RU151775U1 - DEVICE FOR DETERMINING THE TIME OF BLOOD COAGING - Google Patents

Abstract

1. A device for determining the time of coagulation of blood, containing means for placing a blood sample, two measuring metal electrodes located in the area of placement of the blood sample with the possibility of electrical contact with this sample, and a resistance transducer into an electrical signal connected to these electrodes, a time counter, the output of which is connected to the display, characterized in that it further comprises a logic device, a pulse detector and a computer for the second derivative of the electrical signal, ayuschego output impedance converter into an electrical signal and input to the calculator logic device input, output through the second derivative calculator pulse detector connected to a second input of the logic device, the output of which is connected with the meter vremeni.2. The device according to claim 1, characterized in that the electrodes are rigidly placed in a means for placing a blood sample. 3. The device according to p. 1, characterized in that the means for placing blood is made with the possibility of separation from the rest.

Description

The utility model relates to tools for clinical laboratory research, and in particular to devices for monitoring and measuring blood coagulation parameters, and in particular prothrombin time and / or MHO (international normalized ratio). It can be used for personal independent implementation by the needy (sick) of control and measurement of these indicators at home.

Known coagulograph for determining the time of blood coagulation (Koblov LF Methods and devices for kinetic laboratory research. M: Medicine. 1979. S. 51-57), containing a special movable measuring cell made of an insulating material (for example, fluoroplastic) , to place a blood sample, in the bottom of which two metal electrodes are mounted, made with the possibility of contact with a blood sample when the cell oscillates, and a measuring transducer connected to these electrodes.

Blood coagulation time is measured using a coagulograph by recording the instant of occurrence of a continuous electric current in the electrode circuit when the gap between them is closed with fibrin filaments.

The disadvantage of a coagulograph is the need to use a special cuvette for a blood sample, which entails the need to sterilize this cuvette during mass clinical tests, a large volume of blood being analyzed (up to 0.2 ml) and the complexity of the coagulograph design.

The closest in technical essence is a device for determining the coagulation time of blood (PCT N 9406007, G01N 30/47, 1995). A device for determining the coagulation rate of a liquid), containing a horizontal plate made of porous insulating material for placing a blood sample, two measuring metal electrodes located in the area where the blood sample is placed with the possibility of electrical contact with this sample, and a resistance transducer into an electrical signal connected to these electrodes. When a blood sample passes through the pores of a horizontal plate, blood coagulation occurs. Clotting time is determined by the electrical conductivity or total electrical resistance between the two electrodes.

The disadvantage of the described device is the need for additional studies of the correspondence of the moment of blood coagulation with this device and the standard method, as well as the lack of automation of laboratory analysis of blood coagulation time.

The closest in technical essence to the proposed one is a device for its implementation, containing a horizontal plate made of insulating material for placing a blood sample, two measuring metal electrodes located in the area of the blood sample with the possibility of electrical contact with this sample, and a resistance transducer in an electrical signal connected to these electrodes, characterized in that the device is equipped with an additional metal electrode, an additional a resistance transformer into an electrical signal, a reciprocating drive, the movable rod of which is movable vertically, with a sensor for the maximum vertical position of the rod, an electronic coincidence device and an electronic stopwatch, while one of the measuring and additional electrodes is made in the form of wires of the same length, vertically mounted and fixed at a fixed distance from each other on an insulating plate mechanically connected to the end the actuator rod, the lower free ends of these wires being bent at right angles to the vertical, the actuator is configured to immerse the bent ends of the wires in the blood sample while the rod is moving, and the input of the additional resistance transducer into an electrical signal is connected to the measuring and additional electrodes mounted on the insulating plate while the output of the sensor for the vertical position of the rod and the outputs of both converters of resistance to an electrical signal are connected to the input of an electronic device coincidence, and its output is connected to an electronic stopwatch (see RU patent for the invention No. 2187797, M. Cl: G01N 27/02, publ. 08/20/2002).

This design of the device allows absolute measurements of the coagulation time and a more accurate determination of the moment of formation of the fibrin thread when pulling the electrodes from the blood sample to a fixed height due to the sensor of the maximum position of the electrodes and the presence of an additional electrode. However, this device is structurally difficult, because it contains movable mechanical parts and their drive, since the marker is not clearly defined, according to which the countdown ends when the resistance between the electrodes increases.

The technical result of the proposed utility model is to increase the accuracy of measuring blood coagulation time while simplifying the device.

The technical result is achieved in that a device for determining the coagulation time of a blood containing a means for placing a blood sample, two measuring metal electrodes located in the area for placing a blood sample with the possibility of electrical contact with this sample, and a resistance transducer into an electrical signal connected to these electrodes, the time counter, the output of which is connected to the display, additionally contains a logic device, a pulse detector and a second production computer oh the electrical signal coming from the output of the resistance converter into an electrical signal at the input of the calculator and the input of the logic device, the output of the second derivative calculator is connected via a pulse detector to the second input of the logic device, the output of which is connected to a time counter, while the electrodes are rigidly placed in the means for placing the sample blood, while the means for placing a blood sample can be performed with the possibility of separation from the rest.

The prerequisite of this application was the establishment of the fact that the change in resistance between the electrodes located in the area of the blood sample is a nonlinear function in time. In this case, the clotting moment is determined by the characteristic change in resistance between the electrodes. For this, the measured function of the change in the resistance of the sample is twice differentiated by time, and the moment of the abrupt change in the second derivative of this function is recognized as the moment of blood coagulation.

The proposed device is schematically shown in the drawing (Fig. 1).

A device for determining the coagulation time of blood, contains a means 1 for placing a blood sample, two measuring metal electrodes 2 and 3 located in the area for placing a blood sample with the possibility of electrical contact with this sample, the resistance transducer 4 into an electrical signal. The inputs of the resistance converter 4 into an electrical signal are connected to the electrodes 2 and 3. The device also contains a time counter 5, the output of which is connected to the display 6, a logic device 7, the role of which can be performed, for example, by a RS-trigger, a pulse detector 8, and a calculator 9 of the second derivative of the electric the signal coming from the output of the resistance converter 4 into an electric signal to the input of the calculator 9 and the input of the logic device 7. The output of the calculator 9 of the second derivative through the pulse detector 8 is connected to the second input logical unit 7. Logical unit Output 7 is connected to the counter 5 times. The electrodes 2 and 3 are rigidly placed in the means for placing a blood sample. The means 1 for placing a blood sample can be made with the possibility of separation from the rest, as shown in the drawing. The tool 1 for placing a blood sample can be made in the form of a plastic case. The internal cavity of the body may contain a coagulant activator (for example, prothrombin protein) in the form of a dried layer applied during the assembly of the sensor. To eliminate false readings, the body of the tool 1 is made in the form of a closed container (vessel) with an opening (neck) for filling with blood. The inner surface of the body of the tool 1 may have a hydrophilic character for reliable filling with blood without the formation of air bubbles.

All elements of the device are powered from one power supply (not shown in the drawing).

The device operates as follows.

Before measurement, the user brings the device into working condition, turns on the device (the switching elements on devices are not shown in the drawing), having previously connected the means 1 for placing a blood sample to the measuring devices. Then he punctures the skin of the finger with a lancet and puts 1-2 drops of blood into the hole of means 1 to place a blood sample (in this case, regardless of how many drops, one or two, of blood are introduced into means 1, electrodes 2 and 3 should be completely covered with blood). In this case, the resistance between the electrodes 2 and 3 sharply decreases. From the resistance converter 4, a signal is sent to the calculator 9 and to the logic device 7 from the output of which a signal is sent to start the operation of the time counter 5 with the measurement result displayed on display 6. During the measurement the module measures the total electrical resistance of the blood sample and an analysis of its change in time. The moment of blood coagulation is determined by a characteristic change in the nature of the change in resistance. To do this, the measured function of changing the resistance of the blood sample is twice differentiated by time and at the time of the abrupt change in the second derivative of this function, a pulse is applied to the detector 8, from which the signal is supplied to the logic device 7, the output of which turns off the time counter 5 with the information stored on the display 6 , which means with the indication of blood coagulation time.

High measurement accuracy with simplicity of the device is the advantage and advantage of the proposed technical solution compared to the prototype.

Claims (3)

1. A device for determining the time of coagulation of blood, containing means for placing a blood sample, two measuring metal electrodes located in the area of placement of the blood sample with the possibility of electrical contact with this sample, and a resistance transducer into an electrical signal connected to these electrodes, a time counter, the output of which is connected to the display, characterized in that it further comprises a logic device, a pulse detector and a computer for the second derivative of the electrical signal, ayuschego output impedance converter into an electrical signal and input to the calculator logic device input, output through the second derivative calculator pulse detector connected to a second input of the logic device, the output of which is connected with the meter time. 2. The device according to claim 1, characterized in that the electrodes are rigidly placed in the means for placing a blood sample. 3. The device according to p. 1, characterized in that the means for placing blood is made with the possibility of separation from the rest.

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