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. 2018 Sep 27;21(12):1079–1089. doi: 10.1093/ijnp/pyy085

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© The Author(s) 2018. Published by Oxford University Press on behalf of CINP.

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com

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Figure 1. — Electroencephalographic (EEG) effects of propofol treatments. (A) Representative EEG traces are shown under light and deep propofol anesthesia. During the burst-suppression state of deep anesthesia, isoelectric periods are occasionally interrupted by stereotypical bursting activity. (B) Suppression ratio (SR) is plotted vs time for a typical participant (10 treatments shown). SR reflects the fraction of time the EEG is isoelectric and free of bursting activity during each 1-minute epoch. The burst-suppression period was defined as the time interval during which SR >50% (double dotted line). Curves are aligned on the time axis such that the first time point at which the target was reached (SR ≥80%, single dotted line) corresponds to 0 minutes. For each treatment session, 3 summary measures were calculated from the SR curve, as shown in histograms to the right. (C) The duration of the burst-suppression state (number of 1-minute epochs during which SR >50%) characterized the “width” of the SR curve. (D) The “height” of the curve was quantified by the SR intensity (median SR value during the burst-suppression period). (E) The integral of the SR curve (sum of SR values across all 1-minute epochs during the treatment session) summarized EEG suppression with a single number that represented total time in the isoelectric state. Histograms show the distributions of these summary measures across all participants and treatments.