The aim of this study is to evaluate the effects of processed electroencephalogram (pEEG) monitoring on recovery and extubation times, length of stay in the post-anesthesia care unit (PACU), postoperative pain, patient comfort, sedation, development of delirium, and length of hospital and intensive care unit stay in laparoscopic surgeries performed in the Trendelenburg (T) or reverse Trendelenburg (RT) positions.

Materials and Methods: This prospective, randomized, single-center study included a total of 136 patients will be scheduled for elective laparoscopic surgery under general anesthesia. Patients will allocated into four groups according to surgical position (Group T or Group RT) and the use of processed electroencephalogram monitoring (Group TBIS and Group RTBIS). Intraoperative depth of anesthesia will be maintained either by titration guided by processed electroencephalogram indices or according to standard clinical parameters. Extubation time, recovery time, length of stay in the PACU, postoperative pain scores, patient comfort, level of sedation, incidence of delirium, and lengths of hospital and intensive care unit stay will be recorded.

A total of 136 adult patients aged 18-75 yr, classified as American Society of Anesthesiologists (ASA) physical status I-II, and scheduled for elective laparoscopic abdominal surgery with an anticipated duration of at least 1 h will be included.

Patients will be excluded if they had a history of neuropsychiatric disorders, neuromuscular disease, severe cardiovascular or respiratory disease, upper respiratory tract infection within the preceding 14 days, body mass index (BMI) >40 kg m-², alcohol or substance abuse, previous bronchospasm, anticipated difficult tracheal intubation, previous tracheostomy, laryngeal disease or surgery, ASA physical status ≥III, or an actual surgical duration of less than 1 h.

Randomization and Study Groups

Patients will be randomly allocated to one of four study groups according to surgical position and use of processed electroencephalographic monitoring:

Group TBIS: Trendelenburg position with BIS monitoring. Group T: Trendelenburg position without BIS monitoring. Group RTBIS: Reverse Trendelenburg position with BIS monitoring. Group RT: Reverse Trendelenburg position without BIS monitoring. Computer-generated randomization was used for group allocation.

Haemodynamic and respiratory variables, including systolic and diastolic arterial pressure, SpO₂, ETCO₂, peak airway pressure, and BIS values, will be recorded before and after positioning in the Trendelenburg or reverse Trendelenburg position.

Demographic and perioperative data, including age, sex, height, weight, type of surgery, duration of surgery, and duration of anaesthesia, will be collected.

Extubation and recovery times, total desflurane consumption and cumulative EEG suppression time will be recorded for all patients.

PACU discharge time, pain intensity (VAS score), cumulative morphine consumption, additional analgesic (meperidine) requirements, patient comfort, and haemodynamic variables will be assessed at 15, 30, and 60 min after PACU admission.

Delirium screening will ve performed before induction of anaesthesia, at PACU admission, at PACU discharge, and twice daily thereafter (08:00 and 20:00) from postoperative day 1 through postoperative day 3, or until hospital discharge if discharge occurred earlier. Postoperative adverse events, including nausea and vomiting, respiratory depression, bradycardia, hypotension, hypertension, shivering, and urinary incontinence, will be recorded. Intensive care unit (ICU) admission, ICU length of stay, and total hospital length of stay will also be documented.

Inclusion Criteria:

• adult patients aged 18-75 yr, classified as American Society of Anesthesiologists (ASA) physical status I-II, and scheduled for elective laparoscopic abdominal surgery with an anticipated duration of at least 1 h

Exclusion Criteria:

• if they had a history of neuropsychiatric disorders, neuromuscular disease, severe cardiovascular or respiratory disease, upper respiratory tract infection within the preceding 14 days, body mass index (BMI) >40 kg m-², alcohol or substance abuse, previous bronchospasm, anticipated difficult tracheal intubation, previous tracheostomy, laryngeal disease or surgery, ASA physical status ≥III, or an actual surgical duration of less than 1 h

"Individual participant data that underlie the results reported in this article, after de-identification (text, tables, figures, and appendices), will be shared. This will include the Statistical Analysis Plan (SAP). Data will be made available to researchers who provide a methodologically sound proposal, solely to achieve aims in the approved proposal. Proposals should be directed to [hunlugenc@gmail.com]."

Data will be available beginning 6 months and ending 36 months after article publication

Data will be shared with qualified researchers whose proposed use has been approved by an independent review committee