Postoperative Cognitive Function After Different Anesthetic Techniques in Obese Patients

June 18, 2026 updated by: Gaziantep City Hospital

Effects of Low-Flow Sevoflurane, Normal-Flow Sevoflurane, and Total Intravenous Anesthesia on Postoperative Cognitive Function in Obese Patients Undergoing Laparoscopic Abdominal Surgery

Obese patients are at increased risk of postoperative cognitive dysfunction (POCD). The effects of different anesthetic techniques on postoperative cognitive function remain controversial. This prospective randomized study aimed to compare the effects of low-flow sevoflurane anesthesia, normal-flow sevoflurane anesthesia, and total intravenous anesthesia (TIVA) on postoperative cognitive function and recovery characteristics in obese patients undergoing elective laparoscopic abdominal surgery. Cognitive function was assessed using the Mini-Mental State Examination (MMSE) before surgery, at postoperative 30 minutes, and on postoperative day 3.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Obesity is associated with physiological alterations that may increase the risk of postoperative cognitive dysfunction (POCD). The influence of anesthetic techniques on postoperative cognitive outcomes in obese patients remains uncertain.

This prospective randomized study was conducted in obese patients (BMI ≥30 kg/m²) aged 18-65 years undergoing elective laparoscopic abdominal surgery under general anesthesia. Patients were randomly assigned to one of three groups: low-flow sevoflurane anesthesia, normal-flow sevoflurane anesthesia, or total intravenous anesthesia (TIVA). Anesthetic depth was monitored using bispectral index (BIS) monitoring and maintained between 40 and 60 in all groups.

The primary objective was to compare postoperative cognitive function among the three anesthetic techniques using the Mini-Mental State Examination (MMSE). MMSE scores were evaluated preoperatively, at postoperative 30 minutes, and on postoperative day 3.

Secondary objectives included comparison of recovery characteristics, including eye-opening time, extubation time, Modified Aldrete Recovery Scores, and perioperative hemodynamic parameters.

The study was approved by the Marmara University Faculty of Medicine Clinical Research Ethics Committee (Approval No. 09.2022.744) and written informed consent was obtained from all participants before enrollment.

Study Type

Interventional

Enrollment (Actual)

90

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)
    • Istanbul
      • Istanbul, Istanbul, Turkey (Türkiye), 34899
        • Marmara University Faculty of Medicine Pendik Training and Research 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

Yes

Description

Inclusion Criteria:

  • Age between 18 and 65 years
  • Body mass index (BMI) ≥30 kg/m²
  • ASA physical status I-III
  • Scheduled for elective laparoscopic abdominal surgery
  • Provision of written informed consent

Exclusion Criteria:

  • History of psychiatric disease
  • Dementia or known cognitive impairment
  • Hearing or language disorders preventing MMSE assessment
  • Refusal to participate
  • Conversion from laparoscopic to open surgery

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: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Low-Flow Sevoflurane
Patients received sevoflurane anesthesia with a fresh gas flow of 1 L/min during maintenance of anesthesia. Anesthetic depth was maintained with BIS values between 40 and 60.
Drug: Sevoflurane (Volatile Anesthetic)
Maintenance of general anesthesia with sevoflurane inhalation. Patients were assigned to either low-flow (1 L/min) or normal-flow (3 L/min) fresh gas flow anesthesia protocols.
Experimental: Normal-Flow Sevoflurane
Patients received sevoflurane anesthesia with a fresh gas flow of 3 L/min during maintenance of anesthesia. Anesthetic depth was maintained with BIS values between 40 and 60.
Drug: Sevoflurane (Volatile Anesthetic)
Maintenance of general anesthesia with sevoflurane inhalation. Patients were assigned to either low-flow (1 L/min) or normal-flow (3 L/min) fresh gas flow anesthesia protocols.
Experimental: Total Intravenous Anesthesia (TIVA)
Patients received total intravenous anesthesia with propofol and remifentanil infusion. Anesthetic depth was maintained with BIS values between 40 and 60.
Drug: propofol
Maintenance of total intravenous anesthesia using continuous propofol infusion under BIS monitoring.
Drug: Remifentanil
Continuous remifentanil infusion was administered during maintenance of anesthesia according to study protocol.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Mini-Mental State Examination (MMSE) Score
Time Frame: Preoperative, postoperative 30 minutes, and postoperative day 3
Postoperative cognitive function assessed using the Mini-Mental State Examination (MMSE).
Preoperative, postoperative 30 minutes, and postoperative day 3

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Eye Opening Time
Time Frame: End of surgery
Time from discontinuation of anesthetic administration to spontaneous eye opening
End of surgery
Extubation Time
Time Frame: End of surgery
Time from discontinuation of anesthetic administration to tracheal extubation.
End of surgery
Modified Aldrete Recovery Score
Time Frame: Postoperative recovery period
Recovery status assessed using the Modified Aldrete Score.
Postoperative recovery period
heart rate
Time Frame: During surgery
patient's intraoperative measured heart rate
During surgery
mean arterial pressure
Time Frame: during surgery
patient's intraoperative measured mean arterial pressure
during surgery
oxygen saturation
Time Frame: During surgery
oxygen saturation of the patient will be recorded
During surgery
end-tidal carbon dioxide
Time Frame: During surgery
end-tidal carbon dioxide of the patient will be recorded
During surgery

Collaborators and Investigators

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

Sponsor

Gaziantep City Hospital

Investigators

  • Principal Investigator: Ahmet Tunca, MD, Department of Anesthesiology and Reanimation, Gaziantep City Hospital
  • Study Chair: Seniyye Ü Zengin, MD, Department of Anesthesiology and Reanimation, Marmara University Faculty of Medicine, Pendik Training and Research Hospital
  • Study Director: Meliha O Ergün, MD, Department of Anesthesiology and Reanimation, Marmara University Faculty of Medicine, Pendik Training and Research Hospital

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)

January 10, 2023

Primary Completion (Actual)

June 20, 2023

Study Completion (Actual)

June 20, 2023

Study Registration Dates

First Submitted

June 13, 2026

First Submitted That Met QC Criteria

June 18, 2026

First Posted (Actual)

June 24, 2026

Study Record Updates

Last Update Posted (Actual)

June 24, 2026

Last Update Submitted That Met QC Criteria

June 18, 2026

Last Verified

June 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • MU-09.2022.744

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Individual participant data will not be made publicly available due to privacy and confidentiality considerations.

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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