Morbid ObesityNCT07662538
Optic Nerve Sheath Diameter Changes During Bariatric Surgery
An observational study of Morbid Obesity and Obesity, run by Fatih Sultan Mehmet Training and Research Hospital at 1 site in Turkey (Türkiye).
Trial summary
This prospective clinical study aimed to evaluate the effects of pneumoperitoneum and patient positioning on intracranial pressure in patients undergoing bariatric surgery. Intracranial pressure was assessed noninvasively using ultrasonographic optic nerve sheath diameter (ONSD) measurements. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Morbid Obesity, Obesity
- What is being tested?
- Optic Nerve Sheath Diameter Measurement
- How many people
- 58 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 1 Jan 2022to 30 Jan 2024
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Adult patients undergoing bariatric surgery under general anesthesia at our institution. The study population consists of ASA I-III patients aged 18 years and older who underwent preoperative and perioperative optic nerve sheath diameter (ONSD) measurements at predefined time points during surgery.
Who may be able to join
- Patients scheduled for bariatric surgery.
- ASA physical status 1-3
- Patients aged 18 years and older
Who cannot join
- Patients who declined to participate.
- Age <18 years.
- ASA physical status IV.
- Previous cataract surgery.
- Presence of conditions associated with increased intracranial pressure, including hydrocephalus, cerebrovascular disease, or intracranial tumors.
- Ocular conditions that could interfere with optic nerve sheath diameter measurement, including globe pathology or glaucoma
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
Health Sciences University Fatih Sultan Mehmet Training and Research Hospita
Istanbul, Istanbul, 34752
About this study
Official title: Evaluation of Optic Nerve Sheath Diameter Changes During Laparoscopic Bariatric Surgery Performed in Reverse Trendelenburg Position
This prospective clinical study aimed to evaluate the effects of pneumoperitoneum and patient positioning on intracranial pressure in patients undergoing bariatric surgery. Intracranial pressure was assessed noninvasively using ultrasonographic optic nerve sheath diameter (ONSD) measurements. ONSD measurements were performed before anesthesia induction in the supine position (T0), 5 minutes after anesthesia induction (T1), 5 minutes after creation of pneumoperitoneum and placement in the reverse Trendelenburg position (T2), at the 20th minute of pneumoperitoneum (T3), and 5 minutes after termination of pneumoperitoneum and return to the supine position (T4). The study aimed to determine the effects of anesthesia, pneumoperitoneum, and surgical positioning on intracranial pressure during bariatric surgery
Read the detailed description
Obesity and bariatric surgery are associated with physiological changes that may influence intracranial pressure. Pneumoperitoneum and reverse Trendelenburg positioning, commonly used during laparoscopic bariatric surgery, can affect venous return, respiratory mechanics, and cerebral hemodynamics. Ultrasonographic measurement of optic nerve sheath diameter (ONSD) is a noninvasive and reliable method for estimating changes in intracranial pressure.
The aim of this prospective clinical study was to investigate the effects of anesthesia induction, pneumoperitoneum, and patient positioning on intracranial pressure in patients undergoing bariatric surgery. ONSD measurements were obtained at five predefined time points: before anesthesia induction in the supine position (T0), 5 minutes after anesthesia induction (T1), 5 minutes after creation of pneumoperitoneum and placement in the reverse Trendelenburg position (T2), at the 20th minute of pneumoperitoneum (T3), and 5 minutes after termination of pneumoperitoneum and return to the supine position (T4).
Hemodynamic parameters, end-tidal carbon dioxide levels, peak airway pressure, and plateau airway pressure were recorded simultaneously. The primary outcome was the change in ONSD measurements during different stages of the surgical procedure. The study sought to determine whether pneumoperitoneum and patient positioning contribute to changes in intracranial pressure during bariatric surgery.
- Conditions
- Morbid Obesity, Obesity
- Being tested
- Optic Nerve Sheath Diameter Measurement
- Keywords
- Optic Nerve Sheath Diamete, Intracranial Pressure, Pneumoperitoneum, Reverse Trendelenburg Position, Ultrasonography, Bariatric Surgery
- Medical subject headings
- Obesity, Morbid, Obesity, Pneumoperitoneum
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Optic Nerve Sheath Diameter MeasurementDiagnostic test
Ultrasonographic measurement of optic nerve sheath diameter (ONSD) performed at predefined perioperative time points to assess changes in intracranial pressure during bariatric surgery.
| Study group | Role | What they receive |
|---|---|---|
| Bariatric Surgery Patients | Fifty-six patients undergoing laparoscopic bariatric surgery were included in this prospective observational study. Optic nerve sheath diameter (ONSD) was measured ultrasonographically before anesthesia induction (T0), 5 minutes after anesthesia induction (T1), 5 minutes after creation of pneumoperitoneum and placement in the reverse Trendelenburg position (T2), at the 20th minute of pneumoperitoneum (T3), and 5 minutes after termination of pneumoperitoneum and return to the supine position (T4). Receives: Diagnostic Test: Optic Nerve Sheath Diameter Measurement |
What is being measured
The primary outcome is the main question the study is designed to answer.
Optic Nerve Sheath Diameter (ONSD) at T0
ONSD was measured by ultrasonography before induction of anesthesia ,with the patient awake and in the supin position.ONSD was recorded in millimeters(mm)
Measured: within 5 minutes before induction of anesthesia (T0)
optic nerve sheath diameter (ONSD) T1
ONSD measured by ultrasonography 5 minutes after induction of anesthesia ,with the patient in the supin position.ONSD will be reported in millimeters(mm)
Measured: 5 minutes after induction of anesthesia (T1)
Optic Nerve Sheath Diameter (ONSD) at T2
ONSD measured by ultrasonography 5 minutes after pneumoperitoneum and positioning in reverse Trendelenburg. ONSD will be reported in millimeters (mm).
Measured: 5 minutes after pneumoperitoneum and reverse Trendelenburg positioning (T2)
Optic Nerve Sheath Diameter (ONSD) at T3
ONSD measured by ultrasonography 20 minutes after pneumoperitoneum while maintaining the reverse Trendelenburg position. ONSD will be reported in millimeters (mm).
Measured: 20 minutes after establishment of pneumoperitoneum in the reverse trendelenburg position (T3)
Optic Nerve Sheath Diameter (ONSD) at T4
ONSD measured by ultrasonography 5 minutes after termination of pneumoperitoneum and return to the supine position. ONSD will be reported in millimeters (mm).
Measured: 5 minutes after termination of pneumoperitoneum and return to the supine position (T4)
Secondary outcomes (1)
changes in hemodynamic and respiratory parameters
Hemodynamic and respiratory parameters, including systolic, diastolic and mean arterial blood pressure, heart rate, peripheral oxygen saturation (SpO₂), end-tidal carbon dioxide (EtCO₂), peak airway pressure (Ppeak), and plateau airway pressure (Pplateau), were recorded at predefined perioperative time points and evaluated in relation to changes in optic nerve sheath diameter (ONSD).
Measured: from within 5 minutes before induction of anesthesia (T0) to 5 minutes after termination of pneumoperitoneum and return to the supine position (T4).
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted23 Jun 2026
- Study start1 Jan 2022
- Primary completion30 Jan 2024
- Study completion30 Jan 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Morbid ObesityStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 58 participants (actual)
Sponsor and investigators
- Lead sponsor
- Fatih Sultan Mehmet Training and Research Hospital
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07662538
- Sponsor's protocol ID
- ONSD-BARIATRIC-2022
- Status last verified
- Jun 2026
- First submitted
- 16 Jun 2026
- Last updated
- 10 Sep 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 10 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Evaluation of Optic Nerve Sheath Diameter Changes During Laparoscopic Bariatric Surgery Performed in Reverse Trendelenburg Position
- ClinicalTrials.gov ID
- NCT07662538
- Acronym / sponsor ID
- ONSD-BARIATRIC-2022
- Conditions
- Morbid Obesity, Obesity
- Keywords
- Optic Nerve Sheath Diamete, Intracranial Pressure, Pneumoperitoneum, Reverse Trendelenburg Position, Ultrasonography, Bariatric Surgery
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 58 participants (actual)
- Lead sponsor
- Fatih Sultan Mehmet Training and Research HospitalUniversity, hospital or other
- Study start
- 1 Jan 2022 (actual)
- Primary completion
- 30 Jan 2024 (actual)
- Study completion
- 30 Jan 2024 (actual)
- First posted
- 23 Jun 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This prospective clinical study aimed to evaluate the effects of pneumoperitoneum and patient positioning on intracranial pressure in patients undergoing bariatric surgery. Intracranial pressure was assessed noninvasively using ultrasonographic optic nerve sheath diameter (ONSD) measurements. ONSD measurements were performed before anesthesia induction in the supine position (T0), 5 minutes after anesthesia induction (T1), 5 minutes after creation of pneumoperitoneum and placement in the reverse Trendelenburg position (T2), at the 20th minute of pneumoperitoneum (T3), and 5 minutes after termination of pneumoperitoneum and return to the supine position (T4). The study aimed to determine the effects of anesthesia, pneumoperitoneum, and surgical positioning on intracranial pressure during bariatric surgery
Detailed description
Obesity and bariatric surgery are associated with physiological changes that may influence intracranial pressure. Pneumoperitoneum and reverse Trendelenburg positioning, commonly used during laparoscopic bariatric surgery, can affect venous return, respiratory mechanics, and cerebral hemodynamics. Ultrasonographic measurement of optic nerve sheath diameter (ONSD) is a noninvasive and reliable method for estimating changes in intracranial pressure.
The aim of this prospective clinical study was to investigate the effects of anesthesia induction, pneumoperitoneum, and patient positioning on intracranial pressure in patients undergoing bariatric surgery. ONSD measurements were obtained at five predefined time points: before anesthesia induction in the supine position (T0), 5 minutes after anesthesia induction (T1), 5 minutes after creation of pneumoperitoneum and placement in the reverse Trendelenburg position (T2), at the 20th minute of pneumoperitoneum (T3), and 5 minutes after termination of pneumoperitoneum and return to the supine position (T4).
Hemodynamic parameters, end-tidal carbon dioxide levels, peak airway pressure, and plateau airway pressure were recorded simultaneously. The primary outcome was the change in ONSD measurements during different stages of the surgical procedure. The study sought to determine whether pneumoperitoneum and patient positioning contribute to changes in intracranial pressure during bariatric surgery.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Bariatric Surgery Patients | – | Diagnostic Test: Optic Nerve Sheath Diameter MeasurementFifty-six patients undergoing laparoscopic bariatric surgery were included in this prospective observational study. Optic nerve sheath diameter (ONSD) was measured ultrasonographically before anesthesia induction (T0), 5 minutes after anesthesia induction (T1), 5 minutes after creation of pneumoperitoneum and placement in the reverse Trendelenburg position (T2), at the 20th minute of pneumoperitoneum (T3), and 5 minutes after termination of pneumoperitoneum and return to the supine position (T4). |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Adult patients undergoing bariatric surgery under general anesthesia at our institution. The study population consists of ASA I-III patients aged 18 years and older who underwent preoperative and perioperative optic nerve sheath diameter (ONSD) measurements at predefined time points during surgery.
Key inclusion criteria (3 listed)
- Patients scheduled for bariatric surgery.
- ASA physical status 1-3
- Patients aged 18 years and older
Key exclusion criteria (6 listed)
- Patients who declined to participate.
- Age <18 years.
- ASA physical status IV.
- Previous cataract surgery.
- Presence of conditions associated with increased intracranial pressure, including hydrocephalus, cerebrovascular disease, or intracranial tumors.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Optic Nerve Sheath Diameter MeasurementUltrasonographic measurement of optic nerve sheath diameter (ONSD) performed at predefined perioperative time points to assess changes in intracranial pressure during bariatric surgery. | Diagnostic test | Bariatric Surgery Patients |
Primary outcome
Optic Nerve Sheath Diameter (ONSD) at T0
Time frame: within 5 minutes before induction of anesthesia (T0)
ONSD was measured by ultrasonography before induction of anesthesia ,with the patient awake and in the supin position.ONSD was recorded in millimeters(mm)
optic nerve sheath diameter (ONSD) T1
Time frame: 5 minutes after induction of anesthesia (T1)
ONSD measured by ultrasonography 5 minutes after induction of anesthesia ,with the patient in the supin position.ONSD will be reported in millimeters(mm)
Optic Nerve Sheath Diameter (ONSD) at T2
Time frame: 5 minutes after pneumoperitoneum and reverse Trendelenburg positioning (T2)
ONSD measured by ultrasonography 5 minutes after pneumoperitoneum and positioning in reverse Trendelenburg. ONSD will be reported in millimeters (mm).
Optic Nerve Sheath Diameter (ONSD) at T3
Time frame: 20 minutes after establishment of pneumoperitoneum in the reverse trendelenburg position (T3)
ONSD measured by ultrasonography 20 minutes after pneumoperitoneum while maintaining the reverse Trendelenburg position. ONSD will be reported in millimeters (mm).
Optic Nerve Sheath Diameter (ONSD) at T4
Time frame: 5 minutes after termination of pneumoperitoneum and return to the supine position (T4)
ONSD measured by ultrasonography 5 minutes after termination of pneumoperitoneum and return to the supine position. ONSD will be reported in millimeters (mm).
1 secondary outcome
changes in hemodynamic and respiratory parameters
Time frame: from within 5 minutes before induction of anesthesia (T0) to 5 minutes after termination of pneumoperitoneum and return to the supine position (T4).
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 10 Sep 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Morbid Obesity and Obesity, run by Fatih Sultan Mehmet Training and Research Hospital at 1 site in Turkey (Türkiye).
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 6 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 10 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Turkey (Türkiye). Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Optic Nerve Sheath Diameter (ONSD) at T0 (time frame: within 5 minutes before induction of anesthesia (T0)). The study lists 5 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 10 Sep 2026.