MyoTrac Infiniti
™
User Guide
20
Using the MyoTrac Infiniti with AC Power Adapter or Connected to a PC
The MyoTrac Infiniti is designed for safe operation on ungrounded AC power sources. However, if
you are using the MyoTrac Infiniti while it is connected to an
ungrounded
AC power source, for
best results you may need to follow some simple guidelines for skin preparation and electrode
placement. These measures will help to avoid falsely elevated EMG readings while the muscle is at
rest.
If you notice elevated resting EMG levels not related to the patient’s condition, and if this occurs
only when the unit is connected to AC power (directly via the supplied AC adapter or indirectly via a
USB connection to the PC), and if it is necessary to run the MyoTrac Infiniti on ungrounded power
(i.e. no 3rd ground pin on the AC wall socket or on the PC power supply), try the following
techniques to improve the readings.
First, if you are using a PC with only 2 prongs on the wall plug and you have a grounded outlet (3
pin wall sockets with a working ground), plug the ac adapter into the MyoTrac-Infiniti and into the
grounded outlet to provide a ground for the system.
If you have no opportunity to ground either the PC or the AC adapter, use the following electrode
placement tips:
If the EMG site is located on an extremity or limb, be sure to place the REF (black colored)
electrode more proximally (on or closer to the trunk of the body) than the sense electrodes
(yellow and blue), and at least ten centimeters away from either sense electrode.
Prepare the skin under all three electrodes, using a product designed for skin preparation prior
to electrode application (mild abrasives such as NuPrep are effective).
If you are using Ag/AgCl (silver/silver chloride) electrodes, put some conductive electrode
paste or cream on them before applying them to the skin, or try using gel-type rather than dry
Ag/AgCl electrodes.
Resting EMG readings will not be affected by connection to AC power, in the following cases:
Running the MyoTrac Infiniti stand-alone, with no AC power adapter and no connection to the
PC (only on its rechargeable batteries).