BIS Monitoring Guideline - Medical Center Intranet

The following sensor values should be considered when assessing the validity of the BIS index score
but does not have to be recorded on the nursing record.
●Signal Quality Index (SQI):
Indicates quality of EEG signal over the last 63 seconds
Check Sensor skin contact if SQI decreases
●Electromyograph (EMG):
Indicates presence of muscle activity or other high-frequency artifacts (oscillating ventilator modes,
convective warming blanket, fluid warmer, oscillating air mattress)
BIS value is optimal when EMG is absent of minimal, increased EMG may elevate the BIS value.
EMG may occur as a result of pain, lightening sedation, and/or NMB wearing off.
●Suppression Ratio Value (SR):
Indicates the % of time in the last 63 seconds that the EEG signal is suppressed, (↑SR = ↓ BIS and vice
versa). Helpful for monitoring the level of EEG suppression during drug-induced coma management.
●Burst Count (Bursts/min):
Another method of quantifying suppression that provides a measure of the number of EEG bursts per minute. A
parameter (in addition to the SR) that indicates the percent of time over the last minute that the EEG is suppressed.
Also helpful for monitoring the level of EEG suppression during drug-induced coma management.
Considerations for BIS interpretation in the HVC:
1. Clinical judgment should always be used when interpreting the BIS in conjunction with other
available clinical signs.
2. BIS readings should be interpreted in response to stimulation, and in the context of patient
status and treatment plan.
3. Patient movement (EMG) may occur with low BIS values.
4. Patient movement (EMG) may indicate inadequate analgesic level.
5. Artifacts and poor signal quality (SQI) may lead to unreliable BIS values. Potential artifacts
may be caused by poor skin contact, muscle activity or rigidity, head and body motion,
sustained eye movements, excessive interference (nerve stimulators, warming devices, air
mattresses, etc.) Check sensor adherence and reprep sensor circles, review analgesic timing,
reposition other medical equipment, move away from interference.
6. BIS values should be interpreted cautiously in patients with known neurological disorders, in
those taking psychoactive medications and in children less than 1 year old.
Guidelines for BIS Monitoring Utilization in the Heart and Vascular Center
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