Effect of Carbon Dioxide Pressure on Optic Nerve Sheath Diameter in Laparoscopic Transperitoneal Nephrectomy (Lap Optic Nerv)

November 22, 2025 updated by: Umut Arslan, Fatih Sultan Mehmet Training and Research Hospital

Effect of CO2 Pressure on Optic Nerve Sheath Diameter in Laparoscopic Transperitoneal Nephrectomy

Nephrectomy is a surgical procedure performed for various indications, and with the development and increasing availability of advanced diagnostic techniques, its incidence has been rising. Today, in appropriate cases, laparoscopic surgery is recommended due to its minimally invasive nature and its surgical success rates being comparable to those of open surgery. In laparoscopic surgery, to achieve optimal visualization, a 45° lateral decubitus position is applied, followed by the creation of a pneumoperitoneum using carbon dioxide gas. While the cardiopulmonary effects of this procedure have been shown to be minimal, studies on its intracranial effects are limited. Cerebral perfusion pressure is defined as the difference between mean arterial pressure and either central venous pressure or intracranial pressure, whichever is higher. Intracranial pressure can be assessed non-invasively using ultrasonographic measurement of the Optic Nerve Sheath Diameter (ONSD). The retrobulbar segment of the optic nerve is surrounded by a distensible subarachnoid space, which expands in response to increased intracranial pressure. The effect of increased intra-abdominal pressure during laparoscopic surgery on intracranial pressure, and its impact on ONSD, will be evaluated non-invasively.

In patients scheduled for laparoscopic kidney surgery, the Optic Nerve Sheath Diameter will be measured transorbitally using ultrasonography by the investigator at various stages of the surgery (before anesthesia, after anesthesia, in the lateral decubitus position, during pneumoperitoneum, and at routine intraoperative pressure levels). Additionally, standard monitoring parameters such as pulse rate, blood pressure, oxygen saturation, and End-Tidal CO₂ will be recorded. The Optic Nerve Sheath Diameter, which serves as an indicator of increased intracranial pressure, will be compared with variables such as surgical positioning, BMI, ASA score, and other relevant factors.

Study Overview

Status

Enrolling by invitation

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

100

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Turkey (Türkiye)
    • Ataşehir
      • Istanbul, Ataşehir, Turkey (Türkiye), 34100
        • fatih sultan mehmet research and training hospital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Male and female patients aged 31-69 years.
  • Diagnosis of renal cancer (ICD Code C64).
  • Planned laparoscopic radical or partial nephrectomy based on current guidelines and patient consent in the Urology Council.

Exclusion Criteria:

  • Presence of any condition that prevents transorbital measurement of the optic nerve sheath (e.g., orbital trauma, severe periorbital edema, or ocular abnormalities affecting optic nerve imaging)
  • Presence of a medical condition that precludes positioning the patient in a 45-degree lateral decubitus position (e.g., severe scoliosis, respiratory compromise, or spinal instability)
  • Known or suspected intracranial pathology that may independently elevate intracranial pressure (e.g., intracranial tumors, hydrocephalus, recent traumatic brain injury)

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Other: Routine Laparoscopic Pneumoperitoneum
Routine Laparoscopic Pneumoperitoneum of the patients
Diagnostic test: Optic Nerve Sheath Diameter Measurement
Optic Nerve Sheath Diameter Measurement, Oxygen saturation and End Tidal CO2 measurements when Pre-operational Supine position, after intubation, Lateral decubitus position, after Pneumoperitoneum, CO2 pressure level at 14-16-18-20 and Post-operational supine position

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in optic nerve sheath diameter (ONSD) with increasing intraabdominal CO₂ pressure
Time Frame: Preop Supine before intubation → During surgery (baseline supine → lateral decubitus positioning → pneumoperitoneum → each pressure level: 14, 16, 18, 20 mmHg → Postop Supine 5 minutes after extubation of the patient
Change in optic nerve sheath diameter (ONSD) with increasing intraabdominal CO₂ pressure
Preop Supine before intubation → During surgery (baseline supine → lateral decubitus positioning → pneumoperitoneum → each pressure level: 14, 16, 18, 20 mmHg → Postop Supine 5 minutes after extubation of the patient

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Fatih Sultan Mehmet Training and Research Hospital

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

December 1, 2024

Primary Completion (Estimated)

December 1, 2025

Study Completion (Estimated)

January 1, 2026

Study Registration Dates

First Submitted

September 21, 2025

First Submitted That Met QC Criteria

November 22, 2025

First Posted (Estimated)

December 3, 2025

Study Record Updates

Last Update Posted (Estimated)

December 3, 2025

Last Update Submitted That Met QC Criteria

November 22, 2025

Last Verified

November 1, 2025

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • Optic Nerve Sheat Laparoscopy

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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