Patent Publication Number: US-2021169546-A1

Title: Carbon dioxide-based percutaneous cryosurgical system

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application No. 62/664,998 filed on May 1, 2018, which is incorporated by reference, herein, in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to medical devices. More particularly, the present invention relates to a carbon dioxide-based percutaneous cryosurgical system. 
     BACKGROUND OF THE INVENTION 
     Cryotherapy treatment can be effective for treatment of cancer and other pathologies in humans and animals. However, this form of treatment can often been very expensive for the developing world and the veterinary markets where it is used. One driver of the high cost of this treatment is that expensive gas is often used to provide the cooling associated with the cryotherapy. 
     Therefore, it would be advantageous to provide a carbon dioxide-based percutaneous cryosurgical system for effective treatment and reduced cost. 
     SUMMARY OF THE INVENTION 
     The foregoing needs are met, to a great extent, by the present invention, wherein in one aspect a device for cryotherapy includes a probe having an outer surface defining an inner lumen. The device includes a backend component configured to be coupled to the probe. The backend component is configured to be connected to a source of carbon dioxide gas. The backend component includes a lever to enable dispensing the carbon dioxide gas. The device also includes a Joule-Thompson nozzle disposed within the backend component, such that the carbon dioxide gas is throttled to decrease a temperature of the carbon dioxide gas. 
     In accordance with an aspect of the present invention, the device further includes a flow path for carbon dioxide gas from the backend, into the inner lumen of the probe and back out through the backend component. The device includes a source of carbon dioxide gas. The source of carbon dioxide gas takes the form of a conventional carbon dioxide gas tank. The device includes a flange for coupling the probe to the backend component. The backend component includes a vent for venting spent carbon dioxide gas. The backend component includes tubing for coupling to a source of carbon dioxide gas. The shape of the probe is optimized for cryotherapy. The shape of the probe is configured for formation of an ice ball for delivery of cryotherapy. The device further includes an ultrasound component for monitoring cryotherapy treatment. 
     In accordance with another aspect of the present invention, a method of cryotherapy includes providing a flow path for directing CO 2  gas from a room temperature tank into a backend component of a device through gas inflow tubing, into a treatment probe, and back into the backend component. The flow path is configured for throttling the gas though a Joule Thompson nozzle to rapidly cool the gas. The flow path is also configured for flowing the gas into a probe of the device to allow for treatment and exiting the gas from the probe, such that the gas flows back through the backend component of the device. Further, the flow path is configured for venting the gas from the backend component of the device. 
     In accordance with still another aspect of the present invention, the gas flow can be turned on and off directly at the room temperature tank. Consistent internal pressure is ensured via a regulator. The method includes providing an ultrasound component for monitoring the cryotherapy. The probe is configured for cryotherapy. The method includes optimizing a flow path for the flow of CO 2 . In addition, the method includes generating a freeze-thaw-freeze cycles are used to freeze a tumor. The probe is configured to be inserted percutaneously. The method includes providing a flange for coupling the probe to the backend of the device. The method also provides for rapidly cooling the gas to −50° C. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings provide visual representations, which will be used to more fully describe the representative embodiments disclosed herein and can be used by those skilled in the art to better understand them and their inherent advantages. In these drawings, like reference numerals identify corresponding elements and: 
         FIG. 1  illustrates a perspective view of a cryoprobe according to the present invention being used in a surgical setting. 
         FIG. 2  illustrates a sectional view of a distal probe, according to an embodiment of the present invention. 
         FIG. 3  illustrates a side view of a backend component of the cryoprobe, according to an embodiment of the present invention. 
         FIGS. 4 and 5  illustrate a sectional view of a cryoprobe according to an embodiment of the present invention. 
         FIGS. 6A-6C  illustrate side and sectional views of a cryotherapy device, according to an embodiment of the present invention. 
         FIGS. 7A and 7B  illustrate side and sectional views of a probe tip, according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The presently disclosed subject matter now will be described more fully hereinafter with reference to the accompanying Drawings, in which some, but not all embodiments of the inventions are shown. Like numbers refer to like elements throughout. The presently disclosed subject matter may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Indeed, many modifications and other embodiments of the presently disclosed subject matter set forth herein will come to mind to one skilled in the art to which the presently disclosed subject matter pertains having the benefit of the teachings presented in the foregoing descriptions and the associated Drawings. Therefore, it is to be understood that the presently disclosed subject matter is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. 
     An embodiment in accordance with the present invention provides a handheld cryoprobe for use in percutaneous cryotherapy of tumorous masses in the body. Cryotherapy includes any treatment with cold temperature known to or conceivable to one of skill in the art. The device includes a probe attached to a CO 2  gas dispensing system backend. The probe has specifically optimized parameters designed for use with CO 2  gas and is made out of a partially hollowed and threaded aluminum rod of a specific shape, providing maximum heat exchange. The system backend regulates the flow of compressed CO 2  gas while throttling and cooling the gas coolant to the cytotoxically low temperatures necessary for targeted tumor cell death. Additionally, the incoming initial stream of CO 2  gas is throttled by the Joule-Thomson nozzle on the backend to further cool the probe. The low temperature exhaust gas is then used to pre-cool all subsequent incoming gas, resulting in an even lower temperature at the probe tip. This provides a positive feedback loop which is continually decreasing the temperature of the gas. The temperature drop is caused by the Joule-Thomson effect. Using a combination of this precooling heat exchange and the heat exchange in the probe due to the Joule Thomson effect, the probe tip is cooled and produces an ice ball around the cryoprobe. 
     The present invention is optimized for CO 2  at the moment because of its availability and low cost. Other high-end systems typically use costly gases, like nitrogen or argon, which cool to lower temperatures at faster rates but have limited availability for many parts of the world. This handheld system is made specifically to work with CO 2  because it is able to achieve the desired results of cooling human tissue and forming an ice ball around a mass while being usable worldwide. 
       FIG. 1  illustrates a perspective view of a cryoprobe according to the present invention being used in a surgical setting. As illustrated in  FIG. 1 , the system  10  of the present invention includes a cryoprobe  12  and a source of CO 2    14 . The source of CO 2    14  can take the form of a portable gas tank, or any other suitable source of CO 2  known to or conceivable to one of skill in the art. In some embodiments, ultrasound  16  is used to locate the tumor for treatment. After the tumor is located, the cryoprobe  12  is inserted into the tumor. CO 2  flow is then initiated. In a preferred embodiment, freeze-thaw-freeze cycles are used to freeze the tumor. Tumor growth is monitored with the ultrasound  16 . Finally, the cryoprobe  12  is removed and the necrosed tumor is left behind. 
       FIG. 2  illustrates a sectional view of a distal probe, according to an embodiment of the present invention. The probe  100  is configured for insertion into the tumor, where it acts like a heat exchanger freezing the tissue into which it is inserted. The probe  100  includes a shaft  102  defining a lumen  104  through which the CO 2  flows. A proximal end  106  of the probe  100  includes a flange  108  which allows for coupling with the backend component of the cryoprobe, described further herein. The optimized dimensions shown in  FIG. 2  provide maximum heat exchange with the use of CO 2 . This differs from previous cryoprobes because the state of the art for percutaneous cryosurgery is use of nitrogen or argon as the coolant. Therefore, the optimization of the device to allow for effective use with CO 2  is not shown in the prior art. 
       FIG. 3  illustrates a side view of a backend component of the cryoprobe, according to an embodiment of the present invention. The backend component  110  of the cryoprobe supplies compressed gas from the CO 2  tank to the probe. The backend component  110  rapidly cools the CO 2  gas and uses exhausted gas to precool the incoming gas to allow for more efficient and effective cooling with the CO 2  gas. The backend component includes a lever  112  for engaging flow of CO 2  gas. While a lever is shown in  FIG. 2 , it is not necessary in all embodiments of the present invention, as will be further illustrated herein. The flow of gas can be engaged in any way known to or conceivable by one of skill in the art. The backend component  110  also includes a coupling  114  for adding the probe described in  FIG. 2 .  FIGS. 4 and 5  illustrate a sectional view of a cryoprobe, according to an embodiment of the present invention.  FIGS. 4 and 5  illustrate the cryoprobe  116  which includes the probe  100  and the backend component  110 . Gas flows from the room temperature tank into the backend component  110 . The gas can flow through tubing connecting the gas tank to the backend component. The gas is throttled by the Joule Thompson nozzle  118  rapidly cooling the gas from 23 to −50° C. The extremely cold gas  120  flows into the lumen  104  of the probe  100  for cooling that can be directed to treatment. The extremely cold gas  120  then exits the probe and flows back through the backend component  110  from which it is vented out to atmosphere. As the extremely cold gas  120  flows back through the backend component  110 , this extremely cold gas  120  interfaces with the inflow tube, precooling new gas  122  and creating a positive feedback loop to allow the gas and thereby the device to reach temperatures cool enough for effective treatment. 
     Further, an inner lumen of the probe, preferably, is formed from a material with sufficiently high thermal conductivity, such that heat transfer occurs between incoming room-temperature gas and outflowing low-temperature gas so as to pre-cool the incoming gas to further decrease the temperature within the probe, such as, but not limited to, aluminum or stainless steel. A portion of the precooling of the incoming gas occurs within the body contained within the probe. The probe and the backend component are preferably formed from materials that can be sterilized and reused with a solution of bleach and water, ethylene oxide gas, steam sterilization, or any other form of sterilization known to or conceivable to one of skill in the art. In some embodiments, the probe can be removed from the backend component and sterilized or autoclaved separately from the backend of the device. In some embodiments, the probe can include at least a partial cover formed from a material with poor thermal heat transfer, thereby limiting and focusing tissue damage along a length of the probe. 
       FIGS. 6A-6C  illustrate side and sectional views of a cryotherapy device, according to an embodiment of the present invention.  FIGS. 6A-6C  illustrate the cryoprobe  216  which includes the probe  200  and the backend component  210 . Gas flows from the room temperature tank into the backend component  210  through gas inflow tubing  224 . The gas can flow through tubing  224  connecting the gas tank to the backend component. The gas is throttled by the Joule Thompson nozzle (not pictured) rapidly cooling the gas from 23 to −50° C. The extremely cold gas flows into the probe  200  for cooling that can be directed to treatment. The extremely cold gas then exits the probe  200  and flows back through the backend component  210  from which it is vented out of a vent tube  226 . Gas flow is turned on and off directly at the tank. The backend component can also include handle  228 . The handle  228  can be attached proximal to the junction of probe  200  and backend  210  for ease of operability. The handle  228  is made from sufficiently insulating materials so as to protect the operator&#39;s hand from experiencing any cooling. The handle  228  is removable such that the rest of the device may be cleaned separately. The backend component can also include a regulator  230  to ensure consistent internal pressure. 
       FIGS. 7A and 7B  illustrate side and sectional views of a probe tip, according to an embodiment of the present invention. The probe  300  is configured for insertion into the tumor, where it acts like a heat exchanger freezing the tissue into which it is inserted. The probe  300  includes a shaft  302  defining a lumen  304  through which the CO 2  flows. A proximal end  306  of the probe  300  includes a flange  308  which allows for coupling with the backend component of the cryoprobe. The flange  308  can be threaded for easy removal, or exchange of different probes during a procedure. A distal end  310  of the probe  300  includes a cone-shaped tip  312 . The cone-shaped, pointed tip is optimized for use with CO 2 . The cone-shaped, pointed tip is ideal for cryotherapy done percutaneously. It is also possible in some embodiments that multiple probes or a probe with multiple tips can also be used. 
     In some embodiments, the device of the present invention can include a warming device immediately proximal to the point of connection for the probe. This can help to keep healthy tissue at a proper temperature. The warming device can take the form of a closed material through which water can circulate, a warming blanket or heating pad, or any other means of warming known to or conceivable to one of skill in the art. 
     Control of the present invention can in some embodiments be carried out using a computer, non-transitory computer readable medium, or alternately a computing device or non-transitory computer readable medium incorporated into the robotic device. A non-transitory computer readable medium is understood to mean any article of manufacture that can be read by a computer. The computing device can include instructions for usage of the carbon dioxide-based percutaneous cryotherapy system. The computing device can also be used for desired treatment placements and times from predefined imaging parameters. The computing device can also be used to process images taken from imaging such as but not limited to ultrasound and further instructs the user on changes in treatment parameters. 
     Such non-transitory computer readable media includes, but is not limited to, magnetic media, such as a floppy disk, flexible disk, hard disk, reel-to-reel tape, cartridge tape, cassette tape or cards, optical media such as CD-ROM, writable compact disc, magneto-optical media in disc, tape or card form, and paper media, such as punched cards and paper tape. The computing device can be a special computer designed specifically for this purpose. The computing device can be unique to the present invention and designed specifically to carry out the method of the present invention. The operating console for the device is a non-generic computer specifically designed by the manufacturer. It is not a standard business or personal computer that can be purchased at a local store. Additionally, the console computer can carry out communications through the execution of proprietary custom built software that is designed and written by the manufacturer for the computer hardware to specifically operate the hardware. 
     The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.