Which of the following technique is used to evaluate the intraoperative awareness of an individual during anaesthesia?
Cerebral pulse oximetry
End tidal C02
Bispectral index
Colour Doppler
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