Effects of Standard and Modified Z-Trendelenburg Positions on Cerebral Oxygenation and Optic Nerve Sheath Diameter

NCT07632287 | Completed

• 1 other identifier: AEŞH-EK-2026-048
• Study Type: observational
• Target: 70
• Locations: 1 country
• Sites: 1

Brief Summary

The purpose of this study is to compare the effects of the standard Trendelenburg position and the modified Z-Trendelenburg position on cerebral oxygenation and optic nerve sheath diameter (ONSD) in patients undergoing laparoscopic surgery. The prolonged use of the standard Trendelenburg position combined with pneumoperitoneum can increase intracranial pressure and affect cerebral blood flow. In this study, researchers will use non-invasive methods, including Near-Infrared Spectroscopy (NIRS) to monitor regional cerebral oxygenation, and ocular ultrasonography to measure ONSD as an indicator of intracranial pressure changes. The main goal is to determine whether the modified Z-Trendelenburg position serves as a safer physiological alternative by reducing these potential adverse effects compared to the standard position.

Conditions

Laparoscopic Gynecological Surgery

Keywords

Trendelenburg position; Optic Nerve Sheath Diameter; Near-Infrared Spectroscopy; Cerebral Oxygenation; Intracranial Pressure; Modified Z-Trendelenburg; Pneumoperitoneum; Laparoscopic surgery

Outcome Measures

Primary Outcomes (1)

• Change in Regional Cerebral Oxygen Saturation (rSO2)

  Regional cerebral oxygen saturation (rSO2) will be measured bilaterally using Near-Infrared Spectroscopy (NIRS) sensors placed on the patient's forehead. This non-invasive monitoring will be used to evaluate cerebral oxygenation changes during different surgical positions and pneumoperitoneum. Values will be recorded as percentages (%).

  Baseline (before anesthesia induction), at 10, 45, 60, and 90 minutes after establishing pneumoperitoneum and surgical positioning, and 10 minutes after returning to the supine position.

Secondary Outcomes (4)

• Change in Mean Arterial Pressure (MAP)

  Baseline ( 10 minutes after anesthesia induction), at 10,45, 60, and 90 minutes after establishing pneumoperitoneum and surgical positioning, and 10 minutes after returning to the supine position.

• Change in Optic Nerve Sheath Diameter (ONSD)

  Baseline ( 10 minutes after anesthesia induction), at 10, 45, 60, and 90 minutes after establishing pneumoperitoneum and surgical positioning, and 10 minutes after returning to the supine position.

• Change in Peak Airway Pressure (Ppeak)

  Baseline (10 minutes after anesthesia induction), at 10,45, 60, and 90 minutes after establishing pneumoperitoneum and surgical positioning, and 10 minutes after returning to the supine posi

• Change in End-tidal Carbon Dioxide (EtCO2)

  Baseline (10 minutes after anesthesia induction), at 10, 45, 60, and 90 minutes after establishing pneumoperitoneum and surgical positioning, and 10 minutes after returning to the supine positi

Study Arms (2)

Standard Trendelenburg Cohort

Patients undergoing elective laparoscopic surgery placed in the standard straight Trendelenburg position.

Procedure: Standard Trendelenburg Position

Modified Z-Trendelenburg Cohort

Patients undergoing elective laparoscopic surgery placed in the modified Z-Trendelenburg position (head-down tilt combined with leg flexion).

Procedure: Modified Z-Trendelenburg Position

Interventions

Standard Trendelenburg Position PROCEDURE

Placement of the patient in the traditional straight head-down tilt position required for laparoscopic surgical access and pneumoperitoneum

Standard Trendelenburg Cohort

Modified Z-Trendelenburg Position PROCEDURE

Placement of the patient in a modified head-down tilt position combined with leg flexion

Modified Z-Trendelenburg Cohort

Eligibility Criteria

• Age: 18 Years - 80 Years
• Sex: female
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

The study population consists of adult patients up to 80 years of age who \[are admitted to the intensive care unit / are undergoing elective surgery / present to the emergency department\]. The population excludes patients with known increased intracranial pressure, severe cerebrovascular, cardiovascular, or pulmonary diseases, morbid obesity (BMI \> 35 kg/m\^2), pregnancy, and any pre-existing ocular pathologies that could affect optic nerve sheath diameter (ONSD)

You may qualify if:

• Patients aged between 18 and 70 years
• American Society of Anesthesiologists (ASA) physical status I or II
• Scheduled for elective laparoscopic surgery requiring Trendelenburg position
• Provided written informed consent

You may not qualify if:

• Patient refusal to participate
• History of severe cerebrovascular disease
• Known increased intracranial pressure
• Pre-existing ocular pathology that could affect optic nerve sheath diameter (ONSD) measurements (e.g., glaucoma, optic neuritis, ocular trauma)
• Severe cardiovascular or pulmonary disease Body Mass Index (BMI) greater than 35 kg/m\^2 Pregnancy

Sponsors & Collaborators

• Ankara Etlik City Hospital: lead

Study Sites (1)

Ankara Etlik City Hospital

Ankara, Ankara, 06010, Turkey (Türkiye)

Location

MeSH Terms

Conditions

Pneumoperitoneum

Condition Hierarchy (Ancestors)

Peritoneal Diseases; Digestive System Diseases

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Target Duration: 1 Day
• Sponsor Type: OTHER GOV
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Resident Physician, Department of Anesthesiology and Reanimation

Study Record Dates

• First Submitted: May 18, 2026
• First Posted: June 8, 2026
• Study Start: March 6, 2026
• Primary Completion: May 18, 2026
• Study Completion: May 18, 2026
• Last Updated: June 8, 2026

Record last verified: 2026-06

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)