Cryosurgical Device

Abstract

A cryosurgical instrument having a thermally insulating housing containing a cartridge partially filled with a low boiling temperature liquefied refrigerant, such as "Freon" (a mark of DuPont). The cartridge includes a heat conductive tip in contact with the refrigerant and extending from the housing. The housing carries means for selectively venting the unfilled portion of the cartridge to atmosphere. This permits the refrigerant to boil at a reduced temperature, thereby abstracting heat from, and cooling, the tip. 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.

Description

BACKGROUND OF THE INVENTION

This invention pertains to a cryosurgical device employing a low boiling temperature liquid refrigerant. More particularly, it relates to such a device which is self-contained, disposable, and of small size -- rendering it particularly useful for the cryoextraction of cataracts.

A number of cryosurgical devices have been known to the prior art which are self-contained units and which customarily employ a low boiling refrigerant, such as "Freon." Examples of such devices will be found in the following U.S. Pat. Nos.:

2,645,097 Posch

3,343,544 Dunn et al.

3,524,446 Crump et al.

3,529,131 Kanbar et al.

3,575,176 Crump et al.

All of the foregoing are characterized by being self-contained units which enclose a container of pressurized, low boiling temperature, liquid refrigerant. The refrigerant is selectively released from the container into a separate boiler tip. Boiling of the refrigerant reduces the temperature of the tip which is thereupon used for the surgical procedure. One such surgical procedure is adhesion to a cataractous lens for its removal in cataract surgery. Another type of prior art device is disclosed in U.S. Pat. No. 3,270,744 of Katz et al. That device, however, is not normally in a ready condition. It is always vented and accordingly must be separately filled with liquid nitrogen for each use.

It is an object of the present invention to provide a cryosurgical device which is disposable and of small size. Other objects are to provide such a device which is maintained ready for use over long periods of time; which may be simply and quickly actuated when desired; and which does not require transport of liquid refrigerant from its normal container to a separate boiling chamber.

The manner in which the foregoing objects are achieved will be apparent from the following description and appended claims.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided a self-contained, disposable, cryosurgical device incorporating an elongated, sealed container having a first end terminating in a heat conductive tip, and a second end. A liquefied refrigerant partially fills the container and is normally maintained therein at superatmospheric pressure. An insulating housing substantially encloses the container and exposes at least a portion of the tip. Means are provided for selectively venting the container to atmosphere to boil the refrigerant and cool the tip.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of a cryosurgical apparatus in accordance with this invention;

FIG. 2 is an enlarged vertical cross section of the apparatus of FIG. 1;

FIG. 3 is a further enlarged cross section of the operating mechanism of the device of FIG. 2; and

FIG. 4 is a view similar to FIG. 3 illustrating an alternative operating mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT

With particular reference to FIGS. 1 and 2, there is illustrated a cryosurgical device in accordance with this invention which has the same size and shape as a conventional ballpoint pen. It comprises a housing 10 comprising an upper housing 10a, a central barrel 10b, and a tip housing 10c. The housing is preferably formed of a material having poor heat conductance, such as nylon, polypropylene, an acrylic, or other suitable material. Upper housing 10a is closed at its upper end but defines a crylindrical guideway 12 and small vents 13. The inside of barrel 10b has a substantially cylindrical surface 14. The tip housing 10c has an internal tapering surface 16 terminating in a cylindrical passage 18.

Mounted within the housing 10 is a refrigerant container 20. As will be seen from FIG. 3, the upper end of container 20 defines a circular shoulder 22 defining a central opening 24. A cup shaped cap 26 is crimped over the shoulder 22 and defines a central opening 28. Sealed between the upper end of the container 20 and the cap 26 is a rubber diaphragm 30. The tapered lower end of container 20 terminates at a solid, rod-like tip 32 at a matching conical portion 34 of the tip. The tip portions 32, 34 are fabricated from a suitable heat conductive material. It is important to note that container 20 is secured within the housing 10 by contact made only at the cap 26 and at the tip portion 34. The remainder of the container is displaced from the housing 10 to provide a dead air insulating space 36.

Mounted in the guideway 12 of upper housing 10a is an actuating plunger 38 upon which is mounted a hollow needle 44 aligned with the opening 28 in cap 26. A small vent hole 46 is drilled in the side of the hollow needle 44. Contained within upper housing is a plug 47 of felt or other porous, fibrous, or blotter-like material. The plug 47 defines a passage 49 for needle 44.

The device of this invention is supplied to the surgeon with the container 28 partially filled with a suitable liquid refrigerant 51, such as "Freon 12" or "Freon 500." For cataract surgery the apparatus is normally used in an upright position, such as illustrated in FIG. 2. In this position there is a vapor space in the upper region of the container 20. The sealing action of diaphragm 30 causes the vapor and liquid refrigerant to be maintained under pressure at room temperature. When employing "Freon 12," this pressure is approximately 70 psig while, when employing "Freon 500," the pressure is approximately 85 psig.

When the surgeon wishes to activate the device, he simply depresses the actuating plunger 38. This causes the needle 44 to pierce the diaphragm 30. The vaporized refrigerant then passes into needle 44 and through vent hole 46, plug 47, and vents 13 to atmosphere. Reduction of the pressure within container 20 to atmosphere causes the remaining liquid refrigerant to immediately begin boiling and the entire volume of liquid refrigerant drops to its boiling temperature. For "Freon 12" this is -21.degree.F, for "Freon 500" it is -28.degree.F. This causes heat to be rapidly extracted from the tip 32, reducing its temperature and permitting it to be employed for the preferred surgical operation. For a device of the described size, the tip temperature remains at this lower value for approximately 4 minutes, a time amply sufficient to perform the usual cryoextraction. After use, the instrument is simply discarded.

The function of the plug 47 is to soak up any liquid refrigerant while allowing gaseous refrigerant to pass. Several conditions may cause liquid to be present in the upper housing including: the container 20 being too full; violent boiling of the liquid; sloshing of the liquid due to motion of the surgeon's hand; or activation while in other than a vertical position.

An alternative embodiment of the invention is illustrated in FIG. 4. In this embodiment, the needle and diaphragm are replaced by a conventional valve. In the illustration of FIG. 4, parts similar to those previously described have been given identical numerals but with a prime attached. In this embodiment, the puncturable diaphragm is replaced by a valving diaphragm 50 which has an outer annular flange 52 which is engaged by the crimped cap 54 to retain it in place. The valve diaphragm has an enlarged central portion 56 which seals the container by contacting the central opening 58 in the cap. A sidewardly positioned vent 60 in the diaphragm is normally closed by engagement with the cap. The hollow needle is replaced by a reduced diameter stem 62 on the end of a plunger 64. Downward movement of the plunger depresses the central portion 56 of the diaphragm permitting the vapor to exhaust through vent 60 and opening 58 to atmosphere. In the version illustrated in FIG. 4, the plunger 64 is retained in the open valve position by means of a detent 66 which overrides an internal shoulder 68 in the housing. This construction could be modified by making plunger 64 retractable, such as the button on a ballpoint pen. The valve could then be closed to permit defrosting during a surgical procedure.

It is believed that the many advantages of this invention will now be apparent to those skilled in the art. It will be particularly apparent that no transfer of the refrigerant is required in order to effectuate the desired cooling. As a result, the device is much smaller and of simpler construction than devices known to the prior 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.

Claims

We claim:

1. A self-contained, disposable cryosurgical device which comprises: an elongated, sealed container having a first end terminating in an integral heat conductive applicator tip, and a second end; a liquefied refrigerant partially filling said container to define a vapor space therein and normally maintained at super atmospheric pressure, said liquid being in direct physical contact with said tip; an insulating housing substantially enclosing said container but exposing at least a portion of said tip; and means at said second end for selectively venting the vapor space of said container to atmosphere to boil said refrigerant and cool said container and tip.

2. The device of claim 1 wherein said venting means comprises a porous member for passage of refrigerant therethrough.

3. The device of claim 1 wherein said venting means comprises a needle actuatable to puncture the second end of said container.

4. The device of claim 3 wherein said needle is secured to an actuating plunger supported in said housing.

5. The device of claim 4 wherein said venting means comprises a porous member surrounding said needle.

6. The device of claim 1 wherein the second end of said container comprises an elastomeric diaphragm.

7. The device of claim 6 wherein said venting means comprises a needle actuatable to puncture said diaphragm.

8. The device of claim 7 wherein said needle is secured to an actuating plunger supported in said housing.

9. The device of claim 1 wherein the second end of said container comprises a valve and said venting means comprises a valve actuator.

10. The device of claim 9 wherein said valve actuator comprises a plunger supported in said housing.

11. The device of claim 10 wherein said valve comprises an elastomeric diaphragm normally sealing said second end but movable to an open position by said plunger.

12. The device of claim 11 wherein said plunger includes means for retaining said diaphragm in its open position.