Figure 2

DSA and PSD of patients with slow induction at loss of responsiveness to verbal command vs. painful stimulus. Differences in the spectral EEG features in patients with slow induction between the loss of responsiveness to verbal (LOvR) or painful (LOpR) stimulation. (A) Density spectral array (DSA) of the normalized power spectral density (nPSD) for patients undergoing slow induction centred to the LOvR. The development of the characteristic alpha and delta dominant power indicative of an anaesthesia EEG pattern develops prior to LOvR. (B) DSA of the nPSD for patients undergoing slow induction centred to the LOpR. When centred to LOpR the increase in EEG alpha-band power around 10 Hz is more pronounced as if centred to LOvR as in (A). (C) PSD plot showing the normalized spectral power for patients at LOvR (green) and LOpR (blue) in combination with the area under the curve and 95% confidence interval (CI) for each frequency for the 10 s after LOR. Black dots indicate significance and grey dots an AUC > 0.7. At LOpR patients had higher relative power in the 10–15 Hz range. The “x” indicate the boundaries of the 95% CI. (D) Ratio of the spectral power between LOvR and LOpR. The plot highlights that the power in the 10–15 Hz frequency band is significantly higher at LOpR indicated by the black and gray dots in the AUC plot.