Which BIS range is generally targeted for general anesthesia?

• A. 20-30
• B. 30-50
• C. 60-80
• D. 40-60

Answer: (D)

Bispectral Index (BIS) monitors translate EEG patterns into a number from 0 to 100 to reflect depth of hypnosis. For general anesthesia, the target is a level where the patient is unconscious and amnestic but not excessively deep. This is generally around 40 to 60 on the BIS scale. Within this range, you’re aiming for adequate hypnosis to prevent awareness while minimizing the risks associated with too deep anesthesia, such as cardiovascular depression and delayed emergence. Values below about 40 indicate very deep anesthesia (burst suppression risk), while values above about 60 suggest lighter anesthesia with a higher chance of intraoperative awareness. The other ranges align outside the typical maintenance target for general anesthesia.