Health TrialsbyHealthPanel

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

ConditionsAcute Respiratory Distress Syndrome (ARDS)Postoperative
Trial statusRecruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age18+
SponsorRuijin Hospital

About this trial

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.

Eligibility criteria

This trial does not accept healthy volunteers

Qualifiers

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

Disqualifiers

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

Trial design

Design model

Crossover

Treatments tested in this trial

  • 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.

Treatment groups

22 Participants
are divided into 3 treatment groups
Group A: Arm 1: Supine PositionExperimental treatment 1 intervention
Group B: Arm 2: Left Lateral PositionExperimental treatment 1 intervention
Group C: Right Lateral PositionExperimental treatment 1 intervention

Trial outcomes

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.

Time frame
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

1

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

Quantitative ventilation-perfusion mismatch metrics calculated from electrical impedance tomography (EIT) ventilation and perfusion signals, unit: %. Shunt-like %: Proportion of lung pixels with high perfusion but negligible ventilation Dead-space-like %: Proportion of lung pixels with robust ventilation but minimal perfusion These two indicators quantify the severity of pulmonary gas exchange disturbance under different body positions.

Time frame
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.
2

EIT-derived regional ventilation distribution indices

A composite set of regional ventilation distribution parameters calculated from EIT signals, including center of ventilation (CoVX, CoVY), dorsal ventilation ratio (DVR), global inhomogeneity index (GI), ventral/dorsal impedance ratio, and ventilation fraction of four predefined ventrodorsal lung regions (ventral, mid-ventral, mid-dorsal, dorsal, expressed as %), used to evaluate regional ventilation uniformity and spatial distribution.

Time frame
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.
3

EIT-derived regional perfusion distribution indices

Quantitative perfusion parameters calculated from electrical impedance tomography (EIT) perfusion signals, including perfusion center coordinates (CoPX, CoPY), dorsal perfusion ratio (DPR), global perfusion inhomogeneity index, regional perfusion delay, and perfusion percentage of four predefined ventrodorsal lung regions (ventral, mid-ventral, mid-dorsal, dorsal, unit: %). These indices quantitatively characterize spatial perfusion redistribution, perfusion homogeneity, and temporal perfusion lag in supine, left lateral and right lateral positions.

Time frame
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.
4

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

Oxygenation index is calculated to reflect systemic oxygenation status. PaO₂/FiO₂ ratio (unit: mmHg) will be prioritized when arterial blood gas data are available; if arterial blood gas cannot be obtained, SpO₂/FiO₂ ratio will be adopted as the substitute parameter.

Time frame
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.

Other outcomes

Sponsors and contacts

Click on the lead sponsor to view all of their trials.

Ruijin Hospital

Lead sponsor

Source ClinicalTrials.gov
Apply now