What is the difference between monophasic and biphasic defibrillators?

[EJSRN]

What is the difference between monophasic and biphasic defibrillators?? And how many joules do you charge each one? How do you determine the amount of joules to administer?

[rnffemtguy, BSN, RN]

In the simplest terms I can think of to explain:

A monophasic defibrillator delivers a preset shock measured in joules, usually in steps which are selectable on manual models and preset on automatic & semi-automatic defibrillators

A biphasic defibrillator measures impedence through body tissues and selects an appropriate joule amount to deliver succsefull cardioversion without using too much energy which can cause burns or myocardial damage

Biphasic defibrillation is now the standard for all new defibrillators, it first came about in implantable defib/pacers, then made it's apperance in external defibs, I don't think there are many purely monophasic defibs on the market any more......

[sjt9721, BSN, RN]

rnffemtguy said:

...I don't think there are many purely monophasic defibs on the market any more......

Probably just refurbs that are advertised in the back of JEMS & other mags...

[rnffemtguy, BSN, RN]

sjt9721 said:

Probably just refurbs that are advertised in the back of JEMS & other mags...

Yeah I was thinking of seeing if I could pick one up cheap & convert it to a portable battery booster pack

[elthia]

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!!

To quote my ACLS instructor... when in doubt and you have a pt in Vfib or pulseless Vtach and you are going to shock, charge it all the way the machine will go, CLEAR and SHOCK. Most people will not know how to override the machine, so don't worry. Effective CPR and quick defibrillation are what you need.

For cardioversion of other arrhythmias you will have to adjust the amount of joules, but that is for advanced users, and you should have a code team to help you.