Cryosurgical probe with vacuum insulation tube assembly

A vacuum insulation tube assembly which is utilized as a component in a cryosurgical probe. The vacuum insulation tube assembly includes an inner tube; and, an outer tube concentrically positioned about the inner tube. The outer tube is securely soldered at end portions of the inner tube and forms a vacuum space between the inner tube and the outer tube. The vacuum tube assemblies may be conveniently mass produced using a special fixture.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to cryosurgical probes and more particularly to a cryosurgical probe with an improved vacuum insulation tube assembly and method of manufacture thereof which facilitates economical mass production of precision cryosurgical probes.

2. Description of the Related Art

Cryosurgery involving the use of a cryosurgical probe assemblies typically involves the use of cryoprobes that are each attached to a handle that are, in turn, connected to a high-pressure fluid line with a quick-disconnect for attachment to a fluid source.

Cryosurgical probes manufactured by present assignee Endocare, Inc., Irvine, Calif., utilize a vacuum insulation tube that provides selected non-cooling areas on the surface of the cryoprobe. For example, U.S. Pat. Publication US 20050192565 (U.S. patent Ser. No. 11/116,873), to Eum et al, entitled “Detachable Cryosurgical Probe With Breakaway Handle”, incorporated in its entirety herein by reference, discloses such a cryosurgical probe with a vacuum tube. The vacuum tube comprises an inner tube positioned within an outer tube. A vacuum is formed between the two tubes and the ends of the tubes are joined by brazing.

Another example of a cryosurgical probe that uses a vacuum tube is disclosed in U.S. Pat. No. 5,573,532, issued to Z. H. Chang, entitled “Cryogenic Surgical Instrument and Method of Manufacturing the Same”. Again, in this instance the vacuum is formed by brazing.

In all known cryosurgical probes that use these vacuums for insulation the tubes are formed by brazing. Brazing is a relatively expensive endeavor.

SUMMARY OF THE INVENTION

In a broad aspect, the present invention is embodied as a vacuum insulation tube assembly which is utilized as a component in a cryosurgical probe. The vacuum insulation tube assembly includes an inner tube; and, an outer tube concentrically positioned about the inner tube. The outer tube is securely soldered at end portions of the inner tube and forms a vacuum space between the inner tube and the outer tube.

The vacuum tube assemblies may be mass produced using a special fixture. The fixture includes a generally cylindrical vacuum chamber having an upper end, a lower end, and a central axis. A bottom plate is positioned within an interior volume of the vacuum chamber, at the lower end. The bottom plate includes a plurality of spaced elongated bottom plate openings extending therethrough substantially parallel to the central axis. A guide plate assembly is securely supported within the interior volume, at the upper end. The guide plate comprises a plurality of spaced elongated guide plate openings extending therethrough substantially parallel to the central axis. A support plate is securely positioned within an intermediate portion of the interior volume. The support plate includes a plurality of spaced elongated support plate openings extending therethrough substantially parallel to the central axis. A cover assembly is mounted on the upper end of the vacuum chamber for providing access to the vacuum chamber for a plurality of inner tubes and outer tubes that are used to form vacuum insulation tube assemblies. The bottom plate openings, the guide plate openings, and the support plate openings provide access for insertion of the outer tubes and the inner tubes. The lower end of said vacuum chamber has a vacuum conduit in fluid communication with lower ends of the vacuum tube assembly, for connection to a vacuum source for evacuating fluid in spaces between the outer tubes and the inner tubes when concentrically positioned, ends of each respective tube assembly being soldered during operation of the fixture to form the vacuum tube assemblies.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings and the characters of reference marked thereon,FIG. 1illustrates a preferred embodiment of the vacuum insulation tube assembly of the present invention, designated generally as10. The vacuum insulation tube assembly10is utilized as a component in a cryosurgical probe, as will be described below in more detail. It includes an inner tube12; and, an outer tube14concentrically positioned about the inner tube12. The outer tube14is securely soldered at end portions16,18of the inner tube12to form a vacuum space between the inner tube12and the outer tube14. The tubes are preferably formed of stainless steel or titanium alloy. The vacuum insulation tube assembly10includes a thermally insulative spacing element20positioned between the inner tube12and the outer tube14. The spacing element is helically twisted about the inner tube12. It is preferably formed of a ceramic material such as ceramic fiber. The vacuum insulation tube assembly10also includes an o-ring22that is leftover during the manufacturing process for the assembly10, as will be discussed below.

Referring now toFIG. 2, the fixture for manufacturing vacuum insulation tube assemblies10in mass quantities is illustrated, designated generally as24. The fixture24includes a generally cylindrical vacuum chamber26having an upper end28, a lower end30, and a central axis32. A bottom plate34is positioned within an interior volume of the vacuum chamber26, at the lower end30. The bottom plate34includes a plurality of spaced elongated bottom plate openings36extending therethrough substantially parallel to the central axis32. A guide plate assembly38is securely supported within the interior volume, at the upper end28. The guide plate comprises a plurality of spaced elongated guide plate openings40extending therethrough substantially parallel to the central axis32. A support plate42is securely positioned within an intermediate portion of the interior volume. The support plate includes a plurality of spaced elongated support plate openings44extending therethrough substantially parallel to the central axis32.

A cover assembly46is mounted on the upper end28of the vacuum chamber26for providing access to the vacuum chamber26for a plurality of inner tubes12and outer tubes14that are used to form vacuum insulation tube assemblies10. The cover assembly46includes a cover element48including a circular main portion50and a central portion having a circular flange52. It also includes an ejector plate assembly54securely positionable on the end of the circular flange52.

Referring now toFIG. 3, an enlarged view of the guide plate assembly38, it can be the guide plate assembly38includes a plurality of tapered slider assemblies, each designated generally as56. Each tapered slider assembly56includes a spring58positioned within a recessed portion60of an associated guide plate assembly opening40. An elongated tapered slider element62is positioned within the spring58—an upper portion of an internal surface of the tapered slider element62being tapered. A retainer ring64is positioned within the guide plate assembly opening40for retaining the elongated tapered slider element62.

Each tapered slider assembly62cooperates with an associated o-ring plunger assembly, designated generally as66. Each o-ring plunger assembly66includes an o-ring plunger element68operatively positionable within the internal surface of the elongated tapered slider element62for urging an o-ring70into a desired position between the outer tube14and the inner tube12. An o-ring insert pin72is operatively positionable within the o-ring plunger68for supporting the o-ring70. An enlarged view of an o-ring insert pin72is shown inFIG. 4.

In the manufacture of multiple vacuum insulation tube assemblies10, the bottom plate is first securely positioned at the lower end of the vacuum chamber26. Two guide pins74are then inserted which prevent undesired rotation of the various parts of the fixture24. The support plate is then slid into position, as shown inFIG. 2.

Next, precursor inner/outer tube assemblies76are fitted through the support plate openings44and into the bottom plate openings36. Each precursor inner/outer tube assembly76comprises an outer tube14concentrically positioned about an inner tube12. The fixture24may contain about a hundred precursor inner/outer tube assemblies76. Each precursor inner/outer tube assembly76is soldered at one (i.e. bottom) end thereof.

The guide plate assembly38is then securely positioned within the interior volume, at the upper end28. The guide plate assembly38is positioned to provide access to the precursor inner/outer tube assemblies76through the spaced elongated guide plate openings40. The guide plate assembly38has been pre-fitted with tapered slider assemblies56. O-ring plunger assemblies66are then installed into desired positions relative to associated spaced elongated guide plate openings40and their associated tapered slider assemblies56.

The cover assembly46is then mounted on the upper end of the vacuum chamber26via cover screws78. A vacuum is then applied via connection of a vacuum conduit80to a vacuum pump (not shown). After the vacuum chamber26is evacuated, a nut82of the cover assembly46is loosened, allowing the ejector plate assembly54to slide down (by the pressure difference), concomitantly applying a force on the o-ring plunger68. This is shown inFIG. 5. The o-ring plunger68pushes the o-ring insert pin72containing the o-ring70into the desired position between the outer tube12and the inner tube14. The o-ring70serves as a temporary seal.

The cover assembly46is then removed to allow removal of the precursor inner/outer tube assemblies76. The previously unsoldered ends of the precursor inner/outer tube assemblies76are then soldered to form completed vacuum insulation tube assemblies10. Prior to soldering, the outer tube12is preferably crimped against the inner tube14to expel residual air.

The present technique obviates the large investment required for vacuum brazing techniques. However, it offers the advantage of allowing high volume efficiency using these soldering techniques.

Referring now toFIG. 6, utilization of the completed vacuum insulation tube assembly10within a cryosurgical probe is illustrated, the cryosurgical probe being designated generally as84. The cryosurgical probe shown in this example application is of a disposable type. Additionally, it is adjustable so as to allow for variations in the size of the generated ice ball. This type of cryosurgical probe is shown for the purposes of illustration and not limitation. Other types of cryosurgical probes can use the vacuum insulation tube assemblies produced in accordance with the principles of the present invention.

As can be seen inFIG. 7, the cryosurgical probe84includes a disposable probe assembly, designated generally as86and a reusable probe assembly (discussed in more detail below).FIG. 7is broken away in a few places for the purposes of clarity. The reusable probe assembly includes a Joule-Thomson tube88that is connected at an inlet section to a source (not shown) of cryogenic fluid. The fluid source may be, for example, a cryosurgical system such as that manufactured by present assignee, Endocare, Inc., Irvine, Calif., trademarked under the name of CRYOCARE CS™. Such a cryosurgical system typically utilizes argon gas from an argon gas source to provide Joule-Thomson cooling of the cryosurgical probes. Alternatively, nitrogen can be used. Alternatively, a fluid supply system can be utilized that does not require an external fluid supply source. Heating of the cryosurgical probes is typically provided by a helium gas source for providing a helium gas flow through the Joule-Thomson nozzle90of the cryosurgical probe. This provides a heating effect. Such heating of the cryosurgical probes is provided to unstick the probes from the treated tissue for cryoprobe removal. A gas delivery assembly of the disposable probe assembly86includes a fluid conduit subassembly that includes a shaft92and the Joule-Thomson tube88. A stem93is bonded to the shaft92. The shaft92has a freezing zone. The fluid conduit subassembly is for delivering and returning cooling fluid used for cryogenic cooling. Spaced markings94may be provided on the outer surface of the cryosurgical probe84. These markings94may be, for example, at 1 cm intervals.

The disposable probe assembly86of the cryosurgical probe84includes a finger lock assembly including finger lock element96, and a disposable handle assembly98. The finger lock assembly provides detachment of the disposable probe assembly86as discussed in detail in U.S. Pat. Publication No. US 20050192565 (U.S. patent Ser. No. 11/116,873) entitled, “Detachable Cryosurgical Probe With Breakaway Handle”, assigned to the present assignee, which has been discussed above, has been incorporated herein by reference in its entirety.

Referring now toFIG. 8, the reusable probe assembly100includes the manifold assembly102and a reusable handle assembly104secured about the periphery of the manifold assembly102. The reusable handle assembly104includes a first end portion106and a second end portion108. The manifold assembly102includes an outer covering110.

The reusable probe assembly100preferably includes a safety valve assembly, designated generally as112, operatively engaged with the manifold assembly102for impeding cryogenic working fluid flow when the disposable probe assembly86is detached from the reusable probe assembly100.

The reusable probe assembly also preferably includes an electrical confirmation assembly, designated generally as114, operatively engaged with the disposable probe assembly86for providing electrical confirmation that the disposable probe assembly86is connected.

During use, when the disposable probe assembly86is attached, a breakaway collar116is an integral unit that prevents relative rotation between the proximal handle section118and the distal handle section120. In this configuration, the lip121engages an associated lip122of the manifold assembly102of the reusable probe assembly100; thereby securing the reusable probe assembly100to the disposable probe assembly86. During an initial stage of detachment of the disposable probe assembly86, the user rotates the distal handle section in a first direction relative to the proximal handle section118to “break away” breakaway surfaces of the breakaway collar116, allowing the breakaway collar116to radially expand. During an intermediate stage of detachment of the disposable probe assembly86the user counter rotates the distal handle section120in an opposite second direction relative to the proximal handle section118. The relative rotation between the distal handle section120and the proximal handle section118provides axial movement of the distal handle section120toward the proximal handle section118via the engagement of the threaded inner surface119of the distal finger lock element section and the threaded outer surface of the stem107. The axial movement is enabled by the radial expansion of the breakaway collar116. The ramped surfaces of the radially spaced fingers96engage the associated ramp section on the stem107during the axial movement thereby urging the fingers96to open. During a final stage of detachment, the fingers96open sufficiently to allow disengagement of the lip121from the associated lip122of the reusable probe assembly, thus enabling the disposable probe assembly86to be detached from the reusable probe assembly100.

The vacuum insulation tube assembly10may be repositioned as desired relative to the shaft92. This is accomplished by actuating a button assembly, designated generally as122, along a guideway124. This is discussed in detail in U.S. Pat. Publication No. US 20050192565 (U.S. patent Ser. No. 11/116,873) mentioned above. Briefly, a slider assembly126is mechanically connected to the vacuum tube10and to the button assembly122. Thus, the shaft92and the vacuum tube10are capable of moving relative to each other. The button assembly122can be locked into position to prevent unintentional movement. Thus, the size and shape of the generated iceball can be varied in accordance with a specific desired need.

During operation, with the disposable probe assembly86attached to a reusable probe assembly, cryogenic fluid originating from (typically) an argon tank flows through the supply line through the manifold assembly of the reusable probe assembly. The flow is directed through the central passageway in the high pressure stem107via J-T tube88, and out of the J-T port90.

After being expelled from the J-T port90the return fluid is directed in the space between the inner surface of the inner tube12of the vacuum insulation tube assembly10and the outer surface of the J-T tube88. It then flows through openings in the manifold assembly. The return fluid is eventually expelled via a hose of the cryosurgical probe assembly.

In the device illustrated the cryosurgical probe is shown with a pointed tip to provide insertion into the patient's tissue for the desired application. However, it is understood that the tip may be blunt, depending on the application. For example, for certain applications direct insertion is desirable. For other applications, insertion via a cannula/introducer is preferred.

Although application of this device utilizing CT guidance is preferred, the cryosurgical probe10may be used with a variety of guidance tools, such as MRI and ultrasound. In one preferred implementation ultrasound is used for initial guidance, followed up with CT for final confirmation.

Although the present invention has been discussed above with respect to a cryosurgical probe having a rigid outer sheath, the cryosurgical probe may be made to be malleable by including at least one malleable segment thereon. Malleable segments are formed of material that permit reshaping and bending to reposition the ablating surface for greater ablation precision. An example of a cryosurgical probe having malleable characteristics is disclosed and claimed in our co-pending patent application U.S. patent Ser. No. 09/957,337, U.S. Pat. Publication No. US 2003/0055415 A1, published on Mar. 20, 2003 entitled “Malleable Cryosurgical Probe”, incorporated in its entirety herein by reference.

One method for providing malleable characteristics includes providing a malleable shaft with a bellows portion. U.S. Pat. No. 6,767,346, issued to Damasco, et al. entitled “Cryosurgical Probe With Bellows Shaft”, incorporated in its entirety herein by reference, discloses use of a bellows portion for providing the necessary reshaping and bending.

The cryosurgical probe may be constructed to have various angles. For example, a right angled probe is particularly advantageous for interventional radiological applications.

If the detachable cryosurgical probe is utilized in combination with ultrasound the outer sheath may have an echogenic coating with, for example, a porous microstructure having the ability to trap microscopic air bubbles. This creates thousands of highly efficient ultrasound reflectors on the surface of the sheath.

Thus, while the preferred embodiments of the devices and methods have been described in reference to the environment in which they were developed, they are merely illustrative of the principles of the invention.

For example, even though the vacuum insulation tube assembly has been described specifically with respect to the present cryosurgical probe it is understood that it can be used on other types of cryosurgical probes that, for example, may not be single use.

Although the cryosurgical probe system is particularly advantageous for prostate cryosurgery it is also advantageous for many other types of ablation applications, such as radiological applications.

Other embodiments and configurations may be devised without departing from the spirit of the invention and the scope of the appended claims.