A 40 yr old female was given general anesthesia for abdominal surgery during which she was understanding what she is going through and has a very discomfortable feeling about that. After surgery she complained that she can recall all the intraoperative events and it was very discomfortable. Anesthesiologist apologized for the same. This intraoperative awareness could have been evaluated and thus avoided if during anesthesia the patient would have monitored with which of the following?
|B||End tidal volume|
|C||Bispectral index (BSI)|
Bispectral index (BSI).
a. The Bispectral Index is a monitor that can be used in many cases to assess anesthetic depth. It is measured from superficial scalp electrodes and is a processed electroencephalogram.
b. It is possible that this type of monitoring approach will be increasingly used to assess anesthetic depth.
c. A Bispectral index (BIS) monitor is a modern neurophysiological monitoring device which continually analyses a patient's electroencephalograms during general anaesthesia to assess the level of consciousness during anaesthesia.
d. The "depth of anaesthesia" is commonly used as a surrogate for "the likelihood of forming experiences or memory."
e. The use of BIS monitors is increasing.
f. BIS is therefore best described as a monitor of the depth of the hypnotic component of anaesthesia or sedation. It appears to track the effect-site concentration of hypnotic drugs and their effect on the cortical EEG.
g. This is in keeping with BIS reflecting gradually decreasing effect-site concentrations at the end of anaesthesia.
h. BIS demonstrates a dose-response relationship with inhalational and hypnotic intravenous agents, such as propofol and midazolam, which is independent of the agent(s) being used and correlates with clinical assessments of the level of consciousness.
i. Bispectral analysis is the first processed EEG technique to be correlated well with behavioural assessments of level of consciousness. Ketamine, however, causes EEG activation, complicating BIS interpretation