Electrical Impedance Tomography-Derived Dorsal Recruitment-to-Inflation Ratio Identifies PEEP Responsiveness and Risk Phenotypes in ARDS

In the treatment of critically ill patients, mechanical ventilation is a key link, and appropriate mechanical ventilation strategies can open the alveoli and improve oxygenation, while inappropriate mechanical ventilation can increase lung injury and seriously affect the prognosis. Ventilator-related lung injury is mainly concentrated in barotrauma, volumetric injury, shear injury, and biological injury, and the monitoring of respiratory ventilation to the level of local ventilation can help to better assess the state of alveolar opening and alveolar collapse, and help to understand the uniformity of gas distribution in the lungs, which is closely related to lung injury. However, how to achieve simple, bedside and real-time lung ventilation and lung volume assessment in clinical work has always been a difficult problem to be overcome. This study intends to explore the changes of local ventilation and blood flow in the lungs during PEEP trail in patients with ARDS monitored by EIT.

Study Overview

• Status: Completed
• Conditions: ARDS
• Intervention / Treatment: Diagnostic test: Electrical Impedance tomography Monitoring

Detailed Description

1. Background and Rationale ARDS is associated with heterogeneous lung collapse. The recruitment-to inflation (R/I) ratio has emerged as an index of recruitability, but is usually assessed globally. Electrical impedance tomography (EIT) enables regional assessment of ventilation and may provide more precise determinations of recruitable lung regions, particularly dorsal areas.
2. Objectives Primary objective: To compare the predictive value of regional (dorsal and ventral) versus global R/I for recruitment success in moderate-severe ARDS. Secondary objectives: To classify recruitment phenotypes and evaluate associations with oxygenation, compliance improvement, ventilator-free days, ICU length of stay, and 28-day mortality.
3. Study Design Prospective, single-centre observational cohort study in ICU patients with moderate-severe ARDS. All eligible patients undergo standardised recruitment maneuver and EIT monitoring.
4. Study Setting Ruijin Hospital, Shanghai Jiao Tong University School of Medicine ICU, December 2022 - December 2024.
5. Intervention Standardized PEEP step maneuver from 5 → 15 cmH₂O, maintained for 3 minutes. Continuous EIT monitoring of regional compliance, oxygenation, hemodynamics. Dynamic strain cutoff (>0.6) or adverse events terminate the maneuver. Ventilation mode: volume control, tidal volume 4-6 mL/kg predicted body weight, plateau ≤28-30 cmH₂O, FiO₂ titrated for SpO₂ 88-92%.
6. Measurements EIT-derived ΔEELI in dorsal and ventral regions Regional and global compliance (Crec and Crs) R/I calculated: Crec/Crs at baseline PEEP Airway opening pressure by low-flow inflation method Primary outcome: recruitment success (≥10% compliance improvement + ≥20 mmHg PaO₂/FiO₂ increase) Secondary: ventilator-free days, ICU LOS, 28-day mortality, dynamic strain
7. Statistical Analysis Plan Distribution check by Shapiro-Wilk. Paired tests for within-patient comparisons. ROC curves and Youden index for cut-off selection. Multivariate regression for mortality risk factors. Bonferroni correction for multiple comparisons.
8. Safety Monitoring Terminate RM if: MAP <65 mmHg, SpO₂ <88%, arrhythmia onset, dynamic strain >0.6.

• Study Type: Observational
• Enrollment (Actual): 120
• Phase: Phase 2; Phase 3

Contacts and Locations

Study Locations

• China
  • Shanghai Municipality
    • Shanghai, Shanghai Municipality, China, 200025
      • Department of Critical Care Medicine，Ruijin Hospital，Shanghai Jiao Tong University School of Medicine，Shanghai，China.

Participation Criteria

Eligibility Criteria

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

• Sampling Method: Non-Probability Sample

Study Population

This study included adult patients (≥18 years) with moderate-to-severe acute respiratory distress syndrome (ARDS) who were receiving invasive mechanical ventilation in the intensive care unit (ICU) of Ruijin Hospital. All enrolled patients met the Berlin definition of ARDS and had a PaO₂/FiO₂ ratio ≤200 mmHg within 6 hours of screening. A total of 120 patients were consecutively enrolled from December 2022 to December 2024. Patients were stratified by airway closure status for subgroup analyses.

Description

Inclusion Criteria:

• Patients who meet the Berlin definition of ARDS and have been treated with mechanical ventilation (clinical diagnosis of ARDS by the attending ICU physician)
• PaO₂/FiO₂ ≤200 mmHg

Exclusion Criteria:

• Age< 18 or >90 years
• Pneumothorax, pneumomediastinum
• Hemodynamic instability (rising vasopressor need in <6h)
• Contraindications to RM or EIT

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort

Intervention / Treatment

evaluate the feasibility of using EIT to calculate regional recruitment-to-inflation (R/I) ratios; Regional R/I ratios were computed for the global lung, dorsal (dependent), and ventral (non-dependent) regions of interest (ROIs), which were defined as 50% of the ventro-dorsal lung diameter based on EIT imaging.compare the predictive value of regional (dorsal and ventral) versus global R/I for recruitment success in moderate-severe ARDS.

Diagnostic test: Electrical Impedance tomography Monitoring; Standardized PEEP step maneuver from 5 → 15 cmH₂O, maintained for 3 minutes. Continuous EIT monitoring of regional compliance, oxygenation, hemodynamics. Dynamic strain cutoff (>0.6) or adverse events terminate the maneuver. Ventilation mode: volume control, tidal volume 4-6 mL/kg predicted body weight, plateau ≤28-30 cmH₂O, FiO₂ titrated for SpO₂ 88-92%.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
recruitment success percent	recruitment( ≥10% compliance improvement ) and Re-check the blood gas ≥20 mmHg PaO₂/FiO₂ increase mean success	From enrollment to the end of treatment at 7 days

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
28-day mortality	Statistical analysis of 28-day mortality	From enrollment to the end of treatment at 28 days
Change in Sequential Organ Failure Assessment (SOFA) score from baseline to day 7	Change in Sequential Organ Failure Assessment (SOFA) score from baseline to day 7	From enrollment to the end of treatment at 7 days
Length of ICU stay	Length of ICU stay in days	From enrollment to the end of treatment at 7 days
Ventilator-free days at Day 28	Number of days alive and free from mechanical Ventilation with in the first days after enrollment	From enrollment to the end of treatment at 28 days

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in IL-6/IL-10 ratio	Change in IL-6/IL-10 ratio from baseline to day 5 measured by immunoassay	From enrollment to the end of treatment at 5 days
Percentage of patients achieving ventilator-free days	Percentage of patients achieving ventilator-free days	From enrollment to the end of treatment at 7 days
Hospital costs during ICU stay	Hospital costs in USD during ICU stay	From enrollment to the end of treatment at 7 days
Quality of life score at discharge	Quality of life score at discharge measured by EQ-5D-5L instrument (range 0-1)	From enrollment to the end of treatment at 28 days

Collaborators and Investigators

• Sponsor: Ruijin Hospital
• Investigators: Study Chair: Hongping Qu, Department of Critical Care Medicine，Ruijin Hospital，Shanghai Jiao Tong University School of Medicine; Principal Investigator: Jialin Liu, Department of Geriatrics，Ruijin Hospital，Shanghai Jiao Tong University School of Medicine; Study Director: rui zhang, Department of Critical Care Medicine，Ruijin Hospital

Study record dates

Study Major Dates

• Study Start (Actual): December 1, 2022
• Primary Completion (Actual): December 31, 2024
• Study Completion (Actual): December 31, 2024

Study Registration Dates

• First Submitted: December 25, 2024
• First Submitted That Met QC Criteria: February 8, 2025
• First Posted (Actual): February 12, 2025

Study Record Updates

• Last Update Posted (Actual): April 23, 2026
• Last Update Submitted That Met QC Criteria: April 20, 2026
• Last Verified: December 1, 2024

More Information

Terms related to this study

• Keywords: Acute Respiratory Distress Syndrome; Electrical impedance tomography; ventilation/perfusion ratio
• Additional Relevant MeSH Terms: Pathologic Processes; Respiratory Tract Diseases; Lung Diseases; Respiration Disorders; Pathological Conditions, Signs and Symptoms; Respiratory Distress Syndrome; Respiratory Aspiration
• Other Study ID Numbers: 2022325

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
• product manufactured in and exported from the U.S.: No