Monitoring Bispectral Index (BIS™)
Efficia CM Series Rack and Modules Instructions for Use 5-3
BIS Terminology
The BIS module is recommended to monitor the level of consciousness or sedation of the
patient in various situations:
• Neuromuscular blockade
• Mechanical ventilation
• Procedures to bedside
• Patients in the ICU
• Surgical procedures
• Academic research or clinics
The parameters calculated by BIS aim to provide objectively the level of sedation/
awareness of the patient and assist the physician in the administration of sedatives. BIS
has been shown to be strongly correlated to common scales of measurement of
sedation.
BIS Terminology
The following terms will be used throughout this chapter. See page 5-5 for measurement
ranges associated with each term.
• Bispectral Index (BIS)
Range = 0 – 100
The Bispectral Index is a continuous processed EEG parameter that correlates
to the patient’s level of hypnosis, where 100 = awake and 0 = flat line EEG. BIS
was designed to correlate with “hypnotic” clinical endpoints (sedation, lack of
awareness, and memory) and to track changes in the effects of anesthetics on
the brain.
• Electromyography (EMG)
The EMG frequency range contains power from muscle activity (i.e.,
electromyography or “EMG”) as well as power from other high-frequency artifacts.
When the EMG indicator bar is low, it indicates that EMG activity is low. BIS
monitoring conditions are optimal when the bar is empty.
• Signal Quality Index (SQI)
The Signal Quality Index is a measure of the signal quality for the EEG channel
source and is calculated based on impedance data, artifact, and other variables.
Signal quality is optimal when all five bars of the SQI icon are green. When signal
quality is too low to accurately calculate a BIS value, the BIS value and other trend
variables that are adversely affected by artifact will not be displayed on the screen.
• Suppression Ratio (SR)
The Suppression Ratio (SR) is a calculated parameter designed to indicate when an
isoelectric (flat line) condition may exist. Suppression ratio is the percentage of time
over the last 63-second period that the signal is considered to be in the suppressed
state. For example, an SR of 11 indicates isoelectric over 11% of time during the last
63 second review.
1 bar represents power in the 30-38 range
2 bars represents power in the 39-47 range
3 bars represents power in the 48-55 range
4 bars represents power greater than 55
To Next Page
Loading...
