Defibrillation and Cardioversion
9/1/04
Hi all. Another one! As usual, please remember that this is not an “official” reference in any way at
all – it’s what a preceptor would teach to a new orientee at the shop-floor level. Please let me
know when you find mistakes – I’ll fix them right away. Thanks!
1- What is fibrillation?
1-1: What is atrial fibrillation?
1-2: What is ventricular fibrillation?
2- What is de-fibrillation?
3- What is cardioversion?
4- What is a defibrillator?
4-1: the monitor
4-2: the capacitor
4-3: the numbered buttons 1,2,3; output dials
4-4: the paddles and the pads
5- How do defibrillators work?
5-1: What is depolarization?
5-2: What does electricity have to do with it?
5-3: What is a joule?
5-4: What is monophasic defibrillation?
5-5: What is biphasic defibrillation?
5-6: What is “transthoracic impedance”?
6- How do I cardiovert someone?
6-1: Cardioverting a-fib.
6-2: Cardioverting VT-with-a-pressure.
7- How do I defibrillate someone?
7-1: Defibrillating VT
7-2: Defibrillating VF
8- What bad things do I have to watch for during cardioversion or defibrillation?
8-1: Using synchronization correctly.
8-2: Keeping the process orderly.
8-3: Clearing the bed.
8-4: Using contact gel properly – contact burns.
9- What things should I do after the cardioversion/defibrillation?
1- What is fibrillation?
Fibrillation is an arrhythmia that affects either the atria as a pair, or the ventricles as a pair,
producing “a-fib”, or “v-fib”, respectively. (Come to think of it, if a person is in VF, do their atria
fibrillate as well? Does it matter?) Most cardiac rhythms are organized – they’re regular in some
way, producing some sort of regular (as opposed to disorganized), rhythmic motion of the
chambers, hopefully producing a blood pressure. In fibrillation, the cardiac tissue of the chambers
involved wiggles about like (classic phrase) “a bag of worms”. Does a chamber wiggling like a
bag of worms pump any blood, produce a cardiac output, eject any fraction of its contents? No, it
does not!
As I always try to point out, all the waves that you see on EKG strips actually represent some kind
of physical motion of one or the other set of cardiac chambers, and the trick is to try to visualize
what those chambers are doing in any given rhythm situation. Let’s see if a quick review of some
strips helps the visualization process. Can I have the first slide please?
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Here we are: look familiar? Sinus rhythm. Organized, rhythmic, producing stable contraction of
the chambers – first the atria, then the ventricles. So - visualizing on the mental screen, that’s
what I see: nice orderly motion, first above, then below.
Okay so far? Right – next slide, please. OK: atrial flutter. Still organized: the atria are contracting
rapidly, sure, at about 300 bpm, and the ventricles are responding to every third or fourth impulse,
slowly enough that the ventricular chambers have time to fill up nicely between beats, fast
enough to probably maintain a good blood pressure. So I visualize the atria clipping along, with
the ventricles contracting every third or fourth time.
This one? Well – is it organized? Actually it is: see the pattern of doubles? It’s a little easier to
figure out by looking at the lower part of the strip – this is a sinus rhythm, and after every sinus
beat comes a PAC, followed by a compensatory pause. So yes, still organized. “Regularly
irregular”.
How about this one? Yup, VT. Ugly, scary, but still organized, regular – the chambers (which
ones?) are moving in a steady manner. On your mental screen you should see the ventricular
walls contracting very rapidly – do they have time to fill? Should we shock this rhythm? It
depends…
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1-1: What is atrial fibrillation?
How about this one? Not organized? Should we shock this rhythm? A-fib for sure can be a
shockable rhythm, but look at the QRS rate – in the 70’s. What would have to be happening to
make this a shockable situation? What do you visualize here? Atria: bag of worms. Ventricles –
occasional, but normally conducted QRS’s. Are they too slow or too fast to make a blood
pressure? How do you tell?
1-2: What is ventricular fibrillation?
Here’s an ugly one - you probably recognize this one right off. Doesn’t look organized to me!
What rhythm is this? Visualize the ventricles – everybody see the worms? What should we do?
2- What is de-fibrillation?
So: all set on organized, and not organized? The treatment for nasty arrhythmias is often
electical, right? The point is: one type of treatment: cardioversion - is for the organized kind of
rhythm, and the other is, uh…for the other kind! Defibrillation is for disorganized rhythms.
What you want to do is to send a fixed amount of electrical energy along the normal conduction
path of the heart: along the Lead II pathway. Can I have the next slide please?
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(What’s this one? Oh yeah...)
Audience, this is the foxglove plant, the one that digitalis comes from.
(The Chief Review Editor likes flowers…)
Here’s a diagram of the normal lead II: the positive electrode is down near the apex of the
ventricles, the negative one is at the atrial end. Everybody remembers that the normal direction
that the cardiac impulse takes is from the SA node at the northwest corner, up near Oregon,
down and towards the southeast in Florida, where the positive electrode lives? And that the signal
moves along the pathway as the cells depolarize, in sequence, along that pathway?
Negative electrode goes here (Oregon)
(here)
(Ground electrode goes here…)
(here)
Positive electrode here (Florida)
www.arrhythmia.org/ general/whatis/
The idea is that applying an electrical impulse - of a specified amount of power - along the
conduction pathway should depolarize all the rhythm-generating-and-transmitting cells at once.
Bam! (Emeril? That you?) Now, hopefully, one of the normal, built-in, “intrinsic” pacemakers will
take over – and in fact, often enough, they do! Remember: Defibrillation is the method to use in
disorganized rhythms like VF, as in “Go defibrillate that disorganized rhythm, you doofus!” (Got
to watch your language in those emergency situations.)
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2- What is cardioversion?
This is the other one. Cardioversion is the electrical maneuver that you use for organized
rhythms.The difference between cardioversion and defibrillation is pretty simple – the secret lies
in timing the shock correctly. If you’re treating an organized rhythm, and if the electricity you give
the patient happens to arrive during the “vulnerable” period of the T-wave, then the unhappy “Ron-T” thing may occur. Everybody remember what that is?- an ectopic beat, (or a jolt of external
electricity – in either case a stimulating electrical signal) landing in the conduction system during
the vulnerable period can trigger VF. Bad!
So – how to prevent this ugly thing? The defibrillator/cardioverter has the ability to track the
QRS’s, and to stick a visible marker on each one. This lets the machine figure out when it’s safe
to deliver the jolt. All too well do I remember seeing a patient once, cardioverted out of an a-fib
with the machine in defib mode – that’s to say, not synchronized (forgot to push the “Sync”
button, did ya?) – and who immediately went into VF, which responded to a defib shock.
Fortunately.
The three situations where I’ve seen cardioversions occur are:
- Decompensated, rapid atrial fibrillation (afib with “RVR”: rapid ventricular response”) – this
means that the ventricular response rate to the a-fib is so fast that the chambers can’t fill
with blood between the beats. No filling, no blood pressure. Generally if a patient is in rapid
a-fib and still has a blood pressure, the team will try meds first: verapamil, beta-blockers,
etc.
- VT-with-a-pressure (as opposed to VT- with-no-pressure; what ACLS calls “pulseless VT”).
More on how to actually do a cardioversion below.
- SVTs: narrow-complex rhythms, which are usually really bloody fast – up in the 200’s. Can
your ventricles fill and empty properly at that rate? Mine can’t, mate!
All organized rhythms. “Organized” is of course pretty relative: AF is a sort of “just-aboutorganized-enough” rhythm.
4- What is a defibrillator?
The goal here is to try to understand what the machine is trying to do. Let’s say your patient pops
into a nasty rhythm – not handling it very well, not making much of a blood pressure; and you
want to deliver electricity – what do you need?
4-1: The monitor.
First: you need to be able to see what’s going on. This is of course one of the reasons why our
patients are monitored at the bedside: so you can see what rhythm your patient is in. Defibrillators
are built to travel– so they have a monitor screen built in.
Second: suppose you want to cardiovert instead of defibrillate – in other words, deliver a timed
shock rather than a blind one. The machine is going to need to see the rhythm to do this, and you
need to be able to make sure it’s seeing the right thing. This is a useful concept: lots of the
devices in the unit are trying to “see” the patient in one way or the other – your job is to make
sure they do, and that you learn how to interpret what they’re trying to tell you.
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Anyhow, the machine needs to see the patient. You’re either going to have to put sensing wires
on the patient that go back into the defibrillator (which may not have time for), or use the paddles
as sensors. Our machines have a paddle-monitor mode called “quick look” – the procedure is to
gel up the paddles, make sure the monitor is in paddle mode (the word ‘paddle’ appears on our
monitors’ screens). Hold the paddles firmly against the skin in the defib position (with gel!) and
get a good look at the patient’s rhythm. I bet that the newer defib pads do the same thing. I
should know this…
4-2: The capacitor.
Unless you have a really long electric cord, you’ll need a battery to run any transportable medical
device. Rechargeable batteries are why all these devices are so flippin’ heavy, and the
defibrillator is no exception, so we keep ours on rolling carts that we can whip up and down the
unit.
The battery stores electricity, but only if the machine is plugged in when you’re not using it. You
do not want to arrive on the scene with a dead defibrillator! The battery feeds electricity into a
capacitor – this I think of as a black box that holds whatever amount of electricity you choose, for
a fixed amount of time. The capacitor fills up with electricity when you push the button that selects
the charge you want to give. Our machines charge up with sounds that let you know what’s
happening: once you push the button, you hear a rising whine as the charge collects - that turns
into a steady, high-pitched whistle when the machine is ready to discharge. Loud, but effective.
Practice this.
4-3: Numbered buttons: 1,2,3: output dials
Here the goal is to try to keep things very simple: there are three things you need to do when
operating the defibrillator, and the people who make these machines are trying to help you do
them when you may be, let us say, a bit distracted by the situation. I’m going by the machines in
our institution here – make sure you know what to do with your own, although the three moves
are probably the same:
1: Button number one (actually on our machines it’s a dial, but it has a big number one
next to it) turns the machine on, and sets the machine with the joules (the amount of
electrical energy) you want to give.
2: Button number two charges the capacitor to the level you picked. At this point we
hear the rising tones that tell you that the capacitor is charging up, and then the steady
tone that says that it’s ready to go.
3: Button number three lives on the paddles (there are actually two “number three”
buttons, so you don’t squeeze just one by mistake and fire the device before you’re
ready) and discharges them.
4-4: The paddles and the pads:
I hear that (rather like myself), paddles are considered “old-tech” – nowadays the thing to do is to
slap on sticky defibrillation pads that hook up to the machine – the same ones as external pacing
pads – then stand back, charge and discharge the machine from a few feet away. I have seen
this done, but most times in our unit we make one quick defib move or two – there’s much less
defibrillating going on since clotbusters came along and fewer people complete their MI’s.
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In the MICU, I think that the pads are more for the elective cardioversion kind of maneuver rather
than the emergent defibrillation thing. The critical point is that you really want to just jump in there
and shock that rhythm – you don’t want to futz around with the pad packaging, the wires,
changing the cable connectors so the pads are hooked up instead of the paddles…get the job
done quickly. If the paddles are hooked up and ready, use them – don’t waste time; you can hook
up the pads later and leave them on the patient for use if the problem happens again.
5- How do defibrillators work?
5-1: What is depolarization?
(I have to stick this in: my son pointed out a while ago that when a white bear is captured, and
taken from his iceberg to the zoo, he becomes “de-polarized”. Excellent!)
Here’s how I understand it. Cardiac pacing and conduction cells work by a sort of magic ion pump
dance: the concentrated ions on the outside of the cells all flow inwards at once, then outwards
again. Swoosh, swoosh. The charges around the cell reverse as the ions flow in, or out, and the
polarity flips: the cells are de-polarized – then re-polarized. Is that clever engineering, or what?
In the process of the depolarization dance along the cardiac conduction pathway, a measurable
electrical energy is generated: (P-wave for atria, QRS for ventricles – remember?) Then repolarized. (T-wave.) The conduction cells do this dance in sequence, along the conduction route
from the SA node to the AV node, along through the bundle of His, (hey - where’s Her bundle?)
and on downwards through the bundle branches into the contractile tissues in the ventricles.
Fine so far. But what happens in a lethal arrythmia? The big sign hanging on the inside of the
walls of the ventricles says: “whosoever shall paceth these walls the fastest, shall captureth.”
Right?- the fastest pacemaker always captures the heart. So what to do when a rapid, excitable,
unpleasant little terrorist pacemaker down in the ventricles somewhere has taken over the
rhythm, and generates VT?
5-2: What does electricity have to do with it?
As we saw, it turns out that applying a jolt of electricity along the conduction pathway makes all
the cells depolarize at once, interrupting the sequence. In sinus rhythm the conduction cells do
their sequential dance along the normal route. In VT, they establish some other route –
backwards along the normal conduction path? (Anybody know who the EPS fellow is this month?)
Depolarizing all the cells at once interrupts the sequence as it’s travelling – in whatever direction and hopefully lets one of the intrinsic pacemakers take over. Which hopefully it does - but
sometimes doesn’t…what can you do then?
5-3: What is a joule?
(I always tell my family that they’re my joules.)
Well. This is so incredibly simple that no one should have any trouble with it. Ready? Here’s the
encyclopedia: “Joule: unit of work or energy…equal to the work done by a force of one newton
acting through one metre….it equals 107 ergs, or approximately 0.7377 foot-pounds. In electrical
terms, the joule equals one watt-second – i.e. the energy released in one second by a current of
one ampere through a resistance of one ohm.”
I can’t understand why I even had to mention this subject. I mean, really!
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Here’s the way I think of it. A joule is a hunk of electricity. You need a certain amount of electricity
to cardiovert or defibrillate. That electricity is measured in joules. Fortunately for us, the medical
engineering folks have done all the worrying about this, and made nice machines that fill
themselves up with the right amount of joules when we ask them to.
Let us never forget that we know about these amounts through the generosity of many, many
selfless dogs, who went to heaven with frisbees and bones awaiting them (only beef, not
chicken), never knowing that they gave their lives for us…thanks, dogs.
Another way to think of it: I remember being told once that 360 joules is about the same amount
of power that’s required to start a big diesel truck engine. (!)
5-4: What is monophasic defibrillation?
“Monophasic” means that the current delivered by the machine travels in only one direction
between the paddles. This has been the standard way of doing things for many years, but is now
(like your preceptor) seen as out of date, and is being replaced with a newer method, called
“biphasic” defibrillation.
5-5: What is biphasic defibrillation?
Biphasic means that the current initially moves towards the positive paddle, then reverses
direction and heads the other way. (My daughter used to drive this way.) The difference for us at
the bedside is that biphasic shocks seem to be just as effective as the monophasic ones, but at
lower power levels. This is a good thing for a couple of reasons: first, less power applied means
less trauma to the patient. Second, less power required means longer battery life, and apparently
all implanted defibrillators now use biphasic shocks for this reason – they can also be made
smaller. I remember seeing patients come in with what looked like a small brick implanted under
the skin of their chests…
5-6: What is transthoracic impedance?
This is the electrical resistance that the patient’s chest creates between the paddles. If it’s high,
then more electricity will be needed to successfully shock the patient. Apparently the new
automatic external defibrillators that are being put in airports, phone booths and lunchboxes
practically are able to automatically measure a patient’s impedance, and adjust the amount of
electricity they deliver to match: less for a small person, more for a large one – just the right
amount. Nice trick!
6- How do I cardiovert someone?
Okay – let’s cardiovert somebody. Any volunteers from the audience?
Many of the moves that you will make in either cardioversion or defibrillation are the same – so
let’s go over the basics first, and then we’ll get to the specifics.
Let’s remember that the decision to cardiovert means that your patient is not-quite-in-a-code-yet.
As in every critical situation, remember: there’s time - more time than you think - available for you
to make sure of your plan. How long until anoxic brain injury – 3 to 6 minutes, right? Five minutes
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times sixty, that’s 360 seconds – a lot of seconds! There is always all the time you need. Let’s
take a little of that time now to look at what needs to be set up:
Make sure that you have everybody you need. In our hospital, elective cardioversions are
supposed to include the presence of anesthesia, in case the patient codes and needs intubation.
You certainly want to have the team coming if you start a non-elective electrical maneuver!
Make sure your patient has IV access. More is better. If my patient were being intubated (this
situation might turn into an intubation), I’d have a gravity bag dripping slowly. Make sure your line
isn’t infiltrated. (How?)
Make sure your patient is unconscious, or appropriately sedated. This is not a procedure to do on
someone who’s awake.
Make sure your patient is oxygenated. Why is your patient doing this rhythm in the first place?
Ischemia? Or is the rhythm itself creating ischemia, because the heart is using up all the oxygen
it’s getting, going so fast, but still needs more? (That’s what they mean by “rate-related
ischemia”.) Anyhow, more oxygen to the myocardium is usually better than less, so apply some!
(Does your patient have COPD? Why am I asking?)
The Buttons:
Button One: Turn the machine on, and pick the amount of energy you want to give. The ranges
vary for different situations, but the general rules seem to be: for cardioversion start low – usually
50 joules for example, for elective cardioversion out of a “relatively” stable, a-fib with RVR. For
VT/VF, ACLS says to start with 200 joules. (That’s the monophasic machine number – with the
biphasic machine you start with 150 joules.) Usually you turn a twisty dial control to set the joules
level. The numbers are clear, and there’s a simple arrow pointer that you line up with the number
that you want.
Make it a practice, every now and then, to go over to the machine and make sure you know how
to work it. Familiarity comes with time, so do this a couple of times every week - at least when
you’re starting out in the units. Obviously, you don’t want to have to stand there trying to figure
out how the machine works in the middle of some busy situation.
At this point, make sure your patient’s rhythm is clearly visible on the defibrillator monitor.
Cardioversion is by definition elective, so you should have time to do these things, or you’d be
defibrillating, right? In this situation, take the time to connect the patient to the defibrillator’s
sensing cable. External pacing boxes use the same method – generally, they have to see the
patient somehow. Three sticky electrodes set up a standard lead II. Three wires go to a thicker
cable, the cable plugs into a socket on the machine, and you should see the rhythm clearly.
The monitor should let you choose between leads I, II , III (or paddle view –but that’s for quicklook, usually in defib) – choose the one that gives the clearest upright QRS waveform,
Now comes the “synch” button. This is what makes cardioversion different from defibrillation, and
you absolutely must use this properly. Luckily, it’s not hard at all. Push the button. You should see
a blip, or a dot of some kind that the machine puts on each QRS – this shows you that the
machine clearly sees the QRS, and knows when to deliver the shock – remember that
cardioversion has to be properly timed to avoid the T-wave.
Here’s an important point about the difference between cardioversion and defibrillation: with the
synchronization on, the machine will wait after you hit the discharge buttons to make sure of it’s
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timing, and it won’t discharge until it’s ready. So be prepared to hold those paddles down, hit
those buttons, and wait – it might only be a second or two, but if you’re not ready for what the
machine is doing, you may decide that it’s not working.
Button Two: Charge the machine. Listen for the charging tones.
Button Three: This discharges the electricity from the paddles, so make sure that everything is
quite ready before you do this. Several things need to happen:
Make sure the paddles have conduction gel on them. The electricity will not be properly
transmitted to the chest wall without it. Also, even with the gel these paddles will often cause a
second-degree skin burn – imagine what would happen without the gel!
Make sure that you’ve cleared the bed. This means that just before defibrillating, you take a quick
but careful look around to make sure that no one is holding onto the bed, or leaning on it. You
should not be leaning against the bed either – you should get the rails down, and then lean over
the patient with the paddles in your hands. Yes, it’s true that modern beds are electrically
designed so well that any stray electricity should go into the grounding system, but would you
want to be wrong and have to shock your friend the pharmacist who was leaning over the bottom
of the bed, after you put him into VT?
Bed’s clear? Steady tone from the machine? Place the paddles on the chest – here’s an image
from the web…
I know – if it’s elective,
we’re supposed to be
using the pads. What if
you don’t got no pads?
What if you’re in the
CT scanner? Or MRI?
Should you go running
into the scanner room
with the defibrillator?
(NO!) What should you
do?
Who knows what the
round silver thing is?
Has to do with
implanted
pacemakers…
http://www.usuhs.mil/psl/images/defib.JPG
The idea is that the paddles are sending current from one end of the heart to the other: see that?
The upper paddle sits where the negative lead II electrode lives, and the lower one sits where the
positive electrode lives, so the current travels along the normal conduction path, and so
depolarizes the whole system at once. (I know: I repeat myself a lot – my kids remind me all the
time. Those stupid ginkgo pills – I can never remember to take them…)
Hold the paddles down firmly – the book says 25 pounds of pressure – which is more than you
might think. My wife brings a scale to her ACLS classes, and has the student press the paddles
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down on the scale until it reads 25 pounds. (Is she smart or what?) It turns out to be a lot of
pressure.
Clear the bed. Yes, apparently it is quite true that the current can be transmitted to someone
leaning on, or holding onto the patient’s bed. “One, I’m clear! Two – you’re clear! Three –
everybody’s clear!”
Push the third button. Our paddles have a button number three on each of them, so that you
don’t mistake: you have to hit both, deliberately, to discharge the paddles. Remember now: are
you defibrillating or cardioverting here? Will the paddles discharge right away, or will they wait –
and should you?
Watch the patient and the monitor at the same time – this is why you have two eyes, right?, to
watch two things at once? Ask an old ICU nurse how many things he can watch at once…did the
rhythm convert to normal sinus? Or VT? Or worse? Or was there no change at all? What’s the
patient’s pressure like? What’s the sat like? What’s your pressure like?
Ok – let’s do the pads. There’s some discussion about where they should go:
This way, they take the same positions as
the paddles would, right?
http://www.virtualcpr.com/images/defib_pos.jpg
This is the other way: “anteroposterior” pad placement.
There’s all sorts of learned
argument about which way
works better – but we’ve
recently gone with this one.
This pad arrangement does
seem to work better for
transcutaneous pacing…
All other things being equal, the pads really are a nice development. They’re larger in area than
the paddles, and much stickier, which means less chance of burns, better transmission of the
electricity…just make sure you know which method to use, and when.
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6-1: Cardioverting A-fib:
Here’s a nice strip of a not really too rapid a-fib, followed by artifact from the shock, and then –
what? It’s a little fuzzy - I’ve blown it up a bit too big on purpose so you can really see. See the
shock artifact – the big ugly thing there?
How about this next one?
Did it work? What’s the rhythm after the shock?
My wife the ACLS instructor says that you should start with low monophasic discharge
settings, 50 joules, followed by 100, then 200, then 300 if the patient doesn’t convert. A chart out
on the web says that the equivalent biphasic shocks would be: 70, 120, 150, and 170 joules. After
that, you might have to try chemical maneuvers again.
Then again, it does pay to think a little about why your patient is doing this rhythm in the first
place. Is she septic? Does the rapid rhythm mean that her heart is trying to keep the her pressure
up in the face of a totally dilated arterial bed? Maybe she’s dry. Maybe ischemic. Maybe all of the
above. Maybe she’s being totally stressed because of vent-weaning trials that she’s not ready for
– how does the rhythm fit into the whole picture? It always pays to think about these things…
6-2: Cardioverting VT-with-a-pressure:
As opposed to VT-with-no-pressure, right? This scenario is a little closer to a real code situation
than the a-fib one, because these folks are very likely to lose whatever pressure they’ve got, at
any time. Jayne says that you should set up for an elective cardioversion if you’ve got the time,
but be ready to defibrillate pulseless VT at a moment’s notice. In practice, if your patient is sitting
there smiling at you while in VT on the monitor, the team will try chemical cardioversion first. Up
until recently this involved a lidocaine bolus, followed by a drip, then maybe procainamide –
nowadays I understand that the first drug to try is amiodarone, 300mg IV over ten minutes,
followed by a drip, and then maybe the procaine. Would someone please find out and let me
know?
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7- How do I defibrillate someone?
7-1: Defibrillating pulseless VT
7-2: Defibrillating VF
This is by definition a code. In this situation the ACLS is very clear: shock them first. I would just
add – establish unresponsiveness, right? Could be embarrassing if the rhythm turned out to be
monitor artifact of some kind. (Ask me how I learned that.) It also helps to remember if your
patient is a DNR…
Here’s a pretty good strip, probably from an electrophysiology lab: the official description says
that what’s happening here is first sinus rhythm, then pacing impulses to induce VT – then a
defibrillation shock, and then – what?
CCU nurses: what rhythm does that look like, there in the middle? Anybody got some mag in her
pocket?
Defibrillation is obviously not an elective procedure – the studies show that the most effective
thing to do in both pulseless VT and VF is go right on in there and shock them, starting with 200,
then 300, then 360 joules (or 150/150/150 when using a biphasic device.) In this situation you
don’t wait for the paddles to see the patient’s rhythm, you don’t wait for anything. One thing you
should do is to keep the paddles on the patient’s chest between the shocks (“Shock shock
shock!”) – they may be the only system you have running to monitor the patient’s rhythm. The
monitor should be set to “paddle view” when defibbing – there’s a button marked “lead” – push it
a couple of times to cycle through views until the monitor screen says “paddles” – but do that
after you’ve shocked the patient!
8- What bad things do I have to watch for during cardioversion or defibrillation?
We’ve covered a lot of them already:
-
-
Don’t shock a patient who’s awake!
Don’t forget to synchronize when cardioverting – a-fib can be turned into v-fib this
way.
Don’t forget the conduction gel.
Don’t forget to clear the bed.
Try to keep the process orderly. This means keeping yourself calm and deliberate
when you’re not really sure you can. Set up systematically. Set up communication
with the appropriate team member for orders – don’t take orders from two doctors at
once! Do your best.
Remember that no matter what situation you’re in, you may shortly be in a fullfledged code – make sure that backup help is on the way.
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9- What things should I do after cardioversion/defibrillation?
- Monitor the patient carefully – is the patient staying in the converted rhythm?
- Keep the patient well-oxygenated. This is not the time to wean your patient’s oxygen! I
would aim for a sat no lower than 98%. Remember however, about COPD patients and
oxygen treatment…
- Check up on your patient’s labs – does she need K+, or magnesium? Is she acidotic? –
not a helpful thing.
- Get a 12-lead after the cardioversion for documentation- was the patient having chest
pain? Does she still? Is it gone now? Can she tell?
- Talk to the team about cycling re-CPK’s and troponin studies.
- Assess the patient’s skin – does he need treatment for skin burns?