Intraoperatives Neuromonitoring: Elektroenzephalografie

Zusammenfassung

Intraoperatives Neuromonitoring mittels Elektroenzephalografie (EEG) ermöglicht eine Überwachung der Narkosetiefe und soll das Auftreten intraoperativer Wachheit, eines postoperativen Delirs und postoperativer kognitiver Defizite verhindern sowie Prozesszeiten im OP verkürzen. Der Beitrag zeigt, wie Roh-EEG, Spektrogramme und prozessierte Indizes für unterschiedliche Altersgruppen und Anästhetika zu interpretieren sind und welcher klinische Nutzen sich daraus ergibt.

Abstract

Intraoperative neuromonitoring using electroencephalography (EEG) enables anaesthesiologists to monitor the depth of anaesthesia. It is intended to reduce the occurrence of intraoperative wakefulness, postoperative delirium and postoperative cognitive deficits and to shorten process times in the operating room. This article shows how to interpret the raw EEG, spectrograms and processed indices for different age groups and anaesthetics and summarizes the resulting clinical benefits. While propofol and volatile anesthetics produce characteristic frontal EEG signatures with a high activity of coherent α- and δ-waves, ketamine triggers an increase in rapid γ-waves, which leads to incorrectly high indices (BIS, PSI, NI) despite deep anaesthetic levels.

In children, frontal α-waves do not appear until the age of approx. 6 months and valid indices (BIS, PSI, NI) can only be derived starting at an age of approx. 12 months. Furthermore, children of preschool and elementary school age often show epileptiform discharges in the EEG during induction of anaesthesia, what is linked to emergence delirium. In adults, the intraoperative frontal α-power decreases significantly with increasing age and older patients tend to have an increased occurrence of burst suppression patterns during anaesthesia. Clinical benefits of EEG-based neuromonitoring comprise reduced doses of anaesthesia, shorter wake-up times after surgery and a lower incidence of intraoperative awareness during total intravenous anaesthesia. Moreover, anaesthesia guided by processed EEG indices can reduce the incidence of postoperative delirium and postoperative cognitive deficits in older patients. In-depth knowledge about intraoperative EEG changes that go beyond the interpretation of processed indices could lead to a further reduction in intra- and postoperative complications in the future.

Kernaussagen

• Propofol und volatile Anästhetika zeigen intraoperativ im frontalen EEG eine charakteristische EEG-Signatur mit einer hohen Aktivität von kohärenten δ- und α-Wellen. Ketamin löst intraoperativ einen Anstieg schneller γ-Wellen aus, was zu falsch hohen Indizes (BIS, PSI, NI) führt. Eine Prämedikation mit Midazolam führt präoperativ zu einem Anstieg der β-Power und intraoperativ zu einer Aktivierung der frontalen α-Band-Power.

• Frontale α-Wellen treten erst mit ca. 6 Monaten auf und valide Indizes (BIS, PSI, NI) sind erst ab einem Alter von ca. 12 Monaten abzuleiten. Kinder im Vorschul- und Grundschulalter zeigen unter Narkoseeinleitung häufig epileptiforme Entladungen im EEG, was assoziiert ist mit einem häufigeren Auftreten eines Aufwachdelirs.

• Im höheren Lebensalter nimmt die intraoperative α-Power deutlich ab und ältere Patienten neigen zu einem gehäuften Auftreten von Burst-Suppression-Mustern intraoperativ.

• Ein EEG-basiertes Neuromonitoring verringert die intraoperativen Anästhetikadosierungen und verkürzt die Aufwachzeit.

• Ein EEG-basiertes Neuromonitoring ist bei reiner TIVA-Narkoseführung empfehlenswert, um intraoperative Awareness zu vermeiden.

• Eine durch prozessierte EEG-Indizes gesteuerte Narkose kann das Auftreten eines postoperativen Delirs und postoperativer kognitiver Defizite bei älteren Patienten verringern.

Schlüsselwörter

Elektroenzephalografie - intraoperatives Neuromonitoring - Anästhesiologie - Allgemeinnarkose

Key words

electroencephalography - intraoperative neuromonitoring - anaesthesiology - general anaesthesia

Publication History

Article published online:
24 November 2021

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