How to test ECG electrode and contact issues - Health IT

How to test ECG electrode and contact issues

To test before connecting to patient

For more tips and how-to's, visit our tech blog

A common problem that can happen with any ECG is a patient connectivity problem. This is usually either between the metal banana plug on one or more of the patient electrode patches or the patch/clip itself, particularly on the limb electrodes (LL, LA, RL and RA).

Note that these issues can happen even to the most experienced ECG operators and most commonly is not the cause of the way they have affixed the electrode to the patient, but something going on with the patch or the parts connecting it to the patient.

Note: The most important thing to remember is that all four limb electrodes (LL, LA, RL and RA) must be making contact with the patient properly to get a tracing from this ECG device. If ANY of the limb electrodes aren’t making contact (either between the clips and the banana plug) or through the patient patches, there will be no tracing or the tracing will be unstable. Be sure to focus any troubleshooting efforts on these four limb leads first.

Testing ECG leads

  1. Unplug the clips from the end of the banana plugs for the following leads: LL, LA, RL and RA (the limb leads).
  2. Start an ECG capture (without a patient present, just the ECG device connected to the computer).
  3. Touch the four limb lead connectors together. This requires all of the four leads (mentioned in step 1) to be touching each other at the same time by the metal part of the banana plugs.
Figure 1: Metal pins touching each other (limb electrodes only).

4. Look at the screen; the ECG tracing should show what appears to be a flat line for every part except for V1 through to V6. If the banana plugs are held together nicely, then it should be a clean flat line. 

If this works nicely, then the problem is likely with the contact with the clips/patches and/or the patient. Try turning the banana plug a little bit when the clip is on the end to ensure that the metal parts are making good contact. Also, try cleaning the metal banana plugs with an alcohol-based solution and try testing again.

It could also be faulty patches (as the gel on most modern patches can deteriorate over time, particularly if left in a hot/sunny area). Many customers choose to store their patches in a sealed bag/container in the fridge to prolong their life. If none of the above works, try to use a few new patches. Faulty clips can also cause this, so if problems persist, try another clip/patch combination that suits the ECG (talk to your usual distributor about this).