Inappropriately low bispectral index of the elderly during emergence from sevoflurane anesthesia

[...]when the BIS monitor showed an unnaturally deep level of anesthesia during emergence in an elderly patient who has received neuromuscular blockade, anesthesia management should be conducted in consideration of quantitative parameters of anesthetic agents, such as end-expiratory anesthesia concentration and/or the simulated effect site concentration of anesthetics. Because EEG changes with age as reported with the predominance of the low-frequency component in the elderly [4], and because BIS uses a heuristically derived algorithm based on EEG data from healthy adults [7], we think this kind of misappraisal may occur more readily for elderly individuals than for younger adults. [...]this report indicates that BIS monitoring may not adequately reflect the level of anesthesia during emergence in some elderly patients under neuromuscular paralysis.Acknowledgments We thank Satoshi Hagihira for supplying BSA software.