BMI-Adjusted PEEP During One-Lung Ventilation in Thoracic Surgery (SIMPLE-PEEP)

October 8, 2026 updated by: Jesús Manuel Nieves Alonso

Effect of Body Mass Index-Adjusted Positive End-Expiratory Pressure on Respiratory Mechanics During One-Lung Ventilation in Thoracic Surgery

One-lung ventilation (OLV) is required during many thoracic surgical procedures and is associated with reduced functional residual capacity, atelectasis, ventilation-perfusion mismatch, hypoxemia, and potentially ventilator-induced lung injury. Lung-protective ventilation strategies include low tidal volumes, limitation of airway pressures, and positive end-expiratory pressure (PEEP), but the optimal PEEP level during OLV remains uncertain. Fixed PEEP is simple and reproducible but does not account for individual patient characteristics. Body mass index (BMI) is readily available before anesthesia and is associated with respiratory mechanics, making it a pragmatic candidate for simple PEEP individualization.

SIMPLE-PEEP is a prospective, multicenter, pragmatic, open-label, randomized clinical trial including 150 adults undergoing elective pulmonary resection under general anesthesia requiring OLV. Participants will be randomized to either fixed PEEP of 4 cmH2O or BMI-adjusted PEEP calculated as BMI/3 cmH2O. Other key components of lung-protective ventilation will be standardized between groups.

The primary outcome is driving pressure during the first 20 minutes of OLV, assessed at 5, 10, and 20 minutes after OLV initiation. Secondary outcomes include respiratory system compliance and other respiratory mechanics, estimated mechanical power, oxygenation, intraoperative hypoxemia and rescue maneuvers, hemodynamic safety, vasopressor requirements, and exploratory postoperative respiratory outcomes. No investigational medicinal product, additional invasive procedure, or study-specific advanced monitoring is required.

Study Overview

Status

Status

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

Conditions

Conditions

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

Intervention / Treatment

Intervention / Treatment

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

Study Type

Study Type

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

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
150

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Spain
    • Catalonia
      • Barcelona, Catalonia, Spain, 08036
        • Not yet recruiting
        • Hospital Clinic Barcelona
        • Contact:
      • Barcelona, Catalonia, Spain, 08041
        • Not yet recruiting
        • Hospital de la Santa Creu i Sant Pau
        • Contact:
    • Madrid
      • Madrid, Madrid, Spain, 28006
        • Recruiting
        • Hospital Universitario de La Princesa
        • Contact:
      • Madrid, Madrid, Spain, 28007
        • Not yet recruiting
        • Hospital General Universitario Geogorio Marañón
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

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

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  1. Age 18 years or older.
  2. Scheduled thoracic surgery for pulmonary resection requiring general anesthesia and one-lung ventilation.
  3. Written informed consent obtained before any study-specific procedure.

Exclusion Criteria:

  1. Simultaneous participation in another interventional clinical trial that could interfere with the protocol.
  2. Severe hemodynamic instability before the start of the procedure, defined as continuous vasopressor infusion or shock of any etiology.
  3. Severe restrictive lung disease, defined as total lung capacity <50% of predicted or forced vital capacity <50% of predicted.
  4. Body mass index >45 kg/m2.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Supportive Care
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Active Comparator: Fixed PEEP of 4 cmH2O
Procedure: Fixed PEEP

Fixed PEEP of 4 cmH2O
Experimental: BMI-adjusted PEEP calculated as BMI/3 cmH2O
Procedure: BMI-adjusted PEEP

BMI-adjusted PEEP calculated as BMI/3 cmH2O

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Driving pressure during the primary T2-T4 window
Time Frame: 20 minutes

Driving pressure during the primary T2-T4 window, measured at 5, 10, and 20 minutes after initiation of one-lung ventilation and expressed in cmH2O.

In conventional volume-controlled ventilation, driving pressure is calculated as plateau pressure minus applied PEEP.

In pressure-regulated volume-targeted/volume-guaranteed modes, driving pressure is calculated as total end-inspiratory pressure minus applied PEEP.
20 minutes

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Respiratory system compliance
Time Frame: At 5, 10, and 20 minutes after initiation of one-lung ventilation; at 60 minutes when applicable; and at the end of one-lung ventilation, all during the surgical procedure on Day 1.

Respiratory system compliance will be calculated at each applicable time point as tidal volume divided by driving pressure and expressed in mL/cmH2O
At 5, 10, and 20 minutes after initiation of one-lung ventilation; at 60 minutes when applicable; and at the end of one-lung ventilation, all during the surgical procedure on Day 1.
Driving pressure at 60 minutes and at the end of one-lung ventilation
Time Frame: At 60 minutes after initiation of one-lung ventilation, when applicable, and at the end of one-lung ventilation.

Driving pressure will be assessed at 60 minutes after initiation of one-lung ventilation, when this time point is applicable, and at the actual end of one-lung ventilation, to evaluate the persistence of the physiological effect of the assigned PEEP strategy.
At 60 minutes after initiation of one-lung ventilation, when applicable, and at the end of one-lung ventilation.
Estimated mechanical power during one-lung ventilation
Time Frame: At 5, 10, and 20 minutes after initiation of one-lung ventilation; at 60 minutes when applicable; and at the end of one-lung ventilation, all during the surgical procedure on Day 1.

Ventilatory mechanical power will be estimated from prospectively recorded ventilatory parameters using a prespecified calculation method appropriate to the ventilation mode and expressed in J/min.
At 5, 10, and 20 minutes after initiation of one-lung ventilation; at 60 minutes when applicable; and at the end of one-lung ventilation, all during the surgical procedure on Day 1.
Incidence of intraoperative hypoxemia during one-lung ventilation
Time Frame: From initiation until completion of one-lung ventilation during the surgical procedure on Day 1 (up to 1 day).

Intraoperative hypoxemia will be defined as SpO2 <90% sustained for at least 60 seconds during one-lung ventilation with baseline FiO2 0.6, or any episode of SpO2 <90% requiring immediate clinical intervention at the discretion of the attending anesthesiologist.
From initiation until completion of one-lung ventilation during the surgical procedure on Day 1 (up to 1 day).
Incidence of major ventilatory rescue
Time Frame: During the first 20 minutes after initiation of one-lung ventilation on Day 1.

Major ventilatory rescue during the first 20 minutes after initiation of one-lung ventilation will be defined as any intervention that substantially modifies the assigned ventilatory strategy or respiratory mechanics, including modification of PEEP from the assigned value, recruitment maneuver, CPAP to the non-ventilated lung, temporary restoration of two-lung ventilation, or protocol interruption for safety reasons.
During the first 20 minutes after initiation of one-lung ventilation on Day 1.
Incidence of intraoperative hypotension
Time Frame: Intraoperative/periprocedural period on Day 1, from induction of anesthesia until the end of surgery.

Intraoperative hypotension will be defined as mean arterial pressure <65 mmHg sustained for more than 1 minute.
Intraoperative/periprocedural period on Day 1, from induction of anesthesia until the end of surgery.
Requirement for intraoperative vasopressor support
Time Frame: Time Frame: Intraoperative/periprocedural period on Day 1, from induction of anesthesia until the end of surgery.

Proportion of participants requiring vasopressor administration during the intraoperative period. Vasopressor use will be recorded as a measure of the hemodynamic safety of the assigned PEEP strategy.
Time Frame: Intraoperative/periprocedural period on Day 1, from induction of anesthesia until the end of surgery.
Incidence of postoperative pulmonary complications
Time Frame: From the end of surgery until hospital discharge during the index hospitalization (estimated average duration: 3-10 days).

Occurrence of at least one prespecified postoperative pulmonary complication, including acute respiratory failure, pneumonia, acute respiratory distress syndrome, atelectasis, pneumothorax, bronchopleural fistula, aspiration pneumonitis, pulmonary embolism, pleural empyema, bronchospasm, pleural effusion, or need for postoperative respiratory support or reintubation for respiratory deterioration. This outcome will be considered exploratory.
From the end of surgery until hospital discharge during the index hospitalization (estimated average duration: 3-10 days).

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Jesús Manuel Nieves Alonso

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
October 7, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
March 1, 2028

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
March 30, 2028

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
September 21, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 25, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
October 1, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
October 9, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
October 8, 2026

Last Verified

Last Verified

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

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

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

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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