SECTION 7 APPENDIX I: MENUS, PROCESSED VARIABLES AND GLOSSARY
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7-5
7.4 Glossary
Amplitude
The maximum absolute value reached by a voltage or current waveform.
Artifact
An electrical waveform with characteristics that arise from sources other than the heart or
brain.
Bispectral Index
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.
BIS Sensor
A single patient use, disposable, pre-gelled 4 electrode array that is applied directly to the
patient’s forehead to record electrophysiological signals. The BIS sensor tab contains an
electric smart card memory device that stores configuration and identification information.
BISx
The BISx is the small unit that attaches to the BIS VISTA monitor via its own monitor
cable, and attaches to a BIS sensor via the Patient Interface Cable (PIC). It acquires and
processes EEG information and sends it to the monitor for display.
Burst Count
The number of EEG bursts per minute, where a “burst” is defined as a short period of
EEG activity preceded and followed by periods of inactivity (suppression). The duration of
bursts and suppressions can vary from less than half a second to several seconds.
Electroencephalogram (EEG)
A visual representation of the rhythmic fluctuations of electric potential between parts of the
brain (brain waves).
Electromyelogram (EMG)
A visual representation of the power (in decibels) in the frequency range 70 – 110 Hz. This
frequency range contains power from muscle activity as well as power from other high-
frequency artifacts.
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