Stage | Frequency admixture/dominance in EEG per 30s epoch | Depth of anesthesia |
---|---|---|
A | α(8-12 Hz) and β (13-30 Hz) activity, with intermixed eye movement/blinking and myogenic artifact from talking/swallowing | Not applicable (awake) |
B | Fast β and θ (4-7 Hz) but rare δ (1-3 Hz) | Light |
C | δ activity for at least 20% but no more than 50% of epoch | Light to moderate |
D | δ activity for at least 50% of epoch; brief periods of suppression not to exceed 10 s | Moderate |
E | Burst-suppression pattern, with at least 10Â s but no more than 20Â s of suppression per epoch | Profound |
F | Burst-suppression pattern, with at least 20Â s of suppression per epoch | Very profound |