presumed as V-tach, now if it is clear to be SVT and no perfusion then it should be treated as PEA syndrome. Recommended fluids, epinephrine, and of course treatment of the cause of the syndrome.

R/r 911

 

[spidermedic]

I agree that the pulseless tachycardia should be treated and cardioverted like a pulseless V-tach vs a PEA. Often times, if it's a narrow-complex tach, you're actually looking at at pseudo-PEA in which the heart is still reacting to the stimulus, but you just can't palpate a pulse--of course until we get some cheaper ultrasound machines, it's a little tough to tell for sure.

In this case you really need to look at the rhythm and decide whether you've got a flutter, SVT, A-fib or perhaps an accelertated junctional of some sort. You should also be looking away from the epi and more towards correcting the underlying cause(s).

 

[MSDeltaFlt]

I'm not a big fan of "assuming" anything. Pulseless SVT shouldn't be pulseless. If it's narrow and fast, treat the underlying cause(s) like everyone said. If it's wide and fast, light 'em up.

 

[kiwimedic]

Here, we treat SVT as a tachydysrhythmia (because that's what it is ) unless it's puseless in which case we treat it as a cardiac arrest.

From what I understand SVT decreases cardiac output, not stops it all together. I was talking to a fellow medic friend who said that if you deliver an unsyncronized shock to SVT it will likely convert to VF which is why we use sync'd cardioversion.