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Number Conscious

The bispectral index uses EEG readings to assign a nuber to a patient's level of consciousness, allowing doctors to administer more precise doses of anesthesia.

MID TO HIGH 90s:

Patient is fully conscious; responds to normal-volume speech

80 TO LOW 90s:

Lightly to moderately sedated; awake but drowsy

70–80:

Able to respond to loud commands or mild prodding or shaking

60–70:

Deeply sedated; probably unresponsive to speech or touch; low probability of explicit recall of surgical events

40-60:

Under general anesthesia; low probability of consciousness; level considered low enough for most patients to be unaware

20–40:

Deep hypnotic state; extremely low probability of consciousness

1–20:

Burst suppression (a flat EEG line with intermittent bursts of activity)—dangerously low level

0:

Absence of brain activity