Abstract:
A medical vapor system and method is provided. The medical vapor system can include a fluid conduit having an inlet, an outlet and a heating section, the inlet being adapted and configured to be connected to a source of liquid water, a resistance heater disposed and configured to generate heat and conduct the heat to the heating section of the fluid conduit to vaporize liquid water flowing through the heating section, a power supply operatively connected to the heater, and a controller adapted to control production of water vapor by the system. Methods of use are also provided.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit under 35 U.S.C. §119 of U.S. Provisional Application No. 62/111,033, titled “Medical Vapor Generator”, filed Feb. 2, 2015, and U.S. Provisional Application No. 62/153,352, titled “Medical Vapor Generator”, filed Apr. 27, 2015, the disclosures of which are both incorporated by reference as if fully set forth herein. 
     
    
     INCORPORATION BY REFERENCE 
       [0002]    All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. 
       BACKGROUND 
       [0003]    Condensable vapor, such as water vapor, has been used to perform a variety of medical procedures. For example, U.S. Pat. No. 7,993,323 describes a medical vapor generator system that generates and delivers condensable vapor to perform lung volume reduction as an emphysema therapy. Other early medical vapor generators are described in US 2002/0177846 and US 2009/0216220. These publications describe therapeutic methods including treating, e.g., the liver, breast, gall bladder, stomach, pancreas, colon, urinary gladder, prostate, bone, vertebrae, eye and brain. 
       SUMMARY OF THE DISCLOSURE 
       [0004]    A medical vapor system comprising a fluid conduit having an inlet, an outlet and a heating section, the inlet being adapted and configured to be connected to a source of liquid water; a resistance heater disposed and configured to generate heat and conduct the heat to the heating section of the fluid conduit to vaporize liquid water flowing through the heating section, a power supply operatively connected to the heater, and a controller adapted to control production of water vapor by the system. 
         [0005]    In some embodiments, the heating section of the fluid conduit is coiled around at least part of the resistance heater. In one embodiment, the heating section of the fluid conduit is coiled within at least part of the resistance heater. In another embodiment, the system further comprises a housing enclosing the heating section of the fluid conduit and the heater. 
         [0006]    In some embodiments, the housing is a handheld housing comprising a handle. 
         [0007]    In one embodiment, the system further comprises a vapor delivery member adapted to receive vapor from the fluid conduit outlet. In another embodiment, the vapor delivery member comprises a vapor delivery catheter. 
         [0008]    In some embodiments, the controller is further adapted to control electrical current flowing to the heater. 
         [0009]    In one embodiment, the system comprises a temperature sensor adapted to send a signal to the controller corresponding to a temperature of water vapor within the conduit or at the conduit outlet. 
         [0010]    In another embodiment, the system comprises a valve communicating with the controller to control water flow through the fluid conduit. In some embodiments, the system comprises a valve communicating with the controller to control steam flow through the outlet. 
         [0011]    A medical vapor system is provided, comprising a fluid conduit having an inlet, an outlet and a heating section, the inlet being adapted and configured to be connected to a source of liquid water, the heating section being formed of a conductive material, a power supply operatively connected to the heating section to apply a voltage across the heating section to generate resistive heat to the heating section to vaporize liquid water flowing through the heating section, and a controller adapted to control production of water vapor by the system. 
         [0012]    In some embodiments, the heating section is a helix. 
         [0013]    In one embodiment, the system further comprises a housing enclosing the heating section of the fluid conduit and the heater. In some embodiments, the housing is a handheld housing comprising a handle. 
         [0014]    In one embodiment, the system further comprises a vapor delivery member adapted to receive vapor from the fluid conduit outlet. In some embodiments, the vapor delivery member comprises a vapor delivery catheter. 
         [0015]    In one embodiment, the controller is further adapted to control electrical current flowing to the heating section. 
         [0016]    In another embodiment, the system further comprises a syringe and a stepper motor operably connected to a plunger within the syringe, the syringe comprising an outlet in fluid communication with the fluid conduit. In some embodiments, the syringe further comprises an inlet communicable with a water source and an inlet check valve arranged to permit fluid to enter the syringe through the inlet and to prevent fluid from exiting the syringe through the inlet. In further embodiments, the syringe further comprises an outlet check valve arranged to permit fluid to exit the syringe through the outlet and to prevent fluid from entering the syringe through the outlet. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The novel features of the invention are set forth with particularity in the claims that follow. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which: 
           [0018]      FIG. 1  shows an embodiment of the medical vapor generator of this invention. 
           [0019]      FIG. 2  shows another embodiment of the medical vapor generator of this invention. 
           [0020]      FIGS. 3A and 3B  show filling and delivery operations for a medical vapor generator of this invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Because the primary heat delivery mechanism of condensable vapor is the heat released to tissue when the vapor condenses to liquid, it is important to control the quality of the vapor as well as the vapor flow rate. It may also be important to reduce the cost and complexity of medical vapor generators by, e.g., avoiding the use of expensive capital equipment, such as RF generators. Finally, for applications requiring the delivery of condensable vapor to locations within a patient&#39;s body, it may be desirable to generate the vapor close to the portion of the vapor delivery lumen entering the body so as to minimize heat loss and possible condensation before the vapor reaches the target tissue. 
         [0022]    Prior publications have described the use of resistance heaters to vaporize standing water within a vessel and to deliver the water vapor through a conduit or instrument to the target patient tissue. Prior publications have also described the use of RF energy to vaporize water flowing through a conduit within a vapor delivery tool. The prior art has not described the use of an inexpensive resistance heater to vaporize water flowing through a vapor delivery tool. More specifically, the prior art has not disclosed a self-contained portable disposable vapor delivery device containing a fluid flow controller (e.g., a pump or pressurized fluid source), a heating element (e.g., a resistive heater), a vapor generation element (e.g., a lumen or reservoir in which the liquid to vapor phase change occurs), a power supply, and a controller (to, e.g., monitor vapor parameters and to control heating and fluid flow). 
         [0023]      FIG. 1  shows an embodiment of the invention. Medical vapor generator  10  has a fluid conduit  12  receiving liquid water from a water source. In this embodiment, the water source is a stepper motor  1  that advances the piston  3  of a syringe  2 . Motor  1  is powered and controlled by power supply  18  under the control of control system  19 . In some embodiments, power supply  18  is an electrically isolated power supply, such as one or more rechargeable batteries. A user interface  17  enables a user to input vapor delivery parameters and provides output to the user. 
         [0024]    In this embodiment, fluid conduit  12  is a conduit formed of a conductive material, such as a metal hypotube, with a heating portion  20  optionally formed in a helix. Leads  21  and  22  connect direct current from power supply  18  to the heating section  20  to resistively heat the heating section  20  and any water flowing through it from the syringe  2 . In alternative embodiments, and alternating current source may be used. Water flowing through the heating section  20  of conduit  12  is vaporized before entering a vapor delivery member (not shown) connected to connector  26 . One or more temperature sensors, such as thermocouple  23  at the outlet of the heating section  20 , may be used by the control system  19  to obtain information about the temperature of the vapor in order to, e.g., regulate power delivery, maintain a baseline temperature and/or detect and mitigate system failure. 
         [0025]      FIG. 2  shows another embodiment of a medical vapor system  30  according to this invention. In this embodiment, the fluid conduit, the coiled resistance heater and controller are all housed within a single housing  32  having a handle  34  and user input control  36 . In some embodiments, depressing input control  36  starts water vapor generation and delivery, and releasing user input control  36  ceases water vapor generation and delivery. 
         [0026]    Water vapor generated within housing  32  exits into a vapor delivery member. In this embodiment, the vapor delivery member is a removable catheter  38  with an inflatable balloon  40  disposed proximal to the distal exit port  42  of the catheter. Balloon  40  may be inflated using, e.g., a syringe connected at port  44 . The resistance heater may be structured as described above with respect to  FIG. 1 . Other vapor delivery tools may be used connected to the vapor generator of this invention, such as a needle, a double balloon (i.e., a catheter with a balloon proximal and distal to the catheter outlet, or a balloon just distal to the catheter outlet), etc. Power may be supplied via a power cord  35  (connecting to, e.g., wall current) or by a battery disposed within housing  32 . In addition, the power supply element can be removed from the housing in order to reduce cost of the disposable component of the invention, and/or to allow recharging if said power supply is a rechargeable battery. A GUI or other user interface may also be provided in or on housing  32  to receive user inputs (e.g., to control power, vapor flow and/or vapor delivery time) and to display information about the generator and its use. The user inputs can be provided via buttons, touch screen, etc. In some embodiments, the output parameters of the vapor generator (e.g., vapor delivery time, vapor flow rate, etc.) can be preprogrammed so that each unit has a specific set of operating parameters. 
         [0027]      FIGS. 3A and 3B  illustrate a syringe valve arrangement useful for filling the syringe with water and delivering water to the heater. In  FIG. 3A , the stepper motor  1  moves the syringe plunger  3  away from the syringe inlet  9 . An inlet check valve  8  permits water to be drawn into syringe  2  from a water source (not shown), and an outlet check valve  7  keeps syringe outlet  11  closed. In  FIG. 3B , the direction of the stepper motor is reversed. As plunger  3  moves toward syringe outlet  11 , check valve  8  closes and check valve  7  opens, enabling water to be expelled from syringe  7  into the conduit leading to the device&#39;s water heating section. 
         [0028]    An advantage of the medical vapor generator described above is the relatively low heat capacity of the resistive heater section. This provides for the rapid start, and the rapid cessation, of vapor delivery. 
         [0029]    These embodiments of the invention provide a medical vapor delivery device containing a fluid flow controller (such as, e.g., the syringe and stepper motor described above), a vapor generation element (e.g., a resistively heated coiled section of the fluid conduit), a power supply, a controller and a user interface that is portable, self-contained and disposable. 
         [0030]    In some embodiments, the water entering the heating section of the fluid conduit may be preheated in a reservoir upstream of the heating section. Some of the water may also be vaporized prior to entering the heating section of the conduit, with the resistance heater providing added energy to the flowing vapor (or mixture of vapor and liquid) to maintain the quality of the steam by replenishing the heating section at a rate similar to the delivery rate so as to minimize temperature loss in the heating section during vapor delivery. The system may be provided with a dielectric strength exceeding 4 kV to meet medical device safety standards. A valve at the vapor outlet would also enable vapor delivery to cease on demand or in response to a signal from the controller even if vapor production has not yet ceased. 
         [0031]    The baseline condition of the heating element prior to therapy may affect subsequent vapor delivery during therapy. Controlling the temperature and water content before treatment may therefore improve consistency of the vapor treatment. Thus, in some embodiments, energy and/or water may be applied to the heating element to maintain its baseline condition before treatment. In one embodiment, the device is operated in an idle mode in which energy and water are supplied to the heating element at a constant, slow rate to maintain its temperature and water content. Vapor may be generated, but the vapor may condense prior to reaching the outlet of the delivery member. In another embodiment, the idle mode provides a dry idle; energy is applied to heat the heating element (to, e.g., 98° C., with possible feedback control via a thermocouple or other temperature sensor to prevent overheating), but no water is supplied to the heating element. In yet another embodiment, a pre-idle stage is added to the beginning of a therapy session, during which energy and water are supplied for a short period of time, such as 5 seconds, directly before treatment. 
         [0032]    The device&#39;s water source (e.g., syringe  2  in  FIG. 1 ) may be prefilled prior to shipping to the ultimate user. Alternatively, the water source (such as syringe  2  of  FIG. 1 ) may be filled manually (e.g., using another medical syringe) or automatically (using the stepper motor, such as described with respect to  FIGS. 3A and 3B ) just prior to use. In some embodiments, the system&#39;s power supply and controller may be disposed in a first housing and the system&#39;s water source, heater and motor or other pump may be disposed in a second housing. 
         [0033]    Although particular embodiments of the present invention have been described above in detail, it will be understood that this description is merely for purposes of illustration and the above description of the invention is not exhaustive. Specific features of the invention are shown in some drawings and not in others, and this is for convenience only and any feature may be combined with another in accordance with the invention. A number of variations and alternatives will be apparent to one having ordinary skills in the art. Such alternatives and variations are intended to be included within the scope of the claims. Particular features that are presented in dependent claims can be combined and fall within the scope of the invention.