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An impedance device for study of multisegment hemodynamic changes during orthostatic stress
L D Montgomery1, H M Hanish, R A Marker
1Armstrong Aerospace Medical Research Laboratory, Wright-Patterson Air Force Base, OH.
Aviation, Space, and Environmental Medicine
|November 1, 1989
Summary
This study introduces a new impedance device to measure blood flow and volume changes in six body segments during orthostatic stress. This technology enhances understanding of physiological responses to challenges like head-up tilt.
Area of Science:
- Physiology
- Biomedical Engineering
Background:
- Understanding multisegment hemodynamic changes is crucial for assessing physiological responses to orthostatic stress.
- Existing methods may not fully capture dynamic blood flow and volume alterations across multiple body segments.
Purpose of the Study:
- To describe a novel, self-contained impedance device for measuring hemodynamic changes in six body segments.
- To evaluate the device's utility in quantifying physiological responses during various orthostatic stress techniques.
Main Methods:
- Development of a self-contained impedance device with integrated electronics, controller/multiplexer, and PC interface.
- Measurement of electrical transmission characteristics related to blood flow and volume changes.
- Application of the device during head-up tilt, bed rest, and lower body negative pressure protocols.
Main Results:
- The instrument demonstrates linearity over a 0-200 ohm range.
- It provides analog outputs for base impedance, phase angle, pulsatile impedance change, and its first derivative.
- Automated recording of basal impedance values in spreadsheet format with adjustable cycle times (12s to 1h) is possible.
Conclusions:
- The described impedance device offers a comprehensive method for assessing multisegment hemodynamic responses.
- It has potential applications in aerospace research and understanding human physiological adaptation to stress.