DIAGNOSING DISORDERS OF MICROVASCULAR TONE REGULATION MECHANISMS

Abstract

The invention relates to registering changes in vascular tone during and after a functional load, and processing data using spectral analysis methods within the frequency ranges of endothelial (0.0095-0.02 Hz), neurogenic (0.02-0.05 Hz), and myogenic (0.05-0.14 Hz) regulation mechanisms. Furthermore, the temperature of an area of a patient's skin is continuously registered. During the first 1-2 minutes, the temperature of the examined skin surface is increased to 38-42° C., and the heating power is fixed. Temperature fluctuations are registered over the course of 10 minutes The heater is shut-off. Over the course of 10 minutes following the shut-off and a decrease in temperature to 30-32° C., temperature fluctuations continue to be registered, and the obtained values are compared, with coefficients being calculated for the relative change in the amplitudes of the temperature fluctuations, which are then used for determining the existence of a disorder in a vascular tone regulation mechanism.

Claims

1. A method for diagnosing dysfunctions of an endothelial, neurogenic and myogenic mechanisms of vascular tone regulation, comprising: recording changes in a vascular tone during and after a functional load, processing of data with a help of mathematical methods of spectral analysis in frequency ranges corresponding endothelial (0.0095-0.02 Hz), neurogenic (0.02-0.05 Hz) and myogenic (0.05-0.14 Hz) mechanisms of regulation of the vascular tone and essential distinctive attributes, including continuous recording of temperature on a tested portion of a patient's skin by a temperature recorder, increasing a skin surface temperature up to 38-42° C. within first 1-2 minutes, setting of a mode of a permanent thermal power with a recording of temperature oscillations within not less than 10 minutes after a beginning of the a thermal test, followed by deactivating a heating and resuming the recording when the skin surface temperature reduces to 30-32° C., but not later than 10 minutes after, and comparing values recorded, and calculating coefficients of relative change in amplitude of oscillations of the skin temperature, which indicate a dysfunction of the mechanism of vascular tone regulation.

2. The method of claim 1, wherein the coefficients of relative changes in the amplitudes ofthe skin temperature are:
A=(A.sub.1−A.sub.0)/A.sub.0
B=(B.sub.1−B.sub.0)B.sub.0.
C=(C.sub.1−C.sub.0)/C.sub.0 where A.sub.0B.sub.0C.sub.0—are amplitudes of the oscillations of the skin temperature in the endothelial, neurogenic and myogenic frequency ranges after the hot thermal test, respectively, within 10 minutes after a completion of the hot thermal test; A.sub.1B.sub.1C.sub.1are average amplitudes of the oscillations of the skin temperature in the endothelial, neurogenic and myogenic frequency ranges during the hot thermal test, respectively, where A coefficient being lower than 0.7 indicates a dysfunction of the endothelial mechanism of vascular tone regulation, B coefficient being lower than 1.1 indicates a dysfunction of the neurogenic mechanism of vascular tone regulation, and C coefficient being lower than 1.3 indicates a dysfunction of the myogenic mechanism of vascular tone regulation.

3. The method of claim 1, wherein the temperature is measured at a frequency of at least 1 Hz.

4. The method of claim 1? wherein the temperature values are processed with a use of computer software through a wavelet analysis.

5. An electronic temperature recorder used to embody the method described in claim 1, comprising: an external temperature sensor equipped with a heating unit connected to a first channel of a microchip of an A/D converter which is coupled with a microcontroller that transmits data to a PC via an interface, when one chip of the microchip of the A/D converter comprises a three-channel multiplexer, an instrumentation amplifier, a reference voltage source, the temperature sensor, a controlled current source and a sigma-delta converter itself; the microcontroller comprises a Flash memory, a main memory unit, a non-volatile memory (EEPROM), an UART interface for communications with the PC, and a SPI interface to communicate with the A/D converter; and a temperature recorder comprises an optoisolator between the heating unit and a measuring circuit, and the optoisolator between the measuring circuit and a PC signal, and a power supply together with a galvanic isolation unit; and the external temperature sensor comprises a bridge measuring circuit with a theimistor that makes it possible to get rid of common mode noise at an A/D converter input as well as the heating unit based on a SMD-resistors for thermal effects on the patient's skin.

6. The recorder of claim 5, wherein a logic of work and a data storage are implemented by an external software installed on the PC.

Description

DESCRIPTION OF DRAWING TO ILLUSTRATE THE INVENTION

[0050] The drawing shows a schematic block diagram of a preferred embodiment of the electronic temperature recorder.

[0051] FIG. 1 shows: 1—Temperature sensor; 2—Heater; 3—Analog-to-digit converter; 4—Microcontroller; 5—To PC; 6—Interface; 7—UART interface; 8—SPI interface; 9—Optocoupler; 10—Optocoupler+FT232; 11—Power supply unit; 12—Galvanic isolation; AA—Current; BB—Signal; CC—Pulse-width modulation; DD—Control; EE—Data; FF—Pulse width modulation.

[0052] Description of interconnection between elements and units (FIG. 1): The electronic temperature recorder used to embody the method consists of an external temperature sensor connected to A/D converter 3 which transmits the data to the PC. The output of external temperature sensor 1 is coupled to the measuring channel of microchip of A/D converter 3, and the microchip output is coupled to SPI 8 of microcontroller 4 which output is connected to the input of PC5 via USB interface 6. The first output of microcontroller 4 is connected to the control input of A/D converter 3 via SPI 8. The second output of microcontroller 4 is connected to input of heating unit 2 of temperature sensor 1 via optocoupler 9. The third output of microcontroller 4 is connected to PC5 via interface 7 and optocoupler 10. The device is powered via USB and PC5 via power supply unit 11 and galvanic isolation unit 12.

[0053] The measuring part of the recorder is based on the AD7793 microchip produced by Analog devices. One chip of A/D converter 3 comprises three-channel multiplexer, instrumentation amplifier, reference voltage source, temperature sensor, controlled current source and sigma-delta converter itself

[0054] Microcontroller 4 comprises Flash memory, main memory unit, non-volatile memory (EEPROM), UART7 for communications with the PC5 and SPI8 for communications with A/D converter 3.

The Recorder Operates as Follows:

[0055] The signal of sensor 1 is transmitted to the input switchboard, and then—to the instrumentation amplifier. Then the amplified signal is sent to the A/D converter 3. The result of the conversion is read by the microcontroller 4. The microcontroller 4 controls the analog-to-digital converter and the input switch. The microcontroller 4 also performs primary processing, and serves as interface with the control and display unit. The circuit comprises a current stabilizer to feed bridge temperature sensors. The A/D converter unit is designed as a separate measuring substrate. The substrate is galvanically isolated from the measuring circuits connected to the control and display unit.

[0056] The measuring part of the recorder is based on the AD7793 microchip produced by Analog devices. One chip comprises three-channel multiplexer, instrumentation amplifier, reference voltage source, temperature sensor, controlled current source and sigma-delta converter. The main advantage of this scheme is its high accuracy. The AD7793 microchip of the A/D converter has rather high resolution (24-bit) that allows for measurements accurate to a thousandth of a degree at the frequency of 128 Hz. Besides, in order to suppress the noise in the sensor the bridge measurement circuit is used, which contributes to suppression of common mode noise. The built-in multiplexer allows for simultaneous measurements for three channels. Due to the fact that all channels of the A/D converter and reference voltage source are on the same chip, they have very similar characteristics when used in the same process, which makes it possible to minimize temperature drift in the measuring part. In most cases, the primary analog signals taken from the thermistors are represented in millivolts. The use the switchboard for immediate switching of weak signals can serve as a source of noise, interference, and temperature drifts. The fact that amplifier in the AD7793 microchip is located before the power switching unit also positively affects the accuracy.

[0057] The AD7793 microchip made it possible to avoid the use of such elements as temperature sensor of conversion and comparison unit, switchboard, analog-digital converter, and conversion and comparison unit comparing the conversion unit.

[0058] All periphery of the recorder is controlled the ATmega168 microcontroller. The microcontroller allowed us to avoid the use of a number of components, such as setting storage unit, main memory unit, scan signal generator, and encoder.

[0059] The Electronic Temperature Recorder Makes it Possible:

[0060] To record the temperature oscillations of the object under test with a temperature resolution to 0.001° and frequency up to 128 Hz.

[0061] To heat the object under test up to 45° C.

[0062] To transmit data to the PC using special software (hereinafter the Software) which allows for their storage, processing and display on plot.

[0063] To take control commands from the software, such as: “Change the heating power”, “Save/read the calibration coefficients in the microcontroller memory”, and “Change the conversion frequency”.

[0064] The operation of the recorder together with the software made it possible to avoid the use of such elements as: real-time clock, display, keyboard and encoder. As a result of the deployment of the up-do-date components (microcontroller, ADC) in conjunction with external software installed on the PC allows for significant reduce the number of functional units in the electrical circuit by shifting a part of functionality to the software, as well as to simplify and accelerate the process of its eventual improvements.

INDUSTRIAL APPLICABILITY

[0065] The group of inventions relates both to medicine and measuring equipment, and can be advantageously used for registration of patient's skin temperature oscillations for medicinal purposes. The recorder can be made of the available components at the assembly site of instrument-making enterprises. Both method and recorder used for its embodiment will be widely used in medical practice.