Electrical Impedance Tomography-Guided Identification of the Optimal Lateral Position in Postoperative ARDS

NCT07669558 | Recruiting DMC

• 1 other identifier: ARDS-EIT-POS-001
• Study Type: interventional
• Target: 22
• Locations: 1 country
• Sites: 1

Brief Summary

This prospective, randomized crossover physiological study evaluates the effects of lateral positioning (left lateral position and right lateral position) versus the supine position on ventilation-perfusion (V/Q) matching in adult postoperative abdominal surgery participants with acute respiratory distress syndrome (ARDS). Bedside electrical impedance tomography (EIT) will be used to quantify regional ventilation and perfusion (perfusion derived from an intravenous tracer bolus administered during a brief breath-hold) and to calculate global "normal V/Q" (normal V/Q, %). Oxygenation, respiratory mechanics (when applicable), and hemodynamics will be recorded concurrently. Feasibility and safety of the positioning protocol will also be assessed.

Conditions

Acute Respiratory Distress Syndrome (ARDS); Postoperative

Keywords

acute respiratory distress syndrome (ARDS); electrical impedance tomography (EIT; Lateral position; ventilation-perfusion; postoperative abdominal surgery; crossover study; supine position

Outcome Measures

Primary Outcomes (1)

• Global normal V/Q (%) derived from electrical impedance tomography (EIT)

  The percentage of lung pixels categorized as "normal ventilation-perfusion (V/Q)" according to pre-defined ventilation and perfusion signals acquired via EIT.

  Post-stabilization in each body position (supine, left lateral, right lateral); assessments performed once per 60-minute positional stage, with comparative data reported for each position time point.

Secondary Outcomes (12)

• EIT-derived V/Q mismatch components (shunt-like lung pixel percentage, dead-space-like lung pixel percentage).

  Single assessment time point after respiratory and hemodynamic stabilization within each 60-minute positional stage (left lateral, right lateral); all V/Q mismatch data will be reported separately per positional time point for inter-position comparison.

• EIT-derived regional ventilation distribution indices

  Single assessment time point after hemodynamic and respiratory stabilization within each 60-minute positional stage (left lateral, right lateral); comparative data of all indices will be reported separately for each positional assessment time point.

• EIT-derived regional perfusion distribution indices

  Single perfusion assessment time point after respiratory and hemodynamic stabilization within each 60-minute positional stage (left lateral, right lateral); all perfusion index data will be reported separately for each positional assessment time point.

• Oxygenation index (PaO₂/FiO₂ ratio if arterial blood gas sampling is feasible; SpO₂/FiO₂ ratio as an alternative surrogate index).

  Single assessment time point after respiratory and hemodynamic stabilization within each 60-minute positional stage (supine, left lateral, right lateral); oxygenation index values will be reported separately for each positional assessment time point.

• Ventilator-related pressure parameters (plateau pressure, driving pressure).

  Single assessment time point after respiratory and hemodynamic stabilization within each 60-minute positional stage (supine, left lateral, right lateral); all pressure values will be reported separately for each positional assessment time point.

Study Arms (3)

Arm 1: Supine Position

EXPERIMENTAL

Supine position with protocolized stabilization and EIT ventilation/perfusion measurements.

Behavioral: Positioning Intervention

Arm 2: Left Lateral Position

EXPERIMENTAL

Left lateral position with protocolized stabilization and EIT ventilation/perfusion measurements.

Behavioral: Positioning Intervention

Right Lateral Position

EXPERIMENTAL

Right lateral position with protocolized stabilization and EIT ventilation/perfusion measurements.

Behavioral: Positioning Intervention

Interventions

Positioning Intervention BEHAVIORAL

Using a randomized crossover design, all subjects undergo three body position stages in random order. Each position (supine, left lateral, right lateral) is maintained for 60 minutes. Vital signs are stabilized per protocol, followed by EIT assessment of ventilation-perfusion matching. 1. Position stage duration: 60 minutes. 2. Stabilization period before measurement: 45 minutes after position change. 3. Washout: 45-minute supine washout period between position stages. 4. EIT ventilation measurement: after stabilization in each position. 5. EIT perfusion measurement: during breath-hold ≥8 seconds (actual breath-hold time recorded. 6. Tracer bolus: 10 mL of 10% sodium chloride solution OR 10 mL of 5% sodium bicarbonate solution, injected over 2-3 seconds via central or peripheral venous line.

Arm 1: Supine Position; Arm 2: Left Lateral Position; Right Lateral Position

Eligibility Criteria

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

You may qualify if:

• Age ≥18 years
• Postoperative abdominal surgery patients admitted to the ICU with ARDS (Berlin definition)
• Considered able to tolerate protocolized position changes by the treating team
• EIT belt placement and protocol procedures feasible
• Informed consent obtained from the patient or legally authorized representative

You may not qualify if:

• Contraindication to lateral positioning (e.g., unstable spine, uncontrolled bleeding, open abdomen, high-risk surgical wound condition)
• Severe hemodynamic instability or other conditions making participation unsafe
• High risk of airway/vascular line/drain dislodgement not manageable
• Pregnancy
• Refusal of informed consent
• Any other condition deemed inappropriate by investigators

Sponsors & Collaborators

• Ruijin Hospital: lead

Study Sites (1)

Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Department of Critical Care Medicine

Shanghai, China

RECRUITING

MeSH Terms

Conditions

Respiratory Distress Syndrome; Deception

Condition Hierarchy (Ancestors)

Lung Diseases; Respiratory Tract Diseases; Respiration Disorders; Social Behavior; Behavior

Central Study Contacts

Rui Zhang

CONTACT

+86 18801119381; ccmzhangrui@foxmail.com

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Masking Details: Participants complete all three positions in a randomized sequence. The order is generated using random numbers, and the random sequence determines whether the left lateral position or right lateral position is performed first. Blinding is not feasible because of the nature of positioning.
• Purpose: TREATMENT
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: In this randomized crossover study, each participant undergoes three body positions-supine position, left lateral position, and right lateral position-in a randomized order. The sequence (including whether left lateral or right lateral is performed first) is determined by random-number-based randomization. Each position stage lasts 60 minutes. After entering each position, participants are stabilized for 45 minutes before EIT measurements.

Study Record Dates

• First Submitted: June 8, 2026
• First Posted: June 25, 2026
• Study Start: June 28, 2026
• Primary Completion (Estimated): October 31, 2026
• Study Completion (Estimated): October 31, 2026
• Last Updated: July 28, 2026

Record last verified: 2026-06

Data Sharing

• IPD Sharing: Will share

Locations

CN (1)