What is the difference between monophasic and biphasic defibrillators?

Flightline, BSN, RN · Nov 12, 2008

Monophasic is basically DC current. It passes in one direction from one paddle to the next. Biphasic is like an AC jolt, part of the shock goes from one paddle to the next and then reverses from the opposite paddle back. Less energy is required for the same effect.

I believe the joules for monophasic 360, and a biphasic is 200. Therefore there is less myocardial damage using a biphasic defibrillator and many studies that show better results in converting VT and VF. During a code, I believe current ACLS guidelines state that if you are using a monophasic you just keep it on 360 joules for every shock, and if you don't have instructions to the contrary, keep the biphasic defibrillator set on 200 joules.

CABG patch kid, BSN, RN · Nov 12, 2008

Flightline said:
Monophasic is basically DC current. It passes in one direction from one paddle to the next. Biphasic is like an AC jolt, part of the shock goes from one paddle to the next and then reverses from the opposite paddle back. Less energy is required for the same effect.
I believe the joules for monophasic 360, and a biphasic is 200. Therefore there is less myocardial damage using a biphasic defibrillator and many studies that show better results in converting VT and VF. During a code, I believe current ACLS guidelines state that if you are using a monophasic you just keep it on 360 joules for every shock, and if you don't have instructions to the contrary, keep the biphasic defibrillator set on 200 joules.

Just to clarify, I think the Flightline meant biphasic is like an AC jolt and passes one way then reverses back to the opposite paddle. The jolt goes two ways (bi) while a monophasic goes one way. In the second paragraph I think she meant you keep monophasic on 360 joules for every shock.

Not trying to be a jerk and point out mistakes, just trying to clarify

Flightline, BSN, RN · Nov 13, 2008

Quote
Just to clarify, I think the Flightline meant biphasic is like an AC jolt and passes one way then reverses back to the opposite paddle. The jolt goes two ways (bi) while a monophasic goes one way. In the second paragraph I think she meant you keep monophasic on 360 joules for every shock.
Not trying to be a jerk and point out mistakes, just trying to clarify

Not at all. Thank you that's exactly what I meant to say. I must have been self-medicating with Jameson that night. I edited my post to correct it. Again thanks.

ZippyGBR, BSN, RN · Nov 13, 2008

The 'eating the young ' answer is ' if you don't know that should you be anywhere near a manual defib ?'

The geek ( and correct technically answer) is rtfm (read the flipping manual )

Monophasic shocks are purely dc i.e. The potential goes one side of the arbitrary zero point where biphasic delivers part of the shock one side of the arbitrary zero point and the rest the other

Current guidelines say monophasic 360 j and biphasic at the makers recommended setting - which is usually 150 or 200 j depending on the exact waveform used

EJSRN, BSN, RN · Nov 13, 2008

ZippyGBR said:
the 'eating the young ' answer is ' if you don't know that should you be anywhere near a manual defib ?'
the geek ( and correct technically answer) is RTFM (read the flipping manual )
monophasic shocks are prley DC i.e. the potnetial goes one side of the arbitrary zero point where biphasic delivers part ofthe shock one side of the arbitrary zero point and the rest the other
current guidelines say monophasic 360 j and biphasic at the makers recommended setting - which is usually 150 or 200 j depending on the exact waveform used

I'm just trying to learn here. I am new and havn't used one. I guess I shouldn't ask questions....

Editorial Team / Admin · Nov 13, 2008

EJSRN said:
I'm just trying to learn here. I am new and havn't used one. I guess I shouldn't ask questions....

You ask anything you wish, EJSRN. That's why we are here at allnurses.com, to assist and educate in a supportive manner.

Silverdragon102, BSN · Nov 13, 2008

EJSRN said:
I'm just trying to learn here. I am new and havn't used one. I guess I shouldn't ask questions....

Questions are what keeps everyone up to date, things are always changing in this profession so please ask away, only way to learn

allnurses Guide · Nov 13, 2008

Try this

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With the increasing availability of biphasic defibrillators for use in both the manual and shock-advisory modes, considerable confusion has developed as to the appropriate energy levels to be used with these devices. This confusion has arisen partly because of differing recommendations from manufacturers, partly as a result of limited clinical evidence and partly because of the clinical availability of both monophasic and biphasic defibrillators. The differences between these waveforms are the way energy is delivered. Biphasic energy is delivered in two directions, whereas monophasic energies are delivered in one direction. Recommendations of the International Liaison Committee on Resuscitation state that biphasic energies less than or equal to 200 J are as efficacious as escalating higher-energy monophasic shocks.1 Lower-energy biphasic shocks cause less myocardial injury and postresuscitation myocardial dysfunction, and so potentially improve the likelihood of survival.

Biphasic or monophasic defibrillation for adult ventricular fibrillation

Here is a diagram of the different waveforms

And if that's not enough this is a very good read if your interested in defibrillation waveforms and want to learn more about the biphasic truncated exponential waveform or the rectilinear biphasic waveform (I'm a bit geeky when it comes to defibrillators)

https://www.ebme.co.uk/articles/clinical-engineering/biphasic-defibrillation

You'll find all the information you need about the different defibrillators.

The evidence all suggests that biphasic is better energy to use for the termination of shockable rhythms and we will be seeing less monophasic machines in clinical areas.

Hope this is helpful

mukudiya, BSN, RN · May 15, 2009

even i have some uqeries regarding this! how do u identify by just looking at a defibrillator tht it is mono or biphasic? also our anaesthesiologist told us tht only the first shock is of 200 J in biphasic the successive shocks shud be of 360J.but another one told tht there is no energy selection option available to tht amount in biphasic .as a result iam confused!!

sjt9721, BSN, RN · May 15, 2009

EJSRN said:
I'm just trying to learn here. I am new and havn't used one. I guess I shouldn't ask questions....

Relax already!

Zippy was just yanking your chain...just a little good-natured ribbing.

Read the entire post...your question DID get answered.

Editorial Team / Admin · May 15, 2009

mukudiya said:
even i have some uqeries regarding this! how do u identify by just looking at a defibrillator tht it is mono or biphasic? also our anaesthesiologist told us tht only the first shock is of 200 J in biphasic the successive shocks shud be of 360J.but another one told tht there is no energy selection option available to tht amount in biphasic .as a result iam confused!!

You cannot tell by looking at the machine if it is bi or mono. You can check the following to see if your machine is bi-phasic or mono-phasic:

The Main Keypad label
The Part Number (PN) on the manufacturer's label.

The anaesthesiologist is incorrect. With a bi-phasic, first shock is 200 J and subsequent shocks are 200 J.

In many machines, one can go into the machine and override the max 200 J setting and select 300 or 360 J. But, for ACLS protocols with V-fib and Pulseless V-tach, it is initial shock 200 J and subsequent 200 J with a bi-phasic model.