1. Ketamine increases the frequency of electroencephalographic bicoherence peak on the α spindle area induced with propofol 
K. Hayashi, N. Tsuda, T. Sawa, S. Hagihira 
British Journal of Anaesthesia 
Volume 99, Issue 3, Pages (September 2007)
DOI: /bja/aem175
Copyright © 2007 British Journal of Anaesthesia Terms and Conditions

2. Fig 1
Protocol: at 20 min after tracheal intubation, patients received ketamine. Bicoherence values were computed from the points 5 min before and 15 min after injection of ketamine using 3-min periods of data collection. Numbers indicate the time (minutes) from intubation. Measurements for BIS, SEF, power spectrum, and bicoherence are shown.
British Journal of Anaesthesia  , DOI: ( /bja/aem175)
Copyright © 2007 British Journal of Anaesthesia Terms and Conditions

3. Fig 2
The sets of representative raw EEGs and the corresponding power spectra are shown, in a conscious person without propofol, and in a patient before and after injection of ketamine under the propofol-TCI anaesthesia. Arrows indicate spindle peaks. (a) Spindle oscillations were not observed in the raw EEG without propofol. Conspicuous peaks were not found in the power spectrum. Power in the higher frequency bands (β and γ area) was not so reduced. (b) In contrast, sleep spindles were morphologically predominant during propofol-TCI anesthesia. The sleep spindles of around 10 Hz were also predominant in the power spectrum. (c) The spindle oscillations were still observed after the injection of ketamine during propofol-TCI. About 15 min after injection of ketamine during propofol-TCI, a shift of the peak in the α-range to a higher frequency was noted in the power spectrum.
British Journal of Anaesthesia  , DOI: ( /bja/aem175)
Copyright © 2007 British Journal of Anaesthesia Terms and Conditions

4. Fig 3
Typical patterns of average bicoherence values, in the same patients as described in Figure 2, are shown both in the oblique view and the vertical view, respectively. (a) In the conscious condition, no marked bicoherence peak appeared. (b) During propofol-TCI anesthesia, the bicoherence peak around 10 Hz became predominant. (c) About 15 min after injection of ketamine, a shift of the bicoherence peak to a higher frequency was observed.
British Journal of Anaesthesia  , DOI: ( /bja/aem175)
Copyright © 2007 British Journal of Anaesthesia Terms and Conditions

5. Fig 4
Twenty-one normalized power spectra are superimposed and averages (mean) with standard deviation (sds) are shown for the following time points. (a) Thin line, before injection of ketamine during propofol-TCI. (b) Bold line, 15 min after injection of ketamine. sds are shown as perpendicular lines. Power spectra are in a normalized form, i.e. the ratio of individual power to total power within the frequency range from 0.5 Hz to 47.0 Hz at 0.5-Hz intervals (n = 21).
British Journal of Anaesthesia  , DOI: ( /bja/aem175)
Copyright © 2007 British Journal of Anaesthesia Terms and Conditions

6. Fig 5
Twenty-one average bicoherence spectra are superimposed and averages (mean) with standard deviation (sds) are shown for the following time points. (a) Thin line, before injection of ketamine during propofol-TCI. (b) Bold line, 15 min after injection of ketamine. sds are shown as perpendicular lines (n = 21).
British Journal of Anaesthesia  , DOI: ( /bja/aem175)
Copyright © 2007 British Journal of Anaesthesia Terms and Conditions