# AP vs AL defib pad placement



## d_miracle36 (Sep 9, 2012)

Does anyone have any preference on pad placement besides convenience?


----------



## Handsome Robb (Sep 9, 2012)

Usually it's monitor specific unless I'm mistaken. 

For us it's apex/sternum for defib and we can pace in that configuration as well but they prefer anterior/posterior for pacing.


----------



## Christopher (Sep 9, 2012)

Usually when monitors have a preference it is related to how their waveform libraries were made to test their AED functionality. Ant/Lat configurations produce Lead II-like waveforms while Ant/Post configurations produce V1-like waveforms.

The good news is that VF looks like VF whether you're monitoring Lead II or V1 

As for making a difference?

Pad positioning theoretically can make a difference in impedance, which can have a big effect in the energy delivery from the device. Modern biphasic defibrillators will send a test impulse through the pads to determine the impedance between the two pads. It then uses this information to calculate the joules required at the skin to produce the User Specified Energy (say 150 or 200J) at the heart. Usually this is done with an assumption that the heart is in the middle of a sphere in order to make the math nice.

However, Ant/Lat versus Ant/Post has not really shown any difference in the world of defibrillation, but Ant/Post has been shown to be better when pacing the heart. However, keep in mind that transthoracic impedance is a *local* variable, meaning every patient will be different.

Interestingly enough, the biggest modifiable factor EMS has in terms of lowering chest wall impedance is Pad Size and Pad-Skin contact. Using the largest available pads with a good solid contact will result in the lowest impedance.

The key takeaway here is that TTI is _NOT_ related significantly to body mass, patient size, or pad placement but it IS related to Electrode-Skin size and contact.


----------



## d_miracle36 (Sep 9, 2012)

Christopher said:


> Usually when monitors have a preference it is related to how their waveform libraries were made to test their AED functionality. Ant/Lat configurations produce Lead II-like waveforms while Ant/Post configurations produce V1-like waveforms.
> 
> The good news is that VF looks like VF whether you're monitoring Lead II or V1
> 
> ...


We have zolls. I read that for defibrillation purposes they recommend anterior left of sternom and posterior, and when pacing to move the anterior pad to right of sternom. Does that make sense?


----------



## Christopher (Sep 9, 2012)

d_miracle36 said:


> We have zolls. I read that for defibrillation purposes they recommend anterior left of sternom and posterior, and when pacing to move the anterior pad to right of sternom. Does that make sense?



My understanding is for defib it depends on the pads you select. The stat-padz/CPR padz are intended for traditional Ant/Lat placement (they call it Sternal/Apex placement). Their recommendation for cardioversion of atrial arrhythmias is Ant/Post with the Apex/anterior pad to the right of the sternum. Their recommendation for cardioversion of ventricular arrhythmias is Ant/Post with the Apex/anterior pad along the inframamary fold / 5th ICS. This is the same position recommended for pacing.

Again this is based off the operators guides and the pad packaging.


----------



## d_miracle36 (Sep 9, 2012)

Christopher said:


> My understanding is for defib it depends on the pads you select. The stat-padz/CPR padz are intended for traditional Ant/Lat placement (they call it Sternal/Apex placement). Their recommendation for cardioversion of atrial arrhythmias is Ant/Post with the Apex/anterior pad to the right of the sternum. Their recommendation for cardioversion of ventricular arrhythmias is Ant/Post with the Apex/anterior pad along the inframamary fold / 5th ICS. This is the same position recommended for pacing.
> 
> Again this is based off the operators guides and the pad packaging.



Our pads.are either or. We dont have the stat pads yet. On the stat pads isnt the manometer connected to the sternal pads. Can you tear that off if you place the sternal pad posterior? I guess if you use the posterior placement it would make hands on defibrillation safer:unsure:


----------



## Christopher (Sep 9, 2012)

d_miracle36 said:


> Our pads.are either or. We dont have the stat pads yet. On the stat pads isnt the manometer connected to the sternal pads. Can you tear that off if you place the sternal pad posterior? I guess if you use the posterior placement it would make hands on defibrillation safer:unsure:



You can tear/cut off the accelerometer, and I would imagine it would provide wonderful protection against hands-on-defib.

However, given rhythm interpretation is not 100% even with See-Thru CPR, I'd still give a brief pause to interpret.


----------

