Abstract:
An improvement for a control system for a surgical procedure is provided. The control system includes an electrosurgical instrument connectable to a source of electrosurgical energy, and a pump for circulating fluid to the electrosurgical instrument. The improvement includes a pump housing configured and adapted for selective connection in an opening provided in the source of electrosurgical energy. The housing defines a circular chamber formed therein, the circular chamber defining a central axis; an eccentric bore formed therein having a central axis substantially parallel with and spaced apart from the central axis of the circular chamber; an inlet formed therein and in fluid communication with the circular chamber; and an outlet formed therein and in fluid communication with the circular chamber.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application claims the benefit of and priority to U.S. Provisional Application Ser. No. 60/608,037, filed on Sep. 8, 2004, the entire contents of which are incorporated herein by reference. 
     
    
     BACKGROUND  
       [0002]     1. Technical Field  
         [0003]     The present disclosure relates to sterilizable pumps and systems, and more particularly to sterilizable pumps and systems, typically used to circulate sterile fluids and the like, to a target surgical site and/or through a surgical instrument.  
         [0004]     2. Background of Related Art  
         [0005]     A wide variety of pump types have been used in the past for pumping any number of a variety of different liquids for any of a number of different functions and applications. Typically a peristaltic-type pump is used in connection with many medical applications and is applied externally of the fluid delivery tube. Thus, the peristaltic pump does not interfere with the sterile state which must be maintained for the infusion fluid within the fluid delivery tube.  
         [0006]     Many peristaltic pumps are typically used in medical, biomedical and laboratory applications, including and not limited to, irrigation devices and/or systems, suction devices and/or systems, circulation devices and/or systems, and the like. One example of a peristaltic pump is shown schematically in  FIG. 1  and is described in commonly assigned U.S. Pat. No. 6,575,969, the entire contents of which are incorporated herein by reference. This so-called “cool-tip” radiofrequency thermosurgery electrode system includes an example of a pump for circulating cooling fluid.  
         [0007]     More particularly and as seen in  FIG. 1 , an insulated electrode shaft  104  with exposed tip  103  is provided for insertion into a patient&#39;s body so that tip  103  achieves a target volume to be ablated. A high frequency generator such as a radiofrequency generator  107  is provided for supplying RF power to electrode shaft  104 , as shown by the RF power P line. At the same time, electrode shaft  104 , is provided with a temperature sensor, provides feed back to the RF generator or controller circuit  109  relating to a temperature reading To or multiple temperature readings of a similar nature of the tissue coolant fluid or tip arrangement. Depending upon the temperature reading, the RF output power P may be modified by controller  109  by modulating the RF voltage, current, and/or power level, accordingly, to stabilize the ablation volume or process. If temperature rises to boiling, as indicated by temperature measurement To, the power could be either shut off or severely cut back by generator  107  or controller  109 . Thus a feedback loop between power and temperature or any other set of parameters associated with the lesion process can be implemented to make the process safer or to simply monitor the process altogether.  
         [0008]     As further seen in  FIG. 1 , element  108  represents the coolant fluid supply and pump system which can be configured to measure pressure and/or flow. Input flow from element  108  to electrode shaft  104  and output flow are indicated by the arrows to and from the electrode shaft  104  and element  108 , respectively. Accordingly, the controller  109  monitors the procedure and regulates the fluid flow of the coolant between controller  109  and element  108  which, in turn, prevents the electrode from over heating. In conjugation, the combined mediation of flow, power, temperature, or other lesioning parameters could be integrated in controller  109 , and the entire system of generator  107 , element  108 , and controller  109  can be one large feedback control network and system. Fluid bath  110  may also be included with the system as a reservoir of coolant fluid which may also be regulated by controller  109 .  
         [0009]     Typically, element  108 , including the pump, is an integral part of control system  100 . Accordingly, should the pump fail, break down, become contaminated or the like, the entire control system  100  needs to be replaced or extensive work performed on control system  100  in order to replace, remove, sterilize, dispose and/or otherwise treat the pump of element  108 .  
         [0010]     Despite the importance of pump systems in medical, biomedical and laboratory applications, as described above, the use of pump systems in these and many other applications has met with some drawbacks.  
         [0011]     For example, typical rotary peristaltic-type pumps function on rotary action principles, wherein the fluid delivery tube is wrapped around a shaft and is periodically squeezed and/or pinched at varying locations along the length thereof (e.g., by means of rollers that are made to rotate about a central shaft) thus propelling the fluid through the tube.  
         [0012]     An issue which may arise with rotary peristaltic-type pumps is that the fluid delivery tube must recover its cylindrical shape following the passage of each roller thereover (i.e., the fluid squeezes) which may effect the tube&#39;s elasticity and impede the tube&#39;s ability to restore to its normal shape which may unnecessarily limit the operation of the pump.  
         [0013]     Another issue which may arise with rotary peristaltic-type pumps is that the repetitive squeezing and/or pinching of the fluid delivery tube tends to weaken the tubing which, in turn, may lead to eventual leaking during normal usage.  
         [0014]     Accordingly, a need exists for improved pumps and/or systems for use with sterile fluids which overcome at least some of the deficiencies and/or drawbacks of existing pumps and/or systems.  
         [0015]     A need exists for improved pumps and/or pump systems which can be or are sterilized and which are used in connection with the transmission of sterile fluids.  
         [0016]     A need also exists for improved pumps and/or pump systems which can be selectively coupled and un-coupled to and from a driving mechanism of a control system as needed and/or desired.  
         [0017]     A need exists for improved pumps and/or pump systems having interchangeable components, which components may be each individually sterilizable, replaceable and/or disposable.  
         [0018]     A need exists for improved pumps and/or pump systems for use with cool-tip radiofrequency thermosurgery electrode system.  
       SUMMARY  
       [0019]     Sterilizable pumps and systems, typically used to circulate sterile fluids and the like, to a target surgical site and/or through a surgical instrument, are provided.  
         [0020]     According to an aspect of the present disclosure, a pump for selective fluid connection with a control system for circulating fluid to a target surgical site is provided. The pump includes a housing defining a circular chamber formed therein, the circular chamber defining a central axis; an eccentric bore formed therein having a central axis substantially parallel with and spaced apart from the central axis of the circular chamber; an inlet formed therein and in fluid communication with the circular chamber; and an outlet formed therein and in fluid communication with the circular chamber.  
         [0021]     The pump further includes an impeller assembly rotatably supported in the circular chamber of the housing. The impeller assembly includes a shaft operatively supported within the bore of the housing; an impeller having an inner ring operatively connect to the shaft, such that rotation of the shaft results in rotation of the impeller, an outer ring configured and dimensioned for sliding engagement with an inner annular surface of the cylindrical chamber of the housing, and a plurality of radially angled vanes extending between the inner ring and the outer ring, wherein the vanes define a plurality of chambers around the inner ring. Accordingly, when the impeller assembly is positioned within the circular chamber of the housing a portion of the chambers of the impeller, in proximity to the inlet, are un-compressed and a portion of the chambers of the impeller in proximity to the outlet, are compressed.  
         [0022]     According to another aspect of the present disclosure, an improvement for a control system for a surgical procedure is provided. The control system includes an electrosurgical instrument connectable to a source of electrosurgical energy, and a pump for circulating fluid to the electrosurgical instrument. The improvement includes a pump housing configured and adapted for selective connection in an opening provided in the source of electrosurgical energy. The housing defines a circular chamber formed therein, the circular chamber defining a central axis; an eccentric bore formed therein having a central axis substantially parallel with and spaced apart from the central axis of the circular chamber; an inlet formed therein and in fluid communication with the circular chamber; and an outlet formed therein and in fluid communication with the circular chamber.  
         [0023]     The improvement further includes an impeller assembly rotatably supported in the circular chamber of the housing. The impeller assembly includes a shaft operatively supported within the bore of the housing; an impeller having an inner ring operatively connect to the shaft, such that rotation of the shaft results in rotation of the impeller, an outer ring configured and dimensioned for sliding engagement with an inner annular surface of the cylindrical chamber of the housing, and a plurality of radially angled vanes extending between the inner ring and the outer ring, wherein the vanes define a plurality of chambers around the inner ring. Accordingly, when the impeller assembly is positioned within the circular chamber of the housing a portion of the chambers of the impeller, in proximity to the inlet, are un-compressed and a portion of the chambers of the impeller in proximity to the outlet, are compressed.  
         [0024]     It is envisioned that at least the vanes of the impeller are formed from a material selected from the group consisting of elastomeric polymers, plastic polymers, and blends of said elastomeric and plastic polymers.  
         [0025]     The housing may further define a first annular groove formed in a surface of the cylindrical chamber, which first annular groove is in fluid communication with the cylindrical chamber and the inlet; and a second annular groove formed in a surface of the cylindrical chamber, which second annular groove is in fluid communication with the cylindrical chamber and the outlet.  
         [0026]     The pump may further include a cover selectively securable to the housing for retaining the impeller assembly within the cylindrical chamber. Accordingly, a first end of the shaft of the impeller assembly may project from one side of the housing and a second end of the shaft of the impeller assembly may be supported by the cover.  
         [0027]     The pump may further include a sealing member provided around the periphery of the cylindrical chamber.  
         [0028]     In operation, rotation of the impeller assembly results in compression of the chambers of the impeller in the vicinity of the outlet to force fluid out of the pump, and expansion of the chambers of the impeller in the vicinity of the inlet to draw fluid into the pump.  
         [0029]     The housing may be configured and adapted for selective insertion into a complementary opening provided in the control system.  
         [0030]     The pump may further include a gear supported on the first end of the shaft of the impeller assembly.  
         [0031]     It is envisioned that complementary mating elements may be provided on the housing of the pump and in the opening of the source of electrosurgical energy for securing the pump within the opening of the source of the electrosurgical energy.  
         [0032]     The presently disclosed sterilizable pumps and systems, together with attendant advantages, will be best understood by reference to the following detailed description in conjunction with the figures. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0033]     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the detailed description of the embodiments given below, serve to explain the principles of the disclosure.  
         [0034]      FIG. 1  is a schematic diagram of a prior art cool-tip control system for RF heating ablation showing an RF generator, coolant system, fluid bath source, and control system which monitors and regulates critical parameters relating to temperature, power and fluid flow;  
         [0035]      FIG. 2  is a perspective view of a pump according to the present disclosure;  
         [0036]      FIG. 3  is a front elevational view of the pump of  FIG. 2  shown in operative engagement with a motor;  
         [0037]      FIG. 4  is an exploded perspective view of the pump and pump housing of  FIGS. 2 and 3 ;  
         [0038]      FIG. 5  is a front elevational view of the internal configuration of the pump housing of  FIGS. 2-4 ; and  
         [0039]      FIG. 6  is a perspective view of an exemplary control system including an opening for receiving the pump of  FIGS. 2-5  therein. 
     
    
     DETAILED DESCRIPTION  
       [0040]     Referring again to  FIG. 1 , a prior art control system for RF heating ablation is shown generally as  100 . Control system  100  includes an insulated electrode shaft  104  having an exposed tip  103  for insertion into a patient&#39;s body such that exposed tip  103  can achieve a target volume to be ablated. Electrode shaft  104  preferably extends from a hub  106  including connection means (not shown) for connecting electrode shaft  104  to RF generator  107  and coolant supply and pump  108 .  
         [0041]     Preferably, RF generator  107  supplies RF power to electrode shaft  104 , as shown by the RF power connection “P”. At the same time, electrode shaft  104  which includes a temperature sensor (not shown), feeds temperature information back to RF generator  107  and/or a controller circuit  109  relating to a temperature reading To or multiple temperature readings of the tissue coolant fluid or tip arrangement. According to the temperature reading, any modulation of the RF output power “P” is accorded by controller  109 . More particularly, controller  109  modulates the RF voltage, current, and/or power level to stabilize the ablation volume or process. If temperature reading To rises to a boiling point, the power is either shut off or severely cut back to generator  107  by controller  109 . Thus a feedback loop between power and temperature or any other set of parameters associated with the lesion process can be implemented to monitor the overall process.  
         [0042]     In addition, as seen in  FIG. 1 , control system  100  further includes power measurement connections from RF generator  107  to controller  109  and a feedback power control signal from controller  109  to RF generator  107 . The entire heating process may be preconfigured by the operator before the procedure based on the imaging and preplanned calculations of ablation volume verses the tip geometry and other ablation parameters. Thus, controller  109  is capable of regulating the entire heating process by controlling the RF power “P” from generator  107 .  
         [0043]     With continued reference to  FIG. 1 , control system  100  further includes a coolant fluid supply and pump system  108  with potential thermo-monitoring, pressure monitoring, flow monitoring, etc. Input flow from coolant fluid supply and pump system  108  to electrode shaft  104  and output flow from the electrode shaft are indicated by the arrows which connect hub  106  and the coolant fluid supply and pump system  108 . Such input and output flow can be monitored by appropriate pressure or flow monitoring elements or detection devices (not shown). These are well known in the fluid control industry. Accordingly, the fluid flow and the temperature of the coolant can be fed back between controller  109  and coolant supply  108  so the controller  109  can regulate the input and output flow. Combined regulation mediation of flow, power, temperature, and/or other lesioning parameters may also be integrated in controller  109 , the generator  107 , and the coolant supply  108 . The controller  109  may also be configured as one large feedback control network and system.  
         [0044]     It is further envisioned that control system  100  can include a reservoir of coolant fluid  110  which may have possible interior temperature regulation within the fluid bath. Bath temperatures and control signals are fed back and forth to controller system  109 . These parameters also could be integrated in the overall control of the ablation process. Indwelling controllers, electronics, microprocessors, or software may be included to govern the entire process or allow preplanned parameters to be configured by the operator based on the selection of a tip geometry and overall ablation volume which are typically selected according to a tumor or pathological volume to be destroyed. Many variants or interconnections of the block diagram shown in  FIG. 1  or additions of the diagram could be devised by those skilled in the art of fluid control power and regulation systems.  
         [0045]     Turning now to  FIGS. 2-4 , a sterilizable pump in accordance with one embodiment of the present disclosure, for use in control system  100  and with coolant supply  108 , is shown generally as  200 . Pump  200  includes a body or housing  202  defining a chamber  204  (preferably circular) therein. Housing  202  further includes an aperture or inlet  206  (shown in hidden lines in  FIG. 5 ) and a discharge or outlet  208  (shown in hidden lines in  FIGS. 2 and 5 ) formed therein. Housing  202  further includes a bore  210  formed therein for rotatably receiving and/or supporting a shaft  230 , as will be discussed in greater detail below. Preferably, shaft  230  is cylindrical. Bore  210  is sized to receive shaft  230  and an annular bearing collar (not shown) therein. Bore  210  defines the axis of rotation of shaft  230 .  
         [0046]     With reference to  FIGS. 4 and 5 , inlet  206  leads to and is in fluid communication with a first arcuate groove  224  that extends substantially circumferentially through an angle of less than about 180°. Similarly, outlet  208  is in fluid communication with a second arcuate groove  226  that extends substantially circumferentially through an angle of less than about 180°. Preferably, first and second grooves  224  and  226  are independent and isolated from one another. First and second grooves  224  and  226  are formed in the same wall of housing  202 . In particular, first arcuate groove  224  is disposed below second arcuate groove  226 .  
         [0047]     As best seen in  FIG. 5 , bore  210  includes a central axis “X 1 ” (i.e., the axis of rotation of shaft  230 ) which is slightly offset from a central axis “X 2 ” of chamber  204  thereby providing a degree of eccentricity “E” between bore  210  and chamber  204 . As will be described in greater detail below, it is eccentricity “E” which creates the pumping effect of pump  200 . Preferably, central axis “X 2 ” is offset from central axis “X 1 ” in the direction of second arcuate groove  226 .  
         [0048]     As best seen in  FIG. 4 , pump  200  further includes an impeller assembly generally designated as  228 . Impeller assembly  228  includes a shaft  230  to which is operatively connected an impeller  232 . Impeller  232  includes a substantially rigid inner ring  234 , having an inner bore (not shown) allowing inner ring  234  to be secured to shaft  230 , and a substantially rigid outer ring  236 .  
         [0049]     Impeller  232  further includes a plurality of flexible, resilient, elastomeric webs, spokes or vanes  238  extending between an inner tubular hub portion  240  and an outer rim portion  242 . Preferably, vanes  238  maintain inner ring  234  substantially concentric with outer ring  236 . Desirably, vanes  238  extend from hub portion  240  in a substantially arcuate fashion and attach to outer rim portion  242 . Vanes  238  define a plurality of chambers  244  between hub portion  240  and rim portion  242 . Desirably, inner tubular hub portion  240  is secured to an outer surface of inner ring  234  and outer rim portion  242  is secured to an inner surface of outer ring  236 .  
         [0050]     Vanes  238  are preferably molded or fabricated in a single piece from suitable material exhibiting good flexure, fatigue and mechanical properties, such as elastomers (e.g., Neoprene, Nitrile, fluouroelastomer, etc.), plastic (e.g., Teflon, Nylon, etc.), compounds of plastic and elastomers (e.g., Santoprene), or other fabrics (e.g., Kevlar). If molded from Neoprene, it is desirable that vanes  238  have a Shore A hardness range from about 55 to about 85.  
         [0051]     Pump  200  further includes a cover  250  for closing off chamber  204  and retaining impeller assembly  228  therein. Preferably, cover  250  creates a seal around chamber  204  to thereby prevent and/or inhibit the escape of fluids and/or pressure therefrom. As seen in  FIG. 4 , it is envisioned that cover  250  is secured to housing  202  by screws or bolts  252 , however, it is contemplated and within the scope of the present disclosure for cover  250  to be otherwise secured to housing  202  by clamps, adhesives, pins ultrasonic welding and the like. Preferably, a sealing member  254 , in the form of a bead of sealing material or a gasket, may be provided around chamber  204  to further prevent and/or inhibit the escape of fluid or pressure therefrom. Cover  250  is preferably formed to support an end  230   b  of shaft  230 , such as, by a recess or the like (not shown) formed therein. Providing pump  200  with a cover  250  enables pump  200  to be opened after use and for the various components of pump  200 , e.g., shaft  230 , impeller assembly  228 , etc., to be cleaned, sterilized and/or replaced as needed.  
         [0052]     As seen in  FIGS. 2-4 , pump  200  can further include a gear or sprocket  260  supported on or otherwise operatively coupled to a portion  230   a  of shaft  230  extending out of housing  202 . Preferably, shaft  230  and gear  260  are keyed such that rotation of gear  260  transfers a corresponding rotation to shaft  230  and subsequently to impeller assembly  228 . Accordingly, as seen in  FIG. 3 , gear  260  of pump  200  can be operatively coupled to a gear  272  of a motor or other drive mechanism  270 . Alternatively, it is envisioned that shaft  230  of pump  200  can be directly coupled and/or otherwise connected to motor  270 .  
         [0053]     In assembling pump  200 , impeller assembly  228  is positioned in chamber  204  such that when shaft  230  is inserted through bore  210  formed in housing  212 , the eccentricity “E” between chamber  204  in housing  202  and bore  210  at least partially compresses vanes  238  in a radial segment thereof (i.e., closing, squeezing and/or pinching chambers  244  in that radial segment). Meanwhile, vanes  238  in another radial segment thereof are substantially un-compressed (i.e., chambers  244  in the other radial segment are maintained substantially open). With impeller assembly  228  so positioned, cover  250  can be attached to housing  202  to thereby close and/or seal chamber  204 .  
         [0054]     In use, due to the eccentricity between chamber  204  and bore  210 , as impeller assembly  228  is rotated about shaft  230 , chambers  244  of impeller assembly  228  oscillate between at least partially compressed conditions and substantially expanded conditions. This is due to the fact that as impeller assembly  228  rotates, outer ring  236  and/or outer rim portion  242  of impeller assembly  228  rides against an inner annular wall  204   a  (see  FIGS. 4 and 5 ) of chamber  204  of housing  202  while inner hub  240  is driven by shaft  230 . The eccentricity of shaft  230  relative to chamber  204  of housing  202  distorts and/or compresses chambers  244 , thereby creating a rotary peristaltic effect.  
         [0055]     In operation, as shaft  230  is rotated to rotate impeller assembly  228 , fluid (e.g., cooling fluid, water, saline, etc.) enters and/or is otherwise drawn into impeller  232  from inlet  206  and first annular groove  224  to fill the un-compressed chambers  244  in proximity therewith. The fluid is drawn into chambers  244  located proximate inlet  206  and first annular groove  224  due to the localized expansion of chambers  244 , during rotation of impeller assembly  228 , thereby creating a partial vacuum to draw the fluid therein. As impeller assembly  228  is rotated, the fluid is carried by un-compressed chambers  224  of impeller  232  from first annular groove  224  to second annular groove  226  and from inlet  206  to outlet  208 . As the un-compressed chambers  244 , carrying the fluid, are brought into close proximity to second annular groove  226 , eccentricity “E” causes the un-compressed chambers  244  to compress against inner wall  204   a  of chamber  204  and thereby squeeze out or expel the fluid carried therein into second annular groove  226  and out through outlet  208 . Once again, as the compressed chambers  244  are brought into close proximity to first annular groove  224  the compressed chambers  244  begin to uncompress or expand, thereby creating a partial vacuum, to thereby draw additional fluid into chambers  244 . The process is repeated for every revolution of impeller assembly  228 .  
         [0056]     Preferably, as described above, motor  270 , including gear  272 , can be operatively connected to gear  260  of pump  200  to drive and/or spin shaft  230  and in turn impeller assembly  228 . Accordingly, it is envisioned that the faster motor  270  is driven, the faster impeller assembly  228  is driven, and, in turn, the faster the rate of fluid flow through pump  200 .  
         [0057]     It is envisioned that inlet  206  and outlet  208  can each include a valve, a fluid coupling and/or the like (not shown). In this manner, pump  200  can be simply coupled to the output tubing of a source of fluid and to the input tubing of an output source. For example, pump  200  can be fluidly coupled to the input flow line between coolant supply  108  and electrode shaft  104  of control system  100  (see  FIG. 1 ). In this manner, pump  200  provides electrode shaft  104  with a substantially uniform rate of fluid flow therethrough, thereby maintaining a substantially constant temperature during the surgical procedure.  
         [0058]     Following use of control system  100 , pump  200  can be unconnected and/or uncoupled from the input and/or output tubing and pump  200  can be: disposed of; sterilized in its entirety; disassembled for sterilization of the individual components thereof; disassembled for replacement of the individual components thereof; cleaned; and the like. In this manner, pump  200  can be reused for other surgical procedures. Pump  200  may also be disposable or partially reposable. Moreover, the tendency for the inlet and outlet tubing to crack due to the fatigue which may occur during the use of a peristaltic pump is eliminated.  
         [0059]     As seen in  FIG. 6 , it is envisioned that pump  200  may be in the form of a cartridge which may be selectively removably inserted into a slot or opening  120  provided in the housing of or otherwise connected to control system  100  or RF generator  107 . In particular, housing  202  of pump  200  has a particular shape and is selectively insertable into a complementary slot or opening  120  of control system  100  or RF generator  107 . Pump  200 , and either control system  100  or RF generator  107  may include complementary mating elements  280  and  180 , respectively, which permit secure engagement between pump  200  and either control system  100  or RF generator  107 . Upon connection of pump  200  to either control system  100  or RF generator  107 , gear  260  of pump  200  engages gear  272  of motor  270  (not shown in  FIG. 6 ).  
         [0060]     While a peristaltic pump has been shown and described, it is understood that other types of pumps can be used herein without departing from the scope of the invention.  
         [0061]     Although the illustrative embodiments of the present disclosure have been described herein, it is to be understood that the disclosure is not limited to those precise embodiments, and that various other changes and modifications may be affected therein by one skilled in the art without departing from the scope or spirit of the disclosure. All such changes and modifications are intended to be included within the scope of the present disclosure.