Study Population:

Patients undergoing elective laparoscopic cholecystectomy under general anesthesia will be included.

Study Design:

This is an observational study. No interventions outside routine clinical practice will be applied. All procedures will be performed by experienced anesthesiologists according to standard institutional protocols.

Data Collection

Preoperative Data:

The following variables will be recorded from anesthesia charts:

Demographics: age, sex, height, weight, body mass index (BMI) Education level Smoking, alcohol, and substance use status Routine preoperative laboratory tests

Clinical scores:

Charlson Comorbidity Index (CCI) Beck Anxiety Scale ARISCAT Score STOP-BANG Score Montreal Cognitive Assessment (MoCA) ASA Physical Status Classification

Intraoperative Data:

Patients will be observed in two groups based on anesthesia technique:

Desflurane + remifentanyl Total intravenous anesthesia (TIVA: propofol + remifentanyl)

The following parameters will be recorded:

Hemodynamic data: blood pressure, heart rate Oxygenation parameters: SpO₂, SpO₂/FiO₂ ratio Cerebral and depth monitoring: NIRS, BIS Respiratory mechanics Oxygen Saturation Index (OSI = [Pmean × FiO₂] / SpO₂) Mechanical ventilator parameters

Time Points for Measurement:

Before induction After induction After intubation Every 20 minutes intraoperatively After extubation

Additional Intraoperative Variables:

Duration of surgery and anesthesia

Total anesthetic drug consumption:

Desflurane and remifentanyl Propofol and remifentanyl (TIVA group) Intraoperative blood transfusion (yes/no) Total blood loss Urine output Recovery time Postoperative Follow-up ICU admission (planned or unplanned)

Pain assessment using Numeric Rating Scale (NRS):

PACU Postoperative 1st, 3rd, 6th, 12th, and 24th hours

Postoperative Complications:

Nausea and vomiting Hypotension Arrhythmia (bradycardia, tachycardia) Pulmonary edema Atelectasis Pneumonia Pneumothorax Pleural effusion Cognitive dysfunction

Other Outcomes:

Postoperative MoCA and Beck Anxiety Scale scores Length of hospital stay Length of ICU stay (if applicable) Mortality during follow-up

This observational study aims to investigate the relationship between intraoperative cerebral oxygenation and systemic oxygenation parameters in patients undergoing elective laparoscopic cholecystectomy under general anesthesia.

Cerebral oxygenation monitoring using near-infrared spectroscopy (NIRS) has become increasingly important in perioperative care, as it provides real-time, non-invasive information about cerebral perfusion and oxygen balance. However, the relationship between cerebral oxygenation and routinely monitored systemic oxygenation parameters remains unclear. This study is designed to evaluate these associations under standardized clinical conditions.

After obtaining ethics committee approval, patients scheduled for elective laparoscopic cholecystectomy will be prospectively enrolled. All procedures will be conducted according to routine clinical practice without any additional intervention. Anesthesia management will be performed by experienced anesthesiologists following institutional protocols.

Patients will be observed according to the anesthesia technique applied: desflurane-remifentanyl anesthesia or total intravenous anesthesia (TIVA) with propofol-remifentanyl. Intraoperative monitoring will include standard hemodynamic parameters, peripheral oxygen saturation (SpO₂), cerebral oxygenation (NIRS), bispectral index (BIS), respiratory mechanics, and derived indices such as the SpO₂/FiO₂ ratio and oxygen saturation index (OSI).

Measurements will be recorded at predefined time points, including before and after induction, after intubation, after positioning, at 20-minute intervals during surgery, and after extubation. Additional intraoperative data such as anesthetic drug consumption, duration of surgery and anesthesia, blood loss, transfusion requirements, urine output, and recovery time will also be documented.

Postoperative outcomes will include pain scores assessed by the Numeric Rating Scale (NRS) at multiple time points, intensive care unit (ICU) admission, and postoperative complications such as nausea, vomiting, hemodynamic instability, respiratory complications, and cognitive dysfunction. Cognitive and anxiety assessments will be performed using the Montreal Cognitive Assessment (MoCA) and Beck Anxiety Scale. Length of hospital stay, ICU stay, and mortality will also be recorded.

The findings of this study are expected to contribute to a better understanding of the relationship between cerebral and systemic oxygenation and may help optimize intraoperative monitoring strategies in routine anesthesia practice.

Inclusion Criteria:

• Those with ASA 1-2-3
• Those who have undergone laparoscopic cholecystectomy
• Those with BMI between 18-40 kg/m2

Exclusion Criteria:

• Emergency surgeries
• Individuals with neurological disorders, diseases, or drug (opioid or sedative) use that affect cognitive function
• Individuals who do not speak Turkish
• Individuals who have received general anesthesia within the last 7 days
• Individuals with severe organ dysfunction
• Individuals allergic to the drugs used in the study

Adult patients undergoing elective surgery under general anesthesia, receiving either desflurane - remifentanyl or propofol- remifentanyl anesthesia