Cryosurgical apparatus
United States Patent 3886945
There is disclosed a cryosurgical apparatus of the type which operates from a source of compressed gas. It includes a handle portion with removable and interchangeable probes. A defrost valve in the exhaust conduit permits easy and quiet operation by the surgeon. It is constructed in such a manner that the exhaust valve cannot be closed unless the probe is fully seated in the handle. It also includes an improved nozzle which is substantially less critical than prior art nozzles and permits simplified and less expensive construction. The foregoing abstract is not to be taken either as a complete exposition or as a limitation of the present invention. In order to understand the full nature and extent of the technical disclosure of this application, reference must be had to the following detailed description and the accompanying drawings as well as to the claims.
US Patent References:
/1051069.html
Bohme - January 1913 - 1051069
Liquid-fuel burner
Spigelmire - June 1926 - 1588503
Thermal tooth testing instrument
Posch - July 1953 - 2645097
Method and apparatus for low temperature branding of animals
Canoy - November 1968 - 3411483
CRYOSURGICAL INSTRUMENT
Wallach - October 1972 - 3696813
/1051069.html
Bohme - January 1913 - 1051069
Liquid-fuel burner
Spigelmire - June 1926 - 1588503
Thermal tooth testing instrument
Posch - July 1953 - 2645097
Method and apparatus for low temperature branding of animals
Canoy - November 1968 - 3411483
CRYOSURGICAL INSTRUMENT
Wallach - October 1972 - 3696813
Inventors:
Stumpf, Joseph G. (Fairfield, CT)
Andera, Joseph F. (Trumbull, CT)
Andera, Joseph F. (Trumbull, CT)
Application Number:
05/413684
Publication Date:
06/03/1975
Filing Date:
11/07/1973
View Patent Images:
Export Citation:
Assignee:
Frigitronics of Conn., Inc. (Shelton, CT)
Primary Class:
Other Classes:
239/597
International Classes:
A61B18/02; A61F7/12; F25B9/02; A61B18/00; B05B1/00; A61B17/36
Field of Search:
62/293 128/303.1 239/597
US Patent References:
| 3807403 | CRYOSURGICAL APPARATUS | April 1974 | Stumpf et al. |
Primary Examiner:
Pace, Channing L.
Attorney, Agent or Firm:
Buckles, And Bramblett
Parent Case Data:
BACKGROUND OF THE INVENTION
This application is a continuation in part of our copending U.S. Pat. Ser. No. 262,543, filed June 14, 1972 now U.S. Pat. No. 3,807,403, for "Cryosurgical Apparatus".
Claims:
We claim
1. A gas operated cryosurgical instrument which comprises: a handle defining a socket therein; a movable first valve member in said handle; a tubular exhaust conduit terminating at one end in a hollow tip of high thermal conductivity, the other end defining a second valve member and including means detachably securing said exhaust conduit seated within said socket; a gas delivery conduit mounted in said handle and extending through said socket and through said exhaust conduit when so secured and terminating at a nozzle within said tip; means for selectively advancing said first valve member against said second valve member to close said exhaust conduit when said exhaust conduit is fully seated within said socket; and means for limiting the movement of said first valve member to prevent closure of said exhaust conduit when the conduit is not fully seated within said socket.
2. The instrument of claim 1 wherein said first valve member is carried by said gas delivery conduit.
3. The instrument of claim 2 wherein said advancing means comprises a manually operable trigger connected to advance both of said delivery conduit and valve member.
4. The instrument of claim 1 wherein said first valve member comprises a ball.
5. The instrument of claim 1 wherein said nozzle includes a cylindrical gas discharge passage of smaller diameter than said delivery conduit and a smoothly curved reduction passage therebetween.
6. The instrument of claim 1 wherein said advancing means comprises: pivot means within said handle; a rod supported by said pivot means having a first end engaging said first valve member on one side of said pivot means and a second end on the other side of said means; and a manually operable trigger secured to the second end of said rod.
7. The instrument of claim 6 wherein said pivot means comprises a trunnion ball rotatably supported within said handle.
8. The instrument of claim 7 wherein said first valve member is carried by said gas delivery conduit.
9. The instrument of claim 8 wherein said first valve member comprises a ball.
10. The instrument of claim 9 wherein said nozzle includes a cylindrical gas discharge passage of smaller diameter than said delivery conduit and a smoothly curved reduction passage therebetween.
1. A gas operated cryosurgical instrument which comprises: a handle defining a socket therein; a movable first valve member in said handle; a tubular exhaust conduit terminating at one end in a hollow tip of high thermal conductivity, the other end defining a second valve member and including means detachably securing said exhaust conduit seated within said socket; a gas delivery conduit mounted in said handle and extending through said socket and through said exhaust conduit when so secured and terminating at a nozzle within said tip; means for selectively advancing said first valve member against said second valve member to close said exhaust conduit when said exhaust conduit is fully seated within said socket; and means for limiting the movement of said first valve member to prevent closure of said exhaust conduit when the conduit is not fully seated within said socket.
2. The instrument of claim 1 wherein said first valve member is carried by said gas delivery conduit.
3. The instrument of claim 2 wherein said advancing means comprises a manually operable trigger connected to advance both of said delivery conduit and valve member.
4. The instrument of claim 1 wherein said first valve member comprises a ball.
5. The instrument of claim 1 wherein said nozzle includes a cylindrical gas discharge passage of smaller diameter than said delivery conduit and a smoothly curved reduction passage therebetween.
6. The instrument of claim 1 wherein said advancing means comprises: pivot means within said handle; a rod supported by said pivot means having a first end engaging said first valve member on one side of said pivot means and a second end on the other side of said means; and a manually operable trigger secured to the second end of said rod.
7. The instrument of claim 6 wherein said pivot means comprises a trunnion ball rotatably supported within said handle.
8. The instrument of claim 7 wherein said first valve member is carried by said gas delivery conduit.
9. The instrument of claim 8 wherein said first valve member comprises a ball.
10. The instrument of claim 9 wherein said nozzle includes a cylindrical gas discharge passage of smaller diameter than said delivery conduit and a smoothly curved reduction passage therebetween.
Description:
This invention pertains to cryosurgical instruments of the type which are cooled under the influence of high pressure gas escaping from an orifice. Instruments of this type are well known in the art and are widely employed for a number of surgical procedures such as the necrosis of diseased tissue. Several gases exhibit the Joule-Thomson effect and may be used in the operation of the instrument. The most common, however, are nitrous oxide and carbon dioxide.
In instruments of this type, the gas expansion orifice is of an extremely small size and in all prior art instruments the spacing between the orifice and the inner wall of the cooling tip is extremely critical. For example, with prior art instruments, the orifice is positioned approximately 0.050 inch from the inner wall of the tip and the permitted tolerance is only 0.010 inch. This results in such instruments being difficult and costly to manufacture. For example, the parts of such instruments are commonly threaded so that they may be factory adjusted prior to shipment.
Another problem connected with prior art instruments of this type is found in the exhaust valve of instruments which have controlled defrost. For example, one such instrument is normally warm, which means that the exhaust valve is normally closed and the device is filled with compressed gas at bottle pressure. As the bottle gas pressure may commonly be as high as 800 psi, it will be quite apparent that this creates an explosion hazard. The exhaust valve used in this prior art device comprises a cylindrical piston which seats against a small exhaust orifice and is retained in the seated position by means of a heavy spring. The piston is raised against the force of a spring by means of a finger operated toggle. When the surgeon wishes to cool the probe tip, he must apply substantial force to depress the toggle which is, itself, detrimental, particularly in the case of very delicate surgical procedures. Secondly, as soon as the piston begins to leave the orifice, the full bottle pressure, which was formerly applied only to a small area of the piston, is now applied to the full area of the piston end, slamming the piston open with an explosive-like report.
Still another problem with prior art devices arises from the fact that most of them are designed with probe tips of specific shapes and sizes. This requires a surgeon to have different instruments for different surgical applications. It has been proposed to provide a single instrument with interchangeable probes. However this creates a problem due to the high pressures referred to in the preceding paragraph. If a probe were not fully seated, by negligence or otherwise, or if it were not fully seated because of a defect such as stripped threads, the high pressures involved could result in the probe and tip being forcibly ejected during a surgical procedure with potentially disastrous results.
Accordingly, it is a primary object of the present invention to provide an improved cryosurgical instrument of the gas operated type having replaceable and interchangeable probe tips. Another object is to provide such an instrument wherein the exhaust valve cannot be closed to pressurize the instrument unless the probe is fully seated. Another object is to provide such an instrument which is only intermittently exposed to full bottle gas pressure. Another object is to provide such an instrument which has a substantially silent and easily operated exhaust valve. The manner in which these objects are achieved will be apparent from the following description and appended claims.
SUMMARY OF THE INVENTION
The invention comprises a gas operated cryosurgical instrument which comprises a handle and a movable first valve member in the handle. A tubular exhaust conduit terminates at one end in a hollow tip of high thermal conductivity. The other end defines a second valve member and includes means for detachably securing the exhaust conduit to the handle. A gas delivery conduit extends through the exhaust conduit when it is so secured and terminates at a nozzle within the tip. Means are provided for selectively advancing the first valve member against the second valve member to close the exhaust conduit. Means are also provided for limiting the movement of the first valve member to prevent closure of the exhaust conduit when it is improperly secured to the handle.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a cryosurgical instrument in accordance with the present invention connected to a source of bottled gas;
FIG. 2 is an enlarged cross section taken through the instrument of FIG. 1;
FIG. 3 is a cross section of the exhaust valve of FIG. 2 shown in its closed position;
FIG. 4 is a greatly enlarged cross section of the nozzle portion of the apparatus;
FIG. 5 is an illustration of the gas jet obtained with the nozzle of FIG. 4;
FIG. 6 is a cross section taken substantially along the line 6--6 of FIG. 5;
FIG. 7 is an illustration of one type nozzle used in the prior art;
FIG. 8 is a cross section taken substantially along the line 8--8 of FIG. 7;
FIG. 9 is an illustration of another type nozzle used in the prior art;
FIG. 10 is an enlarged cross section showing the orifice of the FIG. 9 nozzle; and
FIG. 11 shows still another type nozzle used in the prior art.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With particular reference to FIG. 1, there is disclosed an instrument of the type utilized in treating cervicitis. It comprises an elongated probe 10 mounted in a handle 12 and terminating in a substantially conical hollow applicator tip 14. A line 16 is connected between the instrument and a suitable source 18 of pressurized gas. A trigger 20 extends from the handle for selective defrosting as will be explained.
Referring to FIG. 2, the handle 12 will be seen to define a recess 22 for the trigger 20 and a T-shaped recess 24 communicating therewith and enclosing a metal T fitting 26. The horizontal portion of fitting 26 has internal threads 28 and the lower end of the vertical portion is provided with similar internal threads 30. Within the vertical portion of the T fitting 26 and near its juncture with the horizontal portion, there is defined an internal shoulder 32. Mounted against the shoulder 32 is a resilient O-ring 34. Bearing against the O-ring 34 is a circular plastic sealing ring 36. A trunnion ball 38 is mounted against the sealing ring 36. The trunnion ball 38 is integral with an upper rod 40 and lower rod 42. The end of upper rod 40 includes a flattened portion 44 which defines an opening 46 therein. Opening 46 is substantially coaxial with the bore of the horizontal portion of T-fitting 26, as illustrated in FIG. 2. The lower rod 42 extends into the recess 22 of handle 12 and the trigger 20 is secured to lower rod 42 by means of a set screw 48. The trunnion ball assembly is retained within the T-fitting by a lower plastic sealing ring 50 supporting the trunnion ball 38, a compression spring 52, and an annular retainer nut 54 threaded into the threads 30. A trigger return coil spring 56, supported within a bore 58 in trigger 20 and seated against the back wall of recess 22, maintains the trigger in its normally extended position as shown in FIG. 2.
The flexible gas delivery line 16 is connected by means of a retainer ring 60 to the end of a stainless steel delivery tube 62 which extends forwardly outward of the handle and terminates at a nozzle 64. The outer diameter of tube 62 is less than the diameter of the opening 46 in the flattened portion 44 of upper rod 40. In one embodiment, the delivery tube 62 is a 15 gauge stainless steel hypodermic tube. The tube 62 passes through a ball 66 to which it is integrally secured as by welding.
The probe tip 10 is a complete assembly which is detachable from the handle portion of the instrument. It comprises a threaded sleeve 68 which screws into the T-fitting 26 as shown. Fixedly secured to the sleeve 68, as by welding, is a stop ring 70. An O-ring 72 provides a seal between stop ring 70 and the T-fitting 26. Fixedly secured to the inside of sleeve 68 is an exhaust conduit 74 which surrounds, and is spaced from, delivery tube 62. The distal end of exhaust conduit 74 carries a sleeve 76 to which is secured the hollow tip 14. Surrounding and spaced from the exhaust conduit 74 is an insulator tube 78, secured at one end to the sleeve 76 and tip 14 and at the other to sleeve 68 and stop ring 70. This tube is provided with a knurled finger grip 80. The end of exhaust conduit 74 forms, with sleeve 68, a tapered valve seat 82.
The construction of nozzle 64 will be best understood by reference to FIG. 4. As will be seen therein, the internal diameter of the delivery tube 62 is reduced via a smooth wall reduction passage 84 to a cylindrical gas discharge passage 86. This configuration is achieved by inserting into the end of the hypodermic tube a hardened wire having an external diameter equal to the desired diameter of the gas discharge passage. The end of the tube is then swaged onto the wire and the wire is removed. In one actual embodiment, the tube 62 has an internal diameter of 0.059 inch and the internal diameter of the gas discharge passage 86 is 0.01065 inch. The distance from the nozzle tip to the beginning of reduction (A FIG. 4) is 0.20 inch and the distance between the nozzle tip and the end reduction (B) is 0.12 inch.
The performance of the nozzle 64 is strikingly superior to those of the prior art. The reason for this is not fully understood but is believed to be due to the smooth continuous inner surface formed by the reduction passage 84 and the gas discharge passage 86. This is believed to prevent gas turbulence and permit laminar flow out of nozzle 64. FIG. 5 illustrates the gas flow from nozzle 64 as actually observed in practice. As will be seen, it presents an elongated "flamelike" appearance and shape. FIGS. 7-11 illustrate three prior art nozzle constructions and the jets obtained thereby. FIGS. 7 and 8 illustrate a pinched tube configuration. FIGS. 9 and 10 illustrate a rolled end construction, and FIG. 11 illustrates a type of orifice known as a "double reduction" orifice which comprises a series of tubes of reduced diameter. The jets from these prior art nozzles appear as indicated. In these prior art nozzles, the distance from the orifice to the wall of the applicator tip is very critical and the spacing must be quite close. As an example, this distance may be 0.050 inch with a tolerance of ± 0.010 inch. In contrast, in utilizing the nozzle of this invention, the distance from the nozzle tip to the wall may be 0.250 inch with a tolerance of ± 0.060 inch. Accordingly, by means of this invention, manufacture and assembly are greatly simplified, resulting in a highly effective instrument at a much lower cost.
The described nozzle construction may be utilized in connection with either a non-defrostable or a defrostable cryosurgical probe. The probe illustrated herein is of the defrostable type. Defrosting is obtained by means of the valve illustrated in detail in FIGS. 2 and 3. When the valve is in its normally open position as shown in FIG. 2, high pressure gas entering through delivery line 16 passes through the delivery tube 62 to nozzle 64. From the nozzle it expands into tip 14 causing the tip to be cooled by the Joule-Thomson effect. The expanded gas then passes rearwardly through exhaust tube 74 and out of the instrument through the T-fitting 26 and the recess 24. If desired, it may be remotely exhausted through an exhaust line enclosing delivery line 16. The high pressure exhaust gas tends to maintain the exhaust valve formed by the ball 66 and the valve seat 82 in its normally open position, with the ball retracted from the seat as shown in FIG. 2. In order to defrost the instrument, the trigger 20 is depressed by the surgeon, whereupon the trunnion ball 38 and the rods 40, 42 assume the positions illustrated in FIG. 3, forcing the ball 66 forwardly against the valve seat 82, forming a gas tight seal. With the exhaust valve closed, gas pressure within tip 14 rises to bottle pressure and the heat of compression causes rapid defrosting of the probe tip. It is important to note, however, that either of two different limit stops restrict the forward movement of ball 66. These include the point C which may be contacted by the upper rod 40 and the point D which may be contacted by the lower rod 42. No matter how much force is exerted on trigger 20, the ball 66 can be driven no further forward than the limit set by a stop. This is a very significant improvement because it means that, if the probe tip 10 is not fully seated within the T-fitting 26, the exhaust valve cannot be closed and pressurization cannot occur.
With an instrument of the type disclosed herein, a single handle and valve unit may be supplied with a plurality of probes and tips for performing various surgical procedures. These may be readily interchanged by the surgeon or his assistant without the danger of a probe being improperly inserted. Furthermore as the valve is normally open, it will be closed only for the period of time during which the surgeon desires to defrost the probe tip. Therefore, the instrument is exposed to full bottle pressure only intermittently and for short periods of time, greatly increasing the safety of the apparatus.
It is believed that the construction and operation of this invention will now be apparent to those skilled in the art. It will also be apparent that a number of variations and modifications may be made in this invention without departing from its spirit and scope. Accordingly, the foregoing description is to be construed as illustrative only, rather than limiting. This invention is limited only by the scope of the following claims.
In instruments of this type, the gas expansion orifice is of an extremely small size and in all prior art instruments the spacing between the orifice and the inner wall of the cooling tip is extremely critical. For example, with prior art instruments, the orifice is positioned approximately 0.050 inch from the inner wall of the tip and the permitted tolerance is only 0.010 inch. This results in such instruments being difficult and costly to manufacture. For example, the parts of such instruments are commonly threaded so that they may be factory adjusted prior to shipment.
Another problem connected with prior art instruments of this type is found in the exhaust valve of instruments which have controlled defrost. For example, one such instrument is normally warm, which means that the exhaust valve is normally closed and the device is filled with compressed gas at bottle pressure. As the bottle gas pressure may commonly be as high as 800 psi, it will be quite apparent that this creates an explosion hazard. The exhaust valve used in this prior art device comprises a cylindrical piston which seats against a small exhaust orifice and is retained in the seated position by means of a heavy spring. The piston is raised against the force of a spring by means of a finger operated toggle. When the surgeon wishes to cool the probe tip, he must apply substantial force to depress the toggle which is, itself, detrimental, particularly in the case of very delicate surgical procedures. Secondly, as soon as the piston begins to leave the orifice, the full bottle pressure, which was formerly applied only to a small area of the piston, is now applied to the full area of the piston end, slamming the piston open with an explosive-like report.
Still another problem with prior art devices arises from the fact that most of them are designed with probe tips of specific shapes and sizes. This requires a surgeon to have different instruments for different surgical applications. It has been proposed to provide a single instrument with interchangeable probes. However this creates a problem due to the high pressures referred to in the preceding paragraph. If a probe were not fully seated, by negligence or otherwise, or if it were not fully seated because of a defect such as stripped threads, the high pressures involved could result in the probe and tip being forcibly ejected during a surgical procedure with potentially disastrous results.
Accordingly, it is a primary object of the present invention to provide an improved cryosurgical instrument of the gas operated type having replaceable and interchangeable probe tips. Another object is to provide such an instrument wherein the exhaust valve cannot be closed to pressurize the instrument unless the probe is fully seated. Another object is to provide such an instrument which is only intermittently exposed to full bottle gas pressure. Another object is to provide such an instrument which has a substantially silent and easily operated exhaust valve. The manner in which these objects are achieved will be apparent from the following description and appended claims.
SUMMARY OF THE INVENTION
The invention comprises a gas operated cryosurgical instrument which comprises a handle and a movable first valve member in the handle. A tubular exhaust conduit terminates at one end in a hollow tip of high thermal conductivity. The other end defines a second valve member and includes means for detachably securing the exhaust conduit to the handle. A gas delivery conduit extends through the exhaust conduit when it is so secured and terminates at a nozzle within the tip. Means are provided for selectively advancing the first valve member against the second valve member to close the exhaust conduit. Means are also provided for limiting the movement of the first valve member to prevent closure of the exhaust conduit when it is improperly secured to the handle.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a cryosurgical instrument in accordance with the present invention connected to a source of bottled gas;
FIG. 2 is an enlarged cross section taken through the instrument of FIG. 1;
FIG. 3 is a cross section of the exhaust valve of FIG. 2 shown in its closed position;
FIG. 4 is a greatly enlarged cross section of the nozzle portion of the apparatus;
FIG. 5 is an illustration of the gas jet obtained with the nozzle of FIG. 4;
FIG. 6 is a cross section taken substantially along the line 6--6 of FIG. 5;
FIG. 7 is an illustration of one type nozzle used in the prior art;
FIG. 8 is a cross section taken substantially along the line 8--8 of FIG. 7;
FIG. 9 is an illustration of another type nozzle used in the prior art;
FIG. 10 is an enlarged cross section showing the orifice of the FIG. 9 nozzle; and
FIG. 11 shows still another type nozzle used in the prior art.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With particular reference to FIG. 1, there is disclosed an instrument of the type utilized in treating cervicitis. It comprises an elongated probe 10 mounted in a handle 12 and terminating in a substantially conical hollow applicator tip 14. A line 16 is connected between the instrument and a suitable source 18 of pressurized gas. A trigger 20 extends from the handle for selective defrosting as will be explained.
Referring to FIG. 2, the handle 12 will be seen to define a recess 22 for the trigger 20 and a T-shaped recess 24 communicating therewith and enclosing a metal T fitting 26. The horizontal portion of fitting 26 has internal threads 28 and the lower end of the vertical portion is provided with similar internal threads 30. Within the vertical portion of the T fitting 26 and near its juncture with the horizontal portion, there is defined an internal shoulder 32. Mounted against the shoulder 32 is a resilient O-ring 34. Bearing against the O-ring 34 is a circular plastic sealing ring 36. A trunnion ball 38 is mounted against the sealing ring 36. The trunnion ball 38 is integral with an upper rod 40 and lower rod 42. The end of upper rod 40 includes a flattened portion 44 which defines an opening 46 therein. Opening 46 is substantially coaxial with the bore of the horizontal portion of T-fitting 26, as illustrated in FIG. 2. The lower rod 42 extends into the recess 22 of handle 12 and the trigger 20 is secured to lower rod 42 by means of a set screw 48. The trunnion ball assembly is retained within the T-fitting by a lower plastic sealing ring 50 supporting the trunnion ball 38, a compression spring 52, and an annular retainer nut 54 threaded into the threads 30. A trigger return coil spring 56, supported within a bore 58 in trigger 20 and seated against the back wall of recess 22, maintains the trigger in its normally extended position as shown in FIG. 2.
The flexible gas delivery line 16 is connected by means of a retainer ring 60 to the end of a stainless steel delivery tube 62 which extends forwardly outward of the handle and terminates at a nozzle 64. The outer diameter of tube 62 is less than the diameter of the opening 46 in the flattened portion 44 of upper rod 40. In one embodiment, the delivery tube 62 is a 15 gauge stainless steel hypodermic tube. The tube 62 passes through a ball 66 to which it is integrally secured as by welding.
The probe tip 10 is a complete assembly which is detachable from the handle portion of the instrument. It comprises a threaded sleeve 68 which screws into the T-fitting 26 as shown. Fixedly secured to the sleeve 68, as by welding, is a stop ring 70. An O-ring 72 provides a seal between stop ring 70 and the T-fitting 26. Fixedly secured to the inside of sleeve 68 is an exhaust conduit 74 which surrounds, and is spaced from, delivery tube 62. The distal end of exhaust conduit 74 carries a sleeve 76 to which is secured the hollow tip 14. Surrounding and spaced from the exhaust conduit 74 is an insulator tube 78, secured at one end to the sleeve 76 and tip 14 and at the other to sleeve 68 and stop ring 70. This tube is provided with a knurled finger grip 80. The end of exhaust conduit 74 forms, with sleeve 68, a tapered valve seat 82.
The construction of nozzle 64 will be best understood by reference to FIG. 4. As will be seen therein, the internal diameter of the delivery tube 62 is reduced via a smooth wall reduction passage 84 to a cylindrical gas discharge passage 86. This configuration is achieved by inserting into the end of the hypodermic tube a hardened wire having an external diameter equal to the desired diameter of the gas discharge passage. The end of the tube is then swaged onto the wire and the wire is removed. In one actual embodiment, the tube 62 has an internal diameter of 0.059 inch and the internal diameter of the gas discharge passage 86 is 0.01065 inch. The distance from the nozzle tip to the beginning of reduction (A FIG. 4) is 0.20 inch and the distance between the nozzle tip and the end reduction (B) is 0.12 inch.
The performance of the nozzle 64 is strikingly superior to those of the prior art. The reason for this is not fully understood but is believed to be due to the smooth continuous inner surface formed by the reduction passage 84 and the gas discharge passage 86. This is believed to prevent gas turbulence and permit laminar flow out of nozzle 64. FIG. 5 illustrates the gas flow from nozzle 64 as actually observed in practice. As will be seen, it presents an elongated "flamelike" appearance and shape. FIGS. 7-11 illustrate three prior art nozzle constructions and the jets obtained thereby. FIGS. 7 and 8 illustrate a pinched tube configuration. FIGS. 9 and 10 illustrate a rolled end construction, and FIG. 11 illustrates a type of orifice known as a "double reduction" orifice which comprises a series of tubes of reduced diameter. The jets from these prior art nozzles appear as indicated. In these prior art nozzles, the distance from the orifice to the wall of the applicator tip is very critical and the spacing must be quite close. As an example, this distance may be 0.050 inch with a tolerance of ± 0.010 inch. In contrast, in utilizing the nozzle of this invention, the distance from the nozzle tip to the wall may be 0.250 inch with a tolerance of ± 0.060 inch. Accordingly, by means of this invention, manufacture and assembly are greatly simplified, resulting in a highly effective instrument at a much lower cost.
The described nozzle construction may be utilized in connection with either a non-defrostable or a defrostable cryosurgical probe. The probe illustrated herein is of the defrostable type. Defrosting is obtained by means of the valve illustrated in detail in FIGS. 2 and 3. When the valve is in its normally open position as shown in FIG. 2, high pressure gas entering through delivery line 16 passes through the delivery tube 62 to nozzle 64. From the nozzle it expands into tip 14 causing the tip to be cooled by the Joule-Thomson effect. The expanded gas then passes rearwardly through exhaust tube 74 and out of the instrument through the T-fitting 26 and the recess 24. If desired, it may be remotely exhausted through an exhaust line enclosing delivery line 16. The high pressure exhaust gas tends to maintain the exhaust valve formed by the ball 66 and the valve seat 82 in its normally open position, with the ball retracted from the seat as shown in FIG. 2. In order to defrost the instrument, the trigger 20 is depressed by the surgeon, whereupon the trunnion ball 38 and the rods 40, 42 assume the positions illustrated in FIG. 3, forcing the ball 66 forwardly against the valve seat 82, forming a gas tight seal. With the exhaust valve closed, gas pressure within tip 14 rises to bottle pressure and the heat of compression causes rapid defrosting of the probe tip. It is important to note, however, that either of two different limit stops restrict the forward movement of ball 66. These include the point C which may be contacted by the upper rod 40 and the point D which may be contacted by the lower rod 42. No matter how much force is exerted on trigger 20, the ball 66 can be driven no further forward than the limit set by a stop. This is a very significant improvement because it means that, if the probe tip 10 is not fully seated within the T-fitting 26, the exhaust valve cannot be closed and pressurization cannot occur.
With an instrument of the type disclosed herein, a single handle and valve unit may be supplied with a plurality of probes and tips for performing various surgical procedures. These may be readily interchanged by the surgeon or his assistant without the danger of a probe being improperly inserted. Furthermore as the valve is normally open, it will be closed only for the period of time during which the surgeon desires to defrost the probe tip. Therefore, the instrument is exposed to full bottle pressure only intermittently and for short periods of time, greatly increasing the safety of the apparatus.
It is believed that the construction and operation of this invention will now be apparent to those skilled in the art. It will also be apparent that a number of variations and modifications may be made in this invention without departing from its spirit and scope. Accordingly, the foregoing description is to be construed as illustrative only, rather than limiting. This invention is limited only by the scope of the following claims.