Operator's Manual

Home Screen Trend Graphs
102
BIS™ Advance Monitor
Label Function Description
The EEG display is not affected by a time
scale change.
5 Case start indicator
The small grey triangle on the horizontal
axis time line indicates the case start, if the
case start occurred during the period seen
on the screen
6 Median Frequency
(MF)
The purple line on the graph indicates the
MF, the line under which 50% of the EEG
power lies.
7 X horizontal axis - time
The horizontal axis indicates the time at
each point on of the DSA graph
8 Current time indicator Small blue vertical line on the horizontal
axis indicates the current time of
monitoring
3.9.5. ASYM Graph
To display ASYM on the home screen, select a display option that includes ASYM as
described in 3.12 Home Screen Options on page 121.
ASYM is the asymmetry between EEG power between the left and right hemispheres
of the brain, over time. The value provided is calculated as EEG power present in the
one hemisphere as compared to total (left and right) EEG power.
ASYM is displayed on the graph as a value between 100 left and 100 right.
Asymmetry data less than 20% are not displayed on the graph, but are available in
the Chart Data screen.
In a situation in which EEG power is equivalent in both hemispheres of the brain,
ASYM = 0. A value with the indicator LEFT, for example, 70% LEFT, indicates that the
left hemisphere has more power, and a value with the indicator RIGHT indicates that
the right hemisphere has more power.
In the graph, ASYM values are shown at each point in time. Thus, the ASYM value can
appear either in the upper (left) part of the graph, indicating that most of the EEG
power resides in the left hemisphere, or in the lower (right) part of the graph,
indicating that most of the power resides in the right hemisphere.