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EEG ‐based monitoring during general anaesthesia and sedation. Studies on cardiac surgery and status epilepticus patients
Author(s) -
MUSIALOWICZ TADEUSZ
Publication year - 2013
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/aas.12124
Subject(s) - medicine , sedation , anesthesia , bispectral index , propofol , sedative , electroencephalography , isoflurane , general anaesthesia , cardiac surgery , status epilepticus , burst suppression , surgery , epilepsy , psychiatry
T aim of this study was to evaluate and compare the utility of different electroencephalography (EEG)-based neuromonitoring methods during general anaesthesia for cardiac surgery and sedation in the intensive care unit (ICU). In the first study, midlatency auditory-evoked potentials (MLAEPs) were evaluated as a measure of the sedation level in cardiac surgery patients during post-operative sedation. The purpose of this study was to evaluate whether graded changes in sedation induced by preand post-operative sedative drugs can be detected by any of the components of MLAEPs. The latency of the Nb component increased significantly after pre-medication, and during deep and moderate sedation, and remained increased the day after surgery. The Na-Pa amplitude was decreased during deep sedation compared with baseline and moderate sedation. In the second study, MLAEPs were evaluated in cardiac surgery patients when anaesthesia was guided with the aid of the bispectral index (BIS). It was tested whether the parameters derived from EEG indicate similar states of anaesthesia with the two different anaesthesia techniques. At similar BIS levels, the latency of the Nb component of MLAEPs was significantly increased after intubation, and both the Nb and Pa components were significantly increased after sternotomy in patients anaesthetised with isoflurane compared with propofol. Our results suggest that the parallel use of these two methods can show differences in the components of anaesthesia. In the third study, the feasibility of the BIS index to assess the EEG burst suppression pattern during anaesthesia for refractory status epilepticus (RSE) in the ICU was evaluated. An excellent correlation was found between the BIS index and bursts per minute in the raw EEG. BIS monitoring represents a useful alternative for titration of an anaesthetic agent to reach sufficient suppression in the EEG. In the fourth study, state entropy (SE) values were compared with the BIS index in patients undergoing general anaesthesia for cardiac surgery. Response entropy (RE) as a predictor for surgical noxious stimulation was also evaluated. A poor agreement between SE and BIS index values was found, but RE was a good predictor of arousal after surgical stimulation. In conclusion, in EEG-based monitoring for the assessment of hypnosis during cardiac surgery, different indices show poor agreement (BIS vs. SE) and indicate different components of anaesthesia (MLAEP vs. BIS). In the ICU settings, EEG-based methods can be used to titrate various levels of sedation and to monitor the response to RSE treatment.