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Original title:
Correlation between the EEG monitors BIS and State entropy and their performance in differentiate consciousness and unconsciousness - an EEG Reanalysis
Translated title:
Korrelation zwischen den EEG Monitoren BIS und State Entropy und ihre Fähigkeit zwischen Wachheit und Bewusstlosigkeit zu unterscheiden - eine EEG Reanalyse
Author:
Imhoff, Mareen
Year:
2018
Document type:
Dissertation
Faculty/School:
Fakultät für Medizin
Advisor:
Schneider, Gerhard (Prof. Dr.)
Referee:
Schneider, Gerhard (Prof. Dr.); Hemmer, Bernhard (Prof. Dr.)
Language:
en
Subject group:
MED Medizin
TUM classification:
MED 520d
Abstract:
Anesthesia is characterized by absence of consciousness and perception and can be separated into distinct subcompnonents: sedation/hypnosis, amnesia, analgesia, stability of vital signs, ablation of autonomic responses and muscle relaxation. Depth of anesthesia must be guaranteed to prevent pain perception, movement and recall of the procedure. Insufficient "depth" of anesthesia may result in intraoperative awareneness with long term effects: anxiety, sleep disturbanc, nightmares, flashbacks or post-traumatic stress disorder. A standardized interview (according to Brice) has been developed to detect intaoperative awareness. It has been designed to detect memories before, after and during surgery. Analysis of brain currents (EEG) may be used to detect the risk of intraoperative awarenesss. EEG is recorded from the surface of the head and measures low voltage oscillations, mainly cortically generated potential fields. EEG characteristics can be described with frequency analysis. EEG frequency spectrum ranges from 0-30 Hz, with increasing levels of overlap with EMG artefacts at frequencies above 30 Hz. Increasing concentrations of anesthetics lead to characteristic changes of the EEG. EEG frequency ranges are named as follows: Alpha () 8-13Hz : relaxed awake person with closed eyes, Beta () > 13Hz : Eye opening or light sedation and benzodiazepines Theta () 4-8Hz: Increasing sedation Delta () 0,5-4Hz: General anesthesia Further increase of anesthetic concentrations lead to EEG burst suppression and cortical silence. To reduce intraoperative awareness and tailor anesthetics to individual requirements, several EEG-based monitors have been developed. The aim of this study is to measure the ability of BIS and SE to differentiate consciousness from unconsciousness. Therefore, SE and BIS values were calculated at the transition between awake and unconscious, i.e. 30sec before and after loss respectively return of consiousness. To assess the patients state of consciousness, patients were asked every 30s to squeeze the investigator´s hand. The transition between consciousness and unconsciousness is a critical range, because BIS and SE are more dynamic than during general anesthesia or complete wakefulness. In addition, EEG recorded during surgical procedures was replayed to SE and BIS simultaneously and the resulting indices were compared. In this study, prediciton probability PK for SE is 0.80 ± 0.03 and for BIS 0.83 ± 0.04. This suggests that SE and BIS may be similar in their performance to predict the state of consciousness at the transition between awareness and unconsciousness. BIS and SE show a good overall correlation with r= 0.78. Therefore, SE and BIS may similar in monitoring the level of consciousness during anesthesia.
Translated abstract:
Allgemeinanästhesie ist gekennzeichnet durch Abwesenheit von Bewusstsein und Wahrnehmung und kann in verschiedene Unterkomponenten eingeteilt werden: Sedierung/Ausschaltung von Bewusstsein, Amnesie, Analgesie/Antinozizeption, Stabilität der Vitalparameter, Dämpfung/Verlust der autonomen Reflexe und Unterdrückung von Bewegung. Die „Tiefe“ der Anästhesie muss sichergestellt werden, sodass der Patient während einer Operation weder Schmerz verspürt, sich bewegen kann noch Erinnerungen an die Prozed...     »
WWW:
https://mediatum.ub.tum.de/?id=1300213
Date of submission:
25.04.2016
Oral examination:
07.05.2018
File size:
1370285 bytes
Pages:
44
Urn (citeable URL):
https://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:91-diss-20180507-1300213-1-7
Last change:
26.07.2018
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