Fig. 7.

Schematic of physiologically motivated model. Emergence occurs as the progression from initial brain state to a threshold brain state (Ω) at which consciousness is regained. The rate of this progression is defined by the rate of exponential decay in expired isoflurane (κ). Suppressed EEG (σ) is modelled as increased anaesthetic depth in (a). The motivating hypothesis for this model is that increased anaesthetic depth is expected to be correlated with increased time to emergence.