Which of the following technique is used to evaluate the intraoperative awareness of an individual during anaesthesia?

Bispectral index (BIS) monitor attempts to measure the effects of anesthesia on a patient's level of consciousness by algorithmically processing the patients EEG and conveing it to a single number, which probably represents the patient's state of awareness. BIS values range from 0 to 100. BIS number < 60: Patient unable to respond to verbal commands BIS number > 70: Corresponds to a higher likelihood of awareness BIS number of 90- 100: Awake BIS numbers between 45 and 60 are, in general, considered to be optimal for a relatively healthy patient undergoing a routine general anesthetic and surgery. Ref:Clinical Anesthesiology By G. Edward Morgan, 4th Edition, Chapter 6