Effect of Intraoperative Position Change on Hemodynamics and Electrocardiography

January 15, 2026 updated by: Fatma Çelik, Firat University

Effect of Intraoperative Position Change on Hemodynamics and Cardiac Electrophysiological Balance Index in Morbidly Obese Patients Undergoing Laparoscopic Sleeve Gastrectomy

The combined effects of obesity-related cardiac structure and function changes, comorbidities, pneumoperitoneum technique, and reverse Trendelenburg position may complicate anesthesia management by affecting intraoperative hemodynamics and cardiac function. Increased intra-abdominal pressure leads to various physiological changes through mechanical and neurohormonal responses. Furthermore, pneumoperitoneum and reverse Trendelenburg position are reported to stimulate the sympathetic nervous system and increase the risk of cardiac arrhythmia.

Obesity-related changes in cardiac structure and function have been shown to predispose to cardiac conduction and repolarization disorders. It has also been stated that obesity directly affects cardiac electrophysiology.

Moreover, obese patients may have hidden risks associated with the development of cardiac arrhythmias due to the adverse contributions of the cardiovascular effects of anesthesia, pneumoperitoneum, and patient positioning during laparoscopic intervention.

The index of cardiac electrophysiological balance (iCEB) is a non-invasive marker calculated by the QT/QRS ratio that can predict malignant ventricular arrhythmias.

The aim of this study was to investigate the effects of intraoperative patient positions on hemodynamics and the index of cardiac electrophysiological balance (iCEB) during laparoscopic sleeve gastrectomy in morbidly obese patients.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Morbidly obese patients who will undergo laparoscopic sleeve gastrectomy will be included in the study.

Patients will be taken to the operating room without premedication after a minimum of 8 hours of fasting. Venous access will be established with a 22 G angiocatheter on the operating table. Routine heart rate, arterial blood pressure, peripheral oxygen saturation (SpO₂), body temperature, bispectral index (BIS) (Bispectral Drager Vista 120 system, Covidien, USA) monitoring will be performed. BIS will be kept between 40 - 60. In addition, 12-lead ECG (Cardioline®) will be used for electrocardiogram (ECG) measurements.

Mechanical ventilation will be provided with a tidal volume of 8 mL/kg (IBW) and a positive end expiratory pressure (PEEP) of 8 cmH₂O. The respiratory rate will be adjusted to maintain end-tidal carbon dioxide (EtCO2) at 35 to 45 mmHg.

Targeted Fluid Management (GDFM) will be provided by continuous Pleth Variability Index (PVI) monitoring by placing a Pulse CO-Oximeter sensor system (Masimo rainbow set® Masimo Corporation, Irvine, CA, USA) on the patients' 4th finger. Hemodynamic targets are both PVI and mean arterial pressure. Fluid loading prescription is based on a PVI value greater than 13%, and vasopressor use is based on a mean arterial pressure < 65 mmHg. If necessary, additional fluids and norepinephrine will be given to maintain mean arterial pressure > 65 mmHg.

A 12-lead ECG will be taken at five intraoperative position measurement points (1. Supine-monitored; 2. After induction; 3. Under general anesthesia-Supine-abdominal inflated; 4. Abdominal inflated-(30% upright) Reverse Trendelenburg; 5. Abdominal deflated-(30% upright) Reverse Trendelenburg). Hemodynamic monitoring [systolic blood pressure (SBP), diastolic blood pressure (DAB), mean arterial pressure (MAP), heart rate (HR)] will be recorded at 5 simultaneous measurement points. All hemodynamic measurements and ECG recordings will be made 3 minutes after the position change to ensure standardization, allow the response to settle after the position change, and prevent the possibility of exaggerated or false data.

All patients will have their surgeries performed by the same surgical team and intra-abdominal pressure will be kept below 15 mmHg.

Demographic data (age, gender, height, weight, BMI), American Society of Anesthesiologists (ASA) physical status classification, preoperative assessment information (comorbidities, medications used), duration of surgery and anesthesia, amount of fluid administered, and amount of norepinephrine to be used when needed will be recorded.

Power analysis was calculated as follows:

Repeated measures, within factors Options: Pillai V, O'Brien-Shieh Algorithm Analysis: A priori: Compute required sample size Input: Effect size f = 0.25 α = 0.05 Power (1-β ) = 0.95 Number of groups = 1 Number of measurements = 5 Corr among rep measures = 0 Output: Noncentrality parameter λ = 20.3125000 Critical F = 2.5226149 Numerator df = 4.0000000 Denominator df = 61.0000000 Total sample size = 65 Actual power = 0.9523977 Pillai V = 0.2380952 Considering that there may be data loss in ECG measurements and evaluations, the number of cases was determined as 80 patients.

Intraoperative hemodynamic and ECG (Heart-electrophysiological balance index (iCEB = QT/QRS ratio) changes in 5 positions will be evaluated.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
80

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

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Study Locations

  • Turkey (Türkiye)
      • Elâzığ, Turkey (Türkiye), 23200
        • Firat University Hospital, Department of Anesthesiology and Reanimation

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Morbidly obese patients undergoing laparoscopic sleeve gastrectomy

Description

Inclusion criteria:

  1. Adult patient planned for elective primary laparoscopic sleeve gastrectomy surgery
  2. Body Mass Index (BMI) ≥ 40 kg/ / m²
  3. Age ≥ 18
  4. ASA physical health class II-III.

Exclusion criteria:

  1. Patient refusal to participate in the study
  2. Those who underwent revision laparoscopic sleeve gastrectomy
  3. Emergency laparoscopic sleeve gastrectomy surgery (stump leakage, etc.)
  4. Secondary surgery in addition to elective laparoscopic sleeve gastrectomy
  5. Patients with previous recurrent abdominal surgery
  6. Patients with electrolyte imbalance
  7. Direct laryngoscopy in ramp position
  8. Multiple intubation attempts due to difficult intubation
  9. Preoperative arrhythmia and heart failure (ejection fraction < 30%)
  10. Renal and liver failure
  11. Patients who require > 8 ml/kg for tidal volume

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

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Evaluation of the QT (ms) interval in morbidly obese patients undergoing laparoscopic sleeve gastrectomy.
Time Frame: The operation takes approximately 2 hours to complete.

Electrocardiograms will be recorded in the following predefined positions:

1. Supine - monitored; 2. Post-anesthesia; 3. Under general anesthesia - Supine - abdominal distension; 4. Abdominal distension - (30% vertical) Reverse Trendelenburg; 5. Abdominal distension reduced - (30% vertical) Reverse Trendelenburg)
The operation takes approximately 2 hours to complete.
Evaluation of QRS (ms) interval in morbidly obese patients undergoing laparoscopic sleeve gastrectomy.
Time Frame: The operation takes approximately 2 hours to complete.

Electrocardiograms will be recorded in the following predefined positions:

(1. Supine - monitored; 2. Post-anesthesia; 3. Under general anesthesia - Supine - abdominal distension; 4. Abdominal distension - (30% vertical) Reverse Trendelenburg; 5. Abdominal distension reduced - (30% vertical) Reverse Trendelenburg)
The operation takes approximately 2 hours to complete.
Evaluation of the cardiac electrophysiological balance index (QT/QRS) in morbidly obese patients undergoing laparoscopic sleeve gastrectomy.
Time Frame: The operation takes approximately 2 hours to complete.
The QT interval will be measured from the beginning of the QRS complex to the end of the T wave, and the QT/QRS (iCEB) ratio will be calculated.
The operation takes approximately 2 hours to complete.
Patient height measurement (in meters)
Time Frame: Height measurement for each patient takes approximately 10 minutes.
All patients' heights will be measured (in meters).
Height measurement for each patient takes approximately 10 minutes.
Patients' body weight measurement (kilograms)
Time Frame: Body weight measurement takes approximately 10 minutes for each patient.
Patients' body weights will also be measured (in kilograms).
Body weight measurement takes approximately 10 minutes for each patient.
Calculation of body mass index (BMI = kg/m²).
Time Frame: This will take approximately 10 minutes for each patient.
Body Mass Index (BMI) is calculated by dividing body weight (kg) by the square of height (m) (BMI = kg/m²).
This will take approximately 10 minutes for each patient.

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Evaluation of patients' blood pressure measurements (mmHg)
Time Frame: The operation takes approximately 2 hours to complete.

Patients' blood pressure will be recorded as systolic, diastolic, and mean blood pressure.

Measurement time points are indicated below:

(1. Supine - monitored; 2. Post-anesthesia; 3. Under general anesthesia - Supine - abdominal distension; 4. Abdominal distension - (30% vertical) Reverse Trendelenburg; 5. Abdominal distension reduced - (30% vertical) Reverse Trendelenburg)
The operation takes approximately 2 hours to complete.
measurement of patients' heart rates (beats/min)
Time Frame: The operation takes approximately 2 hours to complete.

Measurement time points are indicated below:

(1. Supine - monitored; 2. Post-anesthesia; 3. Under general anesthesia - Supine - abdominal distension; 4. Abdominal distension - (30% vertical) Reverse Trendelenburg; 5. Abdominal distension reduced - (30% vertical) Reverse Trendelenburg)
The operation takes approximately 2 hours to complete.

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Firat University

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Fatma Çelik, Assoc. Dr., fatma.celik@firat.edu.tr

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

Helpful Links

Study record dates

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Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
February 10, 2025

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
April 25, 2025

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
May 20, 2025

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
February 6, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 16, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
February 19, 2025

Study Record Updates

Last Update Posted (Estimated)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
January 16, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 15, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
January 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • FiratU-ANEST-FC-01

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

IPD Plan Description

We have not yet decided whether to share the IPDs of our study.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

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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