Standard Operating Procedure (SOP): Nerve Conduction Velocity (NCV)
Measurement using RMS Polygraph
1. Powering On the System:
• Switch on the computer system using the main switch, UPS, and CPU.
• Ensure proper earthing is provided to the RMS Salus NCV Aq-Box.
2. Connecting the NCV Device:
• Verify that the RMS Salus NCV Aq-Box is connected to the CPU.
• Switch on the Salus device.
3. Preparing the Amplifier and Stimulator:
• Ensure the Salus NCV amplifier box and stimulator probe are available for the
procedure.
• Electrode Connections on the amplifier unit as follows:
• Black button electrode: Active (ACT).
• Red button electrode: Reference (REF).
• Insert these into Channel 1 of the amplifier.
• Connect the green flat disc electrode to the common ground (GND) or channel 1
ground port on the amplifier.
4. Preparation and Settings
• Open the Salus NCV software on the desktop.
• At the bottom right corner, enter the patient details (F9), and the correct channel
selection in top left corner.
• For motor nerve testing, select the relevant tab from top left corner.
• Go to new nerve test from bottom right corner and select the relevant nerve and its
side. (E.g Median Left)
• Set the following initial parameters on the top right corner of the open window after
the above step.
mA: 0-100mA (depends on the patient)
Mode of Operation: Remote
Mode: Single.
Rate: 10.
Limit: 100 mA.
Train of Stimuli: 1
Duration: 100 μs (single stimulus).
5. Skin Preparation, Electrode Placement, Polarity:
• Clean the patient’s skin with spirit and cotton at the area of interest.
• Example for the median nerve: Place electrodes near the Abductor Pollicis Brevis
(APB) muscle, stimulation at the wrist and slightly above cubital fossa.
• Fix the electrodes using jelly and micropore tape:
• Black electrode (active): On the belly of the APB muscle;
• Red electrode (reference): Over the tendon of the above muscle 2-3 cm apart from
the active electrode;
• Green electrode (ground): Placed anywhere nearby on the patient, preferably away
from the areas of interest.
• Before starting, check the nerve, it's side and relevant patient details to be tested are
displayed in the upper left corner of the screen.
• Before stimulation, check the nerve conduction direction: Antidromic or
Orthodromic (commonly used). Red light indicates the anode on the stimulator and
shows the direction of current.
6. Stimulation and Data Capture:
• For motor nerve conduction velocity, 2-point stimulation is required, at one at a time.
• Locate the median nerve first at the wrist and (later above cubital fossa), position the
stimulator (orthodromic method).
• Gradually increase the current while delivering stimuli.
• Capture the graph (button on the stimulator) once a clear and accurate response with
maximum amplitude of CMAP is observed. MARK THE POINT OF STIMULATION (very
imp)
• Adjust the vertical marker for the latency, (at baseline where graph takes off) and
horizontal markers for amplitude on the graph. (Baseline to positive peak)
• Move to the next point of stimulation and repeat the last 3 steps.
• Measure the distance of the 2 stimulation points and enter it as millimetres in the
column provided on the screen to get the nerve conduction velocity.
• Save the 2 graphs.
