Evaluation of Intraoperative Awareness and Its Correlation With Processed EEG Biomarkers During Laparoscopic Surgery

Overview

This prospective observational cohort study aims to evaluate intraoperative responsiveness and possible intraoperative awareness in adult patients undergoing elective laparoscopic abdominal surgery under general anesthesia and to investigate their relationship with processed electroencephalography (EEG) biomarkers. Approximately 600 patients will be enrolled. Preoperative assessment will include the 15-item Quality of Recovery questionnaire (QoR-15), State-Trait Anxiety Inventory (STAI), Mini-Mental State Examination (MMSE), and Beck Anxiety Inventory (BAI). Processed EEG monitoring will be performed using the Masimo SedLine system. The system will be applied before induction of general anesthesia and maintained throughout the anesthetic period until extubation. Patient State Index (PSI) values will be recorded at 5-minute intervals from the beginning of surgery until extubation. The isolated forearm technique (IFT) will be performed five times during predefined stages of anesthesia and surgery. The fifth assessment will be performed at any stage of surgery when there is clinical or processed EEG evidence suggesting possible awakening, including a PSI value above 50 and/or accompanying hemodynamic changes such as tachycardia or hypertension. Postoperative assessment will be performed at the 24th postoperative hour and at the second postoperative week. At 24 hours, QoR-15 and structured awareness questioning will be performed. At two weeks, QoR-15, Beck Anxiety Inventory, dream recall, and further assessment of possible intraoperative awareness will be performed. The study will investigate the relationship between PSI changes, isolated forearm technique responses, and postoperative reports suggestive of intraoperative awareness.

: Intraoperative awareness is a clinically important complication of general anesthesia in which patients may experience consciousness and subsequently recall events occurring during anesthesia. Intraoperative responsiveness and postoperative explicit recall represent related but distinct aspects of consciousness during general anesthesia. This prospective observational cohort study will include adult patients undergoing elective laparoscopic abdominal surgery under general anesthesia. Approximately 600 participants will be prospectively enrolled. Before surgery, participants will undergo baseline assessment using the QoR-15, State-Trait Anxiety Inventory, Mini-Mental State Examination, and Beck Anxiety Inventory. Processed EEG monitoring will be performed using the Masimo SedLine system. The SedLine system will be applied before induction of general anesthesia and maintained throughout the anesthetic period until extubation. PSI values will be recorded at 5-minute intervals from the beginning of surgery until extubation. The isolated forearm technique will be used to assess intraoperative responsiveness. The first four IFT assessments will be performed at predefined stages during induction and surgery. A fifth IFT assessment will be performed when the clinical course or monitoring suggests possible awakening, including a PSI value above 50 and/or hemodynamic findings such as tachycardia or hypertension. During the IFT, patients will be instructed to respond to a predefined verbal command, and the presence or absence of a response will be recorded. PSI values corresponding to IFT assessments will be evaluated. Particular attention will be given to increases in PSI associated with positive IFT responses. A positive IFT response together with an increase in PSI will be considered evidence of intraoperative responsiveness and possible intraoperative awareness rather than definitive proof of explicit postoperative awareness. At the 24th postoperative hour, patients will undergo QoR-15 assessment and structured questioning regarding possible intraoperative awareness and recall. At the second postoperative week, QoR-15 and Beck Anxiety Inventory assessments will be repeated, and dream recall and possible intraoperative awareness will be assessed. The study will investigate the relationship between processed EEG-derived PSI values, intraoperative responsiveness detected by the isolated forearm technique, and postoperative reports suggestive of awareness. It will also evaluate associations between possible intraoperative awareness and postoperative quality of recovery, anxiety, and dream recall.