US3800552A - Cryogenic surgical instrument - Google Patents

Abstract

An apparatus for directly converting a gas into a liquid to lower the temperature of a cryogenic surgical instrument. A tube with a linear entrance and exit section is helically wound around a core. A thermal conductive member surrounds the tube between the entrance and exit sections. A gas under pressure is connected to the entrance section of the tube. A sleeve with a closed end frictionally engages and surrounds the thermal conductive member to form a closed chamber adjacent the exit section of the tube. The pressurized gas is throttled upon leaving the exit section causing the temperature in the chamber to be lowered to between 80* to -250* C causing the gas to liquefy. A path through the thermal conductive member from the chamber to the atmosphere will permit thermal energy in the throttled gas to be dissipated to the pressurized gas in the tube. The liquefied gas in the chamber will correspondingly cool the closed end of the sleeve allowing the external surface thereof to be used as a cryogenic surgical probe.

Description

United States Patent 1191 Sollami et al.

1451 Apr. 2, 1974 1 CRYOGENIC SURGICAL INSTRUMENT [75] Inventors: Blase J. Sollami; Thomas J. Bulat; Walter L. Dray, all of Davenport, Iowa [73] Assigriee: The Bendix Corporation, South Bend, Ind.

[22] Filed: Mar. 29, 1972 [21] Appl. No.: 239,088

152 u.s. Cl 62/293, 62/514, l28/303.1

[51] Int. Cl. F251), 19/00 [58] Field Of Search ..'128/303.1;62/293, 514

[56] References Cited UNlTED STATES PATENTS 3,298,371 1/1967 L88 62/293 3,427,815 2/1969 PitlOI 62/514 3,477,434 11/1969 HOOd 128/3031 3,696,813 10/1972 Wallach 62/514 3,704,597 12/1972 Nicholds 62/514 Primary Examiner-Meyer Perlin Attorney, Agent, or FirmLeo H. McCormick, lr.;

William N. Antonis 57 ABSTRACT An apparatus for directly converting a gas into a liquid to lower the temperature of a cryogenic surgical instrument. A tube with a linear entrance and exit section is helically wound around a core. A thermal conductive member surrounds the tube between the entrance and exit sections. A gas under pressure is connected to the entrance section of the tube. A sleeve with a closed end frictionally engages and surrounds the thermal conductive member to form a closed chamber adjacent the exit section of the tube. The

. pressurized gas is throttled upon leaving the exit section causing the temperature in the chamber to be lowered to between 80 to 250C causing the gas to liquefy. A path through the thermal conductive memher from the chamber to the atmosphere will permit thermal energy in the throttled gas to be dissipated to the pressurizedgas in the tube. The liquefied gas in the chamber will correspondingly cool the closed end of the sleeve allowing the external surface thereof to be used as a cryogenic surgical probe.

10 Claims, 6 Drawing Figures CRYOGENIC SURGICAL INSTRUMENT BACKGROUND OF THE INVENTION Cryogenic surgical instruments have been developed for use in treating diseases wherein other methods would be detrimental to the patient. These cryosurgical instruments usually have a tip or probe which is cooled by a low boiling liquid. However, the storage required for low boiling presents a problem to the mobility of the surgical instrument.

Later a cryogenic device was developed wherein cooling of the probe was achieved utilizing the Joule- Thomson effect wherein high pressure gases cool upon expansion. With this device the probe could be cooled to about -80C. At 80C upon touching tissue with the probe, the moisture in the tissue is turned into ice which adheres to the probe. In order to prevent the probe from sticking to tissue, a heating means for instantaneously raising the probe temperature evolved from necessity. Thus, the operator could remove the probe without injury to the healthy tissue. In experimentation where the probe had inadvertently touched healthy tissue, cell destruction has been prevented by immediately warming the end of the probe. However, the surface cells still would be destroyed but in the bodys internal repair process of the damaged cells little or no scar tissue could be observed. This was attributed in part to the dead cells which were disposed of through the function of the body.

SUMMARY OF THE INVENTION It was observed that if the temperature of the probe could be maintained below 80C adherence of the tissue cells to the probe could be averted. However, to achieve a mobile cryogenic surgical unit without the problems associated with liquefied gases, it was considered a necessity that the easily stored gas be converted into a liquid upon demand. To directly convert a gas into a liquid between -80 to 250C we have devised an appropriate cryogenic apparatus. In our apparatus a pressurized gas is connected to a tube which is coiled around a cylindrical core. A thermal conductive material in turn surrounds the tube and a sleeve with a closed end frictionally secured to the conductive material. The closed end of the sleeve and the end of the cylindrical core form a chamber into which the end of the tube extends. Gas under pressure is throttled into the chamber causing the temperature therein to be lowered. A path through the thermal conductive material will permit the throttled gas to escape to the atmosphere. As the throttled gas goes through the thermal conductive material, thermal energy is absorbed and transferred to the pressurized gas in the tube to initially cool this gas before it is throttled in the chamber. In this manner if nitrogen is used as the pressurized gas, the initial throttling systematically reduces the temperature of the pressurized nitrogen to the point where liquefication occurs upon throttling. Once the liquefication has begun, the thermal transfer by the conductive material maintains the overall efficiency at an effective level.

It is therefore the object of this invention to provide a cryogenic surgical apparatus with means to directly convert a gas to a liquid between 80 to -250C.

It is another object of this invention to provide a means of initially cooling a gas under pressure by trans- 2 ferring thermal energy produced by throttling to maintain a portion of the gas in the chamber as a liquid.

It is another object of this invention to provide a cryogenic surgical instrument with the means of liquefying different gases corresponding to the required temperature needed to provide medical treatment.

These and other objects will be apparent from reading this specification and viewing the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic view ofa medical cryogenic system with an enlarged sectional view showing a proposed surgical instrument constructed in accordance with our invention. 1

FIG. 2 is a sectional view substantially along lines 2-2 of FIG. 1 showing the fluid supply tube surrounded by a thermal conductive member.

FIG. 3 is a sectional view alonglines 33 of FIG. 1 showing a top view of the. surgical instrument.

FIG. 4 is a sectional view of another surgical probe for use in the medical cryogenic system of FIG. 1.

FIG. 5 is an enlarged sectional view of a bimetal strip regulator for controlling cryogenic fluid flow through the surgical instrument taken along lines 55 of FIG. 1.

FIG. 6 is a sectional view of a secondary embodiment of a finned cryogenic supply conduit for the surgical instrument of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The medical cryogenic system in FIG. 1 has asupply vessel 10 containing a suitable pressurized gas. The type of gas is chosen for its liquefication temperature, which should be between to 250C, for an example nitrogen gas, whose liquefication temperature is l96C. Acontrol valve 12 is located in theoutlet 14 of thesupply vessel 10 to regulate flow of the pressurized gas therefrom. Asupply line 16 is connected togage 18 which will register the level of pressurized gas flowing from thesupply vessel 10 when the regulator is opened. Thegage 18 in turn is connected tocontainer 20 byconduit 22. Thecontainer 20 is filled with a chemical dryer, such as lithium oxide or a molecular sieve where excessive moisture is removed from the pressurized gas. Thecontainer 20 is connected to a surgical instrument means 26 by adelivery line 24.

The surgical instrument means 26 consists of acylindrical core 28 which has afront end 30 and arear end 32. Thefront end 30 has ashoulder 33 which extends from thecylindrical core 28. Therear end 32 has astepped shoulder 34 which extends from thecylindrical core 28 with afirst ledge 36 and asecond ledge 38. A series ofradial fingers 40 extend from thesecond ledge 38. Acentral bore 42 in therear end 32 is connected by apassageway 44 which terminates between the first andsecond ledges 36 and 38, respectively. Atube 46 has alinear entrance section 48 which extends throughpassageway 44 into thecentral bore 42. The entrance section 48- is sealed in thepassageway 44 and theend 50 thereof centrally located inbore 42. Ajacket member 52 having acentral passageway 56 with aslot 54 is placed around theend 50 oftube 48 and between arearward projection 58 surrounding thecentral bore 42. A slight taper can be present in the external surface of thejacket member 52 adjacent theend 60 of thejacket member 52 so that a tight interference fit will be achieved between theend 50 of the tube and the central passage when theend 60 contacts the bottom 62 of thecentral bore 42. Anadditional seal 57 located betweenjacket 52 and therearward projection 58 provides a unitary structure capable of withstanding fluid pressures delivered by the storage vessel to thetube 46. Theother end 64 of thejacket member 52 retains amale connector 66 which engages afemale connector 68 on theflexible delivery line 24.

Where thetube 46 emerges from thepassageway 44 individually attached fins such as discs orplates 102, see FIG, 6, or a continuous helically woundfin 70 shown in FIG. 2 is secured to thetube 46, until reaching a predetermined length. Thisfinned tube 46 is now wound in a coil series around thecylindrical core 28. Thefin 70 extends to theshoulder 33 and anexit section 72 extends past theend 30 of thecylindrical core 28. After thecoil series tube 46 is located around thecylindrical core 28, a resilient barrier means 74 is alternately wound on thecylindrical bore 28. Sleeve means 76 having an openedend 78 and aclosed end 80 surrounds the resilient barrier means 74. The resilient barrier means being compressed between thecylindrical core 28 and theinternal surface 82 to frictionally retain thesurface 84 of the openedend 78 against theradial fingers 40. Theradial fingers 40 provide a stop for establishing a fixedvolume chamber 86 between the front end of thecylindrical core 28 and theclosed end 80.

MODE OF OPERATION OF THE PREFERRED EMBODIMENT When a surgeon determines cryogenic surgery is necessary to relieve an unwanted tissue condition, he turns thecontrol valve 12 to an open position. The pressure of the fluid (nitrogen for example) flowing from thestorage vessel 10 is registered ongage 18. The fluid passes through the chemical drier where any moisture therein is removed. This fluid under pressure is transmitted through thesupply line 24 into theentrance section 48 of thetube 46. The fluid flows around the coil series and emerges from thetube 46 through theorifice 98 of theexit section 72 into the fixedvolume chamber 86. The fluid which passes through theorifice 98 which has a smaller cross sectional area than theentrance section 48, goes from a high pressure to a lower pressure. This change in pressure is directly proportional to the area oforifice 98 as compared to the area of the fixedvolume chamber 82. When the pressurized gas passes from a high pressure area to a low pressure area throttling occurs with a corresponding drop in the temperature. The cooled gas can now travel around thetube 46 over by thefins 70 in a path to the rear 32 ofcylindrical core 28. The fins being thermally conductive will absorb thermal energy from the cooled gas and dissipate this thermal energy to the gas flowing inside thetube 46. Thus, the gas intube 46 is systematically and sequentially reduced in temperature to a point where the temperature in the fixedvolume chamber 82 approaches -196C if nitrogen is used. When I96C is reached, a portion of the throttled gas is converted into a liquid. The liquid in turn will uniformly distribute its temperature to theclosed end 80 of the sleeve means 76. Theexternal surface 88 of theclosed end 80 can now probe the damaged tissue and surgically destroy the diseased part.

To maintain the liquid in the fixedvolume chamber 86 in any orientation, aliquid absorbing material 90 is placed in the fixedvolume chamber 86. With the liquid in the chamber being inhibited from escaping by following the flow path around thetube 46, thesurgical instrument 26 can be used in any position the surgeon may need. Since this instrument is designed to be hand held in order that the temperature from the body does not affect the thermal transfer between the throttled gas and the pressurized gas in thetube 46, a nonthermalconductive material 92 is placed around the openedend 78. Further, in order to protect the surgeon, the number of fins around the tube as compared to the helically woundtube 46 around the cylindrical core are selected such that the dissipation of thermal energy between the fixedvolume chamber 86 and the gas which passes between thefinger 40 andsurface 84 will not cause discomfort to the hand of a surgeon if exposed to it over a period of time.

In the embodiment shown in FIG. 4 like parts are numbered the same as in FIG. 1. Thetube 46 upon emerging from thepassageway 44 is helically wound around thecylindrical core 28. Ascreen 94 is placed onshoulder 33 and granular particle means 98 poured into the space betweensurface 82 and thecylindrical core 28. The conductive granular particles could be bronze coated with a brazing alloy having a melting point below that of bronze, said conductive granular particles being coated with a flux before placing in the instrument.

When thecavity 100 is filled with this bronze coated flux, the temperature is raised causing the flux to flow and securely bind the particles together in a desired configuration. As the gas flows fromchamber 86, the flow paths available will be many since the individual particles will block any direct flow to theexit 78. Thegranular particles 98 will absorb the thermal energy developed by throttling and dissipate the same to the gas flowing intube 46 as described with reference to FIG. 1.

The size of the fixedvolume chamber 86 and the area of theexit section 72 construction will vary with the particular gas used in the supply chamber. However, as is apparent when nitrogen gas isused, the possibility of fire or damage from breathing a pollutant is greatly reduced. Moreover, in order to conserve the nitrogen supply, aregulator 94 whichis responsive to the liquefication temperature inchamber 86 is attached to the opening on theexit section 72. Theregulator 94, see FIG. 5, has a series ofbimetal strips 96 attached to abase 98. The bimetal strips 96 form anorifice 98 through which the pressurized gas flows into the fixedvolume chamber 86. As the pressurized gas is throttled, the bimetal strips will contract to form an orifice as illustrated bynumeral 100 when the liquefication of the gas has occurred. The bimetal strips being sensitive to temperature change can contract and expand as needed to maintain the temperature on theexternal surface 88 within a preselected temperature range. Equally appropriate regulators such as described in U. S. Pat. Nos. 3,517,525, 3,590,597, 3,630,047 and incorporated herein by reference could be adapted to control the flow of the pressurized gas. However, we have found that thebimetal strip regulator 94 adequately controls the flow of pressurized gas to maintain the cryogenicsurgical instrument 26 within the desired operating range.

We claim:

1. An apparatus for directly converting a gas into a liquid for use in cryosurgery, said apparatus comprising:

' a cylindrical core having a front end and a rear end,

said rear end having a series of radial stops extending therefrom;

a tube helically wound around said core having an entrance section which extends past said rear end and an exit section which extends past said front end;

screen means secured to the front and rear ends of the cylindrical core;

thermal conductive means surrounding said tube from said entrance section to said exit section, said thermal conductive means including granular particle means retained between said screen means, said particle means contacting each other and said tube, a source of gas under pressure connected to said entrance section of said tube; and

sleeve means having a closed end and an open end frictionally engaging and surrounding said thermal conductive means, said open end abutting said radial stops to form a fixed volume chamber between the exit section of the tube and the closed end, said gas under pressure being throttled by passing through said exit section into said fixed volume chamber, said throttled gas lowering the temperature in said fixed volume chamber to between 80 to 250.C by liquefying, said thermal conductive means providing a flow path from said fixed volume chamber around said tube and out said rear end, said flow path providing an escape route for pressurized gas during said throttling, said flow path from the fixed volume chamber being intercepted by the granular particle means causing numerous deflections permitting the granular particle means to absorb thermal energy from the pressurized gas flowing along the path and to transfer this thermal energy to the gas under pressure in the tube by conductions, said liquefied gas conducting a corresponding temperature to said closed end for permitting the external surface thereof to be used as a cryogenic surgical instrument.

2. The apparatus, as recited in claim 1, wherein said exit section of said tube includes:

regulator means responsive to the temperature of the liquefied gas in fixed volume chamber for restricting the flow of the pressurized gas.

3. The apparatus,as recited inclaim 2, wherein said regulator means includes:

a base attached to said exit section; and

a series of bimetal strips attached to said base, said bimetal strips reacting to the temperature in the fixed volume chamber to form anorifice through which the pressurized gas flows into the fixed volume chamber.

4. The apparatus, as recited inclaim 3, whereinsaid thermal conductive means includes:

fin means attached to said tube to form a finned section thereon, saidfinned section cooperating with the granular particle means to said flow path.

5. The apparatus, as recited in claim 4, wherein the length of the finned section as compared to the length of the helical tube is adequate to dissipate sufficient thermal energy from said pressurized gas to eliminate discomfort to an operator in contact with the entrance section of said tube.

6. The apparatus, as recited in claim 5, wherein the external surface of said sleeve means is covered with a thermal non-conductive material to prevent outside thermal energy from affecting dissipation of the internal thermal energy of said gas by the conductive fins.

7. The apparatus, as recited in claim 1, wherein said source of pressurized gas passes through a dryer to re-- move any moisture therefrom which would adversely affect said throttling.

8. The apparatus, as recited inclaim 2, wherein said source of gas passes through a regulator to stabilize the pressure and flow of said gas.

9. The apparatus, as recited in claim 8, wherein said apparatus further includes:

a liquid absorption material located in said fixed volume chamber to retain the liquefied gas in said fixed volume chamber and allow unrestricted movement of said closed end without loss of said liquefied gas through said path.

10. The apparatus, as recited in claim 9, wherein the size of the fixed volume chamber and the exit section of the tube are mated to provide effective throttling for the source of gas under pressure.

Claims (10)

1. An apparatus for directly converting a gas into a liquid for use in cryosurgery, said apparatus comprising: a cylindrical core having a front end and a rear end, said rear end having a series of radial stops extending therefrom; a tube helically wound around said core having an entrance section which extends past said rear end and an exit section which extends past said front end; screen means secured to the front and rear ends of the cylindrical core; thermal conductive means surrounding said tube from said entrance section to said exit section, said thermal conductive means including granular particle means retained between said screen means, said particle means contacting eAch other and said tube, a source of gas under pressure connected to said entrance section of said tube; and sleeve means having a closed end and an open end frictionally engaging and surrounding said thermal conductive means, said open end abutting said radial stops to form a fixed volume chamber between the exit section of the tube and the closed end, said gas under pressure being throttled by passing through said exit section into said fixed volume chamber, said throttled gas lowering the temperature in said fixed volume chamber to between -80* to -250*C by liquefying, said thermal conductive means providing a flow path from said fixed volume chamber around said tube and out said rear end, said flow path providing an escape route for pressurized gas during said throttling, said flow path from the fixed volume chamber being intercepted by the granular particle means causing numerous deflections permitting the granular particle means to absorb thermal energy from the pressurized gas flowing along the path and to transfer this thermal energy to the gas under pressure in the tube by conductions, said liquefied gas conducting a corresponding temperature to said closed end for permitting the external surface thereof to be used as a cryogenic surgical instrument.

2. The apparatus, as recited in claim 1, wherein said exit section of said tube includes: regulator means responsive to the temperature of the liquefied gas in fixed volume chamber for restricting the flow of the pressurized gas.

3. The apparatus, as recited in claim 2, wherein said regulator means includes: a base attached to said exit section; and a series of bimetal strips attached to said base, said bimetal strips reacting to the temperature in the fixed volume chamber to form an orifice through which the pressurized gas flows into the fixed volume chamber.

4. The apparatus, as recited in claim 3, wherein said thermal conductive means includes: fin means attached to said tube to form a finned section thereon, said finned section cooperating with the granular particle means to said flow path.

5. The apparatus, as recited in claim 4, wherein the length of the finned section as compared to the length of the helical tube is adequate to dissipate sufficient thermal energy from said pressurized gas to eliminate discomfort to an operator in contact with the entrance section of said tube.

6. The apparatus, as recited in claim 5, wherein the external surface of said sleeve means is covered with a thermal non-conductive material to prevent outside thermal energy from affecting dissipation of the internal thermal energy of said gas by the conductive fins.

7. The apparatus, as recited in claim 1, wherein said source of pressurized gas passes through a dryer to remove any moisture therefrom which would adversely affect said throttling.

8. The apparatus, as recited in claim 2, wherein said source of gas passes through a regulator to stabilize the pressure and flow of said gas.

9. The apparatus, as recited in claim 8, wherein said apparatus further includes: a liquid absorption material located in said fixed volume chamber to retain the liquefied gas in said fixed volume chamber and allow unrestricted movement of said closed end without loss of said liquefied gas through said path.

10. The apparatus, as recited in claim 9, wherein the size of the fixed volume chamber and the exit section of the tube are mated to provide effective throttling for the source of gas under pressure.

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