What is the bispectral index state (BIS)? Is monitoring the BIS useful in this case?

What is the bispectral index state (BIS)? Is monitoring the BIS useful in this case?

BIS is a processed EEG parameter that was developed to measure patient response during the administration of anesthetics and sedatives. In natural or drug-induced sleep states there are more harmonic and phase relationships between component waves of the EEG. This so-called bi-coherence can be measured by bispectral analysis, not by power spectral analysis. Applying stepwise regression analysis to EEGs from anesthetized subjects in known awake/asleep states led to derivation of the BIS. The regres-sion equation was transformed into a scale from 0 to 100, where 0 represents isoelectric and 100 represents awake. Therefore BIS uses bispectral analysis of the EEG waveform and other features of the EEG to detect subtle changes in levels of sedation, loss of consciousness, and recall. Clinical use of BIS monitoring demonstrates patient variability and response to anesthetic agents. It can be helpful in main-taining the patient at lower concentrations of volatile or hypnotic intravenous agent to obtain useful evoked poten-tials. BIS can assist in determining which anesthetic com-ponent is necessary in hypertensive patients for treatment of increased blood pressure. Patients with a potential narcotic tolerance and/or risk of awareness may be moni-tored to provide appropriate therapy and avoid complica-tions. Clinical studies have demonstrated its usefulness in monitoring anesthetic depth, titrating agents for a “wake-up” test, and providing for a potentially faster emergence from anesthesia.