SU667865A1 - Device for determining rheological properties of biological liquids - Google Patents

Description

(54) DEVICE FOR DETERMINING THE RHEOLOGICAL PROPERTIES OF BIOLOGICAL FLUIDS

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The invention relates to the field of medicine and biology and can be used to determine the rheological properties of biological fluids, mainly blood.

Blood is a suspension of plasma shaped elements and belongs to a non-Newtonian fluid. Various changes in the internal environment of the body are accompanied by changes in the rheological properties of the blood. These changes should be taken into account in cases of hemodynamic and transfusion of preserved blood and blood substitutes injected for their correction. The most accessible criteria are viscosity, fluidity and stickiness of blood cells.

Installations for determining blood viscosity 1 are known, made on the basis of capillary viscometers, in which the measuring capillary is not thermostatted, and the speed of movement of blood in the capillary cannot be set by the researcher.

Known installation 2 for determining the viscosity and fluidity of blood, consisting of a thin measuring capillary, C both

the sides to which the two arms, the inlet and the outlet, are attached, from thicker capillary tubes. The input shoulder through the controlled valve is connected to the pressure system, and the output valve is connected to the atmosphere. The pressure system consists of a pump and a closed damping tank.

The test blood is introduced into one arm of the viscometer and, under the action of the pressure difference in a closed container and the atmosphere, is pushed into the other arm. The stopwatch measures the time it takes for a convex meniscus to travel the distance between two marks on the viscometer arm. The measuring part of the viscometer is placed in a thermostat.

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This installation has the disadvantage that it allows to measure only part of the rheological characteristics (fluidity and viscosity) and gives greater error when measuring, since time is recorded visually, and the pressure is set by the differential in the closed vessel and atmosphere. Since the pressure being set is small (on the order of 0.05-0.5 mm Hg).

 it is comparable with atmospheric pressure fluctuations in the laboratory even during one measurement, which leads to significant errors in the measurements.

The aim of the invention is to expand the range of measurement of the rheological properties of blood and improve the accuracy of their measurements.

The goal is achieved by the fact that the output shoulder of the capillary tube is co-efficient with an additional helix tube, which, in turn, is connected through a transition tube with a container having a pressure element to it.

On the output arm and the adapter tube are placed optical photosensors, elec- tronic. tricly connected with electronic units for measuring speed and volume.

The drawing shows a functional diagram of the proposed device.

The device contains a closed container 1 with an injection element 2 connected by an inlet tube 3 through a valve 4 by means of an elastic tube 5 with an input arm 6, which, in turn, is connected to the measuring capillary 7. The measuring capillary 7 is connected to the output shoulder 8 and spiral tube 9, which is further connected through an adapter tube 10 with a closed container 11, on which the pressure element 12 is mounted. On the output arm 8 are installed optical sensors 13, 14, 15 electrically connected to electronic units: block 16 of Evaluation of blood viscosity, speed measurement unit 17 in arm 8 and volume measurement unit 18 in shoulder 8. Optical sensors 19, 20 electrically connected to electronic units are installed on the transition tube 10: a speed measurement unit 21 and a transition tube volume measurement unit 22 ten.

-:.:. -..-.- ..:.,

A certain amount of blood to be tested is placed in the shoulder 6 through its detachable connection with the valve 4. With the help of the delivery elements 2, 12, the pressure in volumes 1 and P. is created. When the valve 4 is open, under the action of the pressure difference AR between the capacities 1 and 11, the blood column moves successively into the measuring capillary p 7, shoulder 8, spiral tube 9, into the adapter tube 10. At the moment the photosensor 13 passes through the blood column and 14, signals from them are transmitted to viscosity measuring unit 16. In block 16 the following dependence is realized

fl c.t -AR, where o is the viscosity of the blood to be examined;

t | - time of passage by the beginning of the column, blood of a fixed distance between photosensors 13 and 14.

K-const, defined only by the geometric dimensions of the measuring capillary.

When the blood column passes the photo sensors 14 and 15 from the photo sensor 14, the act667865

The signal to the speed measurement unit 17 and from the photo sensor 15 to the speed measurement unit 17 and the volume measurement unit 18. Block 17 operates according to the principle of measuring the time t2 for the passage of the end of the blood column of a fixed distance Si between the photosensors 14 and 15. The speed V is determined by the following formula

v

The signal from the speed sensor 17 is fed to the volume meter 18. In the volume meter 18, the following relationship is realized

Qi K.V.t5 K% -t, where Qj is the volume of blood in the output arm 8;

1c is the time it takes for the blood column to pass the photo sensor 15;

K - const, determined only by the diameter of the capillary of the output arm 8.

In an analogous manner, using photosensors 19, 20 and blocks 21, 22, the volume of blood in the transition tube 10 is determined. Stickiness is defined as the ratio of the volume of blood in the arm 8 and the transition tube 10. Due to the presence of closed containers with pressure elements, the device is provided the ability to measure the rheological properties of blood at different pressures. At the time of measurement, the device is placed in a thermostat.

The device allows the determination of the rheological properties of biological fluids (viscosity, fluidity and stickiness) on one sample, regardless of fluctuations in atmospheric pressure, which improves the accuracy of the results obtained. Installing optical sensors on the measuring capillaries also improves the measurement accuracy and allows you to automatically obtain the necessary data on the rheological properties of the fluid.

Claims (2)

1. Minidprom viscose BK-4 Poltava glass factory. 2. Kolloid Zeitschrift, 1960, 168, 2, 101 - 107.