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Updated: Apr 25, 2026

Monitoring Lung Function with Electrical Impedance Tomography in the Intensive Care Unit
Published on: September 6, 2024
Influence of lung volume, fluid and capillary recruitment during positional changes and exercise on thoracic
Chul-Ho Kim1, Matthew A Fuglestad1, Maile L Ceridon Richert1
1Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, United States.
Unlabelled:
It is unclear how dynamic changes in pulmonary-capillary blood volume (Vc), alveolar lung volume (derived from end-inspiratory lung volume, EILV) and interstitial fluid (ratio of alveolar capillary membrane conductance and pulmonary capillary blood volume, Dm/Vc) influence lung impedance (Z(T)). The purpose of this study was to investigate if positional change and exercise result in increased EILV, Vc and/or lung interstitial fluid, and if Z(T) tracks these variables.
Methods:
12 heart failure (HF) patients underwent measurements (Z(T), EILV, Vc/Dm) at rest in the upright and supine positions, during exercise and into recovery. Inspiratory capacity was obtained to provide consistent measures of EILV while assessing Z(T).
Results:
Z(T) increased with lung volume during slow vital capacity maneuvers (p<0.05). Positional change (upright→supine) resulted in an increased Z(T) (p<0.01), while Vc increased and EILV and Dm/Vc decreased (p<0.05). Moreover, during exercise Vc and EILV increased and Dm/Vc decreased (p<0.05), whereas, Z(T) did not change significantly (p>0.05).
Conclusion:
Impedance appears sensitive to changes in lung volume and body position which appear to generally overwhelm small acute changes in lung fluid when assed dynamically at rest or during exercise.
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