Postoperative ComplicationsULTRASVENT-2NCT07613177
Optimal PEEP for Postoperative Oxygenation and Lung Aeration (ULTRASVENT-2)
A study testing Intraoperative Positive End-Expiratory Pressure (PEEP) Regulation in people with Postoperative Complications and Respiratory Insufficiency, run by Moscow Multidisciplinary Clinical Center "Kommunarka" at 1 site in Russia.
Trial summary
The purpose of this multicenter, randomized controlled trial (ULTRASVENT-2) is to evaluate the effect of different positive end-expiratory pressure (PEEP) levels on postoperative oxygenation and lung aeration in adult patients undergoing elective non-cardiac and non-thoracic surgery under general anesthesia. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Postoperative Complications, Respiratory Insufficiency, Pulmonary Atelectasis
- What is being tested?
- Intraoperative Positive End-Expiratory Pressure (PEEP) Regulation
- Type of treatment
- Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 360 participants
- Where
- 1 siteRussia
- Study dates
- 1 Jul 2026to 20 Dec 2026
- Phase
- Interventional
- 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 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Age greater than or equal to 18 years.
- Planned elective non-cardiac and non-thoracic surgical intervention requiring general anesthesia with mechanical ventilation.
- Airway protection utilizing an endotracheal tube.
- Assignment to one of the four specific surgical strata: non-abdominal, major open abdominal, major laparoscopic abdominal, or low-trauma laparoscopic surgery.
- Baseline lung ultrasound showing no pathological findings, corresponding to a total preoperative LUS score of 0.
- Technical feasibility of performing a postoperative lung ultrasound within the first 2 hours after the completion of surgery.
- Signed written informed consent to participate in the clinical trial.
Who cannot join
- Planned cardiac or thoracic surgery (e.g., coronary artery bypass grafting, valve replacement, heart transplantation, lung resection, esophageal surgery).
- Pneumothorax diagnosed before or during the surgical procedure.
- Inability to adequately visualize the target dorsal-basal lung zones by ultrasound due to physical limitations (e.g., morbid obesity, massive surgical dressings, anatomical anomalies, or dermatological lesions in the scanning area).
- Presence of hydrothorax detected on the baseline preoperative ultrasound.
- Confirmed perioperative aspiration of gastric contents or other foreign material.
- Any pathological changes identified during the baseline ultrasound of the dorsal-basal lung regions (a total preoperative LUS score greater than 0).
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- Requirement for massive blood transfusion during the surgery, defined according to local institutional criteria.
- Surgical interventions directly involving or violating the diaphragm.
- Expected inability to conduct reliable postoperative clinical and ultrasound assessments (e.g., need for deep sedation preventing wakefulness and contact, or planned transfer to another facility).
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Russia1 site
Moscow Multi-disciplinary Clinical Center "Kommunarka"
Moscow, Moscow, 108814
Ivan Shcheparev, MD, PhD, +7 901 908 90 88, is22@list.ru
About this study
Official title: Effect of Positive End-Expiratory Pressure (PEEP) Level on Postoperative Oxygenation and Lung Aeration Assessed by Lung Ultrasound Monitoring: A Multicenter Randomized Controlled Trial (ULTRASVENT-2)
The purpose of this multicenter, randomized controlled trial (ULTRASVENT-2) is to evaluate the effect of different positive end-expiratory pressure (PEEP) levels on postoperative oxygenation and lung aeration in adult patients undergoing elective non-cardiac and non-thoracic surgery under general anesthesia. Moving away from traditional binary outcomes, this study utilizes a continuous functional metric, the non-invasive oxygenation index SpO2/FiO2 (S/F ratio), as the primary endpoint to precisely capture the degree of respiratory function preservation.
Patients will be stratified into four distinct surgical cohorts based on the type and aggressiveness of the procedure: non-abdominal surgery, major open abdominal surgery, major laparoscopic abdominal surgery, and low-trauma laparoscopic surgery. This adaptive design aims to investigate how protective PEEP strategies interact with varying degrees of surgical trauma and intraoperative pneumoperitoneum, allowing the optimization of mechanical ventilation parameters for routine clinical practice.
Read the detailed description
Postoperative pulmonary complications remain a significant cause of morbidity and prolonged hospital stay after major surgical interventions under general anesthesia. While positive end-expiratory pressure (PEEP) is widely used to prevent alveolar collapse, the optimal target levels across different surgical sub-types remain controversial in modern anesthesiology. This trial aims to establish robust clinical evidence regarding perioperative lung protection using a comprehensive functional-anatomical approach.
Primary Endpoint and Measurement Standardization:
The primary outcome of the trial is the non-invasive oxygenation index, the S/F ratio (SpO2/Fraction of inspired oxygen), assessed exactly 2 hours post-extubation in the Post-Anesthesia Care Unit (PACU) and tracked dynamically over the first 24 hours of the postoperative period. To eliminate confounding variables and ensure absolute reproducibility across participating centers, the primary endpoint measurement is strictly standardized according to the following criteria:
- Room Air Breathing (FiO2 0.21): The evaluation is performed while the patient breathes atmospheric air without supplemental oxygen. This eliminates the masking of intrapulmonary shunts and prevents hyperoxia-induced absorption atelectasis.
- Patient Position: The patient must be placed in a strict supine position. This positioning represents the most physiologically challenging state for the respiratory system, inducing cranial displacement of the diaphragm and maximizing gravity-dependent alveolar collapse.
- Full Wakefulness Criteria: The measurement is executed only when the patient reaches a full awake status, defined as a modified Post Anesthesia Recovery Score (PARS) greater than 8, with the specific ventilation sub-score being equal to 2 (ability to deep breathe and cough freely). This cognitive and motor filter guarantees that any recorded functional impairment is caused by true parenchymal collapse rather than residual neuromuscular blockade or opioid-induced respiratory depression.
Differentiated Lung Ultrasound (LUS) Track:
To identify the anatomical substrate behind changes in gas exchange, regional lung aeration patterns will be recorded as the key secondary endpoint using a delta LUS score (postoperative score minus preoperative baseline). The diagnostic burden on the investigators is optimized using two parallel diagnostic tracks:
- Express Track (Strata 1 and 4): A rapid, 2-zone simplified protocol focusing exclusively on the most gravity-dependent bilateral dorsal-basal sectors (Zone 6). This assessment takes 2 to 3 minutes and minimizes interference with routine PACU workflows.
- Panoramic Mapping Track (Strata 2 and 3): A comprehensive 12-zone thoracic mapping performed under Intensive Care Unit (ICU) conditions. Furthermore, a nested validation sub-study will incorporate high-resolution chest computed tomography (CT) scans performed strictly based on clinical indications (such as refractory hypoxemia or suspected pneumonia). CT data will serve as the gold standard reference to calculate the true sensitivity and specificity of the 12-zone ultrasound findings.
Surgical Stratification and Sample Size Design:
Patients will be randomized in a 1:1 ratio to receive either a fixed standard (lower) PEEP or a fixed higher PEEP strategy throughout the intraoperative period (from intubation to extubation). Randomization is performed independently within 4 parallel strata to achieve a total sample size of 320 to 360 patients:
- Strata 1: Non-abdominal surgery (n = 100; PEEP 5 cm H2O versus PEEP 8 cm H2O).
- Strata 2: Major open abdominal surgery (n = 60 to 80; PEEP 5 cm H2O versus PEEP 8 cm H2O).
- Strata 3: Major laparoscopic abdominal surgery (n = 60 to 80; PEEP 7 cm H2O versus PEEP 12 cm H2O).
- Strata 4: Low-trauma laparoscopic surgery (n = 100; PEEP 5 cm H2O versus PEEP 12 cm H2O).
Statistical Analysis Framework:
Data processing will be conducted in the jamovi software environment using General Linear Models (GLM). The analysis will incorporate continuous and categorical baseline covariates (Body Mass Index, age, ASA physical status, and duration of surgery) to reduce residual variance. A key element of the statistical plan is the evaluation of interaction effects between the PEEP level and the specific surgical stratum to determine whether a higher PEEP provides a universal benefit or if its protective role is strictly dependent on the surgical phenotype.
Implementation Protocol Phases:
To guarantee data integrity and eliminate investigator bias, the project is structured into four consecutive logical phases:
Phase 1: Regulatory start, including central registration on ClinicalTrials.gov, Local Ethics Committee (LEC) submission and approval, and prospective publication of the formal Study Protocol manuscript.
Phase 2: Standardized hands-on calibration and training of the core investigator team (4 to 6 specialists) regarding precise zone identification and digital data entry.
Phase 3: A mandatory run-in period dedicated to inter-rater reliability testing. Each investigator must scan a test cohort, and the enrollment of randomized trial patients can begin only after achieving an inter-operator consensus threshold defined as a Cohen's Kappa coefficient greater than or equal to 0.7 and an absolute category agreement greater than or equal to 80%.
Phase 4: Active enrollment utilizing an adaptive recruitment strategy. The trial will commence by enrolling patients in high-volume, low-risk groups (Strata 1 and 4) to seamlessly refine logistical and database processes before activating the complex and labor-intensive ICU-based cohorts (Strata 2 and 3).
- Conditions
- Postoperative Complications, Respiratory Insufficiency, Pulmonary Atelectasis, Positive-End Expiratory Pressure, Hypoxemia
- Being tested
- Intraoperative Positive End-Expiratory Pressure (PEEP) Regulation
- Keywords
- Lung ultrasound, S/F ratio, Perioperative lung protection, Laparoscopic surgery, Open laparotomy
- Medical subject headings
- Postoperative Complications, Respiratory Insufficiency, Pulmonary Atelectasis, Hypoxia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Intraoperative Positive End-Expiratory Pressure (PEEP) RegulationProcedure or surgery
Application of fixed PEEP levels calculated according to surgical aggressiveness and the presence of pneumoperitoneum. Standard PEEP arm utilizes PEEP values of 5 cm H2O. Higher PEEP arm utilizes protective PEEP values of 8 or 12 cm H2O. The assigned PEEP strategy is initiated immediately following endotracheal intubation and maintained continuously until extubation.
| Study group | Role | What they receive |
|---|---|---|
| Standard PEEP Strategy | Active comparator | Patients randomized to this arm will receive a fixed, standard (lower) level of Positive End-Expiratory Pressure (PEEP) throughout the intraoperative period (from intubation to extubation). The specific PEEP value is determined strictly by the surgical stratum: 5 cm H2O for Strata 1 (Non-abdominal surgery), 5 cm H2O for Strata 2 (Major open abdominal surgery), 5 cm H2O for Strata 3 (Major laparoscopic abdominal surgery), and 5 cm H2O for Strata 4 (Low-trauma laparoscopic surgery). All other mechanical ventilation parameters remain standardized (tidal volume 6-8 mL/kg of ideal body weight). Receives: Procedure: Intraoperative Positive End-Expiratory Pressure (PEEP) Regulation |
| Higher PEEP Strategy | Experimental | Patients randomized to this arm will receive a fixed, higher level of Positive End-Expiratory Pressure (PEEP) designed for protective lung ventilation throughout the intraoperative period. The specific PEEP value is tailored to the surgical stratum and abdominal risk: 8 cm H2O for Strata 1 (Non-abdominal surgery), 8 cm H2O for Strata 2 (Major open abdominal surgery), 12 cm H2O for Strata 3 (Major laparoscopic abdominal surgery), and 12 cm H2O for Strata 4 (Low-trauma laparoscopic surgery). All other mechanical ventilation parameters remain standardized (tidal volume 6-8 mL/kg of ideal body weight). Receives: Procedure: Intraoperative Positive End-Expiratory Pressure (PEEP) Regulation |
What is being measured
The primary outcome is the main question the study is designed to answer.
Non-invasive oxygenation index (SpO2/FiO2 ratio)
The primary functional outcome is the SpO2/FiO2 (S/F) ratio, a continuous metric indicating the degree of lung oxygenation. The S/F ratio is calculated by dividing the peripheral capillary oxygen saturation (SpO2) by the fraction of inspired oxygen (FiO2). To ensure standardization, postoperative measurements are performed on room air in a supine position. Measurements are recorded strictly when the patient achieves full wakefulness, which is verified using the modified Post Anesthesia Recovery Score (PARS) as a readiness criteria. The PARS scale ranges from a minimum of 0 to a maximum of 10, where higher scores indicate a better clinical recovery.
Note: The reported outcome is solely the S/F ratio value; the PARS score is used exclusively as a clinical condition to initiate the S/F measurement and is not aggregated into the final outcome value.
Measured: Assessed at 3 time points: preoperatively (baseline); exactly 2 hours post-extubation; and 24 hours post-operation.
Secondary outcomes (3)
Incidence of Postoperative Pulmonary Complications (PPCs)
The composite clinical outcome evaluates the total percentage of patients developing at least one severe respiratory adverse event in the postoperative period. PPCs are strictly defined as the presence of one or more of the following: confirmed hospital-acquired pneumonia, prolonged requirement for supplemental oxygen therapy lasting longer than 24 hours, or the onset of refractory hypoxemia necessitating unexpected transfer to the Intensive Care Unit for non-invasive or invasive mechanical ventilation.
Measured: From the end of surgery up to 7 days post-operation.
Postoperative lung ultrasound score and aeration patterns
Evaluation of the absolute postoperative Lung Ultrasound (LUS) score to assess anesthesia-induced alveolar collapse. A differentiated protocol is used based on surgical strata.
Strata 1 and 4 use a 2-zone express protocol targeting dorsal-basal sectors (total scale range: minimum 0 to maximum 6).
Strata 2 and 3 use a comprehensive 12-zone panoramic thoracic mapping protocol (total scale range: minimum 0 to maximum 36).
For both LUS scales, higher scores indicate a worse outcome (more severe loss of lung aeration and atelectasis). Specific qualitative acoustic patterns (e.g., multiple B-lines, subpleural consolidations, or static bronchograms) are also recorded to validate the numerical LUS score.
Measured: Exactly 2 hours post-extubation in the Post-Anesthesia Care Unit (PACU) or Intensive Care Unit (ICU).
Incidence of Intraoperative Hemodynamic Instability
Frequency of intraoperative hemodynamic instability episodes directly related to mechanical ventilation settings, specifically measured as the requirement for the initiation or dose increase of vasopressor support (ephedrine, phenylephrine, or norepinephrine) to maintain a mean arterial pressure (MAP) greater than 65 mm Hg.
Measured: Intraoperatively (from the moment of endotracheal intubation until extubation).
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted29 May 2026
- Study start1 Jul 2026 (estimated)
- Primary completion1 Dec 2026 (estimated)
- Study completion20 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (7)Papers the sponsor has linked to this study.
- Other trials for Postoperative ComplicationsStudies 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
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- Prospective, multicenter, stratified, parallel-group randomized controlled trial. Participants are independently stratified into 4 parallel surgical strata based on the procedure type: Strata 1 (Non-abdominal surgery), Strata 2 (Major open abdominal surgery), Strata 3 (Major laparoscopic abdominal surgery), and Strata 4 (Low-trauma laparoscopic surgery). Within each distinct stratum, participants are randomized in a 1:1 ratio to receive either a fixed standard PEEP or a fixed higher PEEP strategy from intubation to extubation.
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 360 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Moscow Multidisciplinary Clinical Center "Kommunarka"
- Sponsor type
- Other government
- Responsible party
- Sponsor
- Investigators
- Ivan Shcheparev, MD, PhD, Principal investigator, Moscow Multi-disciplinary Clinical Center "Kommunarka"Denis Protsenko, MD, PhD, Professor, Study director, Moscow Multi-disciplinary Clinical Center "Kommunarka"Efim Shifman, MD, PhD, Professor, Study chair, Moscow Multi-disciplinary Clinical Center "Kommunarka"
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07613177
- Sponsor's protocol ID
- ULTRASVENT-2
- Acronym
- ULTRASVENT-2
- Status last verified
- May 2026
- First submitted
- 19 May 2026
- Last updated
- 29 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: De-identified individual participant data (IPD) that underlie the results reported in the primary publication (including baseline characteristics, intraoperative mechanical ventilation parameters, lung ultrasound scores, and clinical postoperative outcomes) will be made publicly available to ensure absolute transparency and academic reproducibility.
Publications
L D, Kumar R, Patel N, Ayub A, Rewari V, Subramaniam R, Roy KK. Effect of Lung Compliance-Based Optimum Pressure Versus Fixed Positive End-Expiratory Pressure on Lung Atelectasis Assessed by Modified Lung Ultrasound Score in Laparoscopic Gynecological Surgery: A Prospective Randomized Controlled Trial. Cureus. 2023 Jun 12;15(6):e40278. doi: 10.7759/cureus.40278. eCollection 2023 Jun.
PubMed 37448389Miskovic A, Lumb AB. Postoperative pulmonary complications. Br J Anaesth. 2017 Mar 1;118(3):317-334. doi: 10.1093/bja/aex002.
PubMed 28186222Zhang Y, Zhu J, Xi C, Wang G. Effect of driving pressure-guided individualized positive end-expiratory pressure (PEEP) ventilation strategy on postoperative atelectasis in patients undergoing laparoscopic surgery as assessed by ultrasonography: study protocol for a prospective randomized controlled trial. Trials. 2025 Mar 26;26(1):106. doi: 10.1186/s13063-025-08819-5.
PubMed 40140868Frassanito L, Sonnino C, Pitoni S, Zanfini BA, Catarci S, Gonnella GL, Germini P, Vizzielli G, Scambia G, Draisci G. Lung ultrasound to monitor the development of pulmonary atelectasis in gynecologic oncologic surgery. Minerva Anestesiol. 2020 Dec;86(12):1287-1295. doi: 10.23736/S0375-9393.20.14687-X. Epub 2020 Nov 11.
PubMed 33174404Ma J, Sun M, Song F, Wang A, Tian X, Wu Y, Wang L, Zhao Q, Liu B, Wang S, Qiu Y, Hou H, Deng L. Effect of ultrasound-guided individualized positive end-expiratory pressure on the severity of postoperative atelectasis in elderly patients: a randomized controlled study. Sci Rep. 2024 Nov 15;14(1):28128. doi: 10.1038/s41598-024-79105-8.
PubMed 39548165Liao B, Liao W, Yin S, Liu S, Wu X. Effect of ultrasound-guided lung recruitment to reduce pulmonary atelectasis after non-cardiac surgery under general anesthesia: a systematic review and meta-analysis of randomized controlled trials. Perioper Med (Lond). 2024 Mar 27;13(1):23. doi: 10.1186/s13741-024-00379-7.
PubMed 38539248Wu XZ, Xia HM, Zhang P, Li L, Hu QH, Guo SP, Li TY. Effects of ultrasound-guided alveolar recruitment manoeuvres compared with sustained inflation or no recruitment manoeuvres on atelectasis in laparoscopic gynaecological surgery as assessed by ultrasonography: a randomized clinical trial. BMC Anesthesiol. 2022 Aug 16;22(1):261. doi: 10.1186/s12871-022-01798-z.
PubMed 35974310
Study at a glance
From the registry record, last updated by the sponsor on 29 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effect of Positive End-Expiratory Pressure (PEEP) Level on Postoperative Oxygenation and Lung Aeration Assessed by Lung Ultrasound Monitoring: A Multicenter Randomized Controlled Trial (ULTRASVENT-2)
- ClinicalTrials.gov ID
- NCT07613177
- Acronym / sponsor ID
- ULTRASVENT-2 / ULTRASVENT-2
- Conditions
- Postoperative Complications, Respiratory Insufficiency, Pulmonary Atelectasis, Positive-End Expiratory Pressure, Hypoxemia
- Keywords
- Lung ultrasound, S/F ratio, Perioperative lung protection, Laparoscopic surgery, Open laparotomy
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 360 participants (estimated)
- Lead sponsor
- Moscow Multidisciplinary Clinical Center "Kommunarka"Other government
- Study start
- 1 Jul 2026 (estimated)
- Primary completion
- 1 Dec 2026 (estimated)
- Study completion
- 20 Dec 2026 (estimated)
- First posted
- 29 May 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.
The purpose of this multicenter, randomized controlled trial (ULTRASVENT-2) is to evaluate the effect of different positive end-expiratory pressure (PEEP) levels on postoperative oxygenation and lung aeration in adult patients undergoing elective non-cardiac and non-thoracic surgery under general anesthesia. Moving away from traditional binary outcomes, this study utilizes a continuous functional metric, the non-invasive oxygenation index SpO2/FiO2 (S/F ratio), as the primary endpoint to precisely capture the degree of respiratory function preservation.
Patients will be stratified into four distinct surgical cohorts based on the type and aggressiveness of the procedure: non-abdominal surgery, major open abdominal surgery, major laparoscopic abdominal surgery, and low-trauma laparoscopic surgery. This adaptive design aims to investigate how protective PEEP strategies interact with varying degrees of surgical trauma and intraoperative pneumoperitoneum, allowing the optimization of mechanical ventilation parameters for routine clinical practice.
Detailed description
Postoperative pulmonary complications remain a significant cause of morbidity and prolonged hospital stay after major surgical interventions under general anesthesia. While positive end-expiratory pressure (PEEP) is widely used to prevent alveolar collapse, the optimal target levels across different surgical sub-types remain controversial in modern anesthesiology. This trial aims to establish robust clinical evidence regarding perioperative lung protection using a comprehensive functional-anatomical approach.
Primary Endpoint and Measurement Standardization:
The primary outcome of the trial is the non-invasive oxygenation index, the S/F ratio (SpO2/Fraction of inspired oxygen), assessed exactly 2 hours post-extubation in the Post-Anesthesia Care Unit (PACU) and tracked dynamically over the first 24 hours of the postoperative period. To eliminate confounding variables and ensure absolute reproducibility across participating centers, the primary endpoint measurement is strictly standardized according to the following criteria:
- Room Air Breathing (FiO2 0.21): The evaluation is performed while the patient breathes atmospheric air without supplemental oxygen. This eliminates the masking of intrapulmonary shunts and prevents hyperoxia-induced absorption atelectasis.
- Patient Position: The patient must be placed in a strict supine position. This positioning represents the most physiologically challenging state for the respiratory system, inducing cranial displacement of the diaphragm and maximizing gravity-dependent alveolar collapse.
- Full Wakefulness Criteria: The measurement is executed only when the patient reaches a full awake status, defined as a modified Post Anesthesia Recovery Score (PARS) greater than 8, with the specific ventilation sub-score being equal to 2 (ability to deep breathe and cough freely). This cognitive and motor filter guarantees that any recorded functional impairment is caused by true parenchymal collapse rather than residual neuromuscular blockade or opioid-induced respiratory depression.
Differentiated Lung Ultrasound (LUS) Track:
To identify the anatomical substrate behind changes in gas exchange, regional lung aeration patterns will be recorded as the key secondary endpoint using a delta LUS score (postoperative score minus preoperative baseline). The diagnostic burden on the investigators is optimized using two parallel diagnostic tracks:
- Express Track (Strata 1 and 4): A rapid, 2-zone simplified protocol focusing exclusively on the most gravity-dependent bilateral dorsal-basal sectors (Zone 6). This assessment takes 2 to 3 minutes and minimizes interference with routine PACU workflows.
- Panoramic Mapping Track (Strata 2 and 3): A comprehensive 12-zone thoracic mapping performed under Intensive Care Unit (ICU) conditions. Furthermore, a nested validation sub-study will incorporate high-resolution chest computed tomography (CT) scans performed strictly based on clinical indications (such as refractory hypoxemia or suspected pneumonia). CT data will serve as the gold standard reference to calculate the true sensitivity and specificity of the 12-zone ultrasound findings.
Surgical Stratification and Sample Size Design:
Patients will be randomized in a 1:1 ratio to receive either a fixed standard (lower) PEEP or a fixed higher PEEP strategy throughout the intraoperative period (from intubation to extubation). Randomization is performed independently within 4 parallel strata to achieve a total sample size of 320 to 360 patients:
- Strata 1: Non-abdominal surgery (n = 100; PEEP 5 cm H2O versus PEEP 8 cm H2O).
- Strata 2: Major open abdominal surgery (n = 60 to 80; PEEP 5 cm H2O versus PEEP 8 cm H2O).
- Strata 3: Major laparoscopic abdominal surgery (n = 60 to 80; PEEP 7 cm H2O versus PEEP 12 cm H2O).
- Strata 4: Low-trauma laparoscopic surgery (n = 100; PEEP 5 cm H2O versus PEEP 12 cm H2O).
Statistical Analysis Framework:
Data processing will be conducted in the jamovi software environment using General Linear Models (GLM). The analysis will incorporate continuous and categorical baseline covariates (Body Mass Index, age, ASA physical status, and duration of surgery) to reduce residual variance. A key element of the statistical plan is the evaluation of interaction effects between the PEEP level and the specific surgical stratum to determine whether a higher PEEP provides a universal benefit or if its protective role is strictly dependent on the surgical phenotype.
Implementation Protocol Phases:
To guarantee data integrity and eliminate investigator bias, the project is structured into four consecutive logical phases:
Phase 1: Regulatory start, including central registration on ClinicalTrials.gov, Local Ethics Committee (LEC) submission and approval, and prospective publication of the formal Study Protocol manuscript.
Phase 2: Standardized hands-on calibration and training of the core investigator team (4 to 6 specialists) regarding precise zone identification and digital data entry.
Phase 3: A mandatory run-in period dedicated to inter-rater reliability testing. Each investigator must scan a test cohort, and the enrollment of randomized trial patients can begin only after achieving an inter-operator consensus threshold defined as a Cohen's Kappa coefficient greater than or equal to 0.7 and an absolute category agreement greater than or equal to 80%.
Phase 4: Active enrollment utilizing an adaptive recruitment strategy. The trial will commence by enrolling patients in high-volume, low-risk groups (Strata 1 and 4) to seamlessly refine logistical and database processes before activating the complex and labor-intensive ICU-based cohorts (Strata 2 and 3).
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 2
- Model description
- Prospective, multicenter, stratified, parallel-group randomized controlled trial. Participants are independently stratified into 4 parallel surgical strata based on the procedure type: Strata 1 (Non-abdominal surgery), Strata 2 (Major open abdominal surgery), Strata 3 (Major laparoscopic abdominal surgery), and Strata 4 (Low-trauma laparoscopic surgery). Within each distinct stratum, participants are randomized in a 1:1 ratio to receive either a fixed standard PEEP or a fixed higher PEEP strategy from intubation to extubation.
| Arm | Type | Receives |
|---|---|---|
| Standard PEEP Strategy | Active comparator | Procedure: Intraoperative Positive End-Expiratory Pressure (PEEP) RegulationPatients randomized to this arm will receive a fixed, standard (lower) level of Positive End-Expiratory Pressure (PEEP) throughout the intraoperative period (from intubation to extubation). The specific PEEP value is determined strictly by the surgical stratum: 5 cm H2O for Strata 1 (Non-abdominal surgery), 5 cm H2O for Strata 2 (Major open abdominal surgery), 5 cm H2O for Strata 3 (Major laparoscopic abdominal surgery), and 5 cm H2O for Strata 4 (Low-trauma laparoscopic surgery). All other mechanical ventilation parameters remain standardized (tidal volume 6-8 mL/kg of ideal body weight). |
| Higher PEEP Strategy | Experimental | Procedure: Intraoperative Positive End-Expiratory Pressure (PEEP) RegulationPatients randomized to this arm will receive a fixed, higher level of Positive End-Expiratory Pressure (PEEP) designed for protective lung ventilation throughout the intraoperative period. The specific PEEP value is tailored to the surgical stratum and abdominal risk: 8 cm H2O for Strata 1 (Non-abdominal surgery), 8 cm H2O for Strata 2 (Major open abdominal surgery), 12 cm H2O for Strata 3 (Major laparoscopic abdominal surgery), and 12 cm H2O for Strata 4 (Low-trauma laparoscopic surgery). All other mechanical ventilation parameters remain standardized (tidal volume 6-8 mL/kg of ideal body weight). |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (7 listed)
- Age greater than or equal to 18 years.
- Planned elective non-cardiac and non-thoracic surgical intervention requiring general anesthesia with mechanical ventilation.
- Airway protection utilizing an endotracheal tube.
- Assignment to one of the four specific surgical strata: non-abdominal, major open abdominal, major laparoscopic abdominal, or low-trauma laparoscopic surgery.
- Baseline lung ultrasound showing no pathological findings, corresponding to a total preoperative LUS score of 0.
Key exclusion criteria (9 listed)
- Planned cardiac or thoracic surgery (e.g., coronary artery bypass grafting, valve replacement, heart transplantation, lung resection, esophageal surgery).
- Pneumothorax diagnosed before or during the surgical procedure.
- Inability to adequately visualize the target dorsal-basal lung zones by ultrasound due to physical limitations (e.g., morbid obesity, massive surgical dressings, anatomical anomalies, or dermatological lesions in the scanning area).
- Presence of hydrothorax detected on the baseline preoperative ultrasound.
- Confirmed perioperative aspiration of gastric contents or other foreign material.
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 |
|---|---|---|
| Intraoperative Positive End-Expiratory Pressure (PEEP) RegulationApplication of fixed PEEP levels calculated according to surgical aggressiveness and the presence of pneumoperitoneum. Standard PEEP arm utilizes PEEP values of 5 cm H2O. Higher PEEP arm utilizes protective PEEP values of 8 or 12 cm H2O. The assigned PEEP strategy is initiated immediately following endotracheal intubation and maintained continuously until extubation. | Procedure or surgery | Higher PEEP Strategy, Standard PEEP Strategy |
Primary outcome
Non-invasive oxygenation index (SpO2/FiO2 ratio)
Time frame: Assessed at 3 time points: preoperatively (baseline); exactly 2 hours post-extubation; and 24 hours post-operation.
The primary functional outcome is the SpO2/FiO2 (S/F) ratio, a continuous metric indicating the degree of lung oxygenation. The S/F ratio is calculated by dividing the peripheral capillary oxygen saturation (SpO2) by the fraction of inspired oxygen (FiO2). To ensure standardization, postoperative measurements are performed on room air in a supine position. Measurements are recorded strictly when the patient achieves full wakefulness, which is verified using the modified Post Anesthesia Recovery Score (PARS) as a readiness criteria. The PARS scale ranges from a minimum of 0 to a maximum of 10, where higher scores indicate a better clinical recovery. Note: The reported outcome is solely the S/F ratio value; the PARS score is used exclusively as a clinical condition to initiate the S/F measurement and is not aggregated into the final outcome value.
3 secondary outcomes
Incidence of Postoperative Pulmonary Complications (PPCs)
Time frame: From the end of surgery up to 7 days post-operation.
Postoperative lung ultrasound score and aeration patterns
Time frame: Exactly 2 hours post-extubation in the Post-Anesthesia Care Unit (PACU) or Intensive Care Unit (ICU).
Incidence of Intraoperative Hemodynamic Instability
Time frame: Intraoperatively (from the moment of endotracheal intubation until extubation).
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 29 May 2026.
- Background: PubMed 37448389L D, Kumar R, Patel N, Ayub A, Rewari V, Subramaniam R, Roy KK. Effect of Lung Compliance-Based Optimum Pressure Versus Fixed Positive End-Expiratory Pressure on Lung Atelectasis Assessed by Modified Lung Ultrasound Score in Laparoscopic Gynecological Surgery: A Prospective Randomized Controlled Trial. Cureus. 2023 Jun 12;15(6):e40278. doi: 10.7759/cureus.40278. eCollection 2023 Jun.
- Background: PubMed 28186222Miskovic A, Lumb AB. Postoperative pulmonary complications. Br J Anaesth. 2017 Mar 1;118(3):317-334. doi: 10.1093/bja/aex002.
- Background: PubMed 40140868Zhang Y, Zhu J, Xi C, Wang G. Effect of driving pressure-guided individualized positive end-expiratory pressure (PEEP) ventilation strategy on postoperative atelectasis in patients undergoing laparoscopic surgery as assessed by ultrasonography: study protocol for a prospective randomized controlled trial. Trials. 2025 Mar 26;26(1):106. doi: 10.1186/s13063-025-08819-5.
- Background: PubMed 33174404Frassanito L, Sonnino C, Pitoni S, Zanfini BA, Catarci S, Gonnella GL, Germini P, Vizzielli G, Scambia G, Draisci G. Lung ultrasound to monitor the development of pulmonary atelectasis in gynecologic oncologic surgery. Minerva Anestesiol. 2020 Dec;86(12):1287-1295. doi: 10.23736/S0375-9393.20.14687-X. Epub 2020 Nov 11.
- Background: PubMed 39548165Ma J, Sun M, Song F, Wang A, Tian X, Wu Y, Wang L, Zhao Q, Liu B, Wang S, Qiu Y, Hou H, Deng L. Effect of ultrasound-guided individualized positive end-expiratory pressure on the severity of postoperative atelectasis in elderly patients: a randomized controlled study. Sci Rep. 2024 Nov 15;14(1):28128. doi: 10.1038/s41598-024-79105-8.
- Background: PubMed 38539248Liao B, Liao W, Yin S, Liu S, Wu X. Effect of ultrasound-guided lung recruitment to reduce pulmonary atelectasis after non-cardiac surgery under general anesthesia: a systematic review and meta-analysis of randomized controlled trials. Perioper Med (Lond). 2024 Mar 27;13(1):23. doi: 10.1186/s13741-024-00379-7.
- Background: PubMed 35974310Wu XZ, Xia HM, Zhang P, Li L, Hu QH, Guo SP, Li TY. Effects of ultrasound-guided alveolar recruitment manoeuvres compared with sustained inflation or no recruitment manoeuvres on atelectasis in laparoscopic gynaecological surgery as assessed by ultrasonography: a randomized clinical trial. BMC Anesthesiol. 2022 Aug 16;22(1):261. doi: 10.1186/s12871-022-01798-z.
- Individual participant dataSharing planned: Yes. De-identified individual participant data (IPD) that underlie the results reported in the primary publication (including baseline characteristics, intraoperative mechanical ventilation parameters, lung ultrasound scores, and clinical postoperative outcomes) will be made publicly available to ensure absolute transparency and academic reproducibility.
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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.
Ivan Shcheparev, MD, PhD principal investigator
Moscow Multi-disciplinary Clinical Center "Kommunarka"
Denis Protsenko, MD, PhD, Professor study director
Moscow Multi-disciplinary Clinical Center "Kommunarka"
Efim Shifman, MD, PhD, Professor study chair
Moscow Multi-disciplinary Clinical Center "Kommunarka"
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Intraoperative Positive End-Expiratory Pressure (PEEP) Regulation in people with Postoperative Complications and Respiratory Insufficiency, run by Moscow Multidisciplinary Clinical Center "Kommunarka" at 1 site in Russia.
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 7 inclusion and 9 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 29 May 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 Russia. 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 Ivan Shcheparev, MD, PhD (+7 901 908 90 88, is22@list.ru), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Non-invasive oxygenation index (SpO2/FiO2 ratio) (time frame: Assessed at 3 time points: preoperatively (baseline); exactly 2 hours post-extubation; and 24 hours post-operation.). 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 NCT07613177, which also lists 7 linked publications.
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 29 May 2026.