Impact of Reverse Trendelenburg on ONSD in Obesity Surgery

NCT07639502 | Completed

• 1 other identifier: BAGCILAR obezite
• Study Type: interventional
• Target: 90
• Locations: 1 country
• Sites: 1

Brief Summary

This prospective randomized controlled trial aims to investigate the effect of reverse Trendelenburg positioning applied before pneumoperitoneum on optic nerve sheath diameter (ONSD) and, consequently, intracranial pressure during laparoscopic bariatric surgery. Patients will be randomly assigned to two groups, and perioperative changes in ONSD will be compared between the groups. The primary hypothesis of the study is that applying the reverse Trendelenburg position before pneumoperitoneum may attenuate ONSD enlargement and thereby help prevent increases in intracranial pressure.

Conditions

Morbid Obesity

Keywords

Morbid Obesity; Optic Nerve Sheath Diameter (ONSD); Bariatric Surgery; Reverse Trendelenburg Positioning

Outcome Measures

Primary Outcomes (1)

• Change in Optic Nerve Sheath Diameter (ONSD)

  Optic nerve sheath diameter will be measured ultrasonographically at predefined perioperative time points. The outcome measure is the change in ONSD from baseline and the difference between study groups.

  Baseline (before induction of anesthesia), immediately after induction, 5 minutes after pneumoperitoneum and positioning, and at the end of surgery.

Secondary Outcomes (4)

• Mean Arterial Pressure (MAP)

  During the intraoperative period

• Heart Rate

  During the intraoperative period

• Peak Airway Pressure

  During the intraoperative period

• Incidence of Postoperative Nausea and Vomiting (PONV)

  First 24 hours after surgery

Study Arms (2)

Pre-pneumoperitoneum Reverse Trendelenburg Group

ACTIVE COMPARATOR

Reverse Trendelenburg positioning is applied before pneumoperitoneum creation.

Other: Pre-pneumoperitoneum Reverse Trendelenburg Group

Conventional Positioning Group

NO INTERVENTION

Pneumoperitoneum is established in the supine position before reverse Trendelenburg positioning.

Interventions

Pre-pneumoperitoneum Reverse Trendelenburg Group OTHER

Patients are placed in the reverse Trendelenburg position before carbon dioxide insufflation and establishment of pneumoperitoneum.

Pre-pneumoperitoneum Reverse Trendelenburg Group

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Age between 18 and 65 years.
• American Society of Anesthesiologists (ASA) physical status I-III.
• Body mass index (BMI) ≥ 35 kg/m² and scheduled for elective laparoscopic bariatric surgery.
• Ability to provide written informed consent.
• Willingness to participate in the study and comply with study procedures.

You may not qualify if:

• Age younger than 18 years or older than 65 years.
• Refusal or inability to provide written informed consent.
• History of ophthalmologic disease that may affect optic nerve sheath diameter (ONSD) measurements (e.g., glaucoma, optic neuritis, optic nerve tumors, severe ocular trauma, previous ocular surgery).
• Known intracranial pathology, including intracranial hypertension, hydrocephalus, intracranial mass lesions, or cerebrovascular disease.
• Neurological disorders that may influence intracranial pressure measurements.
• Emergency surgery.
• Pregnancy.
• Severe cardiopulmonary disease (e.g., decompensated heart failure, severe pulmonary hypertension, severe chronic obstructive pulmonary disease).
• Inability to obtain adequate ocular ultrasonography images for ONSD measurement.
• Conversion from laparoscopic to open surgery. Intraoperative events requiring deviation from the study protocol.

Sponsors & Collaborators

• Bagcilar Training and Research Hospital: lead

Study Sites (1)

Bagcılar Training Research Hospital

Istanbul, Turkey (Türkiye)

Location

MeSH Terms

Conditions

Obesity, Morbid

Condition Hierarchy (Ancestors)

Obesity; Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Study Officials

• SEZEN KUMAS SOLAK, MD

  Bagcılar Training Research Hospital

  STUDY DIRECTOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: OTHER
• Intervention Model: PARALLEL
• Sponsor Type: OTHER GOV
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principle Investigator

Model Details: Participants will be randomly assigned to one of two parallel groups. In the conventional group, pneumoperitoneum will be established in the supine position, followed by placement in the reverse Trendelenburg position. In the intervention group, patients will first be placed in the reverse Trendelenburg position before pneumoperitoneum creation. Perioperative optic nerve sheath diameter (ONSD), hemodynamic variables, respiratory parameters, and postoperative outcomes will be compared between the two groups to evaluate the effect of pre-pneumoperitoneum reverse Trendelenburg positioning on intracranial pressure during laparoscopic bariatric surgery.

Study Record Dates

• First Submitted: June 1, 2026
• First Posted: June 10, 2026
• Study Start: January 1, 2026
• Primary Completion: April 15, 2026
• Study Completion: June 1, 2026
• Last Updated: June 10, 2026

Record last verified: 2026-06

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)