17 Monitoring EEG
250
Impedance Indicators
About Compressed Spectral Arrays (CSA)
The continuous EEG signal is sampled periodically and this value is stored in a frame. Each frame is
processed using Fast Fourier Transformation (FFT) to provide a frequency spectrum displayed as a
compressed spectral array (CSA).
The CSA window provides an overview of the patient's EEG values over time. It may be configured to
look slightly different on your monitor.
• To view the CSA window permanently embedded on a Screen, select a Screen configured to
display the CSA window.
• To view the CSA window over the current Screen, select the
EEG CSA SmartKey, if configured, or
select
Setup EEG or Main Setup then Show CSA.
Electrode/Skin
Impedance
Symbol Color Displayed
Impedance
Value
Action
Electrode not connected red no value connect electrode
Noisy signal gray 60 kΩ (fixed) check electrode-to-skin
connections
Electrode connected,
impedance above limit
yellow measured value
(e.g. 15 kΩ)
check limit, check
electrode-to-skin contact
Electrode connected,
impedance at or below limit
green measured value
(e.g. 3 kΩ)
no action necessary
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