Electrical Impedance Tomography-Guided Identification of the Optimal Lateral Position in Postoperative ARDS
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
調査の概要
詳細な説明
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. The primary statistical analysis required a minimum of 22 evaluable participants. Recruitment was planned to achieve at least this number to account for potential dropout. Recruitment would be terminated once sufficient evaluable subjects were obtained.
研究の種類
入学 (推定)
段階
- 適用できない
連絡先と場所
研究連絡先
- 名前：Rui Zhang
- 電話番号：+86 18801119381
- メール：ccmzhangrui@foxmail.com
研究場所
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Shanghai、中国
- 募集
- Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Department of Critical Care Medicine
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コンタクト：
- Rui Zhang
- 電話番号：+86 18801119381
- メール：ccmzhangrui@foxmail.com
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参加基準
適格基準
就学可能な年齢
- 大人
- 高齢者
健康ボランティアの受け入れ
説明
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
研究計画
研究はどのように設計されていますか？
デザインの詳細
- 主な目的：処理
- 割り当て：ランダム化
- 介入モデル：クロスオーバー割り当て
- マスキング：なし（オープンラベル）
武器と介入
参加者グループ / アーム |
介入・治療 |
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実験的：Arm 1: Supine Position
Supine position with protocolized stabilization and EIT ventilation/perfusion measurements.
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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.
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実験的：Arm 2: Left Lateral Position
Left lateral position with protocolized stabilization and EIT ventilation/perfusion measurements.
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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.
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実験的：Right Lateral Position
Right lateral position with protocolized stabilization and EIT ventilation/perfusion measurements.
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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.
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この研究は何を測定していますか？
主要な結果の測定
結果測定 |
メジャーの説明 |
時間枠 |
|---|---|---|
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Global normal V/Q (%) derived from electrical impedance tomography (EIT)
時間枠：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.
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The percentage of lung pixels categorized as "normal ventilation-perfusion (V/Q)" according to pre-defined ventilation and perfusion signals acquired via EIT.
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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.
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二次結果の測定
結果測定 |
メジャーの説明 |
時間枠 |
|---|---|---|
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EIT-derived V/Q mismatch components (shunt-like lung pixel percentage, dead-space-like lung pixel percentage).
時間枠：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.
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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.
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EIT-derived regional ventilation distribution indices
時間枠：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.
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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.
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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.
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EIT-derived regional perfusion distribution indices
時間枠：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.
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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.
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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.
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Oxygenation index (PaO₂/FiO₂ ratio if arterial blood gas sampling is feasible; SpO₂/FiO₂ ratio as an alternative surrogate index).
時間枠：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.
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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.
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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.
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Ventilator-related pressure parameters (plateau pressure, driving pressure).
時間枠：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.
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Static respiratory pressure indicators automatically recorded by mechanical ventilator, only collected from participants receiving invasive mechanical ventilation.
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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.
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Respiratory system compliance (ventilator-derived parameter).
時間枠：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.
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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.
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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.
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Circulatory monitoring parameters (heart rate, mean arterial pressure, vasopressor use if available).
時間枠：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.
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Continuous hemodynamic readings collected via bedside invasive monitor for circulatory assessment.
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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.
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Proportion of participants completing all randomized 60-minute positional stages and inter-position washout periods.
時間枠：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.
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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.
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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.
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Number of participants with successful acquisition of analyzable EIT imaging datasets.
時間枠：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.
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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.
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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.
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Proportion of participants capable of maintaining breath-hold for at least 8 seconds during EIT perfusion imaging.
時間枠：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.
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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.
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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.
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Number of participants with any procedure-related adverse event (desaturation, hypotension, arrhythmia, accidental tube/line/drain displacement).
時間枠：Through positional phase completion (from first positional stage start to final post-position washout end); all adverse events captured and tallied during positional testing.
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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.
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Through positional phase completion (from first positional stage start to final post-position washout end); all adverse events captured and tallied during positional testing.
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Number of participants with early study termination secondary to positional intolerance.
時間枠：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.
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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.
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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.
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スポンサー
研究記録日
主要日程の研究
研究開始 (実際)
一次修了 (推定)
研究の完了 (推定)
試験登録日
最初に提出
QC基準を満たした最初の提出物
最初の投稿 (実際)
学習記録の更新
投稿された最後の更新 (実際)
QC基準を満たした最後の更新が送信されました
最終確認日
詳しくは
本研究に関する用語
キーワード
その他の研究ID番号
- ARDS-EIT-POS-001
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