Shocking asystole

[breakaway]

I recently took an advanced CPR course on how to use automated defribrilators. I was surprised to learn that you can't shock a patient in flatline. The instructor didn't really provide an explanation, she just said that asystole was an unshockable rhythm.

 

Does anybody know WHY yo can't use a defribrilator in asystole?

[Lactic Folly]

The more clinical types can correct me, but I believe the purpose of defibrillation is to stop an arrhythmia such as VF/VT and allow the heart's pacemaker to reestablish normal sinus rhythm. In asystole, there is no arrhythmia to interrupt, and your goal is to restore circulation as quickly as possible.

[A-Stark]

Lactic Folly has it right, but a better question would be why would you use an AED in asystole (or PEA) in the first place?

[Ollie]

Yeah basically there's no rhythm so there's nothing to shock. It's a huge pet peeve of mine when you see them shocking asystole on TV (Grey's is a big offender). Most because they inevitably revive the person so it gives the public a really unrealistic view of chances of surviving a code, especially asystole.

[leviathan]

The more clinical types can correct me, but I believe the purpose of defibrillation is to stop an arrhythmia such as VF/VT and allow the heart's pacemaker to reestablish normal sinus rhythm. In asystole, there is no arrhythmia to interrupt, and your goal is to restore circulation as quickly as possible.

Lactate is right; the shock momentarily interrupts all electrical activity in the heart, so if the heart had abnormal electrical activity you hope it starts back up into a normal rhythm. In asystole you have no electrical activity in the first place.

[apache]

yeah, it's pretty funny, it's like when I watch house and I'm like... she has lupus, and it turns out she has some weird bug from Bolivia which germinated in her house unknowingly for 8 months before she got it... but you gotta admit, if you were tv producer you'd want that excitement on your shows, although, knowing some medicine it's sometimes funny to watch...

 

Yeah basically there's no rhythm so there's nothing to shock. It's a huge pet peeve of mine when you see them shocking asystole on TV (Grey's is a big offender). Most because they inevitably revive the person so it gives the public a really unrealistic view of chances of surviving a code, especially asystole.

[estairella]

A heart in asystole - no oxygenated blood going to the heart, you can shock it as many times as you want, but without oxygen it can't function.

 

So that's why you start with CPR -> forcing blood flow and oxygenated blood to go to the coronaries. If you do this for long enough, the cardiomyocytes will start generating electrical activity again (disorganized, arrythmic). When there's sufficient electrical potential -> shock the heart to synchronize everything -> heart starts beating in organized function, sustaining its own oxygen flow.

[Cnussey]

A heart in asystole - no oxygenated blood going to the heart, you can shock it as many times as you want, but without oxygen it can't function.

 

So that's why you start with CPR -> forcing blood flow and oxygenated blood to go to the coronaries. If you do this for long enough, the cardiomyocytes will start generating electrical activity again (disorganized, arrythmic). When there's sufficient electrical potential -> shock the heart to synchronize everything -> heart starts beating in organized function, sustaining its own oxygen flow.

 

Hence the CPR prior and in between shocks.

[Maxime]

Breakaway,

 

Lactic Folly has already answered why you don't give a shock in PEA/asystole. Studies have shown that shocking in asystole might possibly increase mortality, possibly by causing a stunned myocardium, as opposed to pulseless VF/VT, where you have to shock to break the reentrant electrical cycle. So, you could actually diminish your already slim chances of bringing back the patient by shocking him. There are also no indications for external pacing and such in asystole, just doesn't work. Furthurmore, there are no longer any indications either for atropine in PEA/asystole, based on the new ACLS guidelines.

 

So basically, not many things have been shown to be efficacious in PEA/asystole. You ventilate, compress, give vasopressors (never been proven to work, but nice to know you're doing something) and eliminate your usual causes.

 

Does this answer your question?

Maxime

[leviathan]

Lactic Folly has it right, but a better question would be why would you use an AED in asystole (or PEA) in the first place?

An AED is applied to everyone in arrest because you don't know what rhythm they're in. Even once it's on, AEDs don't have an ECG display anyway (except some models that paramedics use) because they analyze the rhythm on their own and determine if a shock is needed.

[A-Stark]

Yeah, I know, it'll say "shock not indicated". I expect everyone here has at least CPR Level C and I've done BLS and NRP at this point too.

[Cnussey]

Yeah, I know, it'll say "shock not indicated". I expect everyone here has at least CPR Level C and I've done BLS and NRP at this point too.

 

Updated mine two weeks ago...got the defib as well. Lol. My previous training was over a decade ago...yikes. It is difficult to screw up using the AED, possible, but difficult.

[breakaway]

So how do you restart a heart that is in asystole? I assume you don't just let them die.

[cheech10]

Chest compressions and drugs (epinephrine for an adrenergic stimulus) to try and restore some blood flow to the heart. If it's not been ischemic too long, it may restart. The problem is asystole is the final common pathway of a dying heart. Generally, the arrest starts in VT/VF or PEA, and after prolonged ischemia ends up in asystole, so by that time it's usually quite difficult to restart it.

[WhenInRome]

Is it harmful do shock someone that is in asystole?

[koft]

Is it harmful do shock someone that is in asystole?

 

It just wastes time that you need to do chest compression to get minimal amounts of volume to circulate!!

________

SC2 REPLAYS

[artistintheambulance]

A more simple analogy - shocking asystole is synonymous with pressing ctrl+alt+delete when your computer isn't even on.

 

My two cents:D

[leviathan]

A more simple analogy - shocking asystole is synonymous with pressing ctrl+alt+delete when your computer isn't even on.

 

My two cents:D

 

Haha nice analogy, I like.

[BPayne]

An AED is applied to everyone in arrest because you don't know what rhythm they're in. Even once it's on, AEDs don't have an ECG display anyway (except some models that paramedics use) because they analyze the rhythm on their own and determine if a shock is needed.

 

Plus, they're not really designed for people who know the difference between different heart rhythms, or lack-thereof.

[giblet]

It just wastes time that you need to do chest compression to get minimal amounts of volume to circulate!!

 

This may be a little stupid, but what's the point of doing chest compressions if there is no way of restarting the patient's heart? I thought that chest compression were jsut a way of buying time until you could permanently fix the problem.

[leviathan]

This may be a little stupid, but what's the point of doing chest compressions if there is no way of restarting the patient's heart? I thought that chest compression were jsut a way of buying time until you could permanently fix the problem.

Sometimes if you do a few minutes of high quality CPR for someone in asystole, and give a few rounds of epinephrine, you can get the heart some meager electrical activity back which you are able to shock into a normal rhythm. It's not very likely though, as asystole is usually a terminal rhythm that you can't fix.

[seeking1]

This may be a little stupid, but what's the point of doing chest compressions if there is no way of restarting the patient's heart? I thought that chest compression were jsut a way of buying time until you could permanently fix the problem.

 

The point of the compressions is to get oxygen already in the body circulating, as the heart is not doing it. As per CPR and AED teaching via the Lifesaving Society, you have an 8 min window from when a person's heart stops beating to start compressions. After that 8 min window, massive brain damage/death due to hypoxia begins.

 

You're right in pointing out the compressions don't restart the heart though. Last I checked, bu don't quote me, CPR has roughly a 2% success rate in restarting the heart.

 

Buying time is a good thing.

[thebouque]

The point of the compressions is to get oxygen already in the body circulating, as the heart is not doing it. As per CPR and AED teaching via the Lifesaving Society, you have an 8 min window from when a person's heart stops beating to start compressions. After that 8 min window, massive brain damage/death due to hypoxia begins.

 

You're right in pointing out the compressions don't restart the heart though. Last I checked, bu don't quote me, CPR has roughly a 2% success rate in restarting the heart.

 

Buying time is a good thing.

 

Less than 1% actually, and it's probably because the patient wasn't in real cardiac arrest. The real figure is closer to 0% I'd say.

[cnb88]

Updated mine two weeks ago...got the defib as well. Lol. My previous training was over a decade ago...yikes. It is difficult to screw up using the AED, possible, but difficult.

 

When I did my First aid/CPR/AED last year the instructor told us that you could stick the pads on the bottom of the feet and it would still work:p

 

My aunt (who's a nurse) said that out of the hundreds of times she's had to do CPR, it's only ever saved someone's life once... :S

[in2bat0r]

Having worked with EMS for two years I have only had ROSC (return of spontaneous circulation) twice, neither were in asystole. An increase in AED's in public places in combination with more bystanders trained in CPR has had a positive effect, it's quite common to have a shockable rhythm and as a consequence more of the "cardiac arrest" responses have positive outcomes. Although, the majority of cases that I have heard of don't survive long and have some sort of deficit.