RU2609056C1 - Cryosurgical apparatus - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to medical equipment, namely to means for cryodestruction of pathological tissues. Cryosurgical apparatus contains reservoir for liquid nitrogen, outer system of gas supply, consisting of high-pressure balloon with helium, two reducers, one stop valve and one two-way valve, flexible heat-insulated tube for liquid nitrogen supply with check valve on its input and tube for coolant discharge, connected with detachable cryoinstrument, which contains detachable working tip, and connected parallel to cryoinstrument to line of gas injection, consisting of heat exchanger with heater, check valve and compressor, connected with its input to tube for coolant discharge with drainage electromagnetic valve and via stop electromagnetic valve and reducer to balloon with helium. Non-heat-insulated vessel, communicating with liquid nitrogen bath in reservoir via valve on the bottom of said vessel, is inserted into reservoir for liquid nitrogen, constantly open to atmosphere. Vessel is hermetically connected with heat-insulated tube for liquid nitrogen supply, and its vapour cavity - with two-way valve of outer system of gas supply, backing vacuum pump is connected to compressor input via electromagnetic valve.

EFFECT: application of the invention makes it possible to provide high cold-productivity of the freezing process and temperature pressure in working tip in mode of coolant injection and in mode of pumping out and forcing mode of replaceable cryoinstrument heating.

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Description

The technical field to which the invention relates.

The invention relates to medical equipment and can be used not only in surgery for the destruction of pathological tissues with the help of cryoapplicators cooled with liquid nitrogen, boiling both under excess and negative atmospheric pressure, but also in cryotherapy of diseases.

The level of technology.

There are many cryosurgical devices (KHA) and cryosurgical instruments (KHI) that operate on the generally accepted principle of pumping liquid nitrogen into the working tip of the KHI. Known, for example, as one of the best analogues in its class KHA (SU 1102096 A). This apparatus contains a cryo-tool, including a heat exchanger, an electric heater and a temperature sensor, a refrigerant source connected to the cryo-tool by a flexible hydraulic line, and including liquid and gas refrigerant solenoid valves, a pressure control valve and a pressure sensor, and a temperature regulator connected directly to the temperature set point with time relay through a push-button switch with a temperature meter. In this apparatus, the goal of temperature stabilization is achieved by the fact that it is equipped with a serially connected comparator, a control unit for electromagnetic valves of liquid and gaseous refrigerant and a pressure regulator.

Note that this apparatus is especially useful in the research problems of practical surgery, when the regulation of the temperature of the refrigerant gives information about the kinetics of the freezing processes in various biological tissues. However, in cryosurgery, the most important indicator of an effective apparatus is not the stability of the set temperature, but the cooling capacity of the freezing process and the minimum temperature at the tip of the cryotool. According to these indicators, the analogue initially turns liquid nitrogen into a refrigerant with worse properties, since raising the vapor pressure in its sealed container to 4 absolute atmospheres increases the equilibrium boiling point of liquid nitrogen by almost 14 degrees, while reducing the latent heat of evaporation by 300 joules per mole [1] compared to normal boiling conditions of liquid nitrogen. The method of injecting refrigerant into the tip of the cryotool, adopted in the analogue, is a fundamental limitation of the performance of almost all cryosurgical devices existing in the world. The disadvantages of the analogue also include the unacceptably large thermal inertia of the preparation of the apparatus for operation and its transitional modes.

A completely different approach to the principle of KHA operation was proposed in the invention (RU 2053719 dated 03.02.1992): not by injecting liquid nitrogen into the working tip of the cryotool, but by pumping nitrogen vapor from the hollow chamber of the tip [2]. A successful option for such an analogue is the already implemented KHA, made according to the patent (RU 2483691 of 03/11/2011). This apparatus includes a liquid nitrogen tank, thermally insulated refrigerant inlet and outlet pipes connected to the working tip, a pumping system installed at the outlet of the refrigerant exhaust pipe and made in the form of a forevacuum pump, and an external gas supply system, characterized in that at the inlet a heat-insulated refrigerant supply pipe is equipped with a check valve, an electromagnetic two-way valve with a throttle is installed at the input of the fore-vacuum pump, and the working tip is made in the form of a removable valve IoTool. This analogue allows to achieve high quality of supercooled liquid nitrogen in the KHI working tip due to pumping out its steam and lowering its temperature to almost a triple boiling point. This embodiment of the apparatus with its almost extreme cooling capacity and the minimum achievable temperature also reduces the total operation time by forcing the heating of the working tip while maintaining the methodological capabilities of analogues and prototype. However, an almost thousandfold increase in the volume of refrigerant vapor in the CHI leads to the problem of miniaturization of the CHI when the diameter of its distal end with a working tip requires about one millimeter. The way to solve this problem is described in the application for the invention No. 2013105231, which is selected as a prototype. The objective of the prototype was to reduce the time it takes to prepare the device for work and to instantly control its operation modes. The prototype includes a sealed liquid nitrogen tank with a drain valve, a thermally insulated supply pipe with a non-return valve at its inlet, and a refrigerant pipe connected to a removable cryotool with a working tip at its distal end, as well as an external gas supply system with a gearbox and a solenoid valve , and differs in that the output of the electromagnetic valve is connected to the inlet of the drainage valve, and the external gas supply system contains a high-pressure cylinder with helium, at ohms of the refrigerant inlet and outlet pipes are connected in parallel to a removable cryo-instrument to an additional closed gas circulation circuit consisting in series of a heat exchanger with a heater, a check valve and a compressor connected to the refrigerant outlet pipe with a drain solenoid valve and through an additional electromagnetic valve and an additional gearbox to that volume same balloon with helium. The set of distinguishing features of such a chemical chemical therapy allows you to instantly turn on the injection of liquid nitrogen into the chemical chemistry under the necessary overpressure in any thin working tips of surgical cryotools. And the introduction of an additional circuit of the circulation of a hot helium gas mixture with residual nitrogen into the KCA design ensures forced heating of the working tip of the replaceable CHI after the stage of freezing biological tissue.

However, the selected prototype has obvious disadvantages. Firstly, its tank for liquid nitrogen under the conditions of KHA operation should be hermetically sealed, withstand the permissible excess pressure and, therefore, have the entire protection system. Secondly, the disadvantage of the prototype is that it limits the boiling point of liquid nitrogen in the working tip of the KHI to a point of 77.3 K.

The aim of the invention is to increase safety and expand the technical capabilities of the cryosurgical apparatus.

Disclosure of the invention.

The task is achieved by the fact that in the cryosurgical apparatus, which includes a tank for liquid nitrogen, an external gas supply system, consisting of a high-pressure cylinder with helium, two gearboxes, one shut-off and one two-way valves, flexible heat-insulated tube for supplying liquid nitrogen with a check valve on its inlet and a refrigerant removal pipe connected to a removable cryotool, at the distal end of which there is a removable working tip, and connected in parallel to a removable cryotool to the gas injection line, consisting in series of a heat exchanger with a heater, a non-return valve and a compressor connected by its inlet to the refrigerant pipe with a drain solenoid valve and through a shut-off solenoid valve and a reducer to a helium cylinder, the liquid nitrogen tank is leaky and constantly open into the atmosphere, and an additional non-thermally insulated vessel is inserted into it, communicating with the liquid nitrogen bath in the tank through the valve at the bottom of this vessel, while the vessel is connected by a germ it is thermally insulated with a liquid nitrogen supply pipe, and its vapor cavity is connected to a two-way valve of the external gas supply system, and a fore-vacuum pump is connected to the compressor inlet in addition to the compressor inlet.

A brief description of the drawings.

The General scheme of the proposed KXA is shown in figure 1, where

1 - tank for liquid nitrogen (LN2);

2 - thermally insulated tube for supplying liquid nitrogen;

3 - check valve at the entrance to the tube 2;

4 - a pipe of removal of refrigerant (steam line);

5 - removable sterilized cryosurgical instrument;

6 - working tip KHI;

7 - heater with heat exchanger for gas;

8 - check valve;

9 - compressor;

10 - drain valve venting refrigerant vapor from the tube 4 into the atmosphere;

11 - the electromagnetic valve connecting the compressor through the gearbox 12 to the high-pressure tank 13;

12 - gear;

13 - high pressure cylinder filled with helium;

14 - gear connected to the cylinder 13;

15 - electromagnetic two-way valve 15;

16 - an additional vessel for liquid nitrogen;

17 - normally open shut-off valve for communication of the vessel 16 with a bath of liquid nitrogen in the tank 1;

18 - solenoid valve connecting the foreline pump to the input of the compressor 9;

19 - foreline pump;

20 is a control and measuring copper-constantan thermocouple for controlling the operating modes of KHA using a PC computer.

Tank 1 is a Dewar vessel or any thermally insulated container for liquid nitrogen with a wide neck, always open to the atmosphere. Therefore, the tank 1 does not require any protective equipment, and the liquid nitrogen LN2 poured into it always boils at a constant temperature of 77.3 K. The additional vessel for liquid nitrogen 16 is non-heat insulated, withstands internal pressure of up to 10 atmospheres, is immersed to the bottom of the tank 1 and is hermetically sealed connected to a two-way valve 15 and a liquid nitrogen supply pipe 2. An electromagnetic two-way valve 15 can either communicate with the atmosphere 16 through its drain outlet 3, or connect it through input 1 to a gearbox 14 for pumping helium into the vessel 16 from the cylinder 13. Since the vessel 16 is not thermally insulated, it is isothermal, i.e. the liquid nitrogen in it cannot be heated or cooled until all liquid nitrogen from the tank 1 has been exhausted. Therefore, the latent heat of vaporization of liquid nitrogen is constant and does not depend on the pressure in this vessel. The remote, distal part of the insulated liquid nitrogen supply pipe 2 as well as the refrigerant removal pipe 4 is made flexible for convenient connection with removable cryosurgical instrument 5 and its working tip 6. Both of these tubes 2 and 4 are interconnected not only by cryosurgical instrument 5, but also additional and serially connected heat exchanger with heater 7, non-return valve 8 and compressor 9. In this closed circuit (5-6-4-9-8-7-2-5), when the drain valve 10 is closed, heated Attiyah helium gas with nitrogen impurity HIC warming to 5 with the tip 6 after the tissue freezing mode. To create the necessary gas compression in this circuit, the compressor inlet 9 is connected through a solenoid valve to a helium 13 high pressure cylinder. A gearbox 14 and a two-way solenoid valve 15 are used to supply helium under a certain pressure to the vessel 16. Forvacuum pump 19 connected through an electromagnetic valve 18 to the compressor inlet 9, is designed to freeze tissue in the mode of pumping refrigerant vapor from the working tip 6 KHI 5 with the drain valve closed 10. Control all operating modes of KHA suschestvlyaetsya via PC computer and copper-constantan thermocouples 20 installed inside the entrance of the refrigerant discharge tube 4. Monitoring temperature CCA regimes conducted every second.

The implementation of the invention.

KHA works as follows. In the standby, starting state, when all KHA solenoid valves are de-energized and the two-way valve 15 and the drain valve 10 are open to the atmosphere, the tank 1 is filled with liquid nitrogen to a certain level. Up to the same level, all communicating cavities of the tubes immersed in the tank 1 are filled with liquid nitrogen, and the vessel 16 is 100% filled through a normally open valve 17. The valve on the cylinder 13 is open, the desired helium output pressure from one to several absolute atmospheres, and on the gearbox 12 - no more than 1.5 atmospheres. After connecting KHA to the mains, the temperature in the heater with heat exchanger 7 stabilizes at a preset level, for example 95 ° C. Connecting a sterilized removable CHC to the liquid nitrogen supply pipe 2 and to the refrigerant discharge pipe 4 leads to the formation of two circuits of possible refrigerant circulation: one is liquid for supplying liquid nitrogen from the vessel 16 through the liquid nitrogen supply pipe 2 to the CHC with the subsequent discharge of cold refrigerant through an open drain valve 10 into the atmosphere and another gas valve through CHI, but without gas escaping to the atmosphere when the drain valve 10 is closed. At the same time, CHA allows the supply of liquid nitrogen to the working tip 6 lowering it under excess helium pressure in the vessel 16 and the subsequent release of refrigerant into the atmosphere through valve 10. Another methodical possibility is to pump the refrigerant vapor out of the tube 4 with a forevacuum pump 19. When the KCA operates in the injection mode, the PC computer closes the normally open valve 17, sealing the vessel 16, then switches the electromagnetic two-way valve 15 to supply compressed helium from the reducer 14 directly into the vessel 16. The warm helium gas is rapidly cooled to a temperature of 77 K, but at the same time its pressure in the generated and p the expanding gas cavity of the vessel 16 remains constant, set by the reducer 14. Under the influence of this static pressure, the flow of liquid nitrogen opens the valve 3 and rushes through the supply pipe 2 to the CHC 5. At the tip 6, the liquid nitrogen boils, taking heat from the tissue in contact with it, and is expelled through the refrigerant discharge pipe 4 and valve 10 to the atmosphere. After the specified exposure of tissue freezing expires, the computer interrupts the supply of liquid nitrogen, opening the two-way valve 15 to discharge the compressed helium into the atmosphere, and the shutoff valve 17 to communicate the vessel 16 to the tank 1. The vessel 16 is re-refilled with liquid nitrogen, and KHA is ready to repeat the freezing cycle. If it is necessary to heat tip 6, the PC closes the drain valve 10, turns on the compressor 9 and opens the valve 11. At the inlet of the compressor 9, the helium pressure set by the reducer 12 is immediately established, and at its output the helium pressure significantly exceeds the inlet pressure. This excess pressure of helium entering the liquid nitrogen supply pipe 2 instantly closes the check valve 3. Intensive heating of the working tip 6 with dense hot helium gas begins, circulating only along the circuit (5-6-4-9-8-7-2-5 ) As soon as the temperature of the tip 6, according to the test and measurement of copper-constantan thermocouple 20, reaches the desired set value (for example, + 10 ° C), the computer closes valve 11, opens valve 10 and turns off compressor 9. All KXA communications will quickly return to their original state, and the device will again be ready to work in any mode, for example, to freeze the affected tissue with a supercooled stream of liquid nitrogen by pumping out liquid nitrogen vapor from the chamber of the working tip (or hollow applicator). In this mode, the computer closes the drain valve 10, opens the valve 18 and turns on the fore-vacuum pump 19. Pumping gas from the refrigerant exhaust pipe 4 leads to the suction of liquid nitrogen from the vessel 16 through the valve 3 that has been opened through the liquid nitrogen supply pipe 2 to the CHC and to its tip 6 , in which liquid nitrogen abruptly boils, and its temperature drops to a value determined by the equilibrium vapor pressure. This mode of operation of KHA can continue until the liquid nitrogen from the tank 1 is completely exhausted.

Industrial applicability.

The proposed cryosurgical apparatus can be implemented by a specialist in practice and, when implemented, ensures the implementation of the claimed purpose, which allows us to conclude that the criterion of "industrial applicability" for the invention is met.

The proposed cryosurgical unit is endowed with broad technical and methodological capabilities to safely perform cryodestruction of pathological tissues using the most effective refrigerant - liquid nitrogen while maintaining (and even increasing) its cooling capacity and temperature pressure in any removable applicators. " The presence in the apparatus of an additional, non-insulated vessel for liquid nitrogen allows to supply high-quality refrigerant to the thinnest cryosurgical instruments and, in general, to consume scarce helium economically. The presence of replaceable tips and open caps in the set allows the surgeon to freeze tissues directly with a stream of supercooled liquid nitrogen.

Thus, due to the fact that the tank for liquid nitrogen is leaky and is constantly open to the atmosphere, and an additional non-heat-insulated vessel is inserted into it, communicating with the liquid nitrogen bath in the tank through a valve at the bottom of this vessel, while the vessel is connected hermetically to the heat-insulated tube supply of liquid nitrogen, and its vapor cavity, respectively, with a two-way valve of the external gas supply system, and in addition to the compressor inlet, it is connected through a solenoid valve forvacuum pump, and the claimed technical result is achieved, namely: achieving a high refrigerating capacity of the freezing process and temperature difference in the operating tip in the discharge mode and in the refrigerant suction mode, forcing the replaceable cryoinstrument mode warming and expansion techniques secure operations.

Literature

1. V.A. Grigoriev, Yu.M. Pavlov, E.V. Amethysts. Boiling of cryogenic liquids, M .: "Energy", 1977, p. 261.

2. V.N. Pavlov, Development of perspective cryogenic surgery apparatus. Cryogenics 40 (2000) 361-363.

Claims (1)

A cryosurgical device, which includes a tank for liquid nitrogen, an external gas supply system, consisting of a high-pressure cylinder with helium, two gearboxes, one shut-off valve and one two-way valve, flexible heat-insulated liquid nitrogen supply pipe with a non-return valve at its inlet and a refrigerant removal pipe, connected to a removable cryotool, at the distal end of which there is a removable working tip, and connected in parallel to the removable cryotool to the gas injection line, consisting after It is necessary from a heat exchanger with a heater, a non-return valve and a compressor connected via its inlet to a refrigerant exhaust pipe with a drain solenoid valve and through a shut-off solenoid valve and a reducer to a helium cylinder, characterized in that it is inserted into the liquid nitrogen tank constantly open to the atmosphere additionally non-insulated vessel communicating with the liquid nitrogen bath in the tank through a valve at the bottom of this vessel, while the vessel is connected hermetically to a thermally insulated liquid supply pipe nitrogen, and its vapor cavity, respectively, with a two-way valve of the external gas supply system, and in addition to the compressor inlet, a fore-vacuum pump is connected via an electromagnetic valve.

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