AtelectasisNCT07775573
Individualized vs Standard PEEP and Oxygen Reserve Index in Laparoscopic Hernia Surgery
An observational study of Atelectasis and Perioperative Oxygenation, run by Fatih Sultan Mehmet Training and Research Hospital at 1 site in Turkey (Türkiye).
Trial summary
During laparoscopic surgery under general anesthesia, lung function can be affected by increased abdominal pressure and patient positioning. Positive end-expiratory pressure (PEEP) is a ventilator setting that helps keep the lungs open during surgery. Read more about this study
- Who is it for?
- Ages 18 to 75 years
- Conditions the study is for
- Atelectasis, Perioperative Oxygenation, Laparoscopic Inguinal Hernia Repair
- What is being tested?
- Standard PEEP Ventilation and Individualized PEEP Ventilation
- Type of treatment
- Injection or infusion, Surgery or procedure
- How many people
- 60 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- Sep 2026to Oct 2027
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
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 75 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Adult patients scheduled for elective laparoscopic unilateral inguinal hernia repair under general anesthesia at Fatih Sultan Mehmet Training and Research Hospital, Istanbul, Turkey.
Who may be able to join
- Aged 18-75 years
- ASA physical status I-III
- Scheduled for elective laparoscopic unilateral inguinal hernia repair under general anesthesia
- Body mass index (BMI) < 35 kg/m²
- Written informed consent obtained
Who cannot join
- Age below 18 or above 75 years
- ASA physical status IV-V
- Emergency surgical procedure
- Severe chronic or restrictive pulmonary disease
- Pulmonary hypertension
- Obstructive sleep apnea syndrome
Show all 14Show fewer
- Preoperative peripheral oxygen saturation < 94% on room air
- Respiratory tract infection within the last two weeks
- Severe cardiac failure (NYHA III-IV)
- Pregnancy
- Communication difficulties preventing NRS assessment
- Surgical complications during the procedure
- Operation duration exceeding 3 hours
- Refusal to provide informed consent
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Turkey (Türkiye)1 site
Istanbul Provincial Health Directorate Fatih Sultan Mehmet Training and Research Hospital
Istanbul, 34000
sena sancak, MD, +905428361205, sancaksenax@gmail.com
About this study
Official title: The Effect of Individualized Positive End-Expiratory Pressure Application on Perioperative Oxygenation Assessed by Oxygen Reserve Index Compared to Standard PEEP in Patients Undergoing Laparoscopic Inguinal Hernia Surgery: A Prospective Observational Study
During laparoscopic surgery under general anesthesia, lung function can be affected by increased abdominal pressure and patient positioning. Positive end-expiratory pressure (PEEP) is a ventilator setting that helps keep the lungs open during surgery. In standard practice, a fixed PEEP level is applied to all patients. An individualized PEEP approach tailors this setting to each patient based on lung recruitment maneuvers.
This study investigates whether individualized PEEP improves oxygenation compared to standard PEEP in patients undergoing laparoscopic inguinal hernia surgery. Oxygenation will be continuously monitored using the Oxygen Reserve Index (ORI), a non-invasive sensor. Lung aeration will also be assessed before and after surgery using bedside lung ultrasound.
Read the detailed description
General anesthesia combined with pneumoperitoneum and Trendelenburg positioning significantly alters respiratory mechanics. These changes can reduce functional residual capacity (FRC), promote atelectasis, and impair gas exchange - particularly in laparoscopic surgery.
Individualized PEEP, determined through a recruitment maneuver followed by PEEP titration, has been shown to reduce driving pressure and improve dynamic lung compliance compared to fixed PEEP strategies.
The Oxygen Reserve Index (ORI) is a novel non-invasive monitoring parameter that continuously tracks partial oxygen pressure changes in the 100-200 mmHg range, providing early warning of desaturation before SpO2 drops.
In this prospective observational study, 60 adult patients (ASA I-III, aged 18-75) scheduled for elective laparoscopic unilateral inguinal hernia repair under general anesthesia will be enrolled. Patients will receive either standard PEEP (5 cmH₂O) or individualized PEEP based on the attending anesthesiologist's routine clinical preference.
Hemodynamic and respiratory parameters including ORI, SpO2, airway pressures, tidal volume, dynamic compliance, and BIS will be recorded at six time points: before anesthesia (T0), 5 minutes post-intubation (T1), 10 minutes post-Trendelenburg (T2), 20 minutes post-Trendelenburg (T3), after desufflation (T4), and at postoperative 20 minutes (T5).
Lung ultrasound scoring (0-3 per zone, 12-zone protocol) will be performed preoperatively and postoperatively to assess atelectasis. Arterial blood gas analysis will provide additional oxygenation data.
The primary outcome is the effect of individualized versus standard PEEP on perioperative oxygenation as measured by ORI. The secondary outcome is the comparison of atelectasis prevention efficacy between the two PEEP strategies assessed by lung ultrasound score.
- Conditions
- Atelectasis, Perioperative Oxygenation, Laparoscopic Inguinal Hernia Repair, Mechanical Ventilation
- Being tested
- Standard PEEP Ventilation, Individualized PEEP Ventilation
- Keywords
- Positive End-Expiratory Pressure, PEEP titration, Oxygen Reserve Index, ORI, Lung Ultrasound, Recruitment Maneuver, Lung Protective Ventilation, Dynamic Compliance, Pneumoperitoneum, Trendelenburg Position
- Medical subject headings
- Pulmonary Atelectasis, Pneumoperitoneum
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Standard PEEP VentilationProcedure or surgery
Mechanical ventilation with a fixed positive end-expiratory pressure (PEEP) of 5 cmH₂O applied throughout the surgical procedure. Volume-controlled ventilation mode with tidal volume 6-8 ml/kg ideal body weight, inspiratory-to-expiratory ratio 1:2, and fraction of inspired oxygen (FiO₂) 0.40. Respiratory rate adjusted to maintain end-tidal CO₂ (EtCO₂) between 35-40 mmHg. No recruitment maneuver is performed.
Individualized PEEP VentilationProcedure or surgery
Individualized PEEP determined by a stepwise recruitment maneuver followed by PEEP titration, applied at 10 minutes after Trendelenburg positioning. The optimal PEEP level is identified based on best dynamic lung compliance and maintained for the remainder of surgery. All other ventilation parameters are identical: volume-controlled mode, tidal volume 6-8 ml/kg, I/E ratio 1:2, FiO₂ 0.40, EtCO₂ 35-40 mmHg.
| Study group | Role | What they receive |
|---|---|---|
| standard PEEP | Patients receiving standard mechanical ventilation with a fixed PEEP of 5 cmH₂O throughout the surgical procedure. Ventilation is maintained in volume-controlled mode with tidal volume 6-8 ml/kg ideal body weight, I/E ratio 1:2, and FiO₂ 0.40. Respiratory rate is adjusted to maintain EtCO₂ between 35-40 mmHg. Anesthesia is maintained with 1.5-2% sevoflurane and remifentanil infusion 0.05-0.5 mcg/kg/min, titrated to BIS 40-60. Receives: Procedure: Standard PEEP Ventilation | |
| Individualized PEEP | Patients receiving individualized PEEP determined by a recruitment maneuver followed by PEEP titration, applied at 10 minutes after Trendelenburg positioning. The individualized PEEP level is maintained throughout the surgery. All other ventilation parameters are identical to the standard PEEP group: volume-controlled mode, tidal volume 6-8 ml/kg, I/E ratio 1:2, FiO₂ 0.40, EtCO₂ 35-40 mmHg. Anesthesia maintained with 1.5-2% sevoflurane and remifentanil 0.05-0.5 mcg/kg/min, BIS 40-60. Receives: Procedure: Individualized PEEP Ventilation |
What is being measured
The primary outcome is the main question the study is designed to answer.
Perioperative Oxygenation Assessed by Oxygen Reserve Index (ORI)
Continuous non-invasive monitoring of the Oxygen Reserve Index (ORI) to assess perioperative oxygenation. ORI values range from 0 to 1 and reflect partial oxygen pressure changes in the 100-200 mmHg range. ORI is recorded at six time points: before anesthesia induction (T0), 5 minutes after intubation (T1), 10 minutes after Trendelenburg positioning (T2), 20 minutes after Trendelenburg positioning (T3), after desufflation (T4), and at postoperative 20 minutes (T5). ORI values will be compared between the standard PEEP and individualized PEEP groups.
Measured: From anesthesia induction to postoperative 20 minutes (approximately 3 hours)
Secondary outcomes (6)
Perioperative Atelectasis Assessed by Lung Ultrasound Score
Lung aeration assessed using a 12-zone lung ultrasound protocol in supine position. Each zone is scored 0-3: 0 = normal aeration (A-lines, fewer than 3 B-lines), 1 = mild interstitial syndrome (3 or more well-defined B-lines), 2 = moderate interstitial syndrome (confluent B-lines), 3 = severe interstitial syndrome or lung consolidation. Total score ranges from 0 to 36. Scores will be compared between standard PEEP and individualized PEEP groups.
Measured: Preoperatively and at postoperative 20 minutes
Dynamic Lung Compliance (Cdyn)
Dynamic lung compliance (Cdyn), expressed in mL/cmH₂O, recorded from the anesthesia ventilator at six predefined perioperative time points. All six observations represent repeated measurements of the same outcome using the same unit of measure
Measured: From anesthesia induction to 20 minutes after admission to the post-anesthesia care unit
Arterial Partial Pressure of Oxygen (PaO₂)
Arterial partial pressure of oxygen (PaO₂), measured in mmHg in blood samples obtained through the radial arterial cannula at the predefined time points.
Measured: From anesthesia induction to 20 minutes after admission to the post-anesthesia care unit
Postoperative Pulmonary Complications
Incidence of postoperative pulmonary complications including desaturation, dyspnea, pneumonia, or respiratory-related hospital readmission assessed at postoperative day 7 via telephone follow-up.
Measured: Up to 7 days after surgery
Arterial Partial Pressure of Carbon Dioxide (PaCO₂)
Arterial partial pressure of carbon dioxide (PaCO₂), measured in mmHg in blood samples obtained through the radial arterial cannula at the predefined time points.
Measured: From anesthesia induction to 20 minutes after admission to the post-anesthesia care unit
Arterial Blood pH
Arterial blood pH, reported as a unitless numerical value in blood samples obtained through the radial arterial cannula at the predefined time points.
Measured: From anesthesia induction to 20 minutes after admission to the post-anesthesia care unit
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted20 Aug 2026
- Study startSep 2026 (estimated)
- Primary completionSep 2027 (estimated)
- Study completionOct 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for AtelectasisStudies 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
- Cohort
- Time perspective
- Prospective
- Enrolment
- 60 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Fatih Sultan Mehmet Training and Research Hospital
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, sena solmaz, Fatih Sultan Mehmet Training and Research Hospital
- Investigators
- öznur demiroluk, MD, Study chair, ISTANBUL PROVINCIAL HEALTH DIRECTORATE FATIH SULTAN MEHMET TRAINING AND RESEARCH HOSPITAL
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07775573
- Sponsor's protocol ID
- ORİPEEP
- Other IDs
- 2025-KAEK-43
- Status last verified
- Aug 2026
- First submitted
- 7 Jun 2026
- Last updated
- 20 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 20 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Effect of Individualized Positive End-Expiratory Pressure Application on Perioperative Oxygenation Assessed by Oxygen Reserve Index Compared to Standard PEEP in Patients Undergoing Laparoscopic Inguinal Hernia Surgery: A Prospective Observational Study
- ClinicalTrials.gov ID
- NCT07775573
- Acronym / sponsor ID
- ORİPEEP
- Conditions
- Atelectasis, Perioperative Oxygenation, Laparoscopic Inguinal Hernia Repair, Mechanical Ventilation
- Keywords
- Positive End-Expiratory Pressure, PEEP titration, Oxygen Reserve Index, ORI, Lung Ultrasound, Recruitment Maneuver, Lung Protective Ventilation, Dynamic Compliance
- Study type
- Observational
- Recruitment status
- Not yet recruiting
- Enrolment
- 60 participants (estimated)
- Lead sponsor
- Fatih Sultan Mehmet Training and Research HospitalUniversity, hospital or other
- Study start
- Sep 2026 (estimated)
- Primary completion
- Sep 2027 (estimated)
- Study completion
- Oct 2027 (estimated)
- First posted
- 20 Aug 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.
During laparoscopic surgery under general anesthesia, lung function can be affected by increased abdominal pressure and patient positioning. Positive end-expiratory pressure (PEEP) is a ventilator setting that helps keep the lungs open during surgery. In standard practice, a fixed PEEP level is applied to all patients. An individualized PEEP approach tailors this setting to each patient based on lung recruitment maneuvers.
This study investigates whether individualized PEEP improves oxygenation compared to standard PEEP in patients undergoing laparoscopic inguinal hernia surgery. Oxygenation will be continuously monitored using the Oxygen Reserve Index (ORI), a non-invasive sensor. Lung aeration will also be assessed before and after surgery using bedside lung ultrasound.
Detailed description
General anesthesia combined with pneumoperitoneum and Trendelenburg positioning significantly alters respiratory mechanics. These changes can reduce functional residual capacity (FRC), promote atelectasis, and impair gas exchange - particularly in laparoscopic surgery.
Individualized PEEP, determined through a recruitment maneuver followed by PEEP titration, has been shown to reduce driving pressure and improve dynamic lung compliance compared to fixed PEEP strategies.
The Oxygen Reserve Index (ORI) is a novel non-invasive monitoring parameter that continuously tracks partial oxygen pressure changes in the 100-200 mmHg range, providing early warning of desaturation before SpO2 drops.
In this prospective observational study, 60 adult patients (ASA I-III, aged 18-75) scheduled for elective laparoscopic unilateral inguinal hernia repair under general anesthesia will be enrolled. Patients will receive either standard PEEP (5 cmH₂O) or individualized PEEP based on the attending anesthesiologist's routine clinical preference.
Hemodynamic and respiratory parameters including ORI, SpO2, airway pressures, tidal volume, dynamic compliance, and BIS will be recorded at six time points: before anesthesia (T0), 5 minutes post-intubation (T1), 10 minutes post-Trendelenburg (T2), 20 minutes post-Trendelenburg (T3), after desufflation (T4), and at postoperative 20 minutes (T5).
Lung ultrasound scoring (0-3 per zone, 12-zone protocol) will be performed preoperatively and postoperatively to assess atelectasis. Arterial blood gas analysis will provide additional oxygenation data.
The primary outcome is the effect of individualized versus standard PEEP on perioperative oxygenation as measured by ORI. The secondary outcome is the comparison of atelectasis prevention efficacy between the two PEEP strategies assessed by lung ultrasound score.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| standard PEEP | – | Procedure: Standard PEEP VentilationPatients receiving standard mechanical ventilation with a fixed PEEP of 5 cmH₂O throughout the surgical procedure. Ventilation is maintained in volume-controlled mode with tidal volume 6-8 ml/kg ideal body weight, I/E ratio 1:2, and FiO₂ 0.40. Respiratory rate is adjusted to maintain EtCO₂ between 35-40 mmHg. Anesthesia is maintained with 1.5-2% sevoflurane and remifentanil infusion 0.05-0.5 mcg/kg/min, titrated to BIS 40-60. |
| Individualized PEEP | – | Procedure: Individualized PEEP VentilationPatients receiving individualized PEEP determined by a recruitment maneuver followed by PEEP titration, applied at 10 minutes after Trendelenburg positioning. The individualized PEEP level is maintained throughout the surgery. All other ventilation parameters are identical to the standard PEEP group: volume-controlled mode, tidal volume 6-8 ml/kg, I/E ratio 1:2, FiO₂ 0.40, EtCO₂ 35-40 mmHg. Anesthesia maintained with 1.5-2% sevoflurane and remifentanil 0.05-0.5 mcg/kg/min, BIS 40-60. |
Who may qualify
- Ages
- 18 to 75 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Adult patients scheduled for elective laparoscopic unilateral inguinal hernia repair under general anesthesia at Fatih Sultan Mehmet Training and Research Hospital, Istanbul, Turkey.
Key inclusion criteria (5 listed)
- Aged 18-75 years
- ASA physical status I-III
- Scheduled for elective laparoscopic unilateral inguinal hernia repair under general anesthesia
- Body mass index (BMI) < 35 kg/m²
- Written informed consent obtained
Key exclusion criteria (14 listed)
- Age below 18 or above 75 years
- ASA physical status IV-V
- Emergency surgical procedure
- Severe chronic or restrictive pulmonary disease
- Pulmonary hypertension
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 |
|---|---|---|
| Standard PEEP VentilationMechanical ventilation with a fixed positive end-expiratory pressure (PEEP) of 5 cmH₂O applied throughout the surgical procedure. Volume-controlled ventilation mode with tidal volume 6-8 ml/kg ideal body weight, inspiratory-to-expiratory ratio 1:2, and fraction of inspired oxygen (FiO₂) 0.40. Respiratory rate adjusted to maintain end-tidal CO₂ (EtCO₂) between 35-40 mmHg. No recruitment maneuver is performed. | Procedure or surgery | standard PEEP |
| Individualized PEEP VentilationIndividualized PEEP determined by a stepwise recruitment maneuver followed by PEEP titration, applied at 10 minutes after Trendelenburg positioning. The optimal PEEP level is identified based on best dynamic lung compliance and maintained for the remainder of surgery. All other ventilation parameters are identical: volume-controlled mode, tidal volume 6-8 ml/kg, I/E ratio 1:2, FiO₂ 0.40, EtCO₂ 35-40 mmHg. | Procedure or surgery | Individualized PEEP |
Primary outcome
Perioperative Oxygenation Assessed by Oxygen Reserve Index (ORI)
Time frame: From anesthesia induction to postoperative 20 minutes (approximately 3 hours)
Continuous non-invasive monitoring of the Oxygen Reserve Index (ORI) to assess perioperative oxygenation. ORI values range from 0 to 1 and reflect partial oxygen pressure changes in the 100-200 mmHg range. ORI is recorded at six time points: before anesthesia induction (T0), 5 minutes after intubation (T1), 10 minutes after Trendelenburg positioning (T2), 20 minutes after Trendelenburg positioning (T3), after desufflation (T4), and at postoperative 20 minutes (T5). ORI values will be compared between the standard PEEP and individualized PEEP groups.
6 secondary outcomes
Perioperative Atelectasis Assessed by Lung Ultrasound Score
Time frame: Preoperatively and at postoperative 20 minutes
Dynamic Lung Compliance (Cdyn)
Time frame: From anesthesia induction to 20 minutes after admission to the post-anesthesia care unit
Arterial Partial Pressure of Oxygen (PaO₂)
Time frame: From anesthesia induction to 20 minutes after admission to the post-anesthesia care unit
Postoperative Pulmonary Complications
Time frame: Up to 7 days after surgery
Arterial Partial Pressure of Carbon Dioxide (PaCO₂)
Time frame: From anesthesia induction to 20 minutes after admission to the post-anesthesia care unit
Arterial Blood pH
Time frame: From anesthesia induction to 20 minutes after admission to the post-anesthesia care unit
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 20 Aug 2026.
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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.
öznur demiroluk, MD study chair
ISTANBUL PROVINCIAL HEALTH DIRECTORATE FATIH SULTAN MEHMET TRAINING AND RESEARCH HOSPITAL
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 Atelectasis and Perioperative Oxygenation, run by Fatih Sultan Mehmet Training and Research Hospital 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 5 inclusion and 14 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: opening soon, as of the sponsor's last update on 20 Aug 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?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact sena solmaz, MD (+905428361205, sancaksenax@gmail.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Perioperative Oxygenation Assessed by Oxygen Reserve Index (ORI) (time frame: From anesthesia induction to postoperative 20 minutes (approximately 3 hours)). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 20 Aug 2026.