Hands- On: Learning to Use Myoguide
The following steps can be used to learn and verify functionality of the Myoguide device.
For first time users, it is a good idea to play with Myoguide on your own, before engaging patients. These exercises will help you learn about measuring EMG and delivering stimulation on your own hand, using surface electrodes. It’s a simple way to learn to use Myoguide without a patient.
This procedure can also be used when experiencing perceived issues related to excess noise or stimulator performance. If perceived issues have been eliminated using the following procedure, the functionality of the Myoguide device can be confirmed and sources of perceived issues can be focussed on electrode quality, electrode placement or proper skin preparation.
Myoguide Set-up Procedure
1.0 Application and setup of electrodes
Using the photo as a guide, place electrodes on the thumb. Feel free to use leaded, snap or tab electrodes. For snap or tab electrodes, you must use the alligator adaptors.
If using leaded surface electrodes, the surface electrode leads can be plugged directly into the Myoguide Input Cable (Model 8008-CT) with red surface electrode connector plugged into red connector on Myoguide input cable, black surface electrode plugged into black connector on Myoguide input cable and green surface electrode connector plugged into green connector on Myoguide input cable.
Tab or Snap type surface electrodes can alternately be used by using the supplied colour coded Myoguide cable adapters (Model 8008-CA, Model 8008-CA-R and Model 8008-CA-G). Simply connect the cable adapters to the corresponding coloured jacks on the Myoguide Input Cable and clip the alligator connector end to the surface electrode tab or snap.
Leaded electrodes should be as short as possible, to avoid extraneous noise pick up from the unshielded high impedance lines. This is true for both this learning exercise, as well as clinically.
When long lines are unavoidable in the clinic, you can reduce noise by eliminating noise sources like fluorescent lights. Noise can also be reduced by twisting the leads, that will wrap the ground wire around the input and reference inputs. This will act as a makeshift shield.
Please clean the skin area where surface electrodes are to be applied using proper skin preparation techniques and apply the electrodes as shown.
NOTE: Surface electrodes must be from an un-opened, non-expired package. As surface electrodes have a shelf life, use of expired or dried out/stale electrodes can cause noise and performance issues which will be seen as excessive noise or failure to display EMG correctly or degraded stimulator performance.
2.0 EMG Mode Verification
Turn on the Myoguide and set the Vol: parameter to 4 (default setting) and the V: parameter to 2.
The volume setting is actual the amplifier’s gain control. The “V” parameter is simply a visual display control.
Myoguide should now display EMG with minimal display deflection when the thumb is at rest and clean larger EMG deflection when thumb is flexed. If this is observed, the device is functioning correctly in EMG Mode.
3.0 Stimulation Mode Verification
To verify Stimulation Mode functionality, press and hold the Mode button on the device until the Stimulation screen is displayed. Set F: parameter (Frequency) to 1 Hz and PW: parameter (Pulse Width) to 500uS. Position the cursor over to the leftmost digit of the mA parameter (adjusts stimulation current by 1mA per step).
Slowly increase the Stimulation current until stimulation is felt in the thumb. Typically, stimulation becomes quite pronounced by 5 or 6 mA. If Stimulation is felt, the device is functioning correctly in Stimulation Mode.
Please play around with the stimulation pulse widths, and you should notice that wider pulse widths can evoke a twitch at a lower current setting. This should be more comfortable for you and subsequently for your patients.
If correct functionality is determined using the above procedure, issues related to noise, movement artifact and stimulation performance are most likely related to electrode quality, sub-optimal electrode placement or skin preparation.
Feel free to contact us if there are any questions. We will be happy to respond and help you with learning to use Myoguide, or solving any performance issues.