Electrosurgical Instrument With Extendable Sheath for Irrigation and Aspiration

1. Field of the Invention

This invention relates generally to the design of electrosurgical instruments and more particularly to a monopolar or bipolar electrosurgical instrument having an extendable lumen which permits selective irrigation and aspiration of the treatment region. In one embodiment, a sheath is reciprocally moveable in relation to the main housing of the electrosurgical instrument and features at least one pressure release port at its distal end to reduce the amount of suction provided to tissue. In an alternative embodiment, a tubular housing having at least one distal electrode extending therefrom is reciprocally movable within a stationary, external sleeve.

2. Discussion of the Prior Art

Monopolar and bipolar electrosurgical instruments typically include an electrode extending from a distal end of a rigid or flexible tube. In these instruments, it is desirable to include a lumen with a distal exit port positioned near the electrodes to supply irrigation fluid and to aspirate that fluid and debris from the region. Although electrodes used on these instruments are configured for optimal contact with tissue, the fact that they generally project outwards makes it difficult to manipulate the distal end of the device to position an irrigation/aspiration port adjacent to tissue, in order to selectively flush one area of a treatment region or to aspirate blood or bodily fluids from the region. Although it is common to include a suction or irrigation lumen within such instruments, the port is often displaced too far from tissue to be optimally effective. This obstruction occurs even when the electrodes are specially dimensioned to enhance irrigation and aspiration. Furthermore, these instruments are typically inserted through the lumen of a laparoscopic trocar or endoscope, within which the protruding electrodes may be damaged as the instrument is negotiated through bends and curves in the lumen.

The present invention solves these problems presented in the prior art by providing a retractable or extendable sleeve or sheath which may be extended distally in relation to the surface holding the electrodes and which, when extended, encompasses the electrode housing and electrodes of the electrosurgical instrument. When extended, the sleeve protects the electrodes during insertion and also functions as an extension of the suction and irrigation port. Thus, when extended, the point at which suction takes place is provided closer to the actual treatment site than was possible using prior art instruments. Alternatively, the housing on which the electrodes are mounted may be retracted into a stationary sleeve, again enabling the orifice of the irrigation/aspiration tube to be effectively placed nearer a treatment region than was possible in the prior art.

It is accordingly a principal object of the present invention to provide a new and improved electrosurgical instrument for insertion into a laparoscopic trocar or endoscope.

Another object of the present invention is to provide a new and improved apparatus for irrigation and aspiration of a treatment region featuring a retractable and extendable sheath to enable application of irrigation and aspiration nearer a treatment region.

It is yet another object of the present invention to provide a new and improved apparatus for irrigation and aspiration of a treatment region featuring a retractable and extendable electrode housing which may be withdrawn into a stationary sheath to enable application of irrigation and aspiration nearer a treatment region.

A further object of the present invention is to provide a new and improved apparatus for attaining a level of controlled suction which will not damage tissue by grasping it too strongly.

A still further object of the present invention is to provide a new and improved apparatus having a sheath which acts as a protective sleeve as the instrument is inserted through a laparoscopic trocar or endoscope.

The present invention provides an electrosurgical instrument having an extendable protective sleeve or sheath which encompasses the distal end of the instrument to protect its electrodes as the instrument is fed through a laparoscopic trocar or endoscope and to provide an effective extension of an irrigation/aspiration lumen. Extension of this sheath in the distal direction moves it to a position which encompasses or shields the electrodes. Extension of the sheath also provides a tube through which irrigation fluid may be directed or which provides suction at a precise site. Thus, the protruding electrodes no longer interfere with the efficacy of aspiration or irrigation of the treatment region as they do in prior art devices. A plurality of small holes dispensed along the sleeve provide relief during aspiration so that the tissue is not grasped too strongly while being treated.

Alternatively, the housing on which the distal electrodes are mounted may be retracted into a relatively rigid stationary sleeve. In either embodiment, the protruding electrodes no longer interfere with placement of the irrigation/aspiration port into the treatment region.

The aforementioned objects and advantages of the invention will become subsequently apparent and reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part thereof, wherein like numerals refer to like parts throughout.

FIG. 1 shows a cross-sectioned view of a prior art electrosurgical instrument;

FIG. 2 shows a partial, side elevation view of a preferred embodiment of the present invention;

FIG. 3 shows a partial, cross-sectioned side view of the embodiment of FIG. 2;

FIG. 4 shows a partial, cross-sectioned side view of a bipolar electrode distal tip arrangement including the present invention; and

FIG. 5 shows a partial, cross-sectioned side view of an alternative embodiment of the present invention.

FIG. 1 shows a partial, cross-sectioned view of a prior art electrosurgical instrument having at least one electrode extending from a distal surface. This electrosurgical instrument, generally depicted as 10, typically includes a tubular member 12 having a proximal end 14 and a distal end 16. Extending from a distal surface 18 is at least one conductive electrode 20 having a flexible conductor means 22 extending from an RF voltage source (not shown). A lumen 24 extends through tubular member 12 and terminates at a distal port 26 in the region of electrode 20 on distal surface 18. The port 26 is used for irrigation and aspiration of the treatment region. Irrigation is necessary to periodically cleanse the treatment region with fluid from a reservoir (not shown). Aspiration is necessary to remove blood and bodily fluids from discrete regions of the tissue surface before treatment can continue. Although placed near electrode 20 in prior art devices, the irrigation/aspiration port 26 is nevertheless generally displaced too far from the tissue to be treated to be optimally effective. In other words, more accurate placement of the irrigation/aspiration port is frequently desired but not attainable due to obstruction caused by the projecting electrodes 20. For example, interference from the projection of the electrode permits only general flushing of the surrounding tissue, not selective flushing of a precise site.

FIG. 2 shows an electrosurgical instrument 30 constructed in accordance with the present invention. It incorporates a protective sheath 32 rigidly affixed to an extender member 34 mounted on a housing 36. Distal and proximal movement of extender member 34 causes sheath 32 to be displaced distally or proximally. Thus, extender member 34 may be displaced proximally, as indicated at 38 (in shadow), to withdraw the distal end 40 of sheath 32 to a proximal position 42. Extending from the underside of housing 36 is a hand grip 44 enclosing a tubular aspiration/irrigation member (FIG. 3). Extending from the proximal end of housing 36 is a power cord 46 having a plug 48 which is adapted to be joined to a conventional RF voltage source (not shown) to energize the electrosurgical instrument. A power switch, generally designated 50, controls voltage supply to the instrument in the known manner. For example, when knob 52 is positioned at proximal location 54, the instrument is turned off, but when it is positioned distally (56, in shadow), it is turned on. Alternatively, it may be controlled by a conventional foot switch (FIG. 5). One or more ports 82 are disposed at the distal end of sheath 32 to moderate the amount of suction through the sleeve, as discussed more fully hereinafter.

FIG. 3 shows a plan, cross-sectional view of the electrosurgical instrument of FIG. 2. In this view, it is apparent that sheath 32 is generally tubular shaped, having a proximal end 58 and a distal end 60. Sheath 32 is preferably formed of semi-rigid plastic material. It is also apparent from this view that sheath 32 surrounds cylindrical rod 62. Rod 62 is preferably also formed from a rigid plastic and includes an insulating distal surface 64, having at least one electrode 66 extending therefrom. Electrode 66 is preferably a hook-shaped tungsten, tungsten alloy or stainless steel rod or tube, but its distal end may be formed in a variety of shapes, as disclosed in the co-pending application Ser. No. 07/728,337, assigned to applicant's assignee. A lumen 68 is molded, drilled or otherwise formed lengthwise through the rod to receive the straight leg portion 70 of the electrode 66, which is joined at its proximal end 72 to a wire 74. The wire 74 joins electrode 66 to switch 50 and, thus, to RF power (not shown). Rod 62 further includes a suction and/or irrigation lumen 76 which extends the full length of the rod 62. At the distal end of suction/irrigation lumen 76 is an entry/exit port 78.

At its proximal end, the irrigation/aspiration lumen 76 is joined to a tubular fluid delivery lumen 80, which extends to a fluid source (not shown). This same source can also be used as a reservoir to collect aspirate.

Positioned near the distal end of sheath 32 is at least one pressure relief port 82. Although a preferred placement that would suffice for most applications requires that two of these ports be placed at a radial distance of about 180.degree., it is envisioned that as few as one port or as many as permitted without compromising the structural integrity of the sheath 32 may be required for some applications. It is suggested that these ports have a diameter of approximately 30/1000 of an inch, although one skilled in the art will recognize that the particular application will determine the desirable port size and number. The ports 82 provide relief so that suction is not applied to the surrounding tissue with too much force, causing tissue damage by grasping the tissue too strongly.

In the view of FIG. 3, the internal construction of extender member 34 becomes apparent. Its cylindrical internal surface 84 further includes voids 86 and 88 dimensioned for receiving detents 90 and 92. In a retracted, proximal position, void 86 mates with detent 90 and void 88 mates with detent 92. In an extended, distal position, void 86 mates with detent 92 and void 88 is not occupied. An O-ring 94 of rubber or other elastomeric material provides a pneumatic seal between sheath 32 and rod 62. Preferably, the O-ring 94 is positioned at the distal end of rod 62 to prevent leakage toward extender member 34.

FIG. 4 is included to demonstrate that the irrigation/aspiration sheath of the present invention may be used with most commonly practiced tip embodiments. In particular, a pair of bipolar electrodes 96 and 98 are shown encompassed within sleeve or sheath 100 and joined to conductors 102 and 104. Sleeve or sheath 100 is analogous in construction to sheath 32. In this embodiment, irrigation/aspiration port 106 is positioned at the distal end of lumen 108. Lumen 108 mates with a fluid delivery means, in a manner similar to the embodiments of FIGS. 2 and 3.

In operation, the extender member 34 is advanced distally until detent 92 is locked within void 86, and electrode 66 is surrounded and shielded by distal end 60 of the sheath. This end is then inserted into a laparoscopic trocar or endoscope until it is positioned within a body region to be treated. Prior to application of RF voltage to electrode 66 as previously described, the sheath 32 must first be retracted, as at 42 in FIG. 2, whereupon detent 90 is locked within void 86. After tissue has been electrosurgically treated and it is desired to, for example, flush the treatment region to remove debris, the extender member 34 is again moved distally, causing sheath 32 to encompass electrode 66. Fluid is withdrawn from a reservoir (not shown) and projected through tubular fluid delivery lumen 80 and through lumen 76, then emitted through port 78, whereupon it flows freely through the treatment region.

It is frequently desired at this time to aspirate the flush fluid from the region. Fluid delivery lumen 80 is then connected to a suction source (not shown), Whereupon flush fluid and debris is withdrawn into the distal end 60 of sheath 32, and through port 78, lumen 76, and tubular fluid delivery means 80 into a conventional reservoir (not shown). The sheath 32 may then be withdrawn by proximal movement of extender member 34 to once again expose the electrode 66 to enable further electrosurgery.

In applications such as those previously described, one skilled in the art will recognize that in addition to regulating the degree of suction applied to a treatment region, the ports 82 also aid in dispersal of flush fluid as it exits the irrigation/aspiration port 78.

FIG. 5 shows a cross-sectional view of an alternative embodiment of the present invention, generally designated 110. As with the embodiment of FIGS. 2 through 4, it may be included on a monopolar or a bipolar instrument. A rigid plastic protective sleeve 112, having a distal end 114 and a proximal end 116, is secured to a housing 118. A cylindrical rod 120 supports at least one electrode 122, which extends from the rod at a distal surface 124. At its proximal end, the rod 120 is joined to an extender member 126. Distal movement of the extender member 126 within slot 128 shifts the proximal end of the rod 120 from a proximal position 130 to a distal position 132, until the distal surface 124 aligns with the opening 134 at the distal end 114 of the sleeve, thus enabling electrode 122 to protrude from within sleeve 112.

The electrode 122 may be formed from tungsten, tungsten alloy, or a curved stainless steel rod or tube, which is inserted into a lumen 136 drilled or otherwise formed lengthwise within rod 120. As described previously for the embodiment of FIGS. 2 through 4, the electrode 122 is likewise joined at 138 to a conductive wire 140. Wire 140 is joined to power supply cord 142, leading to a source of RF voltage 144. Power supply may be controlled by a conventional foot switch 146, or by a hand switch (not shown), as described in reference to FIG. 2. An irrigation/aspiration lumen 148 is also drilled or formed lengthwise through rod 120 from an open end 150. The proximal end of lumen 148 is joined to a tubular fluid duct 152, connected to a container 154, which may alternatively be a fluid reservoir or an aspirate receptacle. An elastomeric O-ring 156 prevents leakage between rod 120 and sleeve 112. Preferably, O-ring 156 is formed from silicone rubber.

The electrosurgical instrument of the present invention can be fabricated from a variety of available materials. For example, various medical grade plastics may be employed in molding the housings 36 and 118, with polycarbonate being preferred. The tubular sleeves 32 and 112 may be extruded polyethylene, polyurethane, polypropylene or Teflon.PHI., with Teflon being preferred. The electrode conductors 74, 102, 104 and 140 are preferably formed from braided strands of stainless steel, although other materials may be used as well. They may be isolated from one another in traversing the length of the rods 62 and 120, but if not isolated, they must themselves be coated with an insulator.

This invention has been described herein in considerable detail in order to comply with the Patent Statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components as are required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices and that various modifications, both as to equipment details and operating procedures, can be accomplished without departing from the scope of the invention itself.