Obesity (Disorder)NCT07341113
Positional Effects on Lung Ventilation and Perfusion in Obesity
An observational study of Obesity (Disorder) and Ventilation Homogeneity, run by Koç University at 1 site in Turkey (Türkiye).
Trial summary
Electrical Impedance Tomography (EIT) is a non-invasive, bedside monitoring tool that provides real-time information on regional ventilation and perfusion. In particular, EIT has the potential to guide individualized mechanical ventilation in obese patients by revealing how gravitational and positional factors alter… Read more about this study
- Who is it for?
- Ages 18 to 65 yearsHealthy volunteers can take part
- Conditions the study is for
- Obesity (Disorder), Ventilation Homogeneity, Perfusion
- What is being tested?
- Standardized body positioning
- How many people
- 40 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 1 Dec 2025to 5 Mar 2026
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 65 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Study population: Healthy non-obese and obese volunteers
Who may be able to join
- -BMI between 18-25 kg/m² or 30-40 kg/m²
Who cannot join
- Individuals with a body mass index (BMI) between 25 and 30 kg/m²,
- Pregnancy
- Respiratory tract infection within the previous two weeks
- Anatomical abnormalities of the chest wall that may interfere with Electrical Impedance Tomography (EIT) measurements.
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Effects of Body Position on Ventilation and Perfusion Distribution in Obese and Non-Obese Healthy Volunteers Assessed by Electrical Impedance Tomography
Electrical Impedance Tomography (EIT) is a non-invasive, bedside monitoring tool that provides real-time information on regional ventilation and perfusion. In particular, EIT has the potential to guide individualized mechanical ventilation in obese patients by revealing how gravitational and positional factors alter regional lung behavior. Assessing the effects of different horizontal positions on both ventilation and perfusion may help optimize respiratory management strategies tailored to body habitus. By comparing obese and non-obese healthy participants across different positions, this study aims to provide novel insights into the postural effects on lung aeration and perfusion distribution, and to highlight the role of EIT in tailoring individualized ventilation strategies.
Read the detailed description
This will be a observational, physiological study involving healthy volunteers divided into two groups: Obese group (BMI 30 - 40 kg/m²) and non-obese group (BMI 18.5 - 24.9 kg/m²). Each participant will serve as their own control across body positions. Baseline measurements will be obtained in upright sitting, followed by randomized order of supine, Trendelenburg (30°), prone, left lateral, and right lateral. Participants' demographic and anthropometric data, including height, weight, chest circumference, waist circumference, and hip circumference, will be recorded. Medical history, current medication use, smoking status, and cumulative smoking exposure (pack-years) will be documented.
Electrical Impedance Tomography (EIT) measurements will be performed using the Infivision ET1000 device. All study procedures will take place in a private room within the General Intensive Care Unit of Koç University Hospital, with privacy ensured throughout the protocol. After removal of upper body clothing, an appropriately sized EIT belt, selected according to chest circumference, will be positioned circumferentially around the thorax at the level of the axillae. A pulse oximetry probe will be applied, and continuous monitoring of heart rate and peripheral oxygen saturation will be maintained during all measurements.
Following a 5-minute stabilization period in the upright sitting position, baseline EIT measurements will be obtained. The following parameters will be recorded: percentage of ventral ventilation, percentage of dorsal ventilation, percentage of ventral perfusion, percentage of dorsal perfusion, Match Index (MI), Dead Space Index (DI), Shunt Index (SI), Global Inhomogeneity Index (GI), and Center of Ventilation (CoV). To minimize potential carry-over effects, the sequence of positions will be randomized individually for each participant. Randomization will be performed using computer-generated random sequences (randomizer.org), with predefined randomization sets created prior to study initiation.
Each position will be maintained for approximately 5 minutes. In each position, end-expiratory lung impedance difference (ΔEELI) will be measured using the upright sitting position as the reference. The total duration of the study protocol is expected to be approximately 30 minutes per participant. The study will be completed once all measurements have been obtained in all positions.
- Conditions
- Obesity (Disorder), Ventilation Homogeneity, Perfusion, Ventilation Perfusion Mismatch, Position Differences, Electrical Impedance Tomography (EIT)
- Being tested
- Standardized body positioning
- Keywords
- obesity, ventilation perfusion, electrical impedance tomography, body positions
- Medical subject headings
- Obesity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Standardized body positioningOther
Standardized changes in body position (supine, Trendelenburg, prone, and lateral positions) performed solely for physiologic assessment of ventilation and perfusion using electrical impedance tomography. This does not constitute a therapeutic or preventive intervention.
| Study group | Role | What they receive |
|---|---|---|
| Non-obese group | Non-obese healthy individuals with BMI between 18.5 - 25 kg/m² Receives: Other: Standardized body positioning | |
| Obese group | Obese healthy individuals with BMI between 30 - 40 kg/m² Receives: Other: Standardized body positioning |
What is being measured
The primary outcome is the main question the study is designed to answer.
MI
Match Index (MI, 0-100%): quantifying the spatial overlap of ventilation and perfusion distributions. MI values will be taken from the device's Match View. Change in Match Index (MI) between obese and non-obese participants across positions will be compared.
Measured: Periprocedural
Secondary outcomes (11)
VV %
Percentage of ventral ventilation across body positions.
Measured: Periprocedural
DV %
Percentage of dorsal ventilation across body positions.
Measured: Periprocedural
VP %
Percentage of ventral perfusion across body positions.
Measured: Periprocedural
DP %
Percentage of dorsal perfusion across body positions.
Measured: Periprocedural
DI %
Dead space index (DI), proportion (in %) of lung units (pixels or ROIs) that are ventilated but not perfused across body positions
Measured: Periprocedural
SI %
Shunt index (SI), proportion (in %) of lung units (pixels or ROIs) that are perfused but not ventilated across body positions
Measured: Periprocedural
GI
Global Inhomogeneity Index (0-100) quantifies how evenly ventilation is distributed across the lung regions. Higher values indicate more heterogeneous ventilation distribution across the lung cross-section.
Measured: Periprocedural
CoV
Center of ventilation (CoV) describes the center of mass of the ventilation distribution along the ventrodorsal axis (0-100, from ventral to dorsal). CoV <40% means more ventral ventilation while >50-55% means more dorsal ventilation.
Measured: Periprocedural
ΔEELI
ΔEELI represents the change in end-expiratory lung impedance measured by EIT between each body position and the upright sitting reference position, reflecting relative changes in end-expiratory lung volume associated with positioning.
Measured: Periprocedural
Heart rate
Heart rate per minute measured by pulse oximetry
Measured: Periprocedural
Oxygen saturation
Oxygen saturation measured by pulse oximetry
Measured: Periprocedural
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted14 Jan 2026
- Study start1 Dec 2025
- Primary completion5 Mar 2026
- Study completion5 Mar 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Obesity (Disorder)Studies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Case crossover
- Time perspective
- Prospective
- Enrolment
- 40 participants (actual)
Sponsor and investigators
- Lead sponsor
- Koç University
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Evren Şentürk, MD, Study director, Koç University School of Medicine
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07341113
- Sponsor's protocol ID
- 2025.510.IRB2.232
- Status last verified
- Dec 2025
- First submitted
- 15 Dec 2025
- Last updated
- 15 Apr 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Data collected for the study, including de-identified individual participant data will be made available to other within 6 months after the publication of this trial, as will additional related documents (study protocol, statistical analysis plan and informed consent form), for academic purposes (e.g , meta-analyses) upon request to the corresponding author, and with a signed data access agreement.
Publications
De Jong A, Wrigge H, Hedenstierna G, Gattinoni L, Chiumello D, Frat JP, Ball L, Schetz M, Pickkers P, Jaber S. How to ventilate obese patients in the ICU. Intensive Care Med. 2020 Dec;46(12):2423-2435. doi: 10.1007/s00134-020-06286-x. Epub 2020 Oct 23.
PubMed 33095284
Study at a glance
From the registry record, last updated by the sponsor on 15 Apr 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of Body Position on Ventilation and Perfusion Distribution in Obese and Non-Obese Healthy Volunteers Assessed by Electrical Impedance Tomography
- ClinicalTrials.gov ID
- NCT07341113
- Acronym / sponsor ID
- 2025.510.IRB2.232
- Conditions
- Obesity (Disorder), Ventilation Homogeneity, Perfusion, Ventilation Perfusion Mismatch, Position Differences, Electrical Impedance Tomography (EIT)
- Keywords
- obesity, ventilation perfusion, electrical impedance tomography, body positions
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 40 participants (actual)
- Lead sponsor
- Koç UniversityUniversity, hospital or other
- Study start
- 1 Dec 2025 (actual)
- Primary completion
- 5 Mar 2026 (actual)
- Study completion
- 5 Mar 2026 (actual)
- First posted
- 14 Jan 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Electrical Impedance Tomography (EIT) is a non-invasive, bedside monitoring tool that provides real-time information on regional ventilation and perfusion. In particular, EIT has the potential to guide individualized mechanical ventilation in obese patients by revealing how gravitational and positional factors alter regional lung behavior. Assessing the effects of different horizontal positions on both ventilation and perfusion may help optimize respiratory management strategies tailored to body habitus. By comparing obese and non-obese healthy participants across different positions, this study aims to provide novel insights into the postural effects on lung aeration and perfusion distribution, and to highlight the role of EIT in tailoring individualized ventilation strategies.
Detailed description
This will be a observational, physiological study involving healthy volunteers divided into two groups: Obese group (BMI 30 - 40 kg/m²) and non-obese group (BMI 18.5 - 24.9 kg/m²). Each participant will serve as their own control across body positions. Baseline measurements will be obtained in upright sitting, followed by randomized order of supine, Trendelenburg (30°), prone, left lateral, and right lateral. Participants' demographic and anthropometric data, including height, weight, chest circumference, waist circumference, and hip circumference, will be recorded. Medical history, current medication use, smoking status, and cumulative smoking exposure (pack-years) will be documented.
Electrical Impedance Tomography (EIT) measurements will be performed using the Infivision ET1000 device. All study procedures will take place in a private room within the General Intensive Care Unit of Koç University Hospital, with privacy ensured throughout the protocol. After removal of upper body clothing, an appropriately sized EIT belt, selected according to chest circumference, will be positioned circumferentially around the thorax at the level of the axillae. A pulse oximetry probe will be applied, and continuous monitoring of heart rate and peripheral oxygen saturation will be maintained during all measurements.
Following a 5-minute stabilization period in the upright sitting position, baseline EIT measurements will be obtained. The following parameters will be recorded: percentage of ventral ventilation, percentage of dorsal ventilation, percentage of ventral perfusion, percentage of dorsal perfusion, Match Index (MI), Dead Space Index (DI), Shunt Index (SI), Global Inhomogeneity Index (GI), and Center of Ventilation (CoV). To minimize potential carry-over effects, the sequence of positions will be randomized individually for each participant. Randomization will be performed using computer-generated random sequences (randomizer.org), with predefined randomization sets created prior to study initiation.
Each position will be maintained for approximately 5 minutes. In each position, end-expiratory lung impedance difference (ΔEELI) will be measured using the upright sitting position as the reference. The total duration of the study protocol is expected to be approximately 30 minutes per participant. The study will be completed once all measurements have been obtained in all positions.
Study design
- Observational model
- Case crossover
- Time perspective
- Prospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Non-obese group | – | Other: Standardized body positioningNon-obese healthy individuals with BMI between 18.5 - 25 kg/m² |
| Obese group | – | Other: Standardized body positioningObese healthy individuals with BMI between 30 - 40 kg/m² |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- Healthy non-obese and obese volunteers
Key inclusion criteria (1 listed)
- -BMI between 18-25 kg/m² or 30-40 kg/m²
Key exclusion criteria (4 listed)
- Individuals with a body mass index (BMI) between 25 and 30 kg/m²,
- Pregnancy
- Respiratory tract infection within the previous two weeks
- Anatomical abnormalities of the chest wall that may interfere with Electrical Impedance Tomography (EIT) measurements.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Standardized body positioningStandardized changes in body position (supine, Trendelenburg, prone, and lateral positions) performed solely for physiologic assessment of ventilation and perfusion using electrical impedance tomography. This does not constitute a therapeutic or preventive intervention. | Other | Non-obese group, Obese group |
Primary outcome
MI
Time frame: Periprocedural
Match Index (MI, 0-100%): quantifying the spatial overlap of ventilation and perfusion distributions. MI values will be taken from the device's Match View. Change in Match Index (MI) between obese and non-obese participants across positions will be compared.
11 secondary outcomes
VV %
Time frame: Periprocedural
DV %
Time frame: Periprocedural
VP %
Time frame: Periprocedural
DP %
Time frame: Periprocedural
DI %
Time frame: Periprocedural
SI %
Time frame: Periprocedural
GI
Time frame: Periprocedural
CoV
Time frame: Periprocedural
ΔEELI
Time frame: Periprocedural
Heart rate
Time frame: Periprocedural
Oxygen saturation
Time frame: Periprocedural
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 15 Apr 2026.
- Background: PubMed 33095284De Jong A, Wrigge H, Hedenstierna G, Gattinoni L, Chiumello D, Frat JP, Ball L, Schetz M, Pickkers P, Jaber S. How to ventilate obese patients in the ICU. Intensive Care Med. 2020 Dec;46(12):2423-2435. doi: 10.1007/s00134-020-06286-x. Epub 2020 Oct 23.
- Individual participant dataSharing planned: Yes. Data collected for the study, including de-identified individual participant data will be made available to other within 6 months after the publication of this trial, as will additional related documents (study protocol, statistical analysis plan and informed consent form), for academic purposes (e.g , meta-analyses) upon request to the corresponding author, and with a signed data access agreement.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Evren Şentürk, MD study director
Koç University School of Medicine
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Obesity (Disorder) and Ventilation Homogeneity, run by Koç University at 1 site in Turkey (Türkiye).
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 15 Apr 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Turkey (Türkiye). Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
MI (time frame: Periprocedural). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07341113, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 15 Apr 2026; AzTrials last refreshed its copy on 31 Oct 2026.