Where do you put the limb leads?

[18G]

I always put them on the chest. Mainly because it reduces artifact in the field with patient's who want to be moving their arms all around. I think this is the premise for this common placement.

Technically, they are supposed to be placed on the limbs. For 12-leads I try to remember to place the limb leads on the limbs since this is where the hospital places them for their 12-leads. It has been said that some variation can be had on the ECG if electrodes are placed differently on different acquisitions (ie pre-hospital places on chest, hospital acquires on limbs = variation in waveforms).

The majority place limb leads on chest from my almost 20yrs of experience.

I can't imagine electrodes on the ankles would work out too well pre-hospital and would think the wires would be off more then on.

 

[8jimi8]

Technically, they are supposed to be placed on the limbs. For 12-leads I try to remember to place the limb leads on the limbs since this is where the hospital places them for their 12-leads. It has been said that some variation can be had on the ECG if electrodes are placed differently on different acquisitions (ie pre-hospital places on chest, hospital acquires on limbs = variation in waveforms).

quoted just to emphasize whomever's idea I adopted about circling your original electrode placement in sharpie. It just leaves a better trail when you have the patient who requires serial ECGs.


You also have to remember the purpose of your monitoring. If you are simply watching a rhythm, chest placement is fine.

If you want DIAGNOSTIC quality, you need to place them correctly. (general you)

 

[systemet]

The electrodes for the limb leads need to be roughly equidistant from the center of the heart.

This is necessary for generating the appropriate negative electrode for the augmented leads e.g. (aVL negative pole = RA + LL; aVR negative pole = LL + LA, aVF negative pole = RA + LA). This is also required to produce an accurate wilson's central terminal (RA + LA + LL) for generating precordial leads.

If, for example, the electrodes are placed on the deltoids and the ankles, the signal from the LL electrode will be weaker versus the signals from the RA and LA electrodes. This will distort any lead that uses the LL electrode (II, III, aVL, aVF, V1-V6, i.e. basically everything).

If the electrodes are going to be placed on the chest, or on the shoulders, then the corresponding ground and LL electrodes need to be on the torso or upper thighs.

If there's a big enough infarct, poor placement might not affect the ST segment enough to alter treatment. But in marginal cases it could be critical. It's best if a system has one standard for landmarking for all 12-leads, and that this is the same standard used by local hospitals. This way old ECGs can be compared to the EMS tracing.

All the best.