Neuro Technology NeuroStim Plus User manual

Neuro Technology, Inc.

Instruction Manual for MicroStim Plus Peripheral Nerve Stimulator
Part Number: 8-1053-62

TABLE OF CONTENTS

1. INTRODUCTION

2. SETUP

3. FAMILIARIZATION WITH CONTROLS

4. INDICATORS

5. OUTPUT JACKS

6. BATTERY REPLACEMENT

7. APPLICATION NOTES

8. SPECIAL CONSIDERATIONS AND CONTRAINDICATIONS

9. SPECIFICATIONS

1.0 INTRODUCTION

This manual is provided to aid the Anesthesiologists/CRNA in the operation of a Peripheral Nerve Stimulator
(PNS).

1.1 The MICROSTIM PLUS Peripheral Nerve Stimulator is a constant voltage stimulator for monitoring
neuromuscular block and evaluating muscle relaxant dosage during surgery and recovery.
Note: The MICROSTIM PLUS should not be used with block needles for Nerve Location (See Section 8.3).
Contact Neuro Technology for special products designed for this application.

2.0 SETUP

2.1 Location of the instrument should be within six to twelve feet of the patient (depending on leadwire length) and
approximately five feet above the floor to provide easy viewing of the touch switches (buttons) and indicators.

2.2 The leadwires should be attached to the instrument while the numbered control knob is in the OFF position. See
Section 7.1 for instructions on the use of gelled electrodes.

2.3 The MICROSTIM PLUS can also be used with Ball Probe Electrodes which are provided with the instrument.
These electrodes plug into the RED and BLACK jacks and are convenient for use in both the Operating Room and
Recovery Room when one does not wish to use the gelled electrodes and leadwires.

3.0 FAMILIARIZATION WITH CONTROLS

3.1 Power is applied to the instrument by rotating the control knob located on the left side of the case in a clockwise
direction until an audible click is heard. When the unit is first turned ON, it will be in the standby mode and no
pulses will be generated. The numbered control knob is used to adjust the amplitude of the output current. The
output current value will be in the range of 0 to 70 mA (milliamperes) which corresponds to the numbers between
the OFF and the Number 10 position on the knob. The numbers on the knob serve as a convenient reference for
remembering the approximate settings of the output amplitude.

3.2 The four touch-switches (buttons) located on the front panel provide a convenient means of controlling the
functions of the instrument. They are operated by using a finger to depress the desired function designated under
each of the four buttons. Each time a pulse is generated, the Pulse LED will flash and an audible click will be heard.

3.3 The DBS button will automatically generate a single set of Double Burst Pulses (DBS 3,3). The DBS function
can be repeated as often as one wishes by depressing the DBS button.

3.4 The Twitch button when depressed and held down produces 1 pulse every second continuously until the button is
released.

3.5 The Tetanus function is momentary and will produce tetanic stimulation as long as the button is held down. The
tetanus frequency is set at the factory for 100 Hz. However, the frequency can be changed to 50 Hz by the following
procedure: Remove the battery cover and take the battery out of the instrument. Inside the battery compartment you
will find a small slide switch marked 50 Hz and 100 Hz. Move the slide switch to the desired tetanus frequency,
reconnect the battery, and replace the battery cover. The instrument is now ready to use.

3.6 The TOF (Train-Of-Four) button, when momentarily depressed, will automatically generate four pulses in a
period of two seconds. The train-of-four pulses can be repeated as often as one wishes by depressing the TOF button
again.

4.0 INDICATORS

4.1 The Pulse LED will flash RED each time an output stimulus pulse is generated.

4.2 An audible click will be heard each time an output stimulus pulse is generated. This enables the user to verify
that the unit is stimulating without observing the Pulse LED.

4.3 The Battery LED (green) will normally be ON. When the battery voltage drops to approximately 6.0 Volts, the
Battery LED will begin flashing. The battery should be replaced at that time.

5.0 OUTPUT JACKS

5.1 There are two output jacks located on the front end of the instrument case. Their colors are RED (+) and BLACK
(-). The output can deliver (with a fresh battery) approximately 70 mA into a 2000 Ohm load.

5.2 The BLACK (-) jack is the negative output or common. The leadwire with the BLACK plug should be connected
to the BLACK (-) jack.

5.3 The RED (+) jack is the positive output. The leadwire with the RED plug should be connected to the RED (+)
jack.

5.4 The Ball Probe Electrodes can also be used with the MICROSTIM PLUS by plugging them into the RED and
BLACK output jacks.

6.0 BATTERY REPLACEMENT

The battery is easily replaced by turning the instrument over and removing the battery cover, unsnapping the old
battery and snapping in a fresh one. The battery should always be replaced with a 9 volt alkaline battery. The
instrument will operate satisfactorily down to a battery voltage of approximately 6.0 volts. At this voltage level, the
Battery LED (green) will begin flashing. When the LED starts flashing, the instrument can still be used, but the
battery should be replaced as soon as possible.

7.0 APPLICATION NOTES (monitoring of neuromuscular function)

7.1 LEADWIRE ATTACHMENT WHEN USING GELLED ELECTRODES
The leadwire with the BLACK plug should be plugged into the BLACK (-) jack located on the front end of the
instrument case and the leadwire with the RED plug should be plugged into the RED (+) jack. Gelled electrodes
should be placed in line with and over the ulnar nerve. The distal (negative) electrode should be placed at the level
of the proximal flexor crease of the wrist. The electrode pair should be placed directly over and parallel to the flexor
carpri ulnaris tendon.

7.2 BASELINE ADJUSTMENT
Before any muscle relaxant is administered, the instrument should be adjusted to provide Supramaximal Stimulation
(SMS). SMS is defined as the level at which additional stimulation current does not increase twitch response. This
setting can be approximated by adjusting the control knob to the level where any further increase in stimulus current
would not increase the level or height of the twitch response. Note the number on the control knob and maintain this
baseline setting throughout the entire procedure.

7.3 TWITCH RESPONSE
The simplest test provided by the PNS is the twitch response where individual stimuli are generated at intervals of
one to ten seconds. Shortly after administering the muscle relaxant, the twitch response will start to become
depressed. At this point more than 70 percent of the receptors should be blocked. When the twitch is completely
eliminated, greater than 90 percent of the receptors are occupied by the relaxant. The twitch can be used as a
quantitative monitor by adjusting the muscle relaxant administration to maintain a faint, but perceptible muscular
contraction (twitch) in response to the PNS. This assures adequate operating conditions while avoiding excessive
relaxant administration. In the event the twitch has been abolished by an inadvertent relaxant overdose, if one waits
until the twitch reappears before administering subsequent relaxant, the incidence of failure of reversal can be
minimized.

7.4 TETANIC STIMULI
When the single twitch response has returned to normal, approximately 20 percent of the receptor pool is free.
Fortunately, the diaphragm needs fewer receptors available to respond normally than do peripheral muscles. This
can be observed clinically in that spontaneous respiration may be detected before an indirectly stimulated response.
However, a patient with 80 percent receptor block may still need to be carefully monitored. Thus, it is important to
have a means of assessing when recovery has proceeded to a more adequate level. It was to this end that the tetanic
stimuli evolved. This is the administration of 50 or 100 Hz stimuli for a period of approximately 5 seconds duration.
The higher frequency puts a greater demand on the neuromuscular synapse because as each successive stimulus
arrives at the nerve ending, it depletes the local store of transmitters so that the amount of acetylcholine available for