RU224452U1 - OPTICAL ANALYZER FOR DETERMINING PLATELET AGGREGATION IN BLOOD - Google Patents

Abstract

The utility model relates to the field of measurement technology and concerns an optical platelet aggregation analyzer. The analyzer contains a vertically placed capillary, the lower end of which is installed in the cavity of a thermostated vessel for a blood sample, and the upper end is communicated with means for periodically sucking and displacing blood from the capillary, and a channel for determining the light transmittance of the sample in the capillary, installed on the side of the lower end of the capillary, connected to management and registration tools. In the middle part of the capillary, a blood sample mixing chamber is additionally formed, made in the form of a spherical expansion in the body of the capillary, the volume V of which is selected from the condition V>Vo, where Vo is the volume of the vessel for the blood sample. The channel for determining the light transmission of the sample includes an optical radiation source and a photodetector installed in the same diametrical plane of the capillary. The technical result is to increase the accuracy of determining platelet aggregation. 2 ill.

Description

The utility model relates to laboratory medical equipment and can be used to analyze platelet aggregation using the optical method.

Platelet aggregation analysis can identify abnormalities in platelet function in patients with severe bleeding. The analysis is necessary to select the correct therapy for the patient.

Devices for analyzing platelet aggregation using optical means are described (for example, RU 2343456 C1, Scientific Research Institute of Space Instrument Engineering" 01/10/2009). The device contains an optically transparent cuvette with a magnetic stirrer placed in a thermostatting block, a laser module configured to lighting the cuvette, and a measuring unit that records the intensity of light scattering, which includes at least one receiver of scattered optical radiation.

A device for express assessment of the aggregation activity of blood cells is described (RU 2750839 C1 LLC "Mednord-T" 07/05/2021), consisting of a measuring unit, including a cuvette for placing a blood sample and a unit for recording and analyzing blood characteristics. The measuring unit contains a digital camera and a laser diode located coaxially with the cuvette. The digital camera is connected to the information processing and display unit. The disadvantage of the device is that platelet aggregation is judged indirectly, since the observed process mainly depends on the secondary link of hemostasis (blood plasma coagulation) and does not allow an unambiguous answer to the question of which drug (antiplatelet agent or anticoagulant) should be recommended to the patient.

The closest device to the one being patented is the device for an optical platelet aggregation analyzer (patent RU 2426990 C1, 08/20/2011 - prototype).

The optical analyzer contains a vessel for a blood sample, a thermostat, a capillary made in the form of a tube of optically transparent material with a narrow channel, a closed chamber of variable volume, a reciprocating drive with a control unit, a level sensor, a light source, forming optical systems, a photoconverter, analog-to-digital converter (ADC) and computer

The disadvantage is the insufficient measurement accuracy due to the fact that the small volume of the capillary, with the recommended flow area of the capillary not exceeding 1 mm, does not make it possible to use the entire volume of the selected blood during mixing.

The utility model is aimed at solving the problem of increasing the accuracy of platelet aggregation measurement by improving the quality of sample mixing, which is the technical result of the utility model.

The patented optical platelet aggregation analyzer contains a vertically placed capillary, the lower end of which is installed in the cavity of a thermostated vessel for a blood sample, and the upper end is communicated with means for periodically sucking and displacing blood from the capillary, and a channel for determining the light transmittance of the sample in the capillary, installed from the lower end capillary connected to control and registration means.

The difference is this.

In the middle part of the capillary, a blood sample mixing chamber is additionally formed, made in the form of a spherical expansion in the body of the capillary, the volume V of which is selected from the condition V>Vo, where Vo is the volume of the vessel for the blood sample. The channel for determining the light transmission of the sample includes an optical radiation source and a photodetector installed in one diametrical plane of the capillary, connected to means for recording and controlling the periodic suction and displacement of blood from the mixing chamber of the sample and the capillary.

The optical analyzer may be characterized in that the means for periodically sucking and expelling blood from the capillary is a closed chamber of variable volume associated with a reciprocating drive and connected to the upper end of the capillary.

The implementation of an analyzer of a patented design makes it possible to increase the accuracy of measuring platelet aggregation by improving the quality of sample mixing. This is ensured by constant mixing of the blood sample (in the upper, spherical expansion of the capillary and the lower reservoir), which makes it possible to perform continuous measurements, and not once per cycle, as in the prototype, when using 100% of the sample for analysis. In addition, this solution makes it possible to refuse to control the upper level of the sample as it flows into the capillary, which significantly simplifies the design and avoids situations with overflow and contamination of the device.

The essence of the utility model is explained in the drawings, where

fig. 1 - design of the optical analyzer;

fig. 2 - graph of the average size of aggregates versus time for the prototype (curve A) and for the patented analyzer (curve B).

In fig. Figure 1 schematically shows the optical analyzer in working condition. The positions indicate: 1 - blood vessel; 2 - sample; 3 - thermostat; 4 - capillary; 41 - lower end of the capillary; 42 - upper end of the capillary; 43 - blood mixing chamber; 5 - a piece of tube; 6 - rod; 7 - means for periodic absorption and displacement of blood; 8 - drive; 9 - drive control unit 8, 10 - optical system, consisting of 11 - light source (LED, semiconductor laser, etc.), 12 - forming optical system (in the simplest case, lens 21), 13 - forming optical system (in in the simplest case lens 22); 14 - photoconverter; 15 - analog-to-digital converter (ADC); computer 16; 21, 22 - lenses; 23, 24 - path of optical rays. H is the distance from the lower end 41 of the capillary to the plane of the optical system. The output of the photoconverter 14 is connected to the input of the ADC 15 and to the control input of the drive 8 control unit 9. The signal from the photoconverter 14 is used as a blood level sensor in the capillary.

Capillary 4 is made of optically transparent material (glass, quartz) with a channel whose diameter is 0.2-1 mm.

Between the lower end 41 and the upper end 42 in the middle part of the capillary 4, a spherical expansion of the capillary is formed - chamber 43, which serves as an intermediate depot and a place for mixing the sample (blood), the volume of which is selected from the condition V>Vo, where Vo is the volume of vessel 1 for blood.

Vessel 1 is placed in a thermostat 3, and the lower end 41 of capillary 4 is placed in the cavity of vessel 1 to ensure its contact with sample 2.

The capillary 4 communicates with the cavity of the closed chamber 7 through a tube 5 put on its upper end 42. One of the walls of the closed chamber 7 can be made in the form of a piston, the rod 6 of which is connected to the reciprocating drive 8. Instead of a piston, a membrane (diaphragm) can be used, which is rigidly fixed along its entire perimeter, similar to how it is implemented in known membrane (diaphragm) pumps.

The device operates as follows.

The blood sample 2 prepared for the study is placed in a vessel 1, preferably made tapering downwards. The lower (first) end 41 of the capillary 4 is immersed in the sample 2, ensuring the minimum possible gap between the end of its lower end 41 and the bottom of the vessel 1. From the upper (second) end 42, the capillary 4 communicates through a piece of tube 5 with the cavity of a closed chamber 7 of variable volume . Capillary 4 is placed vertically, respectively, its ends are designated in this description as lower 41 and upper 42, since in its inclined or horizontal positions under the influence of gravity, platelets and/or their aggregates may settle on the walls of capillary 4, which will accordingly lead to an error in measurements .

The optical channel for determining the change in light transmission during platelet aggregation is installed at a distance H from the lower end of the capillary 4 for reasons of design feasibility, since, regardless of its location, the entire volume Vo of the test sample will pass through it.

The presence of a blood sample mixing chamber 43, made in the form of a spherical expansion in the body of the capillary 4, allows the sample to be mixed continuously in the upper and lower reservoirs alternately: the lower reservoir is vessel 1, as in the prototype, into which the test blood sample is poured, and the upper the reservoir is a spherical expansion on the capillary. When the sample moves up the capillary, it enters a spherical expansion, which serves as an intermediate depot, and in which it is mixed, just as when moving in the opposite direction, mixing occurs in the lower reservoir - vessel 1. It should also be noted that mixing occurs more thoroughly, since almost the entire test sample passes through capillary 4, and not a small part of it, as in the prototype. For example, with a capillary diameter of 200 µm and a working part length of 100 mm, the sample volume in the capillary will be approximately 12 µl, which, with a total sample volume of 500 µl, will be only 2.5%. The presence of a spherical expansion as an intermediate depot allows the entire sample to be pumped through the measuring channel, producing continuous, uniform and complete mixing of the sample, which accordingly leads to increased measurement accuracy. This is due to the fact that platelet aggregation directly depends on the frequency of platelet collisions in the sample, and the frequency of collisions depends on the quality and speed of mixing. It should be noted that the functional activity of platelets changes over time. If platelets do not have time to aggregate after activation, they enter a refractory state (lose their ability to aggregate). Thus, poor-quality and insufficient mixing of the sample leads to the fact that some of the platelets do not participate in the aggregation process, which leads to a decrease in the reliability and, consequently, the accuracy of the measurement. In fact, this should lead to a decrease in the amplitude of the aggregation curve.

In fig. Figure 2 shows a graph of the output signal versus time for the prototype (curve “A”) and for the patented analyzer (curve B). The output signal demonstrates the change in the average size of aggregates in platelet-rich plasma after the addition of the universal aggregation inducer ADP (adenosine diphosphate). It can be seen that, as expected, the average size of aggregates recorded on the patented analyzer significantly exceeds the same readings obtained on the prototype analyzer. This makes it possible to increase the accuracy of measuring platelet aggregation, which is the technical result of the utility model.

Claims (2)

1. An optical platelet aggregation analyzer containing a vertically placed capillary, the lower end of which is installed in the cavity of a thermostated vessel for a blood sample, and the upper end is communicated with means for periodically sucking and displacing blood from the capillary, and a channel for determining the light transmittance of the sample in the capillary, installed on the side the lower end of the capillary, connected to control and registration means, characterized in that in the middle part of the capillary there is an additional chamber for mixing the blood sample, made in the form of a spherical expansion in the body of the capillary, the volume V of which is selected from the condition V>Vo, where Vo is the volume of the vessel for a blood sample, while the channel for determining the light transmission of the sample includes an optical radiation source and a photodetector installed in one diametrical plane of the capillary, connected to means for recording and controlling the periodic suction and displacement of blood from the mixing chamber of the sample and the capillary. 2. The optical analyzer according to claim 1, characterized in that the means for periodically sucking and displacing blood from the capillary are a closed chamber of variable volume connected to a reciprocating drive and connected to the upper end of the capillary.