End-Expiratory Diaphragmatic Residual Contraction Index for Identifying Intrinsic PEEP and Assisting PEEP Titration: A Prospective Physiological Study

This study proposes the End-expiratory Diaphragmatic Residual Contraction (EDRC) index to quantify residual diaphragmatic activity at end-expiration during Pressure Support Ventilation (PSV) mode. The study aims to validate the relationship between EDRC and dynamic intrinsic PEEP (PEEPi), triggering load, patient-ventilator asynchrony, and PEEP responsiveness through a brief, standardized PEEP titration trial conducted within a clinically safe range. This will provide a basis for subsequent individualized PEEP setting guided by EDRC.

Study Overview

• Status: Not yet recruiting
• Conditions: Diaphragm; Speckle Tracking
• Intervention / Treatment: Device: Short-term PEEP Step Trial and EDRC Ultrasound Assessment

• Study Type: Observational
• Enrollment (Estimated): 100

Contacts and Locations

• Study Contact: Name: Huiqing Ge, MD; Phone Number: +8613588706787; Email: gehq@zju.edu.cn
• Study Contact Backup: Name: YIqing Xu, Master; Phone Number: +86 13634115344; Email: xuyiqing@srrsh.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

The study population will consist of adult patients ($\ge$ 18 years) admitted to the Intensive Care Unit (ICU) who are receiving invasive mechanical ventilation in Pressure Support Ventilation (PSV) mode. Participants will be recruited from the ICU at [Insert Name of Hospital/Institution].

The population is characterized by patients who are clinically assessed as having a risk of dynamic intrinsic PEEP (PEEPi,dyn) or are undergoing a spontaneous breathing trial (SBT) as part of the weaning process. All enrolled patients will have an indwelling esophageal balloon catheter placed for the measurement of esophageal pressure (Pes), which serves as the reference standard for respiratory mechanics.

Patients will be screened for eligibility based on hemodynamic stability and the ability to tolerate the study procedures. Specific exclusion criteria include pregnancy, severe esophageal pathology, severe hypoxemia, and conditions precluding diaphragmatic ultrasound imaging (e.g., chest wall tra

Description

Inclusion Criteria:

• Age ≥ 18 years. Patients receiving invasive mechanical ventilation in Pressure Support Ventilation (PSV) mode.

Clinically assessed as having a risk of dynamic intrinsic PEEP (PEEPi,dyn) or experiencing difficult weaning from mechanical ventilation.

Presence of an indwelling esophageal balloon catheter (for reference standard measurements).

Provision of written informed consent from the patient or legally authorized representative.

Exclusion Criteria:

• Pregnancy or lactation. Known esophageal diseases (e.g., esophageal varices, strictures, recent esophageal surgery) or contraindications to esophageal catheter placement.

Severe hemodynamic instability (e.g., requiring high-dose vasoactive support, uncontrolled arrhythmias).

Severe hypoxemia (PaO2/FiO2 < 100 mmHg) or severe hypercapnia with hemodynamic compromise at baseline.

Conditions precluding ultrasound assessment of the diaphragm (e.g., extensive chest wall trauma, large pleural effusion, severe subcutaneous emphysema).

Active spontaneous breathing with severe patient-ventilator asynchrony that cannot be stabilized during the trial.

Anticipated extubation or withdrawal of life-sustaining treatment within the next 24 hours.

Participation in another interventional clinical trial within the last 30 days.

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort

Intervention / Treatment

Patients Undergoing PEEP Step Trial and EDRC Assessment; All enrolled patients will receive a standardized, short-term PEEP step trial while in Pressure Support Ventilation (PSV) mode. The trial consists of sequentially applying PEEP levels of Baseline, -2, +2, +4, and +6 cmH2O relative to the set PEEP. At each step, respiratory mechanics and patient-ventilator synchrony will be monitored. The primary intervention of interest is the assessment of End-Expiratory Diaphragmatic Residual Contraction (EDRC) via ultrasound to identify the presence of intrinsic PEEP (PEEPi) and to determine the optimal level of extrinsic PEEP that minimizes diaphragmatic effort and asynchrony.

Device: Short-term PEEP Step Trial and EDRC Ultrasound Assessment; This intervention involves a standardized, short-term PEEP step trial combined with a novel physiological assessment. During the trial, external PEEP is systematically adjusted in 2 cmH2O increments (Baseline, -2, +2, +4, +6 cmH2O) while maintaining stable Pressure Support Ventilation (PSV) settings. Simultaneously, the End-Expiratory Diaphragmatic Residual Contraction (EDRC) index is evaluated using diaphragm ultrasound speckle tracking. This distinguishes the intervention by providing a non-invasive, real-time quantification of residual diaphragmatic tension at end-expiration, which serves as a surrogate marker for dynamic intrinsic PEEP (PEEPi) and trigger load, distinguishing it from traditional static measurements or esophageal manometry alone.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Diagnostic Efficacy of EDRC-AUC for Identifying Clinically Significant Dynamic Intrinsic PEEP	The primary outcome is the diagnostic efficacy of the End-Expiratory Diaphragmatic Residual Contraction Area Under the Curve (EDRC-AUC) in identifying clinically significant dynamic intrinsic PEEP (PEEPi,dyn ≥ 5 cmH2O) in patients undergoing Pressure Support Ventilation (PSV). The diagnostic performance will be evaluated using Receiver Operating Characteristic (ROC) curve analysis, reporting the Area Under the Curve (AUC), optimal cut-off value, sensitivity, specificity, positive predictive value, and negative predictive value, with esophageal manometry and flow curves as the reference standard.	During the short-term PEEP step trial (each PEEP level is maintained for 5-10 minutes)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Correlation between EDRC-AUC and Respiratory Drive/Load Indices	To evaluate the correlation (using Pearson or Spearman correlation coefficients) between the End-Expiratory Diaphragmatic Residual Contraction Area Under the Curve (EDRC-AUC)	During the short-term PEEP step trial (each PEEP level maintained for 5-10 minutes) and within 30 minutes post-trial
Incidence of Patient-Ventilator Asynchrony Events	To record and compare the total incidence and distribution of patient-ventilator asynchrony events across different PEEP levels. Specific events include:Ineffective triggering;Double triggering;Auto-triggering;Short or long cycling.	During the short-term PEEP step trial (each PEEP level maintained for 5-10 minutes) and within 30 minutes post-trial.
Agreement between EDRC-Guided PEEP and Esophageal Manometry-Guided PEEP	To compare the optimal PEEP level determined by the EDRC minimization principle with the optimal PEEP level determined by esophageal manometry (minimizing driving pressure or PTP). Bland-Altman analysis will be used to evaluate the mean bias and limits of agreement between the two methods.	During the short-term PEEP step trial (each PEEP level maintained for 5-10 minutes) and within 30 minutes post-trial.
Trends in Diaphragmatic Contraction Dynamics Across PEEP Levels	To observe and describe the dynamic trends of diaphragm thickening fraction (DTF) and the EDRC index across all phases of the PEEP step trial (Baseline, -2, +2, +4, +6 cmH2O), assessing the bidirectional effects of extrinsic PEEP on diaphragmatic load.	During the short-term PEEP step trial (each PEEP level maintained for 5-10 minutes) and within 30 minutes post-trial.
Feasibility and Inter-Observer Reliability of EDRC Ultrasound Measurements	Feasibility: The proportion of patients from whom analyzable ultrasound images were successfully obtained; Reproducibility: The intra-class correlation coefficient (ICC) for EDRC-AUC measurements between different operators (inter-observer) and by the same operator at different time points (intra-observer).	During the short-term PEEP step trial (each PEEP level maintained for 5-10 minutes) and within 30 minutes post-trial.
Adverse Events During the PEEP Step Trial	To document any clinical adverse events occurring during the PEEP titration process, including: Hemodynamic instability (e.g., systolic blood pressure decrease >20% or increased requirement for vasoactive drugs); Severe hypoxemia (SpO2 < 88% lasting >1 minute); Severe arrhythmias; Significant respiratory distress or intolerance requiring premature termination of the trial.	During the short-term PEEP step trial (each PEEP level maintained for 5-10 minutes) and within 30 minutes post-trial.

Collaborators and Investigators

• Sponsor: Sir Run Run Shaw Hospital

Publications and helpful links

General Publications

• Umbrello M, Formenti P, Longhi D, Galimberti A, Piva I, Pezzi A, Mistraletti G, Marini JJ, Iapichino G. Diaphragm ultrasound as indicator of respiratory effort in critically ill patients undergoing assisted mechanical ventilation: a pilot clinical study. Crit Care. 2015 Apr 13;19(1):161. doi: 10.1186/s13054-015-0894-9.
• Haudebourg AF, Maraffi T, Tuffet S, Perier F, de Prost N, Razazi K, Mekontso Dessap A, Carteaux G. Refractory ineffective triggering during pressure support ventilation: effect of proportional assist ventilation with load-adjustable gain factors. Ann Intensive Care. 2021 Oct 20;11(1):147. doi: 10.1186/s13613-021-00935-0.
• Chao DC, Scheinhorn DJ, Stearn-Hassenpflug M. Patient-ventilator trigger asynchrony in prolonged mechanical ventilation. Chest. 1997 Dec;112(6):1592-9. doi: 10.1378/chest.112.6.1592.
• MacIntyre NR, Cheng KC, McConnell R. Applied PEEP during pressure support reduces the inspiratory threshold load of intrinsic PEEP. Chest. 1997 Jan;111(1):188-93. doi: 10.1378/chest.111.1.188.

Study record dates

Study Major Dates

• Study Start (Estimated): August 21, 2026
• Primary Completion (Estimated): August 24, 2027
• Study Completion (Estimated): September 3, 2027

Study Registration Dates

• First Submitted: July 5, 2026
• First Submitted That Met QC Criteria: July 5, 2026
• First Posted (Actual): July 13, 2026

Study Record Updates

• Last Update Posted (Actual): July 13, 2026
• Last Update Submitted That Met QC Criteria: July 5, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: 20260627

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No