SU368858A1 - THROMBOZLASTOGRAFvogso; basic ifiiTOiT -: ^ '..K ;; HV: HAI ^ J - Google Patents

Description

one

The invention relates to devices for studying the process of blood coagulation, namely to thromboelastographs.

Thromboelastographs are known that contain a cuvette for the blood to be tested, an electric motor with a mechanism for creating rotational-return movements of the cuvette, a piston mounted in the cavity of the cuvette and connected to an opposing spring and a scheme for registering movements of the piston. However, known thromboelastographs do not provide sufficient accuracy for recording the blood coagulation process and have relatively narrow measurement limits.

The proposed thromboelastograph, in which the indicated deficiencies are eliminated, differs from the known ones in that the threshold scheme is established in it, is included. at the output of the amplifying path of the piston movement detection circuit, an electromagnetic relay, connected at the output of the threshold circuit, n is a mechanism for changing a rigid opposing spring, made, for example, in the form of a ring, clamped between the core and the core of the relay.

FIG. 1 shows a block diagram of the proposed thromboelastograph; in fig. 2 - thromboelastogram recorded using the proposed thromboelastograph.

The thrombus elastograph contains an electric motor /, which communicates by means of an eccentric ;; trick 2 rotational oscillations around the vertical axis of the cuvette 3, filled with the blood under study. With the help of the holder 4, when closing the door of the thermostat 5, the cylinder 6, the torque sensor, is lowered into the cuvette. The holder 4 allows the cylinder to be removed, and in its working position the cylinder locks the thermostat door from accidental opening and possible damage to the chain 7, rigidly connecting the cylinder axis with the flag 8 and measuring counter spring 9. The spring 9 is made in the form of a piece of elastic, for example steel , wire, the upper end of which is rigidly fixed to the wall of the thermostat 5. On the wire there is a ring} 0, placed between the core and the base of the electromagnetic relay //. The ring W is strengthened at such a distance that the stiffness of the spring 9 shortened with the help of the relay 11 is several times, g, for example, 10 times greater than the original size of the core. Measuring counteracting spring 9 can also be made of two equal lengths, r - o of various thicknesses and, consequently, different stiffnesses. The checkbox 8, depending on the oscillation of the cylinder 6, modulates the luminous flux generated by: -: to; och: -: oh: a :: a. 12. feed it into two photoelectric transforms connected by a balanced scheme; 1 body / .. //. When ng-p} light balance differential voltage is amplified by the electronic amplifier 15. To the output of the amplifier 15 is connected self-recording recorder 16 and the threshold scheme / 7; Lastly, at a certain level of output voltage, it turns on a relay 11, which, by clamping its ring 10, shortens the effective length of the measuring counter spring 9. The triggering level of the threshold circuit 17 is chosen corresponding to

the normalized value of blood clot elasticity and fibrin filament stiffness, at which the coefficient characterizing the initial stage of blood coagulation is determined on ordinary thromboelastograms recorded using standard thromboelastographs. The thermostat 5 maintains a constant temperature (37 ° C) by means of a heater 18, a temperature sensor 19, and an electronic device 20. The circuit is powered from the AC mains by the power supply unit 21.

The principle of operation of the thromboelastograph is as follows.

The cuvette 3 is filled with the blood to be tested, placed in a thermostat 5 and through a holder 4 a cylinder 6 is lowered into the cuvette. The electric motor 1 is turned on, which rotates oscillations through the eccentric 2 to the cuvette. When the cuvette is rotated, due to the viscosity of the blood, some moment is created that acts on cylinder 6. Since cylinder 6 is mounted on an uncorrected measuring counteracting spring I, even a slight increase in viscosity of coagulating blood causes the cylinder 6 to rotate and the flag 8 rigidly connected with it 8 and a violation the light balance of the bridge with transducers 13, 14. Since at the beginning of the collapse the stiffness of the fibrin filaments is much less than the elasticity of the measuring spring, the rotation of the cylinder is directly proportional to the stiffness of the fibrin filaments filaments and the output of the sensor characteristic is linear. The unbalance voltage amplified by amplifier 15 controls the recorder 16, which records the changes in this voltage in the form of a thromboelastogram.

Due to the heightened sensitivity and linearity of the transducer and recording over the entire width of the tape recorder, a clearly expressed initial stage of blood coagulation on a linear scale is obtained on a thromboelastogram.

During the coagulation process, the stiffness of the fibrin strands increases and the relationship between the deflections of the flag S and the stiffness of the fibrin strands becomes non-linear. However, when the amplifier 15 reaches a voltage corresponding to the prescribed elasticity of the blood clot and stiffness of fibrin threads, at which the coefficient characterizing the initial stage of blood coagulation is determined on standard thromboelastograms, the threshold circuit 17 and the relay // clamp the ring 10 and shorten the effective length measuring counteracting spring 9. The sensitivity of the thromboelastograph transforming system is reduced by a selected number of times, for example, 10 times. The nonlinearity of the output characteristic decreases so many times. In a thromboelastogram, a sharp jump is obtained and further recording of the thromboelastrogram occurs from a tenfold decrease in level (Fig. 2).

Thus, at the same width of the recorder tape, it is possible to record a 10 times greater amplitude of the thromboelastogram without using a log amplifier. Since the recording during the entire coagulation process is performed on a linear scale, it is easier to determine the amplitude of the thromboelastogram in its different parts by interpolation.

Subject invention

A thromboelastograph containing a cuvette for the blood to be tested, an electric motor with a mechanism for creating rotational-return movements of the cuvette, a piston installed in the cavity of the cuvette, connected to an opposing spring and a piston movement detection circuit, characterized in that, in order to improve the accuracy of recording the process of blood coagulation and the extension of the measurement limits, it has a threshold circuit connected at the output of the amplifying path of the piston movement detection circuit, an electromagnetic relay connected to the output of the threshold circuit and the mechanism for changing the stiffness of the opposing spring, made, for example, in the form of a ring clamped between the core and the core of the relay.

Fy