Apparatus and method for detecting and processing impedance rheogram
First Claim
1. An apparatus for detecting and processing an impedance rheogram, comprising:
- a constant current source for generating a constant current having a frequency range of 20-100 KHz and an amplitude of less than 2 mA;
a pair of output electrodes connected to said constant current source for applying the constant current to a subject'"'"'s body part;
a pair of voltage detecting electrodes for detecting from said body part of voltage signal which represents a change of impedance in response to the constant current applied to the said body part;
means for detecting an impedance signal from said voltage detecting electrodes and for further amplifying and filtering the impedance signal detected thereby;
ECG signal detecting electrodes adapted to be connected to the said body part for detecting an ECG signal generated by the said body part;
means for detecting the ECG signal generated by said ECG signal detecting electrodes, for amplifying and filtering the ECG signal detected, and for generating an R wave sequence from the ECG signal;
digital signal processing means connected to an output of each said means for detecting said impedance signal and said means for detecting said ECG signal wherein said impedance signal, ECG signal and R wave sequence are connected in parallel to said digital signal processing means; and
an output device connected to said digital signal processing means for displaying and recording the impedance signal and ECG signal;
wherein said digital signal processing means performs A/D converting and sampling of said impedance and ECG signals, divides said impedance signal into cycles according to said R wave sequence and performs linear interpolating processing within each cycle, said linear interpolation processing including selection of a predetermined number of interpolating points for each cycle, subsequently performs in-phase superposing-averaging processing of the impedance signal for a predetermined number of cycles and restores the impedance signal according to the interpolating points, and synchronously outputs the impedance and ECG signals to said output device.
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Abstract
An apparatus and method for detecting and processing an impedance rheogram includes a constant current source with output electrodes, an impedance signal detecting circuit having detecting electrodes, an ECG signal detecting circuit having detecting electrodes, a signal processing circuit and an output device. The impedance signal detecting circuit and ECG signal detecting circuit respectively, defect the impedance signal and ECG signal, the signal whereby processing circuit divides the impedance signal into cycles according to an R wave sequence, then performs linear interpolating for each cycle and in-phase superposing-averaging for a certain number of cycles, and restores the impedance waveform according to a predetermined number of interpolating points used for each cycle, so as to automatically trace arrhythmia and eliminate respiration interference to the impedance rheogram.
84 Citations
9 Claims
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1. An apparatus for detecting and processing an impedance rheogram, comprising:
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a constant current source for generating a constant current having a frequency range of 20-100 KHz and an amplitude of less than 2 mA; a pair of output electrodes connected to said constant current source for applying the constant current to a subject'"'"'s body part; a pair of voltage detecting electrodes for detecting from said body part of voltage signal which represents a change of impedance in response to the constant current applied to the said body part; means for detecting an impedance signal from said voltage detecting electrodes and for further amplifying and filtering the impedance signal detected thereby; ECG signal detecting electrodes adapted to be connected to the said body part for detecting an ECG signal generated by the said body part; means for detecting the ECG signal generated by said ECG signal detecting electrodes, for amplifying and filtering the ECG signal detected, and for generating an R wave sequence from the ECG signal; digital signal processing means connected to an output of each said means for detecting said impedance signal and said means for detecting said ECG signal wherein said impedance signal, ECG signal and R wave sequence are connected in parallel to said digital signal processing means; and an output device connected to said digital signal processing means for displaying and recording the impedance signal and ECG signal; wherein said digital signal processing means performs A/D converting and sampling of said impedance and ECG signals, divides said impedance signal into cycles according to said R wave sequence and performs linear interpolating processing within each cycle, said linear interpolation processing including selection of a predetermined number of interpolating points for each cycle, subsequently performs in-phase superposing-averaging processing of the impedance signal for a predetermined number of cycles and restores the impedance signal according to the interpolating points, and synchronously outputs the impedance and ECG signals to said output device. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for detecting and processing impedance rheogram comprising the steps of:
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1) applying a constant current having a frequency in the range of 20-100 KHz and an amplitude of less than 2mA to a part of a subject'"'"'s body; 2) detecting a voltage variation caused by a change of impedance of said body part under the effect of said constant current and using said voltage variation as an impedance signal; 3) simultaneously detecting the subject'"'"'s ECG signal and generating a R waveform sequence therefrom; 4) synchronously converting said impedance signal and ECG signal into respective digital signals and sampling the same at constant time intervals; 5) dividing said sampled impedance signal into cycles according to rising edges of said R wave sequence and conducting in each cycle a linear interpolation for a predetermined number of interpolation points; 6) performing in-phase superposing-averaging for a predetermined number of cycles of an interpolated impedance signal and restoring an impedance waveform according to said interpolating points; and 7) displaying and recording said impedance waveform and synchronized ECG waveform via an output device. - View Dependent Claims (9)
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Specification