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

N/ANot Yet RecruitingNCT07697703

Sir Run Run Shaw Hospital100 enrolled

Overview

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 Type

OBSERVATIONAL

Enrollment

100

Conditions

Speckle Tracking Diaphragm

Interventions

Short-term PEEP Step Trial and EDRC Ultrasound AssessmentDEVICE

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.

Eligibility

Sex: ALLMin age: 18 Years

Medical Language ↔ Plain English

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.

Outcomes

Primary Outcomes

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.

Time frame: During the short-term PEEP step trial (each PEEP level is maintained for 5-10 minutes)

Secondary Outcomes

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)

Time frame: 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.