Bispectral Index (BIS) is an EEG or brainwave monitor that allows a direct measurement of the way sedatives and anesthetics affect the brain. By running the EEG brain wave through a special computer with very special algorithms It provides a clear assessment of the sedation of a patient. It is easy to understand how likely it is the patient will be awake.
This monitor is very helpful during anesthesia because it helps in preventing recall when the patient should be asleep. The last thing you want during your case is to be awake and aware of what is going on during the case. It has also found excellent use in critical care and in sedation for procedures. As helpful as it may be for clinicians they rely also on other techniques to assure the patient is completely asleep.