RU2345700C2 - Automatic computer vasotonometer for measurement of blood pressure in anterior ciliary vessels of eye - Google Patents

Abstract

FIELD: medical equipment; ophthalmology.

SUBSTANCE: pressure indicator consists of optic system, excluding impact of outer interferences, consisting of light diode, elastic element in form of gate, rigidly fixed on one end, microlens on tubular holder on the other end, doubled photodiode, and piezoelectric element, which registers pulsations of vessel walls, which in form of signals are transferred to measurement unit, consisting of power unit, unit of signal amplification and processing, microcontroller, transmitting data to computer for digital signal processing, information presentation, automatic calibration and testing of indicator before each measurement.

EFFECT: increase of accuracy of measurement results and extension of functional possibilities.

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Description

The invention relates to the field of medical equipment, namely to ophthalmology, and is intended for measuring blood pressure in the anterior ciliary vessels of the eye.

Various types of vasotonometers are known - instruments for measuring pressure in the anterior ciliary vessels, in particular various modifications of electronic vasotonometers containing an elastic element that is rigidly fixed on one side and free, with a lens on the end, on the other hand (Daktarvichene E.U. et al. , 1972; Levchenko O.G., 1986; Selitskaya T.I. et al., 1990 and others). The main and fundamental difference is the use of different sensors to record the pressure, fixing the difference in electrical potentials that occurs when the vessel is clamped - capacitive, tensometric, induction.

The closest in purpose and technical solution is a processor vasotonometer (Gndoyan I.A. et al., 1996), which consists of two units - a sensor unit and a measurement unit. The sensor unit is represented by a microlens mounted on the free end of an elastic element with ferromagnetic overlays located between two differential windings and rigidly mounted on the other end in the holder body. The measurement unit includes a power source, an inductive meter power generator, a microprocessor for collecting and presenting measurements on the display, and a pedal for fixing measurement values.

However, this modification, like all other electronic vasotonometers, has disadvantages that significantly reduce the accuracy of the measurement. These include:

1) the effect on the measurement process and obtaining the results of interference of the surrounding electromagnetic field;

2) the effect of the researcher’s reaction on the result when fixing the measurement values;

3) the lack of calibration of the device and testing using a standard standard before starting the measurement.

The aim of the invention is to improve the accuracy of measuring pressure in the anterior ciliary vessels, as well as the reliability and ease of use of the device.

This goal is achieved by the design of the pressure sensor, the structural elements of which are an optical system that eliminates the influence of external interference, consisting of an LED, an elastic element in the form of a damper rigidly fixed at one end, a microlens connected by a tubular holder with the other free end, a dual photodiode, and a piezoelectric an element that records the pulsations of the walls of the vessel, which in the form of signals are transmitted to the measuring unit, consisting of a power supply, an amplification and signal processing unit, microcontroller transmitting data to a computer for digital signal processing, presentation of information, automatic calibration and testing of the sensor before each measurement.

The invention is illustrated by drawings (Fig.1-3).

The structural diagram of the proposed automated computer vasotonometer (Fig. 1) is represented by three main blocks: an optical-mechanical sensor (1), a measuring unit consisting of a power supply (5), an amplification and signal conversion unit of the sensor (2), a microcontroller (3), pedals of inclusion (6) and the personal computer (4).

An optical type pressure sensor (Fig. 2) consists of a holder (7) in which an elastic element (8) is fixed, ending with a shutter (9) and a tubular microlens holder (10) (11). An LED (12) and a dual photodiode (13) are coaxially located in the upper and lower parts of the holder. A sensitive piezoelectric element (14) is located at the attachment point of the elastic element, which makes it possible to register vessel oscillations. In the housing (15) of the sensor there is an opening for a flexible wire (16) that transmits signals to the measuring unit.

Figure 3 shows a graph of the pressure measurement of the anterior ciliary artery of the eye, as well as the point of determination of systolic pressure P _C and diastolic pressure R _D.

Pressure measurement in the ciliary vessels of the eye is carried out in the following way: the patient undergoes epibulbar anesthesia with a 0.25-0.5% solution of dicaine once. The patient tightly presses his head against the facial installation of the slit lamp to limit its mobility. The microlens of the sensor is placed on a selected vessel (anterior ciliary artery or vein) lying episclerally and easily accessible for visualization and compression. The researcher observes a blood vessel through a transparent microlens using a 30x magnification of a slit lamp microscope. By pressing the pedal, the researcher gives a signal to start the installation, thereby starting the analog-to-digital converter (ADC) of the microcontroller of the measuring unit.

The researcher, holding the sensor housing in his hand, reports various forces to the elastic plate, which transfers this force to the flat surface of the microlens, pressing on the front ciliary vessel. The plate deviation is recorded by the optical system, the signals from which are fed through the amplifier to the ADC input of the microcontroller of the measuring unit.

With a gradual increase in pressure on the vessel under the microlenses, pulsations of the vessel walls appear (systolic pressure level P _C , Fig. 3), which are captured by the sensitive piezoelectric element and transmitted through the amplification unit to the input of the ADC of the microcontroller. With a further increase in pressure, the blood flow in the vessel is interrupted and the impulses disappear (diastolic pressure level R _D , Fig. 3).

Having made a series of several measurements, the researcher by pressing the pedal disables the ADC of the microcontroller and stops the data transfer to the computer. The computer software processes the received data as follows: removes the influence of noise, combines pressure and recording pulses, automatically determines the levels of P _C and R _D , and also averages the values of a series of measurements. On the computer display, the researcher sees the pressure parameters, as shown in Fig.3.

Before each measurement, the researcher tests the sensor by measuring the readings of the device in three positions of the deflecting plate, represented by an elastic element connected to the curtain and a tubular holder with a microlens. For this, special reference forms for the sensor are created in the form of a test bench with three positions - point-minimum, mid-point, point-maximum. In addition, the first measurement cycle performs an automatic zero calibration of the sensor, which is performed at rest of the deflecting plate.

The device allows you to measure the pressure in the anterior ciliary vessels in the range from 3 to 80 mm Hg. The accuracy of measuring venous and blood pressure is ± 0.5 mm Hg. Art., and after filtering by digital methods increases to ± 0.15 mm RT. Art.

An automated computer vasotometer was tested in the microsurgical departments of the eye by an adult and a children's public health institution “Volgograd Regional Clinical Hospital No. 1”.

The advantage and positive effect of the inventive automated computer vasotonometer is to significantly increase the accuracy of measuring pressure in the front ciliary vessels by reducing the influence of external noise, automatically recording pressure values from the oscillatory pulses of the vessel, having a calibration and testing system, and meeting other requirements for modern diagnostic equipment : the ability to archive the received parameters, the convenience and ease of use of the device. The proposed vasotonometer is reliable and easy to use, can be used in outpatient and inpatient ophthalmic practice.

Literature

1. Daktarvichene E.Yu., Vashkelene II, Valuzhis A. A device for measuring blood pressure in the episcleral vessels of the eye // Materials XXI scientific. Kaunas Medical Conference in-that. - Kaunas, 1972. - S.175-177.

2. Levchenko O.G. The fluid pressure in water and blood in the episcleral veins is normal and in the eyes with myopia // Act.optology issues: Sborn. scientific labor. - Tashkent, 1986. - P.66-70.

3. Gndoyan I.A., Petraevsky A.V., Eremichev O.S. Processor vasotonometer for measuring pressure in the anterior ciliary vessels // Rat suggestion of the Volgograd Medical Academy No. 3-96 of 12.29.96.

4. Selitskaya T.I., Pyankov V.Z., Zapuskalov I.V. Conjunctival vessels are normal and with pathology. - Tomsk: Publishing house of Tomsk University, 1980. - 120 p.

Claims (1)

An automated computer vasotonometer for measuring blood pressure in the anterior ciliary vessels of the eye, comprising a pressure sensor consisting of a microlens mounted with a tubular rod at the free end of the elastic element and rigidly fixed at the other end in the body holder, a measuring unit containing interconnected amplification unit and signal conversion and a microcontroller configured to transmit a series of measurements to a personal computer with software for processing it, characterized in that an optical system is introduced into the sensor, consisting of a coaxially located on the upper and lower parts of the LED holder and a dual photodiode with a shutter on the elastic element between them, and a sensitive piezoelectric element, configured to detect oscillations of the eye vessel.

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