12 lead placement

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BobBarker

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When training in an ER, we were taught to place the limb leads on the lower left and right abdomen (near the belly button) and the wrists as opposed to the shoulders/wrists or wrists/ankles. When I was on shift the other day, a paramedic asked me why I did that as he never saw it done that way before. We ran the 12 lead both ways and there was not much change at all, so I am assuming either way is fine.
Sooo... where do you guys put your limb leads on?
 
It depends on what’s accessible. It has no real clinical significance for the field paramedic. Cardiologists and EP docs may disagree. I usually use arms and legs, but will use the torso if it’s easier.
pubmed.ncbi.nlm.nih.gov

Does modifying electrode placement of the 12 lead ECG matter in healthy subjects? - PubMed

We provide better and more robust evidence that routine modification of limb electrode placement produces only minor changes to the ECG waveform in healthy subjects. These are not clinically significant according to the 2009 guidelines and thus have no effect on the clinical specificity of the...
pubmed.ncbi.nlm.nih.gov pubmed.ncbi.nlm.nih.gov
 
BobBarker said:
Sooo... where do you guys put your limb leads on?
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where do you think the LIMB leads should go? I mean, they aren't called the torso leads right?
 
Limb position leads is most correct. The main thing torso position placement does is it causes a small amount of right axis deviation. I personally don't consider that significant and don't care where people put it.
 
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Definitely not always feasible to reapply them on a patient’s limbs (i.e., legs) in a 407. Even precordials can take some finagling, but definitely easier.

I guess the question is, will it really affect patient care prior to transferring them to the receiving facility?

I’d think most would know a truly sick cardiac patient when they saw one regardless of where they place the 4-leads.
 
I think the whole "hide" or "create" a STEMI thing is maybe changing QRS complex size. ST change is usually proportional to QRS. Bigger QRS means more ST change. If you're using arbitrary number like 1 or 2 mm ST elevation, it could make ST change pass that threshold. Causing a rightward shift, generally the R wave in lead I would get smaller so probably ST change as well "hiding" a lateral wall MI. A normal axis patient shift rightward would probably point more inferior creating taller R waves in the inferior leads, particularly lead III, "creating" an inferior wall MI. The central terminus in the precordial leads I believe shift too. This is all slightly. I think in reality, if you are comparing the ST change to the size of the QRS complex, you will still be recognizing STEMIs and STEMI mimics. Large QRS means a little bit of ST change might be normal (eg left ventricular hypertrophy, left ventricular aneurysm). Sometimes ST change will be subtle, <1 mm, but will be significant because the QRS is so small. I think if you aren't using abritrary rules, are aware of the changes moving leads around will cause, you should be okay... I think. Could be talking out of my behind, but that's my edumacated guess, lol. I'd be curious to hear the ECG experts thoughts on this (eg TomB, Christopher). I saw a video I think starring TomB where I think he said "limb leads go on limbs" awhile ago. Not sure if his thoughts are the same as when that video was made?

I feel like saying something along the lines of "treat the patient, not the monitor" kinda sends the wrong message. I don't believe you can always set eyes on a patient and figure out if it is an MI. Afterall, we aren't just going through the motions of doing the 12-lead for fun. The big sick vs little sick thing is a good general tool, especially for people not comfortable with 12-leads. You got to consider you might be going down the wrong pathway if your patient is big sick, but the 12-lead isn't showing a STEMI. Consider the possibility it is something else. Will they still benefit going to a STEMI center if another hospital is significantly closer? Can you do serial 12-lead? Will Aspirin and Nitroglycerin still be safe in this patient if I give it? Consider doing serial 12-lead. Gotta be careful of continuation bias just because the patient seems "big sick" or seems like they are having a heart attack.

VentMonkey said:
Definitely not always feasible to reapply them on a patient’s limbs (i.e., legs) in a 407. Even precordials can take some finagling, but definitely easier.
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Dude... I don't know how people are doing 12-leads in the 407. Everytime I do it, the 12-lead printout gives me an EEG readout instead and then neurology will get involved asking me the last seen normal time.
 
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Aprz said:
Dude... I don't know how people are doing 12-leads in the 407. Everytime I do it, the 12-lead printout gives me an EEG readout instead and then neurology will get involved asking me the last seen normal time.
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What's the 407?
 
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Physio wants you to put the limb leads somewhere on the limbs for the 12 lead. Hospital device might be different.

Sometimes limb anatomy or tremors makes this less practical and I’ll put the leads on the torso. Would rather have an EKG that I can read 🤷‍♂️ . Also for rate monitoring I’ll put the leads on the torso, less susceptible to movement that way.
 
Aprz said:
Dude... I don't know how people are doing 12-leads in the 407. Everytime I do it, the 12-lead printout gives me an EEG readout instead and then neurology will get involved asking me the last seen normal time.
Click to expand...
Upper limb leads above the clavicle and lower limb leads just below the nipples helps with artifact in any aircraft.
 
I prefer people to place them on the limbs. Like Tigger mentioned, it's in the LP15 manual. I suspect their reasoning is probably software based and their algorithms are expecting the leads on the limbs.
Also, I've noticed that when people stick them below the clavicle and on the abdomen, they can be rather sloppy about it. Having the LL just off the patient's trachea because the provider was trying to stick an electrode down a tight fitting shirt is sub optimal.
Less patient exposure to just stick the limb leads on the already exposed limbs.
Anecdotally, I have more leads pop off when they're stuffed down someones shirt too. Less of that happening when they're stuck anywhere on the limbs.
 
GMCmedic said:
Upper limb leads above the clavicle and lower limb leads just below the nipples helps with artifact in any aircraft.
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I was trying to joke that I put the 12-lead on the patient's head.
 
I’d add, most of my STEMI activations ground and air most likely have had the limb leads on the torso.

Guess what they still got? Applicable ACS treatment by myself, a repeat 12-leas before the cath lab (hospital dependent), and proper PCI.

Again, I’ll posit. How trivial is this really?
 
Once you understand how the bipolar leads and Einthoven’s Triangle work, you’ll understand that wrists vs shoulders or ankles and abdomen don’t really matter. The polarity of the leads is what’s important, not where on the “extremity” it’s placed. The vector of the conduction between electrodes is what makes the difference.
 
Some machines may have a setting for Limb or Torso placement of the 4 "limb" leads. Just place the leads according to the setting, or place the leads wherever and change the setting to match. Either way, as noted above, you're not going to get a huge difference. My suspicion is that if your machine does have such a setting, it probably applies a correction algorithm to the limb lead readings so that the result more closely matches a "traditional" limb lead placement.

I'd say that for field providers on this topic is pretty simple. If you've got a close "maybe" STEMI or other AMI indicator and you're doing a trunk lead position and your patient looks remotely like they're in need of the services of a cardiologist, err on the side of more likely to be a problem than not and let the hospital sort it all out as they've got the labs too...
 
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