Optimal PEEP Level for Minimizing the Risk of Postoperative Atelectasis: A Retrospective Cohort Study Based on Lung Ultrasound Monitoring

NCT ID: NCT07211074

Last Updated: 2025-10-07

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

RECRUITING

Total Enrollment

450 participants

Study Classification

OBSERVATIONAL

Study Start Date

2025-09-22

Study Completion Date

2026-01-31

Brief Summary

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Background: After surgery with general anesthesia, it is common for parts of the lungs to collapse, a condition called atelectasis. This can lead to low blood oxygen levels and other lung complications. Doctors use a setting on the breathing machine called PEEP (Positive End-Expiratory Pressure) to help keep the lungs open, but the best level to use is still debated.

Purpose of the Study: The goal of this research is to find a PEEP level that minimizes the risk of lung collapse and low oxygen levels after surgery. The investigators will use lung ultrasound, a safe and non-invasive imaging method, to check the health of the lungs at the patient's bedside.

The investigators will not assign treatments; they will observe the outcomes based on the PEEP level chosen by the patient's anesthesiologist during routine care. A simplified ultrasound scan will be used to score the amount of lung collapse before and after surgery. The main outcomes will be the frequency of lung collapse and the frequency of low oxygen levels (defined as SpO₂ of 90% or less).

Detailed Description

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Background and Rationale Postoperative pulmonary complications (PPCs) are a significant cause of morbidity and mortality, associated with a nearly 20% increase in lethality and prolonged hospital stays. The most common PPC is atelectasis, which can trigger more severe complications and develops in up to 90% of patients following the induction of general anesthesia. While computed tomography (CT) is the gold standard for diagnosing atelectasis, lung ultrasound (LUS) has emerged as a rapid, reliable, and validated bedside tool that is superior to standard chest radiography, with a high sensitivity (87.7%) and specificity (92.1%) compared to CT.

A key strategy for preventing atelectasis is the application of positive end-expiratory pressure (PEEP). While ventilation with zero PEEP is considered harmful, the optimal level remains controversial. Large randomized trials (e.g., PROVHILO, PROBESE) have not shown a benefit for universally high PEEP strategies (e.g., 12 cm H₂O) and have noted an increased risk of hemodynamic instability. This contrasts with other studies suggesting benefits from moderate or individualized PEEP levels. This study designed to address this gap by analyzing data to identify a PEEP threshold associated with minimal atelectasis and desaturation, using a simplified LUS monitoring protocol.

Study Objectives The primary objective of this study is to evaluate the effectiveness of a simplified LUS protocol for monitoring postoperative atelectasis and to determine a PEEP level associated with the minimum frequency and severity of atelectasis.

Specific study tasks include:

* To assess the frequency and severity of postoperative atelectasis in patients with different airway management strategies and PEEP levels.
* To determine an optimal PEEP threshold for minimizing the risk of atelectasis and desaturation using ROC analysis.
* To compare the rates of atelectasis and desaturation (SpO₂ ≤90%) between patient subgroups.
* To conduct a multifactorial analysis of risk factors for developing postoperative atelectasis and desaturation.
* To evaluate the prognostic value of the LUS score for predicting the risk of postoperative desaturation.

Study Design and Methodology This is a single-center, retrospective cohort study conducted at the National Medical and Surgical Center n.a. N.I. Pirogov. The level of PEEP not assigned by the protocol but determined by the attending anesthesiologist as part of routine clinical practice.

A simplified 2-zone LUS protocol will be used, focusing on the posterior-basal lung regions most susceptible to collapse. Lung aeration will be quantified using a 4-point scoring system (0-3), with 0 indicating normal aeration and 3 indicating major consolidation. Scans will be performed by one of three competent investigators before anesthesia and within the first hours after surgery, once the patient is fully awake.

Conditions

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Postoperative Pulmonary Complications (PPCs) Postoperative Atelectasis Lung Ultrasound

Study Design

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Observational Model Type

COHORT

Study Time Perspective

RETROSPECTIVE

Study Groups

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ETT with PEEP ≤7 cm H₂O

This cohort consists of patients who underwent surgery with general anesthesia managed with an endotracheal tube (ETT) and a positive end-expiratory pressure (PEEP) of 7 cm H₂O or less. This group will include 250 patients in the final analysis

No interventions assigned to this group

ETT with PEEP ≥8 cm H₂O

This cohort consists of patients who underwent surgery with general anesthesia managed with an endotracheal tube (ETT) and a positive end-expiratory pressure (PEEP) of 8 cm H₂O or greater. This group will include 119 patients in the final analysis

No interventions assigned to this group

Laryngeal Mask

This cohort consists of patients who underwent surgery with general anesthesia managed with a laryngeal mask (LM) for airway protection. This group will include 81 patients in the final analysis

No interventions assigned to this group

Eligibility Criteria

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Inclusion Criteria

* Patients undergoing surgical intervention under general anesthesia with mechanical ventilation.
* Airway protection managed with either an endotracheal tube or a laryngeal mask.
* A normal baseline ultrasound of the posterior-basal lung regions, corresponding to a score of 0 on the lung ultrasound scale.

Exclusion Criteria

* Patients undergoing cardiac or thoracic surgery.
* Presence of a perioperatively identified pneumothorax.
* Inability to obtain adequate ultrasound visualization of the target lung zones.
* Presence of hydrothorax.
* Confirmed perioperative pulmonary aspiration.
* Presence of any pathological findings on the initial baseline ultrasound of the posterior-basal lung regions.
* Requirement for massive blood transfusion during the operation.
* Patients undergoing surgery on the diaphragm.
* Prolonged residual sedation lasting more than 2 hours post-operation
Minimum Eligible Age

18 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

No

Sponsors

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State Budgetary Healthcare Institution, National Medical Surgical Center N.A. N.I. Pirogov, Ministry of Health of Russia

OTHER

Sponsor Role lead

Responsible Party

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Responsibility Role SPONSOR

Principal Investigators

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Boris Teplykh, MD

Role: STUDY_DIRECTOR

Pirogov National Medical and Surgical Center

Ivan Shcheparev, MD, PhD

Role: PRINCIPAL_INVESTIGATOR

Pirogov National Medical and Surgical Center

Locations

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Pirogov National Medical and Surgical Cente

Moscow, , Russia

Site Status RECRUITING

Countries

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Russia

Central Contacts

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Ivan Shcheparev, MD, PhD

Role: CONTACT

+7 901 908 90 88

Boris Teplykh, MD

Role: CONTACT

+7 916 616-60-38

Facility Contacts

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Ivan Shcheparev, MD, PhD

Role: primary

+7 901 908 90 88

References

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Writing Committee for the PROBESE Collaborative Group of the PROtective VEntilation Network (PROVEnet) for the Clinical Trial Network of the European Society of Anaesthesiology; Bluth T, Serpa Neto A, Schultz MJ, Pelosi P, Gama de Abreu M; PROBESE Collaborative Group; Bluth T, Bobek I, Canet JC, Cinnella G, de Baerdemaeker L, Gama de Abreu M, Gregoretti C, Hedenstierna G, Hemmes SNT, Hiesmayr M, Hollmann MW, Jaber S, Laffey J, Licker MJ, Markstaller K, Matot I, Mills GH, Mulier JP, Pelosi P, Putensen C, Rossaint R, Schmitt J, Schultz MJ, Senturk M, Serpa Neto A, Severgnini P, Sprung J, Vidal Melo MF, Wrigge H. Effect of Intraoperative High Positive End-Expiratory Pressure (PEEP) With Recruitment Maneuvers vs Low PEEP on Postoperative Pulmonary Complications in Obese Patients: A Randomized Clinical Trial. JAMA. 2019 Jun 18;321(23):2292-2305. doi: 10.1001/jama.2019.7505.

Reference Type BACKGROUND
PMID: 31157366 (View on PubMed)

Mazzinari G, Zampieri FG, Ball L, Campos NS, Bluth T, Hemmes SNT, Ferrando C, Librero J, Soro M, Pelosi P, Gama de Abreu M, Schultz MJ, Serpa Neto A; for REPEAT on behalf of the PROVHILO, iPROVE, and PROBESE investigators and the PROVE Network investigators. High Positive End-expiratory Pressure (PEEP) with Recruitment Maneuvers versus Low PEEP during General Anesthesia for Surgery: A Bayesian Individual Patient Data Meta-analysis of Three Randomized Clinical Trials. Anesthesiology. 2025 Jan 1;142(1):72-97. doi: 10.1097/ALN.0000000000005170.

Reference Type BACKGROUND
PMID: 39042027 (View on PubMed)

Yoon HK, Kim BR, Yoon S, Jeong YH, Ku JH, Kim WH. The Effect of Ventilation with Individualized Positive End-Expiratory Pressure on Postoperative Atelectasis in Patients Undergoing Robot-Assisted Radical Prostatectomy: A Randomized Controlled Trial. J Clin Med. 2021 Feb 19;10(4):850. doi: 10.3390/jcm10040850.

Reference Type BACKGROUND
PMID: 33669526 (View on PubMed)

Cho S, Oh HW, Choi MH, Lee HJ, Woo JH. Effects of Intraoperative Ventilation Strategy on Perioperative Atelectasis Assessed by Lung Ultrasonography in Patients Undergoing Open Abdominal Surgery: a Prospective Randomized Controlled Study. J Korean Med Sci. 2020 Oct 12;35(39):e327. doi: 10.3346/jkms.2020.35.e327.

Reference Type BACKGROUND
PMID: 33045769 (View on PubMed)

Young CC, Harris EM, Vacchiano C, Bodnar S, Bukowy B, Elliott RRD, Migliarese J, Ragains C, Trethewey B, Woodward A, Gama de Abreu M, Girard M, Futier E, Mulier JP, Pelosi P, Sprung J. Lung-protective ventilation for the surgical patient: international expert panel-based consensus recommendations. Br J Anaesth. 2019 Dec;123(6):898-913. doi: 10.1016/j.bja.2019.08.017. Epub 2019 Oct 3.

Reference Type BACKGROUND
PMID: 31587835 (View on PubMed)

Ma 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.

Reference Type BACKGROUND
PMID: 39548165 (View on PubMed)

Liao 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.

Reference Type BACKGROUND
PMID: 38539248 (View on PubMed)

Wu 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.

Reference Type BACKGROUND
PMID: 35974310 (View on PubMed)

Related Links

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https://www.pirogov-center.ru/english/about/

Official website of the Pirogov National Medical and Surgical Center

Other Identifiers

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NMSC-03-25

Identifier Type: -

Identifier Source: org_study_id

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