Clinical monitoring for depth of anesthesia: Bispectral index (BIS)

Bispectral index (BIS) is the first scientifically validated and commercially supported monitor for anesthetic drug effect on CNS. BIS integrates four EEG parameters into a single variable. This enables tracking of the EEG change associated with the changes in depth of anesthesia from awake state to electrical silence. However, we should note some pitfalls in clinical use of BIS. BIS is not a magic number but a value calculated from EEG. Checking raw EEG is still important when using BIS monitor.