GE Cardiolab II Plus Service Manual page 58

Appendix A – Maintenance and Troubleshooting
ECGs are Flat
Stimulus Artifact on Intracardiac Channels
A-8
Ensure that the soft scale is no greater than 1/4. Also, abnormally
high gain settings for ECGs may contribute to an offset problem.
Check the filter settings for the signal.
Continued problems with signal offset may mean that the amplifier
needs calibration. Calibration must be performed by a trained GE
Service personnel.
When inspecting a full 12 lead, is there any one signal which is
flatline?
If Lead I is flat and all other signals are good, apply a new left leg
patch.
If Lead II is flat and all other signals are good, apply a new left
arm patch.
If Lead III is flat and all other signals are good, apply a new right
arm patch.
If changing the patch doesn't help, swap the suspected limb lead wire
with any of the other lead wired.
In many cases, an abnormally low soft scale value can lead to
flatlines. Values of 1/8 and 1/4 are recommended.
Select Reset Hardware from the amplifier test window under the
Administration menu.
It may be necessary to replace the ECG cable (the cable between the
amplifier and the limb leads).
If using a simulator to test the ECG signals, always make sure the
right leg lead is attached to the ground of the simulator.
NOTE
If this is the first case in which you have seen this problem, the
problem is most likely with a "case variable". A case variable is
something which has changed since the last case was performed.
Catheters and catheter extenders are good examples of case
variables. If the amplifier has worked properly in the past, it is
doubtful that is has suddenly developed a stim artifact problem. New
or re-sterilized catheters may have a short or bad connection.
Does the artifact occur when pacing from one catheter but not from
others?
If yes, connect a catheter that is not producing stim artifact to
the same inputs on the catheter input module (CIM) where the
Cardiolab® II Plus Amplifier Manual 2002938-002E