Fig. 1.
Experimental design and the quantification of electroencephalographic burst suppression. (A) Experimental design and timeline. The electroencephalogram was recorded throughout the entire experiment, and the three periods during baseline, anesthesia and recovery, as indicated in bold horizontal lines, were concatenated for the analysis. (B) The time courses of suppression ratio (SR) from propofol infusion to 5 min after the discontinuation of isoflurane for individual participants. For each participant, the time of loss of consciousness (LOC) was marked in white cross, while the start and end time of isoflurane exposure were labeled in red dots. The electroencephalographic recording was temporarily interrupted before the discontinuation of isoflurane in participant 20. (C) The duration of induction time (from propofol infusion to LOC), the time from LOC to the start of isoflurane administration (Iso-start), and the elapsed time from the isoflurane administration to the start of burst suppression (BS-start, defined as the first time window with SR greater than 20%). (D) The mean SR value for each consecutive 30-min segment during the 3-h isoflurane exposure period. In (C and D), the gray dots represent the individual data, horizontal lines represent median, and error bars represent the interquartile range. *Indicates adjusted P < 0.05 versus the 0 to 30 min, 30 to 60 min, 60 to 90 min, and 90 to 120 min segments by Friedman test followed by post hoc Dunn tests. ROC, recovery of consciousness.