Evoke
®
SCS System Clinical Manual
CLIN-UMAN-005175
Revision: 9.00
Page 32 of 101
variability.
b.
If the measured sensitivity is low (near 10 µV, see Section 6.11) and the
stimulation frequency is low (e.g. 10-20 Hz), try increasing the stimulation
frequency (see Section 8.1) to reduce the variability. If you change the
stimulation frequency, you will need to check the ECAP measurement and re-
measure the activation plot (repeat the steps from Section 6.10 onwards).
4.
Monitor the rolling plot through various postures. Ask the patient to move into various
postures such as sitting, standing and lying on their back (supine) while you watch the
rolling plot to see how the closed-loop control responds. The ECAP amplitude will show
some variability, but the average ECAP amplitude should track the target level (Figure
6.22), and changes in current should track the patient’s movement (Figure 6.21). If they
don’t, you may need to adjust the ECAP measurement settings (see Section 6.10).
5.
During the posture changes, if the patient reports large changes in stimulation intensity
when they change postures, you may decrease the Patient Sensitivity setting. If the
patient reports discomfort with stimulation sensation while they are not moving, you
may increase the Patient Sensitivity setting (see Section 8.2).
Figure 6.20: Rolling plot with closed-loop disabled (gray background) then closed-loop
enabled (orange background).
Top:
ECAP amplitude (black line) and target value (orange line);
bottom
: Current (black line).
