Morbid Obesity
Conditions
Keywords
Morbid Obesity, Optic Nerve Sheath Diameter (ONSD), Bariatric Surgery, Reverse Trendelenburg Positioning
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.
Detailed description
Obesity is associated with physiological alterations that may affect intracranial dynamics during laparoscopic surgery. In bariatric procedures, the creation of pneumoperitoneum and the use of reverse Trendelenburg positioning are essential for optimal surgical exposure. However, pneumoperitoneum increases intra-abdominal pressure and may impair venous return from the brain, potentially leading to elevations in intracranial pressure (ICP). These effects may be particularly relevant in obese patients, who are more susceptible to hemodynamic and respiratory changes during surgery. Direct measurement of ICP using intraventricular or intraparenchymal catheters remains the gold standard; however, these invasive techniques are not feasible in routine surgical practice because of the risks of hemorrhage, infection, and other complications. Ultrasonographic measurement of optic nerve sheath diameter (ONSD) has emerged as a reliable, noninvasive surrogate marker for assessing changes in ICP and has been widely used in perioperative and critical care settings. Previous studies have demonstrated that pneumoperitoneum may increase ONSD during laparoscopic procedures. Reverse Trendelenburg positioning has been shown to facilitate cerebral venous drainage and may attenuate increases in intracranial pressure. However, the effect of the timing of reverse Trendelenburg positioning relative to pneumoperitoneum creation has not been adequately investigated, particularly in patients undergoing bariatric surgery. This prospective randomized controlled trial aims to evaluate whether applying the reverse Trendelenburg position before pneumoperitoneum can reduce perioperative increases in ONSD during laparoscopic bariatric surgery. Eligible patients undergoing elective laparoscopic bariatric surgery will be randomly assigned to one of two groups. In the conventional group, pneumoperitoneum will be established before reverse Trendelenburg positioning. In the intervention group, reverse Trendelenburg positioning will be applied before pneumoperitoneum creation. ONSD measurements will be performed using ocular ultrasonography at predefined perioperative time points. Hemodynamic parameters, including mean arterial pressure and heart rate, as well as respiratory variables including end-tidal carbon dioxide and peak airway pressure, will also be recorded.
Interventions
OTHERPre-pneumoperitoneum Reverse Trendelenburg Group
Patients are placed in the reverse Trendelenburg position before carbon dioxide insufflation and establishment of pneumoperitoneum.
Sponsors
Bagcilar Training and Research Hospital
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
OTHER
Masking
NONE
Intervention model description
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.
Eligibility
Sex/Gender
ALL
Age
18 Years to 65 Years
Healthy volunteers
Yes
Inclusion criteria
* Age between 18 and 65 years. * American Society of Anesthesiologists (ASA) physical status I-III. * Body mass index (BMI) ≥ 40 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.
Exclusion criteria
* 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.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Optic Nerve Sheath Diameter (ONSD) | Baseline (before induction of anesthesia), immediately after induction, 5 minutes after pneumoperitoneum and positioning, and at the end of surgery. | 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. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Mean Arterial Pressure (MAP) | During the intraoperative period | Mean arterial pressure measured during surgery |
| Heart Rate | During the intraoperative period | Heart rate measured during surgery. |
| Peak Airway Pressure | During the intraoperative period | Peak airway pressure measured during surgery |
Countries
Turkey (Türkiye)
Contacts
STUDY_DIRECTORSEZEN KUMAS SOLAK, MD
Bagcılar Training Research Hospital
Outcome results
None listed