Surgery – Diagnostic testing – Measuring electrical impedance or conductance of body portion
Reexamination Certificate
2001-10-25
2003-11-18
Hindenburg, Max F. (Department: 3736)
Surgery
Diagnostic testing
Measuring electrical impedance or conductance of body portion
Reexamination Certificate
active
06650933
ABSTRACT:
FIELD OF INVENTION
This invention relates to medicine and may be used as medical equipment for integral assessment of the condition of a human being or an animal
BACKGROUND OF THE INVENTION
Known in the art are methods for diagnosis of the physiological condition of a biological object, which include collecting a sample of a biological fluid from a biological object and placing it in a cell for analysis, passing an electrical current from a frequency and amplitude modulated generator through the cell containing the biological fluid, measuring the impedance Y
1
of the biological fluid sample, assessing the physiological condition of the biological object under the sample conductivity (U.S. Pat. No. 3,949,736; U.S. Pat. No. 4,038,975).
An advantage of the said method is that the impedance is measured with a frequency and amplitude modulated generator, which raises its descriptiveness.
A drawback of the said method is that the impedance is measured by a potential method, i.e., by registering voltages at a resistor dividing circuit, which impairs the measurement accuracy. When measuring impedances of biological fluids, the measurement accuracy is also significantly influenced by the ambient conditions, such as the ambient temperature, humidity, etc. The method provides for direct measurements of the impedance values of a biological medium without any regard to these factors. Moreover, a cell with a relatively large electrode area is used in the said method. Taking into account the fact that the measured biological medium has air inclusions, the stationary construction of the terminals and the cell does not allow to conduct accurate measurements for a long time interval, since in the course of time the terminals are covered with an oxide film and the cell accumulates the residues of the biological medium. The method does not provide for express (within a very short time) diagnosis of the physiological condition of a biological object by comparing the data on the impedance of a sample with the reference data that is also changed under the influence of the ambient atmosphere.
Also known in the art is a device for diagnosis of the physiological condition of a biological object, which comprises a cell for placing a biological fluid therein, a generator connected to the analysis cell and a differential amplifier and a measuring means connected in series, the said analysis cell is made with the possibility of being connected to the said differential amplifier (U.S. Pat. No. 1,387,980).
The said device also comprises a thermistor arranged in the cell, a current-to-voltage converter, a temperature compensator, a limiting amplifier, an analog-digital converter.
An advantage of the said device is the improved measurement accuracy owing to the monitoring and compensation of temperature-related factors.
The limitations of that technical solution are as follows: the device may be operated only at a fixed frequency and a fixed voltage of the generator, since the cell is included into the feedback loop of the amplifier, which leads to unstable operation of the circuit when the amplitude or the frequency of the generator is changed; the differential amplifier is connected to the voltage terminals of the cell, which additionally impairs accuracy and contributes to unstable operation of the circuit at the selected operation mode of the device—subtraction of voltages; the construction of the cell and the circuit is complicated due to the use of a thermistor and a current-to-voltage converter, a temperature compensator and an analog-digital converter; all the limitations due to the use of a stationary cell and the terminals are preserved, such as time-depended conductance of the terminals and the shell of the cell.
SUMMARY OF THE INVENTION
It is the primary object of this invention to provide a method for diagnosis of the physiological condition of a biological object, according to which a sample is collected and a biological fluid is analyzed so as to improve the functional capabilities, raise the accuracy and objectivity of measurements with due regard to the influence of the ambient atmosphere and that of errors of measuring means to the analysis data, as well a create a device for diagnosis of the physiological condition of a biological object, wherein a generator, a differential amplifier and other technical means are made and interconnected so as to enlarge the inventory of measuring means, raise the accuracy and expand the range of measurements, improve the convenience of operation and simplify the whole construction and, thus, to raise the quality and accuracy of measurements.
According to this invention, this object is achieved by improving the known method of diagnosis of the physiological condition of a biological object that involves collecting a sample of a biological fluid from the biological object, placing the sample in an analysis cell, passing a current supplied by a frequency and amplitude modulated generator through the analysis cell containing the biological fluid, and measuring the conductivity Y
1
of the biological fluid sample, which conductivity is served to assess the physiological condition of the biological object, such improvement consists in that a biological fluid sample is collected from a biological object after leaving the quiescent state and awakening, a reference biological fluid is additionally used, a current of the same frequency and amplitude is passed through the reference biological fluid and its conductivity Y
R
is measured at constant temperatures of the reference and the analysis cell containing the biological fluid, the conductivity values Y
1
and Y
R
are compared by determining the ratio N
1
=Y
1
/Y
R
, where N
1
lower than 1 evidences the normal condition of the biological object and N
1
greater than 1 attests to a disorder in the physiological condition of the biological object.
Some other embodiments of the method are possible wherein:
as the reference biological fluid a sample collected from a reference biological object is used, which is placed in the reference cell similar as to its electrical parameters to the analysis cell; and the conductivity Y
R
of the biological fluid sample contained in the reference cell is measured;
as the biological fluid reference a resistor is used that has the conductivity equal to that of the biological fluid and the analysis cell;
a second sample is collected from the biological object in the wake time before the first meal and is placed in an additional analysis cell similar as to its electrical parameters to the said analysis cell, the conductivity Y
2
of the second sample is measured, the ratio N
2
=Y
2
/Y
R
is determined by the biological fluid conductivity in the additional analysis cell (
18
) and that in the reference cell, and the condition of the immune system is assessed by the compliance with the relation N
1
/N
2
>1, where at the value N
1
<1 the immune system activity grows, but if N
1
approaches to 1 it is reduced;
saliva is used as the biological fluid;
urea is used as the biological fluid;
blood is used as the biological fluid.
The object of this invention is also attained owing to that the known device for the diagnosis of the physiological condition of a biological object contains the analysis cell intended for placing a biological fluid therein, a generator connected to the analysis cell and a differential amplifier, a detector and a measuring unit connected in series, the said analysis cell being made with the possibility of being connected to the differential amplifier; according to the invention, the differential amplifier is made with first and second current summing inputs, the generator is connected to the first summing input of the differential amplifier, additionally introduced are an amplifier having the first and the second summing inputs, a voltage regulator, a reference cell intended for placing a reference biological fluid into it, an electrode connected to the second summing input and made with the possibility of its spatial displacement for making conta
Dellett & Walters
Hindenburg Max F.
Szmal Brian
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