Abstract:
Male and female mating pieces of a gas-assisted electrosurgical accessory connector are connectable together by radially contacting a sealing surface formed on one mating piece with a resilient radially-compressible sealing member carried on the other mating piece. A gas-tight seal exists along a length of the sealing surface as the two mating pieces connect with relative connection movement. The existence of the gas-tight seal over a range of relative connection movement maintains the seal if the mating pieces should become slightly disconnected. The mating pieces are also restrained against separation from one another. A recess is formed in one of the mating pieces and a retention member carried on the other one of the mating pieces is biased into contact with the recess. Separation of the two connected members requires manual force to extract the retention member from the recess. The amount of manual force required is greater than that normally experienced from movement during use, thereby inhibiting unintentional separation.

Description:
This invention relates to gas-assisted electrosurgery, and more particularly to a new and improved accessory connector for connecting a gas-assisted electrosurgical accessory to a gas-assisted electrosurgical unit which includes an electrosurgical generator and a gas delivery apparatus. The accessory connector is less susceptible to gas leaks, is more resistant to unintentional disconnection or separation of internal gas sealing surfaces, and is backwards compatible with certain previous gas-assisted electrosurgical accessory connectors, among other improvements. 
   BACKGROUND OF THE INVENTION 
   Electrosurgery involves the application of radio-frequency (RF) electrical energy to cut a patient&#39;s tissue, to coagulate blood flow from the tissue, or to both cut and coagulate simultaneously. An electrosurgical generator creates the RF electrical energy, and the RF energy is applied to the tissue by an applicator or pencil-like handpiece which is manipulated by a surgeon to cut and coagulate. Gas-assisted electrosurgery additionally involves conducting the RF energy to the tissue in a stream of ionized conductive gas. The gas stream clears blood and other fluids from the surface of the tissue, thereby allowing the RF energy to interact directly with the tissue without the fluid diverting all or part of the electrical energy away from the tissue. The transfer of the RF energy through the ionized gas stream directly to the tissue without diversion from fluid achieves an enhanced electrosurgical effect. U.S. Pat. No. 4,781,175 and Re U.S. Pat. No. 34,780 are exemplary of gas-assisted electrosurgery apparatus. Both of these U.S. patents are assigned to the same assignee as the present application. 
   A nozzle at the distal end of the handpiece shapes the gas into a flow stream of desired characteristics. An electrode is positioned within the nozzle to ionize the gas and to transfer the RF energy into conductive pathways within the gas stream. An accessory hose conducts the gas flow from a gas delivery apparatus to the nozzle, and an accessory conductor conducts the RF energy from an electrosurgical generator to the electrode within the nozzle. The accessory hose and conductor and the nozzle and electrode are part of the gas-assisted electrosurgical accessory. 
   An accessory connector connects the accessory hose and conductor to a housing of a gas-assisted electrosurgical unit, which includes the electrosurgical generator and gas delivery apparatus. The accessory connector permits different gas-assisted electrosurgical accessories to be used and replaced as necessary or desirable. One mating piece of the accessory connector is connected to the accessory handpiece, and another complementary mating piece of the accessory connector is connected to the housing of the gas-assisted electrosurgical unit. The accessory connector transfers the gas flow and RF energy from the gas-assisted electrosurgical unit into the accessory hose and onto the accessory conductor of the accessory. 
   In some gas-assisted electrosurgery accessories, such as probes used in gastrointestinal electrosurgical applications, the pencil-like handpiece and the cord are either not used or they are considerably modified in form. For example, in a gas-assisted gastrointestinal electrosurgical probe, the accessory hose takes the form of a small diameter gas-conducting tube that extends directly from the accessory connector to the end of the gas-conducting tube where the nozzle is located. The accessory conductor extends within the gas conducting tube. No pencil-like handpiece exists, because the end of the gas-conducting tube with the nozzle and the internal electrode is manipulated by an endoscope or a laparoscope into which the probes inserted. A gastrointestinal probe of this type is an example of a gas-assisted electrosurgery accessory used to perform minimally invasive electrosurgical procedures. A variety of other types of accessories using handpieces and different lengths of cords and different configurations of nozzles are available to perform other open types of electrosurgical procedures. 
   The accessory connector should transfer the gas flow and the RF electrical energy without leakage to the ambient environment. In a typical gas-assisted electrosurgical procedure, the surgeon selects a desired gas flow and a desired amount of electrosurgical energy to be applied to the tissue. In many cases, the amount of gas flow and the amount of the electrical energy are coordinated to achieve a desired electrosurgical effect. If gas leaks from the accessory connector, the desired amount of gas will not be delivered from the nozzle, and the desired electrosurgical effect may not be achieved. Similarly, if current leakage or conduction of some of the RF energy occurs at the accessory connector, the desired electrosurgical effect may not be achieved. RF energy leakage at the accessory connector or any other location along the cord or within the handpiece, can cause an unintended burn to the surgeon, operating room personnel or the patient, or may damaged the electrosurgical generator. 
   An example of a gas-assisted electrosurgery accessory connector is described in U.S. Pat. No. Re 34,780. The gas sealing capability of the accessory connector described in this U.S. patent is achieved by an axial contact seal. The gas-confining integrity of such a seal depends upon the two mating pieces of the accessory connector remaining in an axially forced-together relationship. Such a relationship is achieved by screwing together the complementary threads of the two mating pieces until the two sealing surfaces axially contact one another. While this threaded-together relationship provides an effective gas-tight axial contact seal in most circumstances, it is possible for the threaded connection of the two mating pieces to loosen over the relatively lengthy duration of many surgical procedures due to the continual movement of the cord and the handpiece. It is not unusual for the threaded connection to loosen if the cord is accidentally stepped on, pulled or bumped by operating room personnel while performing the surgical procedure. Loosening of the two connected mating pieces of the accessory connector, even to a small degree, is likely to cause the sealing surfaces of the accessory connector to separate slightly, resulting in a leak gas. 
   The surgeon and the operating room personnel are not likely to recognize a leak at the accessory connector. The surgeon&#39;s attention is focused almost exclusively on creating the desired affects at the surgical site. The surgeon depends almost exclusively on the operating room personnel to supply the necessary equipment for use when the surgeon needs that equipment. In addition to serving the needs of the surgeon, the operating room personnel are focused on many other responsibilities associated with the surgical procedure, such looking after and monitoring as the welfare of the patient. The tissues encountered during a typical electrosurgical procedure vary substantially in electrical impedance and vascularity, both of which have a significant impact on the electrosurgical effect achieved. Since the surgeon expects variations in the surgical effect due to tissue differences, the surgeon may not recognize that the performance of the gas-assisted electrosurgical unit may have become compromised as a result of a gas leak at the accessory connector, resulting from continual movement of the cord and the handpiece during the procedure or from the cord having been accidentally stepped on, pulled or bumped during the surgical procedure. 
   The problems of gas leaks at the accessory connector may be aggravated with gas-assisted gastrointestinal electrosurgical probes. A relatively small diameter gas-conducting tube is required for insertion into an instrument channel of the endoscope or laparoscope. The endoscope or laparoscope must be relatively narrow to permit it to be inserted within a lengthy hollow organ in the gastrointestinal tract or to be inserted within an inflated body cavity. The gas flow rate through the relatively small diameter gas-conducting tube is less, causing the effect of a relatively small leak to magnify the extent of deviation of the gas flow from the nozzle, thereby impacting the expected performance. 
   These and other considerations have led to the improvements of the present invention. 
   SUMMARY OF THE INVENTION 
   In general, the present invention pertains to a new and improved gas-assisted electrosurgery accessory connector which does not depend on an axial contact seal for confining gas flow within the accessory connector. Instead, the improved accessory connector of the present invention uses a radial compression seal. The radial compression seal maintains a leak-free seal even if the two mating pieces of the accessory connector become somewhat loosened during the course of a surgical procedure. In addition, the new and improved accessory connector biases the two mating pieces of the accessory connector into a fully connected relationship to resist unintentional loosening of the two mating pieces. These and other improvements are achieved in a manner which permits backward-compatible use of certain pre-existing accessory connectors of the type described in U.S. Pat. No. Re 34,780. The backwards compatibility allows the improvements of the present invention to be incorporated in the mating piece of the accessory connector which is connected to the housing of the gas-assisted electrosurgical unit, so that existing previous accessories can be used. Furthermore, improvements in the mating piece of the accessory connector which is attached to the accessory does not prohibit the use of that accessory with the complementary mating piece of the previous form of the accessory connector. Thus, the improvements in both mating pieces of the present accessory connector may be used with the previous forms of the complementary mating pieces unknown gas-assisted accessory connectors, without the necessity to change the mating piece attached to the housing of the gas-assisted electrosurgical unit and without the necessity to purchased new accessories. 
   In accordance with these and other improvements, the new and improved gas-assisted electrosurgical accessory connector is formed by two mating pieces which are connectable to one another with a relative connection movement along an axis toward one another. A sealing surface is formed on one mating piece, and the sealing surface extends generally parallel with the axis for a distance along the axis. A resilient radial sealing member is carried on the other mating piece at a location which contacts and seals against the sealing surface with radial force upon the two mating pieces connecting with relative connection movement. 
   Other preferable aspects of the improved accessory connector include extending the sealing surface parallel to the axis over a predetermined length to permit the sealing member to contact and seal against the sealing surface over a range of relative connection movement of the two mating pieces. The sealing member is an annularly shaped resilient O-ring which is radially compressed to establish a gas-tight seal for confining a gas flow from the gas-assisted electrosurgical unit through the connected mating pieces to the accessory connector. 
   Another aspect of the improved accessory connector includes a retention mechanism operative between the connected mating pieces. The retention mechanism restrains the connected mating pieces against separation from one another. Preferably, the retention mechanism comprises a recess formed on one of the mating pieces and a retention member carried on the other one of the mating pieces. The retention member moves into the recess upon the two mating pieces connecting with relative connection movement, and the retention member moves out of the recess with manual force applied between the mating pieces to separate them from one another. 
   Still another aspect of the present invention includes a method of connecting together two mating pieces of a gas-assisted electrosurgical accessory. The method comprises connecting the two mating pieces by moving the two mating pieces together along an axis in a relative connection movement, contacting a sealing member carried on one mating piece with a sealing surface formed the other mating piece and which extends generally parallel with the axis for a distance along the axis, and resiliently compressing the sealing member in a radial direction relative to the axis in contact with the sealing surface to establish a gas tight seal over a range of the relative connection movement. 
   Preferably the method involves conducting a gas flow and RF electrical energy between the connected two mating pieces, contacting and sealing the sealing member with the sealing surface over a range of relative connection movement of the two mating pieces over a portion of the predetermined length of the sealing surface, and conducting the gas flow and the RF electrical energy in a space circumscribed by the sealing surface and the contact of the sealing member with the sealing surface. 
   Another aspect of the method of the present invention involves restraining the connected mating pieces against separation. Preferably the restraint is accomplished by moving a retention member carried by one mating piece into a recess formed the other mating piece upon the two mating pieces connecting with relative connection movement, and moving the retention member out of the recess with manual force applied between the two connected mating pieces to separate the mating pieces from one another. 
   A more complete appreciation of the scope of the present invention and the manner in which it achieves the above-noted and other improvements can be obtained by reference to the following detailed description of presently preferred embodiments taken in connection with the accompanying drawings, which are briefly summarized below, and by reference to the appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a gas-assisted electrosurgical accessory connector, a gas-assisted electrosurgical accessory, and a broken-away portion of a gas-assisted electrosurgical unit otherwise shown primarily in block diagram form. 
       FIG. 2  is an exploded perspective view of the accessory connector shown in  FIG. 1 , with female and male mating pieces separated from one another and shown from a rear perspective compared to the front perspective of the accessory connector shown in  FIG. 1 . 
       FIG. 3  is a perspective view of the female and male mating pieces of the accessory connector shown in  FIG. 2 , shown separated from one another and with the components of the female mating piece exploded. 
       FIG. 4  is a perspective view similar to  FIG. 3 , shown from a front perspective compared to the rear perspective view shown in  FIG. 3 . 
       FIG. 5  is an exploded perspective view of the male mating piece of the accessory connector shown in  FIGS. 1-4 . 
       FIG. 6  is an axial cross-sectional view along an axis of the male mating piece of the accessory connector shown in  FIGS. 1-5 , taken substantially in the plane of line  6 - 6  in  FIG. 2 . 
       FIG. 7  is a transverse cross-sectional view taken substantially in the plane of line  7 - 7  of  FIG. 6 . 
       FIG. 8  is a transverse cross-sectional view taken substantially in the plane of line  8 - 8  of  FIG. 6 . 
       FIG. 9  is an axial cross-sectional view of the female mating piece of the accessory connector shown in  FIGS. 1-4 , taken substantially in the plane of line  9 - 9  in  FIG. 2 . 
       FIG. 10  is a transverse cross-sectional view taken substantially in the plane of line  10 - 10  of  FIG. 9 . 
       FIG. 11  is a transverse cross-sectional view taken substantially in the plane of line  11 - 11  of  FIG. 9 . 
       FIG. 12  is a transverse cross-sectional view taken substantially in the plane of line  12 - 12  of  FIG. 9 . 
       FIG. 13  is an axial cross-sectional view of connected female and male mating pieces, similar to a combination of  FIGS. 6 and 9 , taken substantially in a vertical plane through an axis of the accessory connector shown in  FIG. 1 . 
       FIG. 14  is an enlarged partial view of  FIG. 13  illustrating a gas-tight seal created by an O-ring located between the connected female and male mating pieces shown in  FIG. 13 . 
       FIG. 15  is an enlarged cross-sectional view taken substantially in the plane outline  15 - 15  of  FIG. 13 . 
       FIG. 16  is an cross sectional view, related to  FIG. 13 , of the male portion of the accessory connector shown in  FIGS. 1-5 , shown in a connected relationship with a prior art form of a female mating piece of a gas-assisted electrosurgical accessory connector. 
   

   DETAILED DESCRIPTION 
   An accessory connector  20  incorporating the present invention is shown in  FIGS. 1 and 2 . The accessory connector  20  connects a gas-assisted electrosurgical accessory  22  to a conventional gas-assisted electrosurgical unit  24 . The gas-assisted electrosurgical unit  24  includes a conventional electrosurgical generator  26  and a conventional gas delivery apparatus  28 , both of which are typically contained wholly or partially within a housing  30  (partially shown) of the gas-assisted electrosurgical unit  24 . The electrosurgical generator  26  generates radio frequency (RF) electrical energy of preselected characteristics from conventional alternating current power, and applies the RF electrical energy on a supply conductor  32  within the housing  30 . The gas delivery apparatus  28  includes a source of preferably-inert and ionizable gas (not shown), from which a flow of gas of preselected and controlled characteristics is derived and supplied within the housing  30  through a supply conduit  34 . 
   A female mating piece  36  of the accessory connector  20  is connected to receive the RF energy from the supply conductor  32  and the gas flow from the supply conduit  34 . A male mating piece  38  of the accessory connector  20  connects with the female mating piece  36  to receive the RF energy and the gas flow transferred from the female mating piece  36 . The male mating piece  38  conducts the RF energy and gas flow to the electrosurgical accessory  22 . The accessory  22  is connected to the electrosurgical unit  24  by the connection of the mating pieces  36  and  38 . Preferably, the male mating piece  36  forms a part of the accessory  22 . 
   In the form shown in  FIG. 1 , the accessory  22  includes a pencil-like applicator or handpiece  42  connected to one end of a flexible gas-conducting accessory hose  44 . The handpiece  42  also includes a nozzle  46  from which a flow of gas issues. The gas flow from the male mating piece  38  is conducted through the hose  44  and into the handpiece  42  and out of the nozzle  46 . The characteristics of the nozzle  46  shape the gas flow into a desired flow stream (not shown) which is applied to the patient&#39;s tissue (not shown). An electrode (not shown) is located within the nozzle  46 . The electrode within the nozzle  46  is connected to an accessory electrical conductor  48  which, in the form of the accessory shown in  FIG. 1 , is located within the accessory hose  44 . The accessory conductor  48  conducts the RF energy from the male mating piece  38  to the electrode within the nozzle  46 . The RF energy applied to the electrode within the nozzle  46  ionizes the gas flowing through the nozzle  46  and is transferred to the patient&#39;s tissue in ionized conducted pathways within the flow stream of gas issuing from the nozzle  46 , to create the desired electrosurgical effect. 
   In the form of the gas-assisted electrosurgical accessory  22  shown in  FIG. 1 , the accessory hose  44  and the internal accessory conductor  48  constitute a cord  50  which connects the handpiece  42  to the accessory connector  20 . The length of the cord  50  many vary according to type of accessory  22 . Not all gas-assisted electrosurgical accessories  22  include the handpiece  42 . For example, a gas-assisted gastrointestinal electrosurgical probe utilizes only a flexible gas-conducting tube or supply hose which terminates at a nozzle. The supply hose fits within an endoscope or a laparoscope, and the surgeon manipulates the position of the nozzle end of the hose by manipulating the endoscope or the laparoscope within a hollow organ or within an expanded body cavity of the patient. 
   The accessory connector  20  transfers the gas from the gas-assisted electrosurgical unit  24  to the accessory  22  in a manner which significantly improves its ability to avoid and prevent gas leaks. The accessory connector  20  also offers a significantly improved ability to resist accidental loosening and separation of the mating pieces  36  and  38 , to further avoid gas leaks. The accessory connector  20  conducts the RF energy from the electrosurgical unit  24  to the accessory  22  in a manner which does not divert, leak or short-circuit the RF energy to the housing  30  or to the surrounding ambient environment. The configuration of each mating piece  36  and  38  allows each mating piece to be connected to and used in a backward compatible manner with the pre-existing complementary mating pieces of pre-existing gas-assisted electrosurgical accessories  22 . These and other advantages and improvements will become more apparent from the details of the accessory connector  20 , described below. 
   Details of the male mating piece  38  of the connector  20  are shown generally in  FIGS. 1-4  and more specifically in  FIGS. 5-8 . The male mating piece  38  of the connector  20  is essentially the same as a previous prior art configuration of a gas-assisted accessory connector, with the exception of certain detents  74  described below. As shown in  FIGS. 5 and 6 , the male mating piece  38  includes an external hollow sleeve member  52  within which there is positioned an interior hub member  54 . In general, the sleeve member  52  connects the male mating piece  38  to the female mating piece  36  (as shown in  FIG. 13 ), and positions the hub member  54  to receive the gas flow and RF energy from the female mating piece  36 . The accessory hose  44  and the accessory conductor  48  are connected to the hub member  54  to transfer the gas flow and the RF energy to the handpiece  42 . 
   The sleeve member  52  has a relatively larger-diameter generally-cylindrical end portion  56  and a relatively smaller-diameter generally-cylindrical end portion  58 . The larger end portion  56  and the smaller end portion  58  are respectively located on a front or forward end and a rear or rearward end of both the sleeve member  52  and the male mating piece  38 . An interior sidewall  64  of the larger end portion  56  tapers with a slightly decreasing radius from the front end to a radially-extending abutment shoulder  66 . An interior sidewall  68  of the smaller end portion  58  tapers with a slightly decreasing radius from the rear end to the abutment shoulder  66 . The abutment shoulder  66  is located near the axial center of the hollow interior of the sleeve member  52 , and the larger end portion  56  transitions to the smaller end portion  58  at approximately the location of the abutment shoulder  66 . 
   The exterior surface of the larger end portion  56  includes threads  70  which project outwardly from a location starting approximately midway along the length of the larger end portion  56  and terminating approximately adjacent to the abutment shoulder  66 . The threads  70  are used to connect the male mating piece  38  to the female mating piece  36 , by screwing the threads  70  into complementary threads ( 114 ,  FIGS. 9 and 13 ) of the female mating piece. The smaller end portion  58  is used as a handle or grip to rotate the sleeve member  52  when screwing it into the female mating piece  36 . The smaller end portion  58  extends from the female mating piece  36 , thereby enabling the smaller end portion  58  to be gripped when rotating the sleeve member  52  to connect or disconnect the male mating piece  38  from the female mating piece  36 . 
   The abutment shoulder  66  includes a forward-facing contact surface  72  that contacts the rear end of the hub member  54  when the sleeve member  52  is advanced into the female mating piece  38  during connection of the two mating pieces  36  and  38 . The advancement of the sleeve member  52  and the abutment shoulder  66  forces the hub member  54  forward into operative contact with components of the female mating piece. 
   A series of circumferentially spaced detents  74  are formed in a forwardmost edge  75  of the larger end portion  56 . The detents  74  are indentions or recesses which are indented rearwardly from the forwardmost locations along the forward edge  75 . The detents  74  are used in the manner described below to assist in maintaining the sleeve member  52  in a position restrained from unintentional loosening or unscrewing from the female mating piece  36 . With the exception of the detents  74 , the configuration of the male mating piece  38  is essentially the same as a prior art configuration. The prior art male mating piece has a smooth cylindrical forward edge, without the series of circumferentially spaced detents  74 . 
   The hub member  54  includes a hollow spool-like body portion  76  having a front annular ridge  78  and a rear annular ridge  80 . The forward-facing contact surface  72  of the abutment shoulder  66  contacts a rearward-facing contact surface  82  of the rear annular ridge  80 . Force from the sleeve member  52  is transferred to the hub member  54  through the contact of the two surfaces  72  and  82 . The surfaces  72  and  82  are relatively smooth, thereby permitting the forward-facing contact surface  72  to rotate relative to the stationary rearward-facing contact surface  82 , while the sleeve member  52  rotates relative to the hub member  54  when connecting the mating pieces  36  and  38  ( FIG. 13 ). The annular ridges  78  and  80  align the hub member  54  relative to the interior surface  64  of the larger end portion  56  to keep the hub member  54  generally centered within the hollow interior of the sleeve member  52  to facilitate connecting the mating pieces  36  and  38 . 
   A hollow stub portion  84  extends integrally from the rear of the spool-like body portion  76 . The hub member  54  is retained relative to the sleeve member  52  by the slight radial extension of a radially inward-facing edge  83  of the abutment shoulder  66  into a slight annular recess  85  formed into the hub member  54  between the spool-like body portion  76  and the stub portion  84 . The radially inward facing edge  83  of the abutment shoulder  66  extends into the recess  85  only a very slight amount, thereby allowing the hub member  54  to be snapped into the retained position within the sleeve member  52 . There is sufficient clearance between the edge  83  and the recess  85  to avoid interference when the sleeve member  52  is rotated relative to the hub member  54  during connection of the mating pieces  36  and  38 . 
   A gas passageway  86  is defined through the center of the hollow spool-like body portion  76  and the hollow stub portion  84 . The gas passageway  86  extends from the forward end of the hollow spool-like body portion  76  to the rear end of the stub portion  84 . The accessory hose  44  is connected to the rear end of the stub portion  84 . The inside surface of the smaller end portion  58  has a larger diameter than the stub portion  84  and the accessory hose  44  to permit the hose  44  to be connected to the hub member  54  within the interior of the smaller end portion  58 . The gas flow transferred from the female mating piece  36  enters the gas passageway  86  at the forward end of the spool-like body portion  76 , flows through the hollow interior of the hub member  54 , and enters the accessory hose  44  at the rear end of the stub portion  84 . 
   The gas flow transferred from the female mating piece  36  is confined within the gas passageway  86  by an O-ring seal  88  located at the forward end of the hub member  54 . The O-ring  88  surrounds the gas passageway  86  and creates the seal between the forward end of the hub member  54  and the adjoining outward portions of the female mating piece  36 . A relatively short sleeve-like extension  90  extends forward from the front end of the spool-like body portion  76  outside of the gas passageway  86 . An annular groove  91  is formed in the extension  90 . The O-ring  88  is placed over the sleeve-like extension  90  and is seated within the annular groove  91 . The O-ring  88  is expanded slightly when placed over the extension  90 , and the force created by the slight expansion of the resilient material of the O-ring  88  maintains the O-ring  88  within the annular groove  91  during connection and disconnection of the mating pieces  36  and  38 . A forward-facing surface  93  extends radially outward from the sleeve-like extension  90  at a position to the rear of the annular groove  91 . The surface  93  extends from the sleeve-like extension  90  radially outward to the radially outer edge of the forward annular ridge  78 . 
   A metallic connector electrode  92  extends through the hollow center of the spool-like body portion  76  within the gas passageway  86 . A rear end of the connector electrode  92  is connected to the accessory conductor  48  located within the accessory hose  44 . The connection between the accessory conductor  48  and the connector electrode  92  is conventional, such as by swaging or soldering. The connector electrode  92  is surrounded by an insulating sleeve  94  within the hollow interior of the spool-like body portion  76 . The insulating sleeve  94  is an integral part of the spool-like body portion  76 . As shown in  FIG. 7 , the insulating sleeve  94  is held in the center position within the hollow interior of the spool-like body portion  76  by ribs  96  which extend radially within the hollow interior of the spool-like body portion  76  between the body portion  76  and the sleeve  94 . The ribs  96  are oriented parallel to the gas flow through the gas passageway  86 , and therefore do not restrict or block the gas flow in the open spaces between the ribs  96  within the passageway  86 . The ribs  96  extend to the spool-like body portion  76  only from the rear portion of the insulating sleeve  94 . The front portion of the sleeve  94  extends in a cantilevered manner, as shown in  FIG. 8 . The ribs  96  retain the insulating sleeve  94  in a fixed position within the gas passageway  86 . The connector electrode  92  is inserted into the insulating sleeve  94  and is retained in a fixed position within the insulating sleeve  94 , preferably by insert molding. Retained in this manner, the connector electrode  92  is maintained in an centered position at the axis of the male mating piece  38 . 
   The insulating sleeve  94  terminates before reaching the forward end of the connector electrode  92 , thereby exposing a forward end  98  of the connector electrode  92 . The exposed forward end  98  permits the connector electrode  92  to make electrical contact with an electrical socket ( 128 ,  FIGS. 9 and 13 ) of the female mating piece  36  to transfer the RF electrical energy from the gas-assisted electrosurgical unit  24  to the accessory  22  ( FIG. 1 ). 
   Details of the female mating piece  36  of the accessory connector  20  are shown generally in  FIGS. 1-4  and more specifically in  FIGS. 3 ,  4  and  9 - 12 . The improvements of the present invention reside primarily, but not exclusively, in the female mating piece  36 . The female mating piece  36  includes a receptacle housing  102  to which a tailpiece  104  is attached by screws  106 . The receptacle housing  102  and the tailpiece  104  are formed of a dielectric insulating material. A flange  108  extends outward from the housing body  102 , and holes  110  in the flange  108  receive screws  111  or other fasteners to attach the female mating piece  36  to the housing  30  of the gas-assisted electrosurgical unit  24  ( FIG. 1 ). 
   The receptacle housing  102  defines an outward-opening receptacle  112  at an outer end of the female mating piece  36 . The forward portion of the male mating piece  38 , including approximately all of the larger cylindrical end portion  56  of the sleeve member  52  and the components within the larger end portion  56  ( FIG. 6 ), are inserted into the receptacle  112  when the mating pieces  36  and  38  are connected ( FIG. 13 ). An outer end of the tailpiece  104  connects to the inner end of the receptacle housing  102 . The supply conductor  32  from the electrosurgical generator  26  ( FIG. 1 ) and the supply conduit  34  from the gas delivery apparatus  28  ( FIG. 1 ), are connected to an inner end of the tailpiece  104 . The tailpiece  104  delivers the gas and the RF energy to the female mating piece  36 . 
   Internal threads  114  of the receptacle housing  102  surround the outer end of the receptacle  112  to mesh with the external threads  70  on the larger cylindrical end portion  56  ( FIGS. 5 and 6 ) of the sleeve member  52  of the male mating piece  38  when the mating pieces  36  and  38  are connected ( FIG. 13 ). The receptacle  112  continues inwardly from the inner termination point of the internal threads  114  to an intermediate wall  116  which extends transversely across the receptacle  112  at a location between the outer and inner ends of the receptacle housing  102 . A hollow cylindrical sleeve  118  is attached to the intermediate wall  116  and projects outwardly from the intermediate wall  116  into the receptacle  112 . An opening  120  is formed through the intermediate wall  116  in alignment with an elongated hollow interior  122  of the hollow sleeve  118 , as shown in  FIG. 10 . Gas flow from the tailpiece  104  is conducted through the opening  120  and into the interior  122  of the sleeve  118 . 
   The hollow sleeve  118  extends outwardly from the intermediate wall  116  to an outermost position which is approximately radially adjacent to the inner terminal end of the internal threads  114 . The hollow sleeve  118  is located concentrically about an axis of the receptacle  112  ( FIGS. 4 ,  9 - 11 ). Because the hollow sleeve  118  has an outside diameter which is less than the inside diameter of the receptacle  112  at positions radially adjacent to the hollow sleeve  118 , the space between the outside of the hollow sleeve  118  and the inside of the receptacle housing  102  defines an annular slot  124 . The inner end of the annular slot  124  terminates at the intermediate wall  116 . The annular slot  124  is also concentric with the axis of the receptacle  112 . The annular slot  124  receives the forward non-threaded portion of the larger cylindrical end portion  56  of the sleeve member  52  of the male mating piece  38  when the external threads  70  of the male mating piece  38  ( FIGS. 5 and 6 ) engage and mesh with the internal threads  114  of the receptacle  112  ( FIG. 13 ). 
   Ribs  125  extend radially inward from the hollow sleeve  118  within its hollow interior  122  to a hollow tube-like socket holder  126 , as shown in  FIGS. 4 ,  9  and  11 . The ribs  125  position a socket holder  126  concentrically with the hollow sleeve  118  and concentrically about the axis of the receptacle  112 . The socket holder  126  receives and holds an electrical socket  128 . The electrical socket  128  transfers the RF energy from the supply connector  32  ( FIG. 1 ) to the forward end  98  of the connector electrode  92  of the male mating piece  38  ( FIG. 13 ). The ribs  125  are spaced at approximately equal circumferential intervals ( FIG. 11 ) to permit the gas to flow between them from the opening  120  in the intermediate wall  116  through the interior  122  of the hollow sleeve  118 . 
   An outer end of the hollow sleeve  118  includes an interior recess  129  which extends generally concentrically with the axis of the receptacle  112 . The recess  129  includes a cylindrical sidewall  130  which faces radially inward. The outside surface of the O-ring  88 , which is attached to the forward sleeve-like extension  90  of the spool-like body portion  76 , contacts the cylindrical surface  130  of the recess  129  when the male mating piece  38  is connected to the female mating piece  36  ( FIGS. 13 and 14 ). The O-ring  88  is slightly compressed in a radial direction, between the sleeve like extension  90  and the cylindrical sidewall  130 , thereby establishing a radial seal between the sleeve  118  of the female mating piece  36  and the forward end of the spool-like body portion  76  of the male mating piece  38  ( FIGS. 13 and 14 ). The radial seal, established by compression of the O-ring  88  between the extension  90  and the inside cylindrical sidewall  130 , confines the gas to flow from the interior  122  of the hollow sleeve  118  into the gas passageway  86  of the spool-like body portion  76  ( FIG. 13 ). The gas seal from the radially compressed O-ring  88  remains effective even though the mating pieces  36  and  38  may not be fully tightened in their connected relationship. The outer end of the hollow sleeve  118  also includes a outer edge contact surface  131 , which extends radially outward with respect to an axis through the hollow sleeve  118 . The outer edge contact surface  131  contacts, or is positioned closely adjacent to, the surface  93  of the male mating piece  38 , when the pieces  36  and  38  are connected ( FIGS. 13 and 14 ). 
   At the inner end of the receptacle housing  102 , a cylindrically-shaped socket  132  extends from the intermediate wall  116 . The socket  132  extends inwardly away from the intermediate wall  116  on the opposite side from which the receptacle  112  extends outwardly away from the intermediate wall  116  ( FIGS. 3 and 9 ). A tubular-shaped channel  134  extends inward from the intermediate wall  116  at a location outside of the socket  132  ( FIGS. 3 ,  9  and  12 ). The channel  134  extends parallel to an axis of the receptacle  112  at a location which aligns axially with the annular slot  124 . An outer end  136  of the channel  134  opens through the intermediate wall  116  and into the annular slot  124 . A metal ball  138  is biased into the outer end  136  of the channel  134  by a coiled bias spring  140 . The spring  140  is located inwardly behind the metal ball  138  and biases the metal ball outwardly within the channel  134 . The outwardly biased ball  138  contacts and fits within one of the detents  74  formed in the forwardmost edge  75  of the larger cylindrical end portion  56  of the sleeve member  52 , when the mating pieces  36  and  38  are connected ( FIGS. 13 and 15 ). The ball  138 , biased by the spring  140  into a detent  74 , prevents accidental and unintentional unscrewing or disconnecting of the male mating piece  38  from the female mating piece  36  in a manner described more completely below. 
   The tailpiece  104  includes an outward-extending cylindrically-shaped sleeve  142 . The cylindrically shaped sleeve  142  is received within the socket  132  of the housing receptacle  102  when the tailpiece  104  and the receptacle housing  102  are connected ( FIG. 12 ). An attachment flange  144  of the tailpiece  104  extends outwardly from the sleeve  142  at a location adjacent to the inward extent of the sleeve  142 . Two screw plugs  146  are located on the receptacle housing  102  at diametrically-opposite positions outside of the cylindrically-shaped socket  132 . Holes  148  ( FIGS. 3 and 12 ) are formed in the attachment flange  144  in alignment with the screw plugs  146 , and the screws  106  extend through the holes  148  and connect with internally threaded openings  152  ( FIG. 12 ) in the screw plugs  146  to connect the tailpiece  104  to the receptacle housing  102 . 
   The tailpiece  104  includes a gas connection tube  154 . The outer end of the gas connection tube  154  communicates with the interior of the sleeve  142 . The inner end of the gas connection tube  154  is connected to the supply conduit  34  from the gas delivery apparatus  28  ( FIG. 1 ). Gas flows through the gas connection tube  154  into the tailpiece  104  and into the female mating piece  36 . The tailpiece  104  also includes an electrical connection tube  156 . The electrical connection tube  156  is located concentrically with the axis through the receptacle  112 . An electrical terminal  158  is located within the electrical connection tube  156 , and the inner end of the electrical terminal  158  is received in a socket portion of a conventional female crimp-on connector terminal  159  which has been crimped onto the RF supply conductor  32 . The electrical socket  128  is connected to the outer end of the electrical terminal  158 . In this manner, RF energy from the electrosurgical generator  26  ( FIG. 1 ) is conducted from the supply conductor  32  into the tailpiece  104  and the female mating piece  36 . 
   The cylindrically-shaped sleeve  142  of the tailpiece  104  has an outer diameter slightly smaller than the inner diameter of the cylindrically-shaped socket  132 . An annular groove  160  is formed around the sleeve  142  and an O-ring  162  is retained within the groove  160 . When the sleeve  142  is inserted into the socket  132 , the O-ring  162  creates a gas-tight seal between the inside cylindrical surface of the socket  132  and the outside cylindrical surface of the sleeve  142 . A hollow interior chamber  164  is defined by the connected sleeve  142  and socket  132 . The forward end of the gas connection tube  154  opens into the interior chamber  164 , so that the gas flowing from the gas connection tube  154  enters and fills the interior chamber  164 . The inner end of the hollow sleeve  118  also opens into the interior chamber  164 , so that gas from the interior chamber  164  flows into the interior  122  of the sleeve  118 . 
   The electrical terminal  158  includes first and second raised annular ridges  166  and  168  located between its inner and outer ends ( FIGS. 3 ,  4  and  9 ). The ridges  166  and  168  support and locate an O-ring  170  at a middle location along the length of the electrical terminal  158 . When the electrical terminal  158  is located in the electrical connection tube  156 , the O-ring  170  creates a gas-tight seal between the inside surface of the electrical connection tube  156  and the electrical terminal  158 , thereby preventing gas from leaking from the interior chamber  164  by flowing inwardly along the electrical terminal  158  and out of the inward end of the electrical connection tube  156 . 
   The conventional crimped-on female terminal  159 , after having been crimped on to the RF supply conductor  32 , is inserted outwardly into the electrical connector tube  156  from the inner end of the tube  156 . The tube  156  and the terminal  159  have appropriate geometry that allows the terminal  159  to snap into a retained position within the tube  156 . The inner end of the electrical terminal  158 , after having been connected to the electrical socket  128  and the O-ring  170 , is then inserted inwardly into the connector tube  156  from the outer into the tube  156 , to establish the electrical connection from the RF supply conductor  32  to the electrical socket  128 . 
   An alignment prong  176  extends outwardly from the attachment flange  144 , at a location to extend into the channel  134  when the receptacle housing  102  and the tailpiece  104  are connected ( FIGS. 9 ,  13  and  15 ). The coiled spring  140  surrounds the alignment prong  176 . The alignment prong  176  in conjunction with sleeve  142  orient the tailpiece  104  with the receptacle housing  102  for proper assembly, due to the nonconcentric position of the electrical socket  128  with respect to an axis through the socket  132  of the receptacle housing  102 . The alignment prong  176  extends outwardly a sufficient distance within the channel  134  to avoid contacting the ball  138  when the ball makes contact with the forward edge  75  of the larger cylindrical end portion  56  of the sleeve member  52 . In this manner, the ball  138  is resiliently biased outward only from the force of the coiled spring  140 . The inside transverse dimension of the channel  134  and the outside transverse dimension of the alignment prong  176  allow the coils of the spring  140  to flex freely without adversely diminishing the bias force from the spring  140 . 
   Details of the connection relationship of the female and male mating pieces  36  and  38  of the connector  20  are shown generally in  FIGS. 13-15 . The connected-together relationship occurs when the larger cylindrical end portion  56  of the sleeve member  52  is screwed into the receptacle  112  of the receptacle housing  102 , until the forward edge  75  of larger cylindrical end portion  56  of the sleeve member  52  is at an inwardmost location within the annular slot  124  which abuts the intermediate wall  116 . The smaller cylindrical end portion  58  is gripped and rotated to engage and mesh the external threads  70  of the sleeve member  52  with the internal threads  114  of the receptacle  112 , thereby advancing the sleeve member  52  forwardly and into the receptacle  112 . The forward movement of the sleeve member  52  causes the contact surface  72  of the abutment shoulder  66  to push against the rear-facing contact surface  82  of the rear annular ridge  80  of the spool-like body portion  76 , thereby moving the hub member  54  forward and into the receptacle  112 . 
   The forward movement of the hub member  54  pushes the forward end  98  of the connector electrode  92  into the hollow outer end  174  of the electrical socket  128 . With the forward end  98  of the connector electrode  92  inserted within the hollow outer end  174  of the electrical socket  128 , a continuous electrical connection is established between the electrosurgical generator  26  and the electrode (not shown) within the nozzle  46  of the accessory  22  ( FIG. 1 ). Electrical energy generated by the electrosurgical generator is conducted through the RF supply conductor  32  to the electrical terminal  158  and the connected electrical socket  128  of the female mating piece  36 . The connector electrode  92  of the male mating piece  38  receives the electrical energy from the electrical socket  128  and transfers it through the accessory conductor  48  to the electrode (not shown) within the nozzle  46  of the handpiece  42  ( FIG. 1 ). 
   The forward movement of the hub member  54  moves the O-ring  88  into the recess  129  in the outer end of the hollow sleeve  118 . The O-ring  88  is compressed between the cylindrical sidewall  130  of the recess  129  and the sleeve-like extension  90  of the spool-like body portion  76  of the hub member  54  ( FIG. 14 ). In this compressed state, the gas seal O-ring  88  confines the gas flowing from the interior  122  of the hollow sleeve  118  into the gas passageway  86  of the hub member  54 . The gas from the gas delivery apparatus  28  flows through the supply conduit  34  to and through the gas connection tube  154 , the interior chamber  164 , and into the interior  122  of the sleeve  118  of the female mating piece  36 . Because of the gas seal obtained by the O-ring  88 , the entire amount of gas flow is transferred from the interior  122  of the sleeve  118  into the gas passageway  86  of the spool-like portion  76  and into the stub portion  84  of the male mating piece  38 . The gas flows from the stub portion  84  and into the accessory hose  44  to the nozzle  46  of the handpiece  42  ( FIG. 1 ). 
   Establishing the gas-tight seal does not depend upon the male mating piece  38  being screwed into the female mating piece  36  to the maximum extent possible. Instead, the seal created by the O-ring  88  remains gas tight so long as the O-ring  38  is compressed against the cylindrical sidewall  130 , as shown in  FIGS. 13 and 14 . The O-ring  88  maintains the gas-tight seal through the accessory connector  20  even if the male mating portion  38  becomes slightly loosened from the female mating portion  36 . A slight axial separation of the mating pieces does not destroy the gas-tight seal until enough axial movement has occurred to withdraw the O-ring  88  from contact with the cylindrical sidewall  130 . Therefore, if the male mating piece  38  is bumped or otherwise loosened, the gas-tight seal will not necessarily be lost. 
   Because the force created by the resilient compression of the O-ring  88  is radial, its resilient compression force does not push the mating pieces  36  and  38  away from one another to establish a leak, as is possible in the prior art form of the accessory connector shown in  FIG. 16 . Rather, the radial force from compression of the O-ring  88  frictionally helps to resist the separation of the mating pieces. 
   The ability to tolerate a slight amount of separation of the mating pieces  36  and  38  is contrasted to the prior art arrangement shown in  FIG. 16 . Instead of the cylindrical recess  129  which creates the cylindrical sidewall  130  ( FIGS. 9 ,  13  and  14 ) to establish the radial compression seal, the prior art female mating piece  36 ′ has a frustoconically shaped surface  180  located at the outer end of the hollow sleeve like member  118 ′. The O-ring  88  contacts the frustoconically shaped surface  180  principally in axial compression. Consequently, any slight loosening of the mating pieces, such as might result from the natural movement of the accessory during the surgical procedure or as a result of accidentally bumping or jostling the accessory, causes a slight axial separation of the O-ring  88  from the frustoconically shaped surface  180 , thereby creating a gas leak. Consequently, the gas-tight seal can only be maintained so long as the mating pieces are completely and tightly connected. Since movement of the accessory  22  ( FIG. 1 ) during the surgical procedure is persistent, thereby creating the possibility of slightly loosening the connection of the mating pieces, the radial seal established by the O-ring  88  within the recess  129  ( FIGS. 9 ,  13  and  14 ) maintains the improved gas-tight seal. 
   In addition to maintaining an improved gas-tight seal, the accessory connector  20  inhibits unscrewing the mating pieces  36  and  38  by the use of the outward-biased metal ball  138  which interacts with the detents  74  formed on the forward edge  75  of the large cylindrical end portion  56  of the sleeve-like member  52 , as shown in  FIGS. 13 and 15 . As the large cylindrical end portion  56  of the sleeve member  52  moves forward and inwardly into the receptacle  112 , the forward edge  75  contacts the ball  138  at the outer end  136  of the channel  134 . The forward edge  75  pushes the ball  138  inwardly against the biasing spring  140  due to the forward advancement of the sleeve member  52 . After the sleeve member  56  has been screwed into the receptacle  112  to a certain extent, a forwardmost portion  182  of the forward edge  75  between the detents  74  begins contacting and transversing across the ball  138 . The ball  138  moves from one forwardmost portion  182  into an adjoining detent  74 , as the sleeve member  52  rotates. As the sleeve member  52  continues to advance forwardly, the spring  140  is compressed more by the forwardmost portions  182  of the front edge  75 , and the ball  138  is biased more deeply into the detents  74 . As the ball  138  is forced more deeply into each detents  74 , more rotational force is required to push the ball  138  out of each detent  74  by rotating the sleeve member  52 . The maximum forward advancement of the sleeve member  52  is limited by the surface  93  of the hub member  54  coming into contact with the surface  131  of the sleeve  118  as shown in  FIGS. 13 and 14 . The rotation of the sleeve member  52  stops when the ball  138  is pushed inwardly into a detent  74  by the bias force from the compressed spring  140 . 
   The bias force from the spring  140  which pushes the ball  138  into a detent  74  creates resistance to the rotation of the sleeve member  52 . To rotate the sleeve member  52  after the ball  138  has been positioned in a detent  74 , the bias force from the spring  140  must be overcome by pushing the ball  138  inwardly so that the ball  138  moves out of the detent  74 . The sleeve member  52  must be gripped and significant force applied to rotate it and overcome the bias force from the spring  140  to move the ball  138  out of the detent  74 . The amount of force required is significant. The typical jostling and continued movement of the accessory hose  44  during the course of the surgical procedure is insufficient to create enough force to rotate the sleeve member  52  and push the ball  138  out of the detent  74  in opposition to the bias force from the spring  140 . The opposition force from the bias spring  140  therefore prevents or substantially inhibits the sleeve member  52  of the male mating piece  38  from unintentionally loosening and unscrewing out of the receptacle  112  of the female mating piece  36 . 
   The resistance created by the compressed bias spring  140  and the ball  138  assists in preventing the male mating piece from inadvertently unscrewing from the female mating piece. However, even if the male mating piece does unscrew slightly from the female mating piece, or is not completely tightened when the connection is initially established, the radial compression of the gas seal from the O-ring  88  still maintains a fluid tight seal. The resistance to unscrewing the male mating piece from the female mating piece can be overcome to disconnect the male mating piece  38  from the female mating piece by firmly gripping the smaller cylindrical end portion  58  of the sleeve member  52  and rotating the sleeve member  52 . Thus, although the male mating piece is inhibited from unintentionally loosening, the inhibition is not so great as to prevent disconnecting the female and male mating portions. Other significant improvements will become apparent upon recognizing the significance of the present invention. 
   A presently preferred embodiment of the present invention and many of its improvements have been described with a degree of particularity. This description is a preferred example of implementing the invention, and is not necessarily intended to limit the scope of the invention. The scope of the invention is defined by the following claims.