a diagrammatic representation of a laparoscopic tissue resection system 10 is shown in fig1 . system 10 operates in conjunction with a conventional insufflator 12 which provides pressurizing fluid to a patient 14 in a conventional manner . while the preferred embodiment utilizes co 2 , it will be understood that a suitable fluid medium other than co 2 could also be used within the scope of this invention . system 10 comprises a powered resection system 20 further comprising a drive console 22 connected by an electrical cable 24 to a handpiece 26 . the handpiece includes a rotatable motor ( not shown ) which may be controlled by a foot switch 28 or by switches directly located on the handpiece ( not shown ). as best seen in fig2 handpiece 26 is adapted to receive a laparoscopic shaver blade assembly 30 which is preferably disposable and selectively attachable to the distal end of handpiece 26 . while in an alternate embodiment handpiece 26 and shaver 30 may be conventional , single - lumen arthroscopic - type components , in the preferred embodiment shown in fig1 and 2 , shaver 30 is a dual - lumen device comprising an elongated hollow outer tube 32 having a proximal end 34 attached to the distal end of handpiece 26 and a distal end 36 provided with a window opening 38 . an elongated hollow inner tube 40 is rotatably received within the interior of outer tube 32 such that its proximal end 42 is detachably secured to a rotating drive within the handpiece ( not shown ) and its distal end 44 is provided with a cutting edge . the hollow interior 50 of the inner member is one lumen and is joined to an aspirating channel 52 within the handpiece which , as will be understood below , is connected to a vacuum source . shaver 30 also comprises a gas return channel 60 -- the second lumen -- having a proximal end 62 joined to a channel 64 within the handpiece and a distal end 66 having an opening 68 . in the preferred embodiment , gas return channel 60 is formed as an integral part of outer tube 32 and handpiece 26 is provided with both inflow and outflow channels . the extra gas inflow channels in the handpiece and the shaver blade assembly distinguish the laparoscopic shaver system disclosed herein from a conventional arthroscopic shaver system . laparoscopic tissue resection system 10 also comprises a pressure maintenance system 70 which has a pump console 72 for driving and controlling a peristaltic pump 74 . pump 74 is attached to handpiece 26 via a gas outflow line 76 joined at its distal end to aspiration channel 52 within the handpiece . the proximal end of line 76 is connected to a suction canister and the output side of the suction canister is connected via an inflow line 80 to the rollers of the peristaltic pump . the other end of line 80 continues beyond the rollers and becomes inflow line 82 connected to the gas inflow channel 64 within handpiece 26 . it will be understood that suction canister 78 retains any tissue debris carried by the gas aspirated from the body while permitting the gas to circulate through the pump tubing . a filter ( not shown ) may be included , if necessary , to reduce any particulate matter in the gas although , since there is no return to the insufflator there is little or no need to filter the gas prior to its return ( depending upon the suction canister design and operation ). the laparoscopic shaver assembly 30 generally passes through a cannula 84 which serves as the entryway through a body portal . as best seen in fig3 in the preferred embodiment cannula 84 has an annular seal 86 at its proximal end and simply provides a passageway for shaver 30 . while in this embodiment the gas inlet return back into the body cavity is via opening 68 at the distal end of shaver 30 , the alternate embodiment described below with respect to fig4 and 5 actually utilizes the body of the cannula as the gas return line . one advantage of system 10 is that a conventional cannula may be used since the remaining components comprise a self - contained system having all of the elements needed to recirculate the gas to maintain pressure in the body cavity . the alternate embodiment shown in fig4 is a laparoscopic tissue resection system 100 which is in many respects identical to system 10 shown in fig1 . thus , a powered resection system 120 having a console 122 , an electric cable 124 and handpiece 126 is utilized to provide powered resection . the shaver blade assembly 128 attached to the handpiece is identical to the dual lumen structure of shaver 30 although the gas inflow channel which was used in the shaver 30 for returning gas to the body cavity may be connected via handpiece 128 to an optional irrigation fluid source 130 joined to the inflow channel via line 132 . a surgeon could utilize this irrigation fluid either continually or selectively ( if controlled by a valve , not shown ) to clean the resection site during the procedure . the spent irrigating fluid and the tissue debris and gas within the body cavity would then be aspirated through the handpiece via suction line 140 to a pump 142 as in the previous embodiment . in this embodiment , however , the return line 144 from the pump is connected directly to the input port 146 of inflow cannula 150 , best seen in fig5 . port 146 is in fluid communication with an outlet port 148 at the distal end of the cannula ( downstream from any seal between the cannula and the blade assembly ). the use of inflow cannula 150 enables system 100 to utilize a dual - lumen laparoscopic shaver blade assembly 128 and handpiece 126 or a conventional single - lumen arthroscopic shaver blade assembly 128a and handpiece 126a . since conventional arthroscopic type shaver blades and handpieces do not normally have a separate gas inflow channel , it will be understood that in such a configuration , handpiece 126a and shaver blade assembly 128a would not enable use of the optional irrigation fluid via line 132 . it will also be understood that a dual - lumen shaver blade assembly may be created by modifying a single - lumen assembly to utilize the annular space between the inner and outer members as one of the lumens , as more fully described in a co - pending application assigned to the assignee hereof and incorporated by reference herein . a peristaltic pump has the advantage of facilitating the control of the volume of gas removed from the body cavity . thus , the control system of the pump can control the pump speed to provide the desired vacuum . the volume of gas removed from the suction line is simply transferred to the inflow line thus minimizing the change in pressure in the body cavity . internal communications between the pump and the handpiece drive console adjusts the speed of the pump accordingly . increased speed of the shaver blade will resect tissue at a faster rate than a slower speed and will result in increased suction on the resected tissue , thus requiring faster pump operation . it will be understood that numerous modifications and improvements may be made to the preferred embodiment of the invention disclosed herein without departing from the spirit and scope thereof .
a powered tissue resection system for use during endoscopic surgical procedures in which a body cavity is filled with a gas medium to maintain pneumoperitoneum . a powered tissue resection device is utilized to simultaneously resect and aspirate tissue from the surgical work site within the gas - filled body cavity . along with the aspirated tissue a portion of the ambient fluid medium is aspirated . a separating means is provided to separate the resected tissue and other debris from the fluid medium , generally carbon dioxide , and return the latter to the body cavity to maintain pneumoperitoneum .