The Effects of Anesthesia on Postoperative Cognitive Functions in Patients Undergoing Sleeve Gastrectomy

June 4, 2026 updated by: Sehit Prof. Dr. Ilhan Varank Sancaktepe Training and Research Hospital

The Effects of Total Intravenous Anesthesia and Inhalational Anesthesia on Postoperative Cognitive Functions in Patients Undergoing Sleeve Gastrectomy

In this study, the investigators want to examine the effects of intravenous anesthetic drugs and gases on cognitive functions in the postoperative period in individuals who will undergo surgery for obesity. The investigators believe that the anesthesia method we apply with inhalation gases is also as reliable method as total intravenous anesthesia for postoperative cognitive functions in these patients who undergoe sleeve gastrectomy.

The anesthesia method applied intravenously and with inahalational gases have been applied safely for many years. Comparisons between these two anesthesia technics in obese individuals and for postoperative cognitive dysfunctions are limited.

Studies on the examination of cognitive functions in postoperative patients have gained momentum with the use of neuropsychiatric tests performed on patients who have undergone cardiac surgery and these tests have also been performed on individuals who have undergone non-cardiac surgery. And yet, similar declines in cognitive functions have been observed. For these reasons, the effects of surgery itself and anesthesia methods on cognitive functions have been studied up to date.

In this study, the investigators plan to evaluate patients who will undergo obesity surgery in both anesthesia methods by the recovery times from anesthesia and the residual effects of anesthesia, and after awakening they plan to evaluate their cognitive functions with neuropsychiatric tests that will be performed at certain intervals.

Study Overview

Status

Recruiting

Conditions

Detailed Description

The aim of this study is to investigate the effects of TIVA (Total Intravenous Anesthesia) and inhalational anesthesia on postoperative cognitive functions in patients undergoing sleeve gastrectomy as a bariatric surgery, to determine the residual effects of anesthetic drugs and to determine recovery times, to observe mental changes caused by the anesthesia method and surgical intervention, to evaluate postoperative cognitive functions with neurocognitive tests, and to try to determine the most appropriate anesthesia method for the patient as the method with faster recovery, better patient comfort and less cognitive function changes. The investigators think that they can safely choose inhalation anesthesia, like TIVA, in patients who will undergo obesity surgery.

The relationships between the choice of anesthesia method and the recovery in obese patients remain unclear. Obesity-related physiological changes, such as increased cardiac output, may affect the pharmacokinetics of anesthetic agents by increasing the volume of distribution and clearance of the drug. However, it is difficult to assess the extent of these changes. In fact, no significant clinical difference has been shown in terms of recovery times between obese and non-obese patients anesthetized with inhalation agents in clinical studies.

TIVA and inhalational anesthesia have been used safely up to date, and both are routinely used in patients undergoing laparoscopic bariatric surgery. Although TIVA was once seen as a promising alternative to inhalational anesthesia; in morbidly obese patients with different clinical and metabolic profiles, the high lipid solubility and slow metabolic elimination of intravenous anesthetics, in addition to manual administration of these drugs, are limited even in computer-controlled automated systems such as TCI (Target Controlled Infusion) devices and CLADS (Closed Loop Anesthesia Delivery System) designed to provide predefined plasma concentrations based on patient response and multi-compartmental pharmacokinetic algorithms.

In another study conducted to determine the optimum anesthesia method in obese patients, TIVA and inhalational anesthesia were applied in sleeve gastrectomy, and TIVA showed better recovery, lower pain scores, lower incidence of postoperative nausea and vomiting, and shorter PACU (Post Anesthesia Care Unit) stay.

A consensus group was formed to develop terminology similar to that used in cognitive classifications of the general population to be used in the investigation of cognitive function changes after anesthesia and surgery. This working group suggested using the term "POND"(Perioperative Neurocognitive Disorders) as a comprehensive term for cognitive disorders defined in the preoperative and postoperative periods, and decided to call the cognitive decline present in the preoperative period "NCD" (Neurocognitive Disorder), the form defined as a clear and acute event within the first 7 days after the effects of postoperative surgery and anesthesia excluded as "Postoperative Delirium", the cognitive decline observed in the time period up to 30 days after surgery "Delayed Neurocognitive Recovery" and the form observed up to 12 months "POCD" (Postoperative Cognitive Dysfunction).

Since there are differences in the definition and measurement parameters of postoperative cognitive dysfunction, neurophysiological examination is required. However, both preoperative and postoperative cognitive functions can be evaluated with some mini tests. For this purpose, we planned to apply MMST (Mini Mental State Examination) and ACE (Addenbrooke's Cognitive Examination) tests to our patients at certain intervals in our study.

After the approval decision numbered 2024/226 of the Scientific Research Ethics Committee of Sancaktepe Sehit Prof. Dr. Ilhan Varank Training and Research Hospital, we trained residents in our clinic to perform MMST and ACE tests. The patients who will undergo sleeve gastrectomy, have been evaluated by the multidisciplinary council for obesity surgery at the General Surgery Clinic of Sancaktepe Sehit Prof. Dr. Ilhan Varank Training and Research Hospital and they will be informed about the study by a randomly selected anesthesia resident during the preoperative visit one day before the surgery, and patients verbal and written informed consents will be obtained in accordance with the informed consent forms.

After the consents are taken, a randomly assigned resident will perform MMST and ACE tests on the patients the day before surgery. Patients will be administered inhalational anesthesia or TIVA according to the preference of a random anesthesia specialist physician who is going to work at that day in the operating room of general surgery.

The study will not interfere with the selection of anesthesia method and equal numbers of patients in both groups enrolled. All intraoperative data will be obtained primarily from the hospital information system, medical records and devices, anesthesia follow-up documents, patient follow-up forms and test forms.

The power analysis was performed using the G*Power (v3.1.7) programme to determine the sample size. The power of the study is expressed as 1-β (β =Type II error probability). The effect size was calculated as d=2.954 and it was calculated that in order to obtain 99% power at the α=0.01 level, there should be 20 patients in each group and at least 40 patients in total. Considering that there may be losses during the study process, it was decided to exceed this number and 60 patients were included in the study.

The data will be analyzed using the SPSS 25.0 package program. The Kolmogorov Smirnov test will be used to check whether the distribution of the data is normally distributed, and descriptive statistical methods (Mean, Standard Deviation, Median, IQR, frequency, ratio) will be used when evaluating the study data. Independent t test will be used for two group comparisons showing parametric distribution, and One Way Anova Test analysis methods will be used for more than two group comparisons. Mann-Whitney U test will be used for two group comparisons not showing parametric distribution, and Kruskal Wallis test will be used for more than two group comparisons. Spearman correlation and Pearson correlation analysis will be used to determine the relationship between them. Chi-Square test will be used in the evaluation of categorical data. Significance will be evaluated at p<0.05 levels for all values.

Study Type

Observational

Enrollment (Estimated)

60

Contacts and Locations

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

Study Contact

Study Contact Backup

Study Locations

  • Turkey (Türkiye)
    • Sancaktepe
      • Istanbul, Sancaktepe, Turkey (Türkiye), 34785
        • Recruiting
        • Şehit Prof. Dr. İlhan Varank Sancaktepe Training and Research Hospital
        • Contact:

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

Sampling Method

Probability Sample

Study Population

In a population of patient group who will undergo sleeve gastrectomy as bariatric surgery under general anesthesia in Sancaktepe Sehit Prof. Dr. Ilhan Varank Research and Training Hospital in Istanbul and who have passed the multidisciplinary council for bariatric surgery.

Description

Inclusion Criteria:

Patients of both sexes, Patients Aged between 18 and 65 years, Patients classified as ASA(American Society of Anesthesiologists) physical status I- III, Patients with a BMI (Body Mass Index) between 35 and 50 kg/m² scheduled to undergo sleeve gastrectomy as a type of bariatric surgery for the first time.

Exclusion Criteria:

Patients classified as ASA physical status 4 or high, Patients with known allergy to any of the drugs used in the study, Patients with bleeding disorders, Patients with serum creatinine levels >2 mg/dL, Patients with severe arrhythmias and EF<30%, Patients with a known history of drug abuse are excluded.

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

Cohorts and Interventions

Group / Cohort
"Total Intravenous Anesthesia"

We planned to visit patients who will undergo sleeve gastrectomy the day before the surgery and perform MMST and ACE tests. All patients will undergo electrocardiogram, pulse oxygen saturation, arterial blood pressure monitoring and bispectral index and near infrared spectroscopy. Induction agents will be used according to ideal body weights, and after intubation, ventilation parameters will be set to ventilation control mode/pressure control mode, taking into account ideal body weights and lung protective mechanical ventilation parameters. All monitoring parameters will be noted. "Total Intravenous Anesthesia" group will receive propofol and remifentanil infusions. Dose adjustments will be made according to hemodynamic parameters, NIRS and BIS values, and the total dose used throghout will be noted.

Postoperative eye opening, extubation and recovery times will be noted and both groups are going to be evaluated by postoperative cognitive tests at certain postoperative intervals.
"Inhalational Anesthesia"

We planned to visit patients who will undergo sleeve gastrectomy the day before the surgery and perform MMST ve ACE tests. All patients will undergo electrocardiogram, pulse oxygen saturation, arterial blood pressure monitoring and bispectral index and near infrared spectroscopy. Induction agents will be used according to ideal body weights, and after intubation, ventilation parameters will be set to ventilation control mode/pressure control mode, taking into account ideal body weights and lung protective mechanical ventilation parameters. All monitoring parameters will be noted. "Inhalational Anesthesia" group will receive sevoflurane and remifentanyl infusion. EtSevo and total remifentanyl doses will be noted as adjusted with hemodynamic parameters, NIRS, BIS values accordingly.

In both groups, postoperative eye opening, extubation and recovery times will be noted and both groups are going to be evaluated by applying postoperative cognitive tests at certain postoperative intervals.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
detecting postoperative delirium, delayed neurocognitive recovery and POCD (postoperative neurocognitive disorder)
Time Frame: Mini Mental State Examination(MMSE) Score and Addenbrooke's Cognitive Examination(ACE) Score Preoperative baseline (1 day before surgery), postoperative 1st, 6th, 12th, and 24th hours, postoperative 3rd and 7th days, and postoperative 1st and 3rd months.

Primary Outcome Measure 1:

Time to Eye Opening After Cessation of Anesthetics The time from discontinuation of anesthetic agents to spontaneous eye opening in response to verbal stimulation will be recorded.

Time Frame: From cessation of anesthetic agents until eye opening at the end of surgery.

Primary Outcome Measure 2:

Time to Obey Verbal Commands After Cessation of Anesthetics The time from discontinuation of anesthetic agents until the patient obeys simple verbal commands will be recorded.

Time Frame: From cessation of anesthetic agents until obeying verbal commands at the end of surgery.

Primary Outcome Measure 3:

Time to Extubation The time from discontinuation of anesthetic agents until successful tracheal extubation will be recorded.

Time Frame: From cessation of anesthetic agents until extubation at the end of surgery.

Primary Outcome Measure 4:

Time to Reach Aldrete Recovery Score 9-10 The time required to achieve an Aldrete Recovery Score of 9-10 in the post-anes
Mini Mental State Examination(MMSE) Score and Addenbrooke's Cognitive Examination(ACE) Score Preoperative baseline (1 day before surgery), postoperative 1st, 6th, 12th, and 24th hours, postoperative 3rd and 7th days, and postoperative 1st and 3rd months.

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Hypertension, hypotension, hypoxia, hypercarbia, brady/tachycardia, VAS (Visual Analogue Scale), nausea and vomiting, bleeding, fever, wound infection, pulmonary complications, length of stay in intensive care unit and hospital.
Time Frame: 1 hour in the recovery room.
Any hypertension, hypotension, hypoxia, hypercarbia, brady/tachycardia that may develop during the patient's 1-hour follow-up in the recovery room will be noted, and pain status will be assessed with VAS, nausea-vomiting status and overall patient satisfaction will be assessed. In addition, conditions such as bleeding, fever, wound infection, pulmonary complications that may develop in the patient will be noted, and the length of stay in the intensive care unit and hospital will be recorded.
1 hour in the recovery room.

Collaborators and Investigators

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

Sponsor

Sehit Prof. Dr. Ilhan Varank Sancaktepe Training and Research Hospital

Investigators

  • Study Chair: Nuray Turkut, Şehit Prof. Dr. İlhan Varank Sancaktepe 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)

September 30, 2025

Primary Completion (Actual)

April 30, 2026

Study Completion (Estimated)

July 30, 2026

Study Registration Dates

First Submitted

August 28, 2025

First Submitted That Met QC Criteria

June 4, 2026

First Posted (Actual)

June 9, 2026

Study Record Updates

Last Update Posted (Actual)

June 9, 2026

Last Update Submitted That Met QC Criteria

June 4, 2026

Last Verified

June 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • Ivstrh- 2024/226

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

We will not share IPD.

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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