Effect of Spontaneous Breathing in APRV Mode on Respiratory Physiology of ARDS Patients

NCT07798154 | Not Yet Recruiting

• 2 other identifiers: PROTO-APRV-2026-01MR-42-26-065895
• Study Type: interventional
• Target: 15
• Locations: 1 country
• Sites: 1

Brief Summary

This is a single-center, prospective, randomized, three-period crossover physiological study in adult patients with moderate-to-severe acute respiratory distress syndrome (ARDS, PaO₂/FiO₂ ≤150 mmHg). Each enrolled subject will receive all three APRV ventilation conditions in random sequence: low-level spontaneous breathing (spontaneous minute-ventilation proportion 10%-30%), high-level spontaneous breathing (31%-50%), and fully suppressed spontaneous breathing as control. A 30-minute wash-out period is set between each condition to restore unified physiological baseline. Primary outcome is ventilation-perfusion mismatch percentage (mismatch%) measured by Electrical Impedance Tomography (EIT). Secondary outcomes include EIT-derived pulmonary parameters, respiratory mechanics, hemodynamics, diaphragmatic function and safety profiles. Only short-term, reversible ventilator and sedation adjustments will be performed; routine clinical management remains unchanged throughout the trial.

Conditions

Acute Respiratory Distress Syndrome

Keywords

Airway Pressure Release Ventilation; spontaneous breathing; electrical impedance tomography; ventilation-perfusion mismatch

Outcome Measures

Primary Outcomes (1)

• Ventilation-perfusion mismatch percentage (Mismatch%)

  Ventilation-perfusion mismatch percentage (Mismatch%), calculated as the sum of dead-space percentage and shunt percentage measured by electrical impedance tomography (EIT). A composite index reflecting overall ventilation-perfusion mismatch, assessed at baseline and under three APRV experimental conditions. Unit: %

  Baseline and at the end of each 30-minute experimental condition during the study intervention period.

Secondary Outcomes (44)

• Match percentage(match%)

  Baseline and at the end of each 30-minute experimental condition during the study intervention period.

• Pendelluft amplitude

  Baseline and at the end of each 30-minute experimental condition during the study intervention period.

• Dead-space percentage

  Baseline and at the end of each 30-minute experimental condition during the study intervention period.

• Shunt percentage

  Baseline and at the end of each 30-minute experimental condition during the study intervention period.

• Global inhomogeneity index (GI)

  Baseline and at the end of each 30-minute experimental condition during the study intervention period

Other Outcomes (20)

• Incidence and severity of adverse events

  During each APRV experimental intervention period

• Rate of premature intervention discontinuation for safety concerns

  During each APRV experimental intervention period

• Inspired oxygen fraction (FiO₂)

  Baseline and at the end of each 30-minute experimental condition during the study intervention period.

Study Arms (3)

Low-level spontaneous breathing under APRV

EXPERIMENTAL

APRV ventilation with spontaneous-contributed minute-ventilation proportion maintained at 10%-30%. A stabilization period of 30 minutes is performed before data collection

Device: APRV ventilation with low-level spontaneous breathing

High-level spontaneous breathing under APRV

EXPERIMENTAL

APRV ventilation with spontaneous-contributed minute-ventilation proportion maintained at 31%-50%. A stabilization period of 30 minutes is performed before data collection.

Device: APRV ventilation with high-level spontaneous breathing

Fully suppressed spontaneous breathing under APRV

EXPERIMENTAL

APRV ventilation with spontaneous breathing completely suppressed by deep sedation (RASS-4 to -5). A stabilization period of 30 minutes is performed before data collection.

Device: APRV ventilation with fully suppressed spontaneous breathing

Interventions

APRV ventilation with low-level spontaneous breathing DEVICE

APRV ventilation mode, spontaneous-contributed minute-ventilation proportion maintained at 10%-30%. 30-minute stabilization before outcome measurement.

Low-level spontaneous breathing under APRV

APRV ventilation with high-level spontaneous breathing DEVICE

APRV ventilation mode, spontaneous-contributed minute-ventilation proportion maintained at 31%-50%. 30-minute stabilization before outcome measurement.

High-level spontaneous breathing under APRV

APRV ventilation with fully suppressed spontaneous breathing DEVICE

APRV ventilation mode, spontaneous breathing fully suppressed by deep sedation (RASS-4 to -5). 30-minute stabilization before outcome measurement.

Fully suppressed spontaneous breathing under APRV

Eligibility Criteria

• Age: 18 Years - 80 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• \. Age ≥18 and ≤80 years old. 2. Diagnosed with moderate-to-severe ARDS according to the 2023 global ARDS definition.
• \. Within 48 hours of invasive mechanical ventilation. After 1-hour low-tidal-volume pressure-controlled ventilation following ARDSnet strategy, arterial blood gas shows PaO₂/FiO₂ ≤ 150 mmHg.
• \. Written informed consent is obtained from the patient or their legal surrogate decision-maker after full explanation of the study by the principal investigator or authorized study physician.

You may not qualify if:

• \. Refractory shock defined as persistent hyperlactatemia and/or prolonged capillary refill time, fluid-resistant, requiring norepinephrine ≥ 0.5 μg/kg/min.
• \. Severe chronic medical conditions severely affecting cardiopulmonary function: severe chronic obstructive pulmonary disease, interstitial lung disease, pulmonary embolism, right-heart failure, pulmonary hypertension, or severe arrhythmia.
• \. Radiologically confirmed bronchopleural fistula, status post lobectomy, or other major thoracic surgery.
• \. Contraindications to electrical impedance tomography (EIT): extensive chest skin injury or infection, implanted cardiac pacemaker or defibrillator, etc.
• \. Contraindications for esophageal manometry placement: esophageal obstruction, perforation, severe esophageal varices, etc.
• \. Diaphragmatic hernia, severe chest wall deformity, or significant pulmonary bullae.
• \. Significant coagulation abnormalities (PT or APTT prolonged ≥2 times upper limit of normal, or INR\>2.0) with active bleeding risk.
• \. Severe intracranial hypertension (\>20 mmHg), severe traumatic brain injury (GCS ≤8), or neuromuscular disorders.
• \. Pregnant or breastfeeding women. 10. Patients already receiving ECMO therapy. 11. Expected survival time \<24 hours judged by attending physician. 12. Body mass index (BMI) \>35 kg/m². 13. Previously enrolled in this study or participating in other interventional clinical trials.

Sponsors & Collaborators

• Union Hospital, Tongji Medical College, Huazhong University of Science and Technology: lead

Study Sites (1)

Wuhan Union Hospital, Tongji Medical College, Huazhong University of Science and Technology

Wuhan, Hubei, 430022, China

Location

MeSH Terms

Conditions

Respiratory Distress Syndrome

Condition Hierarchy (Ancestors)

Lung Diseases; Respiratory Tract Diseases; Respiration Disorders

Study Officials

• xiaojing zou, MD

  Union Hospital, Tongji Medical College, Huazhong University of Science and Technology

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Xiaojing Zou

CONTACT

+86-27-85351606; 249126734@qq.com

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Chief Physician

Model Details: Each participant receives all three APRV ventilation conditions in random sequence with 30-minute wash-out period between successive conditions. This is a three-period crossover self-controlled physiological study

Study Record Dates

• First Submitted: August 20, 2026
• First Posted: September 1, 2026
• Study Start: October 1, 2026
• Primary Completion (Estimated): November 1, 2026
• Study Completion (Estimated): December 1, 2026
• Last Updated: September 1, 2026

Record last verified: 2026-08

Data Sharing

• IPD Sharing: Will not share

Locations

CN (1)