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High-sensitivity, high-linearity, low-leak, self-balanced impedance cardiograph
Medical Progress Through Technology
|January 1, 1983
Summary
A new impedance cardiograph offers precise measurements for evaluating stroke volume. Preliminary tests show strong correlation with established methods, highlighting its potential in cardiovascular monitoring.
Area of Science:
- Biomedical Engineering
- Medical Instrumentation
- Cardiovascular Physiology
Background:
- Accurate non-invasive monitoring of cardiovascular parameters is crucial for clinical diagnosis and research.
- Existing impedance cardiography devices may have limitations in precision, range, or multi-functionality.
Purpose of the Study:
- To describe a novel impedance cardiograph with specific technical characteristics.
- To evaluate the performance of this instrument for stroke volume measurement.
Main Methods:
- Development of an impedance cardiograph featuring a preadjustable current generator (0-4 mA rms at 100 kHz, crystal-controlled).
- Incorporation of high sensitivity (up to 50 V/Ω, 2 mΩ resolution) and low nonlinearity (max 2%).
- Utilizing a modified Arenson's bridge for self-balancing and multi-modal operation (plethysmograph, respirograph, intracardiac Z-meter).
Main Results:
- The instrument demonstrated a flat frequency response (0-19 Hz) and minimal leak current (0.7 µA rms at 50 Hz).
- Preliminary impedance cardiography tests showed a correlation coefficient > 0.8 when compared to thermodilution-derived stroke volume using Kubicek's method.
Conclusions:
- The described impedance cardiograph is a versatile and accurate instrument for cardiovascular monitoring.
- Its performance suggests suitability for reliable stroke volume assessment in clinical settings.