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Updated: Aug 6, 2026
Monitoring Lung Function with Electrical Impedance Tomography in the Intensive Care Unit
Published on: September 6, 2024
Posture-related ventilation redistribution and associated factors in healthy subjects assessed by electrical
Hirofumi Tsuji1, Yukio Fujita1, Kazuya Tanimura1
1Department of Respiratory Medicine, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8521, Japan.
Background:
Ventilation distribution varies with body position because of gravitational loading, thoracic morphology, and respiratory muscle activity. Electrical impedance tomography (EIT) enables real-time assessment of regional ventilation; however, quantitative characterization of posture-related ventilation redistribution and its associated factors in healthy subjects remains limited.
Objective:
To characterize posture-dependent changes in regional ventilation distribution using EIT in healthy subjects and to explore anthropometric and diaphragmatic factors associated with gravity-related ventilation redistribution.
Methods:
10 healthy male volunteers underwent EIT measurements during quiet breathing in the supine, right lateral decubitus, prone, left lateral decubitus, and sitting positions. Regional ventilation was quantified using predefined regions of interest. Posture-related redistribution was evaluated using Δ ventilation distribution, defined as within-subject changes in regional ventilation proportion relative to supine, to detect subtle redistribution. Associations between Δ ventilation distribution and body mass index (BMI), cardiothoracic ratio (CTR), diaphragm thickness change ratio, and diaphragmatic excursion (DE) were also analyzed.
Results:
Lateral decubitus positioning induced marked gravity-dependent redistribution toward dependent lung regions, with greater asymmetry in the right lateral position. Although overall dorsoventral ventilation patterns appeared similar among supine, prone, and sitting positions, Δ ventilation distribution analysis detected subtle but significant regional redistribution during prone and sitting. Redistribution during lateral positioning was associated with CTR and BMI, whereas redistribution during sitting was associated with DE.
Conclusions:
Posture-related ventilation redistribution may reflect interactions between gravitational loading, thoracic morphology, and diaphragmatic motion. These exploratory findings provide a sensitive physiological framework for quantifying regional redistribution and may improve understanding of position-dependent respiratory mechanics.
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