Optic Nerve Sheath Diameter Changes During Bariatric Surgery

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

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Key information

Conditions

Morbid Obesity Body Weight Digestive System Diseases Nutrition Disorders Nutritional and Metabolic Diseases Obesity Obesity, Morbid Overnutrition Overweight Pathological Conditions, Signs and Symptoms Peritoneal Diseases Pneumoperitoneum Signs and Symptoms

Age range

18 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

Health Sciences University Fatih Sultan Mehmet Training and Research Hospita

Istanbul, 34752, Turkey (Türkiye)

About this study

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.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

The study will include patients who have undergone bariatric surgery, are over 18 years of age, and belong to the ASA 1-ASA 3 risk group.

Exclusion criteria

Patients who do not wish to participate, those who have undergone cataract surgery, patients under 18 years of age, ASA 4 patients, patients with increased intracranial pressure, those with diseases that may cause increased intracranial pressure (hydrocephalus, stroke, brain tumor, etc.), those with eye pathology, and glaucoma patients will be excluded from the study. -

Treatment and study plan

Optic Nerve Sheath Diameter Measurement

Diagnostic Test

Ultrasonographic measurement of optic nerve sheath diameter (ONSD) performed at predefined perioperative time points to assess changes in intracranial pressure during bariatric surgery.

Primary outcomes

Change in Optic Nerve Sheath Diameter (ONSD)

Time frame: Preoperative and perioperative period (T0, T1, T2, T3, and T4)

Assessment of changes in ultrasonographic optic nerve sheath diameter measurements during different stages of bariatric surgery.

Sponsors and collaborators

Lead sponsor

Fatih Sultan Mehmet Training and Research Hospital

Other

Registry information

Official study title

Evaluation of Optic Nerve Sheath Diameter Changes During Laparoscopic Bariatric Surgery Performed in Reverse Trendelenburg Position

Important dates

Study start: 2022
Primary completion: 2024
Study completion: 2024
First posted: Jun 23, 2026
Registry last updated: Jun 23, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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