[Depth of anesthesia, awareness and EEG]

Area of Science:

• Anesthesiology
• Neuroscience
• Medical Monitoring

Context:

• Inapparent adverse intraoperative wakefulness remains a significant challenge in modern anesthesia.
• This can lead to adverse postoperative recovery outcomes for patients.
• Current monitoring techniques have limitations in reliably detecting or predicting intraoperative awareness.

Purpose:

• To evaluate various methods for monitoring intraoperative wakefulness during general anesthesia.
• To assess the efficacy of clinical autonomic signs, isolated forearm technique, processed EEG, and mid-latency auditory evoked potentials (MLAEP).
• To determine the most reliable indicator of intraoperative awareness.

Summary:

• Clinical autonomic signs and PRST-score are insufficient for predicting wakefulness.
• The isolated forearm technique is reliable but time-limited.
• Processed EEG (BIS, SEF) quantifies anesthetic effects but is less suitable for detecting awareness.
• Mid-latency auditory evoked potentials (MLAEP) demonstrate a dose-dependent depression by anesthetics, correlating with wakefulness states.
• Hierarchical correlations exist between MLAEP values and different levels of intraoperative awareness, with established thresholds for common anesthetics.

Impact:

• Mid-latency auditory evoked potentials (MLAEP) show significant potential as a reliable method for assessing anesthetic depth and detecting intraoperative wakefulness.
• Further research in diverse patient populations and with various anesthetics is needed to establish MLAEP as a routine monitoring tool.
• Improved intraoperative awareness detection can enhance patient safety and postoperative outcomes.