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Segmental composition of whole-body impedance cardiogram estimated by computer simulations and clinical experiments
P K Kauppinen1, T Kööbi, J Hyttinen
1Tampere University of Technology, Ragnar Granit Institute, FIN-33101 Tampere, Finland.
Insights
Whole-body impedance cardiography (ICGWB) measures cardiac output (CO) by analyzing impedance variations. This study found ICGWB signals originate evenly from body segments, providing comprehensive circulatory data.
Area of Science:
- Biomedical Engineering
- Cardiovascular Physiology
Background:
- Whole-body impedance cardiography (ICGWB) is a proposed method for measuring cardiac output (CO).
- The distribution of impedance variations related to heart activity across the body is not well understood.
Purpose of the Study:
- To determine the origin and contribution of different body segments to stroke volume (SV) measurements using ICGWB.
- To investigate the theoretical properties of ICGWB using a whole-body computer model.
Main Methods:
- Investigated impedance in extremities and trunk in 15 healthy volunteers.
- Utilized a computer model of whole-body anatomy as a volume conductor.
- Analyzed heart-related amplitude variations in ICGWB signals.
Main Results:
- Computer modeling indicated basal impedance primarily originates from extremities.
- Clinical experiments showed heart-related ICGWB signal variations arise more evenly from body segments, with the trunk contributing slightly more than limbs.
- The ICGWB signal is a weighted sum of segmental pulsatile events.
Conclusions:
- ICGWB signals provide physiologically meaningful data from nearly the entire circulatory system.
- The findings clarify the segmental contributions to ICGWB, supporting its use for comprehensive cardiovascular assessment.
Abstract:
Whole-body impedance cardiography (ICGWB) has been proposed as a feasible means of measuring cardiac output (CO). However, the source distribution of heart-related impedance variations in the whole body is not known. To establish how much of a signal originates in each segment of the body and what the contribution of each is to stroke volume (SV) in ICGWB, impedance in the extremities and trunk were investigated in 15 healthy volunteers. In addition, the theoretical measurement properties of ICGWB were studied using a computer model of the whole-body anatomy as a volume conductor. The model confirmed the expected result that most of the basal impedance originates from the extremities. Clinical experiments revealed that the heart-related amplitude variations in the ICGWB signal originate more evenly from various body segments, the trunk slightly more than the arms or legs. The heart-related ICGWB signal represents a weighted sum of segmental pulsatile events in the body yielding physiologically meaningful data on almost the whole circulatory system.