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

22. juni 2026 opdateret af: Ruijin Hospital

Effect of Left Lateral, Right Lateral, and Supine Positioning on Ventilation-Perfusion Matching Assessed by Electrical Impedance Tomography in Adult Postoperative Abdominal Surgery Patients With ARDS: A Prospective Randomized Crossover Physiological Study

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.

Studieoversigt

Status

Ikke rekrutterer endnu

Betingelser

Intervention / Behandling

Detaljeret beskrivelse

Postoperative abdominal surgery patients commonly develop atelectasis, diaphragmatic dysfunction, and heterogeneous ventilation. When complicated by ARDS, ventilation-perfusion mismatch may worsen oxygenation and ventilatory efficiency. Prone positioning may be limited in this population because of abdominal incisions, drains, and intra-abdominal pressure concerns. Lateral positioning is frequently used in critical care and may improve V/Q coupling by changing gravitational gradients, chest wall mechanics, and pulmonary blood flow distribution; however, quantitative bedside evidence comparing left and right lateral positions is limited.

EIT is a radiation-free bedside functional imaging technique that can continuously monitor regional ventilation. In combination with a brief breath-hold and an intravenous tracer bolus, EIT can derive perfusion-related signals, enabling bedside quantification of V/Q matching.

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. EIT ventilation recording is obtained after stabilization, followed by an EIT perfusion assessment performed during a breath-hold of at least 8 seconds (actual breath-hold time recorded). During the breath-hold, a rapid intravenous tracer bolus is administered: 10 mL of 10% sodium chloride solution or 10 mL of 5% sodium bicarbonate solution, injected over 2-3 seconds via a central or peripheral venous line. Between position stages, participants return to the supine position for a 45-minute washout period. The primary endpoint is the difference in global normal V/Q (%) among the three positions. Secondary endpoints include other EIT-derived V/Q indices, oxygenation indices, respiratory mechanics, hemodynamic changes, and feasibility/safety outcomes.

Undersøgelsestype

Interventionel

Tilmelding (Anslået)

24

Fase

  • Ikke anvendelig

Kontakter og lokationer

Dette afsnit indeholder kontaktoplysninger for dem, der udfører undersøgelsen, og oplysninger om, hvor denne undersøgelse udføres.

Studiekontakt

Studiesteder

  • Kina
      • Shanghai, Kina
        • Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Department of Critical Care Medicine
        • Kontakt:

Deltagelseskriterier

Forskere leder efter personer, der passer til en bestemt beskrivelse, kaldet berettigelseskriterier. Nogle eksempler på disse kriterier er en persons generelle helbredstilstand eller tidligere behandlinger.

Berettigelseskriterier

Aldre berettiget til at studere

  • Voksen
  • Ældre voksen

Tager imod sunde frivillige

Ingen

Beskrivelse

Inclusion Criteria:

  • 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

Exclusion Criteria:

  • 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

Studieplan

Dette afsnit indeholder detaljer om studieplanen, herunder hvordan undersøgelsen er designet, og hvad undersøgelsen måler.

Hvordan er undersøgelsen tilrettelagt?

Design detaljer

  • Primært formål: Behandling
  • Tildeling: Randomiseret
  • Interventionel model: Crossover opgave
  • Maskning: Ingen (Åben etiket)

Våben og indgreb

Deltagergruppe / Arm
Intervention / Behandling
Eksperimentel: Arm 1: Supine Position
Supine position with protocolized stabilization and EIT ventilation/perfusion measurements.
Adfærdsmæssigt: Positioning Intervention

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.
Eksperimentel: Arm 2: Left Lateral Position
Left lateral position with protocolized stabilization and EIT ventilation/perfusion measurements.
Adfærdsmæssigt: Positioning Intervention

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.
Eksperimentel: Right Lateral Position
Right lateral position with protocolized stabilization and EIT ventilation/perfusion measurements.
Adfærdsmæssigt: Positioning Intervention

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.

Hvad måler undersøgelsen?

Primære resultatmål

Resultatmål
Foranstaltningsbeskrivelse
Tidsramme
Global normal V/Q (%) derived from electrical impedance tomography (EIT)
Tidsramme: 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.
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.

Sekundære resultatmål

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

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.
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
Tidsramme: 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.
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.
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
Tidsramme: 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.
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.
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).
Tidsramme: 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.
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.
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).
Tidsramme: 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.

Static respiratory pressure indicators automatically recorded by mechanical ventilator, only collected from participants receiving invasive mechanical ventilation.

  • Plateau pressure: Static airway plateau pressure, unit: cmH₂O
  • Driving pressure: Calculated as plateau pressure minus PEEP, unit: cmH₂O These two pressure metrics reflect alveolar mechanical load under controlled ventilation.
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.
Respiratory system compliance (ventilator-derived parameter).
Tidsramme: Single assessment time point after respiratory and hemodynamic stabilization within each 60-minute positional stage (supine, left lateral, right lateral; all compliance values will be reported separately for each positional assessment time point.
A comprehensive respiratory mechanics index calculated as tidal volume divided by driving pressure, unit: mL/cmH₂O. Measurement is limited to invasively ventilated participants to evaluate the overall distensibility of lungs and chest wall.
Single assessment time point after respiratory and hemodynamic stabilization within each 60-minute positional stage (supine, left lateral, right lateral; all compliance values will be reported separately for each positional assessment time point.
Circulatory monitoring parameters (heart rate, mean arterial pressure, vasopressor use if available).
Tidsramme: Two predefined assessment time points within each 60-minute positional stage (supine, left lateral, right lateral): 1) after full respiratory and hemodynamic stabilization; 2) around breath-hold and contrast bolus injection for perfusion acquisition.

Continuous hemodynamic readings collected via bedside invasive monitor for circulatory assessment.

  • Heart rate: unit: beats per minute (bpm)
  • Mean arterial pressure (MAP): unit: mmHg These two parameters reflect systemic circulatory stability during positional adjustment and EIT perfusion measurement.
  • Binary categorical indicator for vasopressor administration status and continuous dosage recording of vasopressors; administration status (yes/no) and dosage (μg/kg/min) to evaluate circulatory support intensity.
Two predefined assessment time points within each 60-minute positional stage (supine, left lateral, right lateral): 1) after full respiratory and hemodynamic stabilization; 2) around breath-hold and contrast bolus injection for perfusion acquisition.
Proportion of participants completing all randomized 60-minute positional stages and inter-position washout periods.
Tidsramme: Through study positional phase completion (from initiation of the first positional stage to the end of the final washout period following the last positional assessment); completion status data will be summarized across all participants.
Binary participant-level endpoint (unit: proportion [%]) calculated as the number of participants who fully finished all three predefined body position stages and corresponding washout intervals divided by total enrolled participants. Used to assess overall study procedural feasibility.
Through study positional phase completion (from initiation of the first positional stage to the end of the final washout period following the last positional assessment); completion status data will be summarized across all participants.
Number of participants with successful acquisition of analyzable EIT imaging datasets.
Tidsramme: Through study positional phase completion (from initiation of the first positional stage to the end of the final washout period following the last positional assessment); successful EIT acquisition counts will be aggregated for all enrolled subjects.
Count-based feasibility metric (unit: number of participants). Defined as participants with complete, artifact-free EIT ventilation and perfusion images eligible for post-hoc quantitative regional lung function analysis.
Through study positional phase completion (from initiation of the first positional stage to the end of the final washout period following the last positional assessment); successful EIT acquisition counts will be aggregated for all enrolled subjects.
Proportion of participants capable of maintaining breath-hold for at least 8 seconds during EIT perfusion imaging.
Tidsramme: Through positional phase completion (from first positional stage start to final post-position washout end); breath-hold compliance proportions summarized across all perfusion assessment time points.
Proportional feasibility endpoint (unit: proportion [%]). Calculated as participants who sustained ≥8-second breath-hold during contrast bolus perfusion scans divided by all participants undergoing EIT perfusion measurement.
Through positional phase completion (from first positional stage start to final post-position washout end); breath-hold compliance proportions summarized across all perfusion assessment time points.
Number of participants with any procedure-related adverse event (desaturation, hypotension, arrhythmia, accidental tube/line/drain displacement).
Tidsramme: Through positional phase completion (from first positional stage start to final post-position washout end); all adverse events captured and tallied during positional testing.
Safety count endpoint (unit: number of participants). Captures all acute adverse events directly associated with positional changes and EIT image acquisition during the study protocol.
Through positional phase completion (from first positional stage start to final post-position washout end); all adverse events captured and tallied during positional testing.
Number of participants with early study termination secondary to positional intolerance.
Tidsramme: Through positional phase completion (from first positional stage start to final post-position washout end); all early termination events documented and counted for pooled safety analysis.
Tolerability safety metric (unit: number of participants). Records participants withdrawn prematurely from positional testing due to respiratory, hemodynamic or clinical intolerance to supine, left lateral or right lateral positioning.
Through positional phase completion (from first positional stage start to final post-position washout end); all early termination events documented and counted for pooled safety analysis.

Samarbejdspartnere og efterforskere

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Sponsor

Ruijin Hospital

Datoer for undersøgelser

Disse datoer sporer fremskridtene for indsendelser af undersøgelsesrekord og resumeresultater til ClinicalTrials.gov. Studieregistreringer og rapporterede resultater gennemgås af National Library of Medicine (NLM) for at sikre, at de opfylder specifikke kvalitetskontrolstandarder, før de offentliggøres på den offentlige hjemmeside.

Studer store datoer

Studiestart (Anslået)

16. juni 2026

Primær færdiggørelse (Anslået)

31. oktober 2026

Studieafslutning (Anslået)

31. oktober 2026

Datoer for studieregistrering

Først indsendt

8. juni 2026

Først indsendt, der opfyldte QC-kriterier

22. juni 2026

Først opslået (Faktiske)

25. juni 2026

Opdateringer af undersøgelsesjournaler

Sidste opdatering sendt (Faktiske)

25. juni 2026

Sidste opdatering indsendt, der opfyldte kvalitetskontrolkriterier

22. juni 2026

Sidst verificeret

1. juni 2026

Mere information

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Nøgleord

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Andre undersøgelses-id-numre

  • ARDS-EIT-POS-001

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