There are
two commonly performed paravertebral facet ablations, cervical and
lumbar. Patients selected for this procedure are those that have failed
conservative treatment of low back pain or cervicogenic pain. Patients
posted for this procedure should have undergone a diagnostic facet block, under
fluoroscopy, at the Pain Control Center. The record should clearly state
the levels at which the radiofrequency should be performed.
The
patient's position in the OR should be prone. The OR table should be
rotated in order to permit the free use of the fluoroscopy C-arm. The
patient should be fully monitored and an IV started. A pillow should be
placed under the abdomen and under the lower extremities. The bed should
be placed in a modified jackknife position.
The patients
undergoing radiofrequency ablation should be monitored and minimal amounts of
narcotics should be used. Excessive sedation would undermine the
physicians effort to locate the adequate paresthesia. Excessive
administration of opioids will increase the threshold for pain and for
stimulation, thereby confusing and prolonging the procedure.
1. Make sure that the grounding pad has
been placed on the patient and connected to its proper input connection at the
front of the RF generator.
2. Turn the POWER on.
3. Check the STATUS SCREEN.
4. Select TEST from the MODE
settings
5. Select STIM from the MODE
settings.
6. Place the STIM VOLTAGE RANGE
switch to the 0-1V position. Turn the OUTPUT CONTROL
knob clockwise increasing its output while reading the STIMULATION VOLTAGE.
An adequate test should show the STIMULATION VOLTAGE to increase to 1
volt.
7. Turn the STIM VOLTAGE RANGE
switch to the 0-10V position. Turn the OUTPUT control knob
clockwise increasing the output and at the same time check the STIMULATION
VOLTAGE to make sure that it reaches 10 volts. Once this has been
tested turn the OUTPUT CONTROL back to 0.
8. Hit the RATE SELECT button
and check the PULSES PER SECOND. You should be able to observe
this change from 2 hertz to 5, 10, 20, 50, 75, and 100. Go to the DURATION
SELECT button and observe the changes in PULSE DURATION.
9. Press the LESION button at the
MODE selector.
10. Check the LESION TIME turning
first the knob counterclockwise to 0 and then clockwise to 120 making sure that
both readings have been documented in the digital screen.
11. Turn the TIMER switch
off.
12. Check the AUTOMATIC
OVER-TEMPERATURE CONTROL option by first rotating the dial counterclockwise
and then clockwise and checking the temperature screen to document that the
full range of temperatures are available.
13. Turn the switch for the AUTOMATIC
OVER-TERMPERATURE CONTROL to the on position.
Once the
RF-lesion generator system has been checked, connect the sterile THERMOCOUPLE
to its corresponding connection at the front the RF generator. At this
point the MODE select switches should all be in the off position as well
as the OUTPUT switch. The OUTPUT CONTROL knob should be
turned down to 0. The LESION TIMER should have been set by the
physician as well as the AUTOMATIC OVER-TEMPERATURE CONTROL option.
Confirm that the STIM VOLTAGE RANGE switch is in the 0-1V
position. Confirm that the TIMER switch is in the off
position. Confirm that the grounding patch is attached to the patient and
to the RF generator. During the procedure you will be asked by the
physician to either "stimulate" or "lesion".
Stimulation:
1. When asked to stimulate, press the STIM
button at the MODE selector.
2. Confirm that the STIM VOLTAGE
RANGE switch is on the 0-1V position.
3. Press the RATE SELECT button
until the PULSES PER SECOND screen reads 100 hertz.
4. Select the ON switch from the OUTPUT
SWITCH selector.
5. Slowly increase the OUTPUT CONTROL
knob clockwise while looking at the STIMULATION VOLTAGE and the response
of the patient to this increase. At this point the attending physician
should be asking the patient to identify the onset and location of a
paresthesia. A paresthesias with a STIMULATION VOLTAGE lower than
0.5V is considered to be ideal.
6. Turn the OUTPUT CONTROL knob
counterclockwise to 0.
7. Press the RATE SELECT button
until 02 hertz is observed in the PULSES PER SECOND screen. Turn
the OUTPUT CONTROL knob clockwise this time observing for muscle
contractions. No muscle contractions should be observed in the lower or
upper extremities below a stimulation voltage of 3.0V or 2.5 times the
threshold stimulation observed for sensory perception.
Lesion:
1. Once the selected nerve has been
identified, the physician will remove the THERMOCOUPLE from the needle
and 0.5-0.25 ml of 2% lidocaine will be injected through the needle.
30-60 seconds later the THERMOCOUPLE will be placed back in the needle
and the surgeon will ask you to proceed with the lesion.
2. Confirm that the LESION button
has been selected from the MODE. Confirm that the TIMER
switch is in the off position and the MAXIMUM DESIRED TEMPERATURE
switch is in the on position.
3. Select the ON switch from the OUTPUT
switch. Slowly turn the OUTPUT CONTROL knob clockwise observing
thE TEMPERATURE and the IMPETANCE.
4. Once the selected temperature is
obtained stop increasing the OUTPUT CONTROL and turn the TIMER
switch ON. A lesion will be created and the RF generator will be
turned OFF once the elected time period has been reached.
Looking
for a paresthesia:
Your surgeon
might ask you to help to identify the nerve by using the stimulator. This
is accomplished by selecting the STIM switch from the MODE,
selecting the ON switch from the OUTPUT SWITCH CONTROL, and
turning the OUTPUT CONTROL knob clockwise until a STIMULATION VOLTAGE
of 0.5V is reached while the pulse rate is 50 hertz. Make sure that the STIM
VOLTAGE SWITCH is in the 0-1V position. Once the lesions have
been produced the physician will ask you to provide them with 0.5% bupivacaine
plus 80 mg Depo-medrol. Please provide 1 ml of bupivacaine for every needle
placement.