Abstract:
A fluid management system receives fluid from a fluid source and delivers the fluid to a medical probe having a first fluid infusion and aspiration circuit and a second fluid infusion and aspiration circuit. The system also transfers fluid from the medical probe to a collection container. A controller operates a first pump and valve assembly to selectively deliver fluid inflow from the fluid source to one of the first fluid infusion and the second fluid infusion and aspiration circuit. The controller further operates a second pump and valve assembly to selectively transfer fluid outflow to the collection container from one of the first fluid infusion and aspiration circuit of the medical probe and the second fluid infusion and aspiration circuit of the medical probe.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of and priority to Provisional Application No. 62/107,953 (Attorney Docket No. 37644-712.101), filed Jan. 26, 2015, the entire content of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to fluid management systems and devices for resecting and removing tissue from the interior of a patient&#39;s body, for example in a transurethral resection of prostate tissue to treat benign prostatic hyperplasia. 
         [0003]    Many electrosurgical and other minimally invasive procedures are performed though endoscopes which introduce an electrosurgical tool to target tissue via a body lumen or cavity. For example, prostate tissue resection may be performed using an electrosurgical resection tool which is placed using an endoscope located via the urethra. In such instances, it is often necessary to introduce saline or another fluid both to the body lumen in to create a working space and provide visibility and to the working end of the resection tool to enhance resection and/or collect debris. 
         [0004]    Heretofore, fluids have often been introduced using a saline drip to the body lumen and/or the tissue resection area. The use of saline drips is simple but often lacks a degree of control and accountability that would be desirable. Active pumping systems have also been proposed, but such systems are frequently complicated and bulky, and often two separate pumping systems are needed to deliver separate fluid flows to the body lumen/cavity and to the tissue resection area. 
         [0005]    For these reasons, it would be desirable to provide improved and alternative fluid management systems and methods which can be compact, easy to operate, and which minimize the need for redundant hardware. It would further desirable if such systems and methods allowed a simplified ability to keep track of fluid accumulation in the patient. At least some of these objectives will be met by the inventions described and claimed below. 
       SUMMARY OF THE INVENTION 
       [0006]    In a first aspect of the present invention, a fluid management system is configured to receive fluid from a fluid source, to deliver fluid to a medical probe having a first fluid infusion and aspiration circuit and a second fluid infusion and aspiration circuit, and to transfer fluid from the medical probe to a collection container. The fluid management system comprises a first pump and valve assembly, a second pump and valve assembly, and a controller. The controller is configured to operate the first pump and valve assembly to selectively provide fluid inflow from the fluid source to one of the first fluid infusion and aspiration circuit of the medical probe and the second fluid infusion and aspiration circuit of the medical probe. The controller is further configured to operate the second pump and valve assembly to selectively transfer fluid outflow to the collection container from one of the first fluid infusion and aspiration circuit of the medical probe and the second fluid infusion and aspiration circuit of the medical probe. 
         [0007]    In a first specific embodiment of the fluid management system, the pump of the first pump and valve assembly is operable to reverse flow direction and the valves of the first pump and valve assembly include a pair of one-way valves oriented to provide inflow to the pump from the fluid source in both flow directions. A pump of the second pump and valve assembly may also be operable to reverse flow direction where the valves of the second pump and valve assembly include a pair of one-way valves oriented to provide outflow from the pump to the first fluid infusion and aspiration circuit of the medical probe when the pump is operated in a first flow direction and to provide outflow from the pump to the second fluid infusion and aspiration circuit of the medical probe when the pump is operated in a second flow direction. The one-way valves are adapted to direct fluid flows between first and second flow paths in response to the first and second flow directions established by the pumps. 
         [0008]    In an alternative specific embodiment of the fluid management system, the pumps of the first and second pump and valve assemblies are each operable to deliver flow in a single flow direction and the valves of the first and second pump and valve assemblies include three-way valves that are selectively positionable by the controller to (1) deliver fluid inflow from the fluid source to one of the first fluid infusion and aspiration circuit of the medical probe or the second fluid infusion and aspiration circuit of the medical probe and to (2) provide fluid outflow to the collection container from one of the first fluid infusion and aspiration circuit of the medical probe and the second fluid infusion and aspiration circuit of the medical probe. 
         [0009]    In still other embodiments of the fluid management system of the present invention, the controller may be further configured to maintain a fluid operating parameter delivered by the fluid management system within a pre-determined range. The fluid operating parameter may consists of a first pump speed, a second pump speed, and a targeted pressure delivered to the first fluid infusion and aspiration circuit of the medical probe. The fluid operating parameter may be established by a first pump speed, a second pump speed, and a targeted pressure delivered to the second fluid infusion and aspiration circuit of the medical probe. 
         [0010]    In yet further embodiments of the fluid management system of the present invention, the first and second pumps are peristaltic pumps, and the peristaltic pumps may be operable in a first rotational direction to deliver fluid inflow and collect fluid outflow from the first fluid infusion and aspiration circuit of the medical probe. The pumps will usually also be operable in a second rotational direction to deliver fluid inflow and collect fluid outflow from the second fluid infusion and aspiration circuit of the medical probe. The first and second pump and valve assemblies may include tubing sets that carry the valves, and the valves may be one-way valves. 
         [0011]    The fluid management systems of the present invention may be incorporated into minimally invasive surgical systems which further comprise a viewing scope having a working channel and including the first fluid infusion and aspiration circuit. Such minimally invasive surgical systems may also comprise a surgical tool configured to be introduced through the working channel of the viewing scope and including the second fluid infusion and aspiration circuit. 
         [0012]    In a second aspect of the present invention, an electrosurgical resection method for treating a patient&#39;s prostate comprises (1) providing a fluid management wherein a pump system circulates fluid in a first path through a transurethral device to allow endoscopic viewing within the prostate urethra and (2) providing a fluid management wherein a pump system circulates fluid in a second path to through a transurethral device to assist in electrosurgical tissue resection. The first and second providing steps may provided by first and second independent fluid management systems or, alternatively, may be provided by a single fluid management system configured to operate in first and second modes. 
         [0013]    In a third aspect of the present invention, an electrosurgical method for resecting a patient&#39;s tissue comprises establishing an inflow of fluid using a first pump and establishing an outflow of fluid using a second pump. The inflow of fluid from the first pump is directed both to a viewing scope in a patient lumen or body cavity and to a resection tool engaged with target tissue. The outflow of fluid from the viewing scope in the patient lumen or body cavity as well as from the resection tool engaged with the target tissue is collected using the second pump. In specific embodiments of the electrosurgical methods, the inflow of fluid is selectively directed to the viewing scope by operating the first pump in a first flow direction and to the resection tool by operating the first pump in a second flow direction. The outflow of fluid may be selectively collected from the viewing scope by operating the second pump in a first flow direction and from the resection tool by operating the second pump in a second flow direction. Typically, the first pump comprises a rotary peristaltic pump configured to be selectively driven in first and second rotational directions, and the second pump comprises a rotary peristaltic pump configured to be selectively driven in first and second rotational directions. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0014]      FIG. 1  is a side view of a tissue resecting probe and block diagram of systems and operating components corresponding to the invention. 
           [0015]      FIG. 2  is a perspective view of the working end of the resecting probe of  FIG. 1  showing the inner resecting sleeve in a proximal or retracted position providing a window-open position. 
           [0016]      FIG. 3  is another perspective view of the working end of the resecting probe of  FIG. 1  showing a resilient element that interfaces with the reciprocating inner sleeve at the distal end of its stroke. 
           [0017]      FIG. 4A  is a sectional view of the working end of  FIG. 2  with the reciprocating resecting sleeve in a proximal position at the beginning of its stroke in a window-open position. 
           [0018]      FIG. 4B  is a sectional view of the working end as in  FIG. 4A  with the reciprocating resecting sleeve in a distal position at the end of its stroke in a window-closed position. 
           [0019]      FIG. 5A  is a sectional view of the shaft of the probe of  FIG. 1  taken along line  5 A- 5 A of  FIG. 4A . 
           [0020]      FIG. 5B  is a sectional view of the shaft of the probe of  FIG. 1  taken along line  5 B- 5 B of  FIG. 4A . 
           [0021]      FIG. 6A  is a longitudinal sectional view of the shaft and handle of the probe of  FIG. 1  showing the motor and drive mechanism with the resecting sleeve at the beginning of its stroke in a window-open position. 
           [0022]      FIG. 6B  is an enlarged sectional view of the working end of  FIG. 6A  with the resecting sleeve at the beginning of its stroke. 
           [0023]      FIG. 7A  is a longitudinal sectional view of the shaft and handle as in  FIG. 6A  showing the motor and drive mechanism with the resecting sleeve at the end of its stroke in a window-closed position. 
           [0024]      FIG. 7B  is an enlarged sectional view of the working end of  FIG. 7A  with the resecting sleeve at the end of its stroke. 
           [0025]      FIG. 8  is an enlarged sectional view of the distal portion of the window of the working end of  FIGS. 2-3 . 
           [0026]      FIG. 9  is an illustration of a method of using a device similar to that of  FIG. 1  in a tissue resection procedure in a patient&#39;s prostate, wherein the resection is initiated within the urethra. 
           [0027]      FIG. 10  is an illustration of an alternative method of using the device of  FIG. 1  in a tissue resection procedure in a patient&#39;s prostate wherein the distal end is penetrated into the lobe of the prostate. 
           [0028]      FIG. 11  is a representation of a method of fluid management with the device of  FIG. 1  in an interstitial tissue resection procedure in a patient&#39;s prostate. 
           [0029]      FIG. 12A  is a diagram of a fluid management system employing bidirectional flow pumps for use with the device of  FIG. 1  that is operating in a first mode to provide fluid flows to a first working space. 
           [0030]      FIG. 12B  is a diagram of the fluid management system of  FIG. 12A  that is operating in a second mode to provide fluid flows to a second working space. 
           [0031]      FIG. 13A  is a diagram of an alternative embodiment of the fluid management system employing three-way valves for use with the device of  FIG. 1  that is operating in a first mode to provide fluid flows to a first working space. 
           [0032]      FIG. 13B  is a diagram of the fluid management system of  FIG. 13A  that is operating in a second mode to provide fluid flows to a second working space. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0033]      FIGS. 1-3  illustrate an electrosurgical tissue resecting system  100  that includes a hand-held single-use tissue resecting device or probe  105 . The device  105  has a handle portion  108  that is coupled to an elongated shaft or extension portion  110  that has an outer diameter ranging from about 2 mm to 5 mm. In one variation, the device is adapted for performing a TURP procedure (transurethral resection of the prostate) and the shaft portion  110  extending about longitudinal axis  112  can have a length suitable for introducing though an endoscope or cystoscope to thereby access a male patient&#39;s prostate to resect and remove tissue. 
         [0034]    Referring to  FIG. 1 , it can be seen that the handle  108  carries an electric motor  115  for reciprocating or rotating a resecting element, which in the variation of  FIG. 1-3  is an inner sleeve  120  that reciprocates in a passageway  122  defined within the interior of an outer sleeve  125  to resect tissue interfacing window  128  in the outer sleeve. Resected tissue slugs are captured in channel  132  in inner sleeve  120  and can be extracted or moved in the proximal direction in the channel by both positive and negative pressures on either side of the tissue slug as will be described below.  FIGS. 2-3  illustrate the working end  140  of the resecting device  105  with the moveable inner resecting sleeve  120  in a retracted position relative to window  128 . The motor  115  in handle  108  is operatively coupled to an electrical source  145  and controller  150  by electrical cable  152 . The controller  125  can include algorithms adapted to control motor voltage which in turn can control the speed of reciprocation or rotation of the resecting sleeve  120  as will be described below. 
         [0035]    Still referring to  FIG. 1 , the system  100  includes an RF source  155  operatively coupled by cable  158  to first and second opposing polarity electrodes  160 A and  160 B in the working end  140  ( FIG. 2 ). The distal end  162  of inner sleeve  120  comprises a first or active electrode  160 A which is adapted to form an electrosurgical plasma for resecting tissue as is known in the art. The second or return electrode  160 B can comprise a medial portion of outer sleeve  125  and/or the distal tip component of the shaft portion  110 . 
         [0036]      FIG. 1  further illustrates that the system  100  includes a remote fluid source  165  which has flow line  166  extending to a coupling  168  in handle  108 . The fluid source  165  can comprise a bag of saline and flow line  166  is in fluid communication with a flow channel  170  in the shaft portion  110  to carry fluid through to handle  108  to the working end  140  by means of a pump mechanism  175  carried in the handle  108  ( FIG. 4A ). 
         [0037]      FIG. 1  also shows that the system  100  has a remote negative pressure source  180  that has suction line  182  that couples to fitting  184  in the handle  108 . The negative pressure source  180  communicates with a tissue-extraction channel  132  in the resecting sleeve  120  for assisting in extracting tissue from the site of the resection, for example in the patient&#39;s prostate (see  FIGS. 9-10 ) 
         [0038]    As can be understood from  FIG. 1 , the controller  150  includes algorithms for operating and modulating the operating parameters of the subsystems, including the RF source  155 , the fluid source  165  and associated pump mechanism  175 , the negative pressure source  180  and the motor  115  via motor voltage. As will be described below, in some operating modes, the controller  150  may adjust operating parameters of all subsystems during each reciprocation cycle of the resecting sleeve  120  to achieve various operating objectives. 
         [0039]    Now turning to  FIGS. 4A-7B , the structure and operation of the working end  140  can be described. A similar device can be made with a sharp tip or a rounded tip for different approaches for prostate resection. In one variation shown in  FIGS. 2-4B , it can be seen that the distal end body  186  with a sharp tip  188  of the device is sharp for penetrating tissue. In a resection procedure in a prostate  190  (see  FIG. 10 ) such a sharp tip  188  is adapted for extending outward from the working channel  192  of an endoscope or cystoscope  194  to penetrate through the urethra  195  into a prostate lobe  196  under suitable imaging such as ultrasound. This method would spare the urethra  195  except for one or more puncture sites. In another embodiment shown in  FIG. 9 , the device can have a rounded distal tip  198  and the resection procedure can be started within the urethra  195  and progress outwardly into the prostate lobe  196  in a method similar to conventional TURP procedures which use an RF loop and which do not spare the urethra  195 . 
         [0040]      FIGS. 2, 3 and 4A-4B  illustrate the movement of the resecting sleeve  120  and explain how the working end  140  is configured to resect tissue, for example in a prostate. Referring to  FIGS. 2, 3 and 4A , the inner resecting sleeve  120  is typically fabricated of thin-wall stainless steel but any other suitable materials can be used. The inner sleeve  120  has a thin insulating coating  202  around it exterior except for a distal end portion  162  that comprises electrode  160 A. The exposed distal portion  162  that comprises electrode  160 A can have a length ranging from about 1 mm to 6 mm. In one variation, the inner sleeve has an OD of 0.106″ and an ID of 0.098″. The insulating coating is parylene, but other dielectric polymers or ceramic coating are possible, such as PFA, polytetrafluroethylene (PTFE), FEP (Fluorinated ethylenepropylene), polyethylene, polyamide, ECTFE (ethylenechlorotrifluoro-ethylene), ETFE, PVDF, polyvinyl chloride or silicone. The proximal end of inner resecting sleeve  120  is coupled to the electrical cable  158  within handle  108  and to a first pole of the RF source  155  ( FIG. 1 ). 
         [0041]    In  FIGS. 2, 4A-4B and 5A-5B , it can be seen the outer sleeve  125  at the working end  140  comprises an assembly of outer sleeve  125  and thin wall intermediate sleeve  205  that when combined with outer sleeve  125  defines a flow channel  170  between the sleeves (see  FIG. 5A ). The intermediate sleeve  205  can extend to the handle  108  or can terminate in a medial region of shaft portion  110  as indicated in  FIGS. 4A and 5B . Thus, it can be understood that inner sleeve  120  reciprocates in passageway  122  that is defined by intermediate sleeve  125 . In  FIGS. 2 and 3 , it can be seen that the window  128  is defined by edges  206  and  208  of the outer sleeve  125  and intermediate sleeve  205 , respectively, and the edges are welded or sealed by an insulating coating so that flow channel  170  has no open terminal portion around window  128 . In  FIGS. 4A-4B , a continuous parylene coating  212  (or other insulating coating) is provided about the exterior of outer sleeve and around the window  128  and in the passageway  122  in the intermediate sleeve  205 . This coating  212  can extend proximally from the window from 5 mm to 50 mm to a terminal edge  215  (see  FIGS. 2, 3 and 4A ). Proximal to the edge  215  of the coating  212  on the outer sleeve is the exposed surface of outer sleeve  125  which comprises the return electrode  160 B. The proximal end of inner resecting sleeve  120  is coupled to electrical cable  158  within handle  108  and thus to a second pole of the RF source  155 . 
         [0042]      FIGS. 3, 4A-4B, and 8  illustrate that the flow channel  170  has a open termination  220  facing in the proximal direction in the center of dielectric element  222  that is fixed to distal end component  186 . In one variation as shown in  FIG. 8 , the dielectric element  222  is of a resilient material such as silicone and with a circular edge  226  that fits over and grips metal edge  228  of the distal end component  186 . In the enlarged view of  FIG. 8 , it can be seen that flow channel  170  transitions to gap  232  in the dielectric element  222  which allows fluid to flow from channel  170  through gap  232  and then in a reversed (proximal) direction through open termination  220 .  FIGS. 4A-4B and 8  show that dielectric element  222  has a circular ledge  235  around open termination  220  that is adapted to project slightly into and engage the electrode  160 A and distal end  162  of inner sleeve  120  when this sleeve is at its distal-most position in each cycle of its reciprocation. The dielectric element  222  thus can form a seal with distal end  162  of the inner sleeve  120  at the distal-most position of its stroke. As will be described below, during a brief interval when inner sleeve  120  is at the end of its stroke and sealed against the dielectric element, then the pump mechanism  175  can provide a fluid flow burst through channel  170  and open termination  220  which causes resected tissue to be pushed proximally in tissue extraction channel  132  in inner sleeve  120 . 
         [0043]      FIGS. 1, 6A and 7A  show in general indicate how the single motor  115  in handle operates to both reciprocate the inner resecting sleeve  120  and the pump mechanism  175 . In  FIG. 6A , it can seen that motor  115  together with an internal gear reduction mechanism rotates shaft  240  which is coupled to a rotating drive collar  244  which converts rotary motion to axial motion. An arcuate or partly helical slot  245  in the drive collar  244  cooperates with a pin  248  in non-rotating body  250  that is keyed in the handle  108  and fixed to the proximal end  252  of the inner resecting sleeve  120 . The motor  115  can comprise any suitable electrical motor, for example, a brushless electric motor. The motor  115  (and operation of other subsystems) can be actuated by a user-operated switch, which typically is a footswitch but also could be a handswitch. As can be understood from  FIGS. 6A-7B , the rotation of drive collar  244  will cause non-rotating body  250  to reciprocate and cause the inner sleeve  120  to move between the window-open position of  FIGS. 6A-6B  and the window-closed position of  FIGS. 7A-7B . In one variation, referring to  FIGS. 6A-7B , the drive collar  244  can rotate 360° with a continuous arcuate slot  245  to thus move the inner resecting sleeve  120  in a mechanical manner both in the distal direction to resect tissue captured in the window and in the proximal direction to re-open the window. In another embodiment, the drive collar  244  can operate as a cam to move the inner sleeve in the distal direction while also loading a spring mechanism (not shown), and then the spring mechanism can move the inner sleeve in the proximal direction back to the window-open position. 
         [0044]    The speed of motor  115  can be constant through a cycle of reciprocation at a rate between 1 Hz to 5 Hz, or the controller  150  can use an algorithm to alter motor voltage to cause the motor to move the inner sleeve forward (distal direction) to resect tissue at a first speed and then move backward (proximal direction) at a second speed. In one variation as further described below, the controller  150  can control the RF source  155  to provide a constant power level which is adapted to generate a plasma about electrode  160 A for resecting tissue during the forward stroke and then the same plasma can be used on the backward stroke to coagulate the tissue surface. In this variation, the backward stroke can be slowed down to provide a longer interval in which electrode  160 A contacts tissue to increase the depth of coagulation. In the variation just described, motor voltage was modulated to alter the speed of the inner sleeve. It should be appreciated that the drive sleeve can rotate at a constant rate and the arcuate slot  245  in drive collar  244  and the cooperating pin  248  can be designed to provide the inner sleeve  120  with different effective forward and backward speeds. This would achieve the same result as modulating motor voltage to alter reciprocating speed. 
         [0045]      FIGS. 1, 6A and 6B  also illustrate how the motor  115  in handle  108  actuates the pump mechanism  175 . In  FIG. 6A , it again can seen that motor  115  rotates the drive collar  244  which in turn engaged pin  248  and causes the non-rotating body  250  to reciprocate.  FIG. 6A  also shows an actuator  260  fixed to the inner sleeve  120  within handle  108  that reciprocates to drive the pump mechanism  175 . Referring to  FIGS. 6A and 7A , the actuator  260  extends laterally and is coupled to cylindrical element  264  that also reciprocates in the handle  108 , with part of its stroke extending into a bore in the drive collar  244 . The cylindrical element  264  is coupled to shaft  265  of a piston  268  that moves back and forth in pump chamber  270  to thereby pump fluid from fluid source  165  through channel  170  ( FIGS. 4A-5B ) to the working end  140 . It can be seen that piston  268  has o-rings  274  to seal the pump chamber  270  and fluid can be delivered to the pump mechanism through flow line  166  ( FIG. 1 ) by gravity or other suitable means such as a pump. The fluid flows into and out of the pump chamber  270  can be facilitated by one-way valves are known in the art. 
         [0046]    In the variation shown in  FIGS. 6A-7B , the pump system  175  is actuated by the drive collar  244  which operates the resecting sleeve  120 , and thus the reciprocation rate and/or the varied speed of the piston shaft  256  will match that of the resecting sleeve. The flow rate of fluid through the system will then be determined by the selected speed profile of the inner sleeve&#39;s reciprocation. In another variation, it is preferable to have a pulse of fluid flow through channel  170  and open termination  220  within a very brief time interval when then inner sleeve  120  is at the end of its stroke and sealed against the dielectric element  222 . In this variation, the pulse of liquid can range from 1 cc to about 5 cc and is adapted to push a slug of resected tissue under positive pressure in the proximal direction in the tissue extraction channel  132 . In order to provide such a pulsed flow, the drive collar  244  can have a second arcuate slot to drive a second pin (not shown) to drive the piston shaft  265  with any selected interval. In one variation, the pulse of fluid flow occurs within less than 0.2 seconds or less than 0.1 seconds. In another embodiment, the drive collar  244  can operate both the resecting sleeve  120  and the piston shaft  265  in unison and the fluid can flow into an intermediate reservoir in handle  108  (not shown) which can be configured to release the fluid into channel  170  only within a selected time interval. 
         [0047]      FIG. 9  illustrates a step in a method of using the device  100  of  FIG. 1  to resect tissue in a patient&#39;s prostate. In the method of  FIG. 9 , the physician introduces a cystoscope  194  transurethrally to view the prostate. The shaft  110  of a rounded end probe  100  is advanced through the working channel  192  of the cystoscope and after viewing appropriate landmarks as known in the art, the device is actuated to resect and extract tissue. In this method, a saline irrigation fluid is controllably delivered by a pump (or gravity flow) to the site through another channel in the cystoscope to immerse the treatment site in saline. In operation, the negative pressure source  180  can be actuated continuously, which communicates with tissue extraction channel  132  in the inner sleeve and functions to draw tissue into window  128 . At the same time, the negative pressure source  180  will remove saline from site when the window is open to thus cause circulation of fluid through the treatment site, which will remove blood and debris to keep the saline clean for enhancing endoscopic viewing of the resection procedure. The saline inflows can be managed by any conventional fluid management system as is known in the art, wherein such systems include pressure sensing or pressure calculation mechanisms for monitoring and controlling fluid pressure in the treatment site. The working end  140  then can be moved axially and rotationally under direct endoscopic vision while the resecting sleeve  120  is actuated to resect and extract tissue. As described above, the actuation of a switch, such as a foot pedal will cause the controller to actuate (i) reciprocation of the resection sleeve  120 , (ii) the pump mechanism  175 , (iii) the negative pressure source  180 , and the RF source  155 . In one variation, the RF source  155  is controlled to operate continuously at a power level that created a plasma about electrode  160 A to resect tissue as the sleeve  120  moves in the distal direction across window  128 . In this variation, the plasma about electrode  160 A coagulates tissue in contact with the electrode  160 A as it moves in the proximal direction. The resected tissue slugs are captured in a collection container (not shown). In other methods of coagulating tissue in TURP procedure shown in  FIG. 9 , (i) the resecting sleeve can be moved in the proximal direction at a slower speed to allow the plasma about electrode  160  to be in contact with tissue for a longer interval, (ii) the controller can switch the output and/or power from RF source  155  to a different parameter for better coagulation on the return stroke of the resecting sleeve  120 , and/or (iii) the resecting sleeve  120  can be stopped in a selected position within window  128  and the RF output and power can be delivered between electrodes  160 A and  160 B to allow the physician to manipulate the working end to coagulate targeted tissue. In the event that the system is operated in different modes, for example a plasma resection mode and a coagulation mode, then a conventional electrosurgical foot pedal system may be used with a first pedal for tissue resection and a second pedal for coagulation. 
         [0048]      FIG. 10  illustrates another method of using device  100  of  FIG. 1  to resect tissue in a patient&#39;s prostate. In the method of  FIG. 10 , the physician again introduces a cystoscope  194  transurethrally into a patient&#39;s prostate, and then advances shaft  110  of a sharp-tipped probe  100  through the working channel  192  of the cystoscope and thereafter through the urethra  195  into the prostate lobe  196 . In this method,  FIG. 10  shows that the tissue resection is done interstitially and thus viewing is needed which can be provided by ultrasound system  285  or another suitable type of imaging. In one variation, the ultrasound system is a TRUS system as known in the art. A conventional fluid management system can be used as described above to irrigate and maintain fluid pressure in the urethra  195 . In  FIG. 10 , a target of the treatment is to resect and extract tissue region  286  wherein fluid from within the urethra  195  may not flow into the cavity being resected in the prostate lobe and for this reason fluid flow from the working end  140  can fill the space around the working end  140 . In one variation, the pump mechanism  175  operates during the reciprocation cycle and saline will flow through channel  170  and outward from open termination  220  and outward from window  128  into the resected cavity, except for when the window  128  is closed. The saline thus irrigates the space around the working end  140  and supports the RF plasma formation about electrode  160 A. In this method, the fluid flow volume through channel  170  can be set at any selected volume per cycle of reciprocation, for example from 0.5 cc to 10 cc&#39;s. This selected volume can be unrelated to an optional pulsed volume when the window  128  is closed. The volumes of fluid pumped can be adjusted by design of the volume of the pump chamber and piston stroke. In another embodiment, the probe shaft  110  could be configured with another flow channel to deliver fluid to the space in the prostate lobe  196  around the working end  140 . 
         [0049]    Still referring to the resection method of  FIG. 10 , the working end  140  also can be operated in another manner to cause coagulation. As described above, the resecting sleeve  120  can be stopped in a selected position within window  128  and optimal RF output and power can be delivered between electrodes  160 A and  160 B to heat fluid in the space around the working end  140  which will effectively coagulate tissue around the resected cavity. In such a coagulation mode, a foot pedal can be used to activate the system, and in on variation the foot pedal could be tapped to cause the coagulation mode to operate for a predetermined time interval, for example 10 seconds, 20 seconds, 20 seconds or 60 seconds. In another variation, the foot pedal could be depressed to actuate the coagulation mode until the pedal is released. 
         [0050]    While the above embodiments have described a system that has a single motor  115  that operates both the resecting sleeve  120  and the pump mechanism  175 , another variation could have a first motor in handle  108  that operates the resecting sleeve  120  and a second motor that actuates the pump mechanism  175 . This option would allow the controller  150  to independently modulate parameters of both systems during each cycle of reciprocation and thus potentially allow for more modes of operation 
         [0051]    In the embodiment of  FIGS. 1-3 , the distal end of the probe has a fixed sharp tip  188 . In another embodiment, a sharp tipped needle (not shown) could be extended and retracted from the distal body  186  by manipulation of an actuator portion in handle  108 . In this variation, the needle tip would be extended only when the physician penetrated the working end through the urethra  195  (cf.  FIG. 10 ). Thus, during the steps of resecting tissue in the prostate lobe under imaging, the dull tip of the probe would make it impossible or unlikely that the physician could inadvertently push the tip into the bladder  290  or through the prostate capsule wall. 
         [0052]    In general, the tissue resecting device corresponding to the invention comprises a handle and elongated sleeve assembly comprising a windowed outer sleeve and an inner sleeve adapted to move relative to the window to resect tissue, and a motor in the handle configured to move the inner sleeve and operate a pump to provide a fluid flow through a channel in the sleeve assembly. In one variation, the tissue resecting has an inner resecting sleeve that is adapted to reciprocate relative to the window. In another embodiment, the resecting sleeve is adapted to rotate relative to the window. In another embodiment, the resecting sleeve is adapted to reciprocate and rotate relative to the window. 
         [0053]    In another aspect of the invention, the pump mechanism  175  of  FIGS. 1, 6A and 7A  is a positive displacement pump and more specifically a piston pump. In other variations, the pump can be is selected from the group consisting of piston pumps, screw pumps, impeller pumps, peristaltic pumps, vane pumps, lobe pumps, plunger pumps and diaphragm pumps. 
         [0054]    In another aspect of the invention, the resecting sleeve  120  comprises an electrode for electrosurgically resecting tissue. In another variation, the resecting sleeve can have a blade edge for cutting tissue. 
         [0055]    In another aspect of the invention, the tissue resecting system includes a probe with an elongated sleeve assembly comprising a windowed outer sleeve and an inner sleeve adapted to move in a cycle to resect tissue interfacing with the window, and a pump mechanism in or proximate the handle configured to provide a fluid flow through a channel in the sleeve assembly. The pump mechanism can be adapted to provide the flow at a constant rate over each cycle of the inner sleeve, or the pump mechanism can be adapted to provide the flow at a non-constant rate over each cycle of the inner sleeve. In one variation, the pump is operated to provide a pulsed fluid flow. 
         [0056]    In another aspect of the invention, the tissue resecting system includes a probe having an elongated outer sleeve with a closed distal end with a side-facing window that opens to an interior lumen in the sleeve, with an inner sleeve adapted to move longitudinally in the lumen between window open and window closed positions to thereby resect tissue in the window, and a resilient element disposed in distal end of the lumen adapted to interface with the distal end of the inner sleeve when in its distal-most position. In this variation, the system also includes a flow channel within the outer sleeve having an open termination in or proximate to the resilient element, wherein the resilient element is configured to contact the inner sleeve in its distal most position to seal the distal end of the passageway in the inner sleeve. 
         [0057]    In another aspect of the invention, the tissue resecting system includes a probe having an elongated outer sleeve with a closed distal end and side-facing window that opens to an interior lumen, a motor driven inner sleeve adapted to reciprocate longitudinally in a first distal direction across the window to resect tissue and in a second proximal direction to thereby open the window wherein the inner sleeve carries an electrode for applying RF energy to tissue and wherein a controller moves the inner sleeve in the first direction at a first speed and moves the inner sleeve in the second direction at a second different speed. Different RF parameters can be used in the first and second directions. 
         [0058]      FIGS. 11, 12A and 12B  illustrate a fluid management system of the invention that is configured for use in the interstitial resection and extraction of tissue as shown in the method of  FIG. 10 .  FIG. 11  depicts an interstitial resection method as in  FIG. 10 , except with further details on fluid management and fluid flows. 
         [0059]    In  FIG. 11 , it can be seen that a Foley catheter with balloon  375  is in place in the bladder  376  which creates a working space  380  in the urethra  195  in which a controlled fluid pressure is required to maintain an open space to allow for endoscopic viewing. In  FIG. 11 , it can be further see that that the working end  140  of resecting device  105  is penetrated into the prostate lobe  196  and another transient working space  385  is created around the working end  140 . As described above, during operation, the working end  140  requires a suitable inflow of saline to enable the plasma ablation and a suitable outflow to extract resected tissue slugs through the tissue-extraction channel  132  in resecting sleeve  120 . 
         [0060]      FIGS. 12A-12B  are graphic representations of a fluid management system  400  that include two peristaltic pumps  405 A and  405 B as is known in the art, which is adapted to provide fluid flows to both working spaces  380  and  385  as shown in  FIG. 11 . A first pump or infusion pump  405 A is adapted to provide controlled inflows from a single saline fluid source  410  to a targeted site, which in this case can be either site  380  in the urethra  195  or site  385  about the device working end  140  ( FIG. 11 ). The system  400  has second pump or suction pump  405 B for providing controlled outflows from a working space. The controller  420  within the system  400  then includes algorithms that modulate the pump speeds to maintain an operating parameter, such as fluid pressure in the working site or space. Other operating parameters such as inflow and outflow rates may be set within a range. 
         [0061]    In order to simultaneously maintain a targeted operating parameter in two working spaces, two fluid management systems with a total of four pumps could be used. 
         [0062]      FIGS. 11, 12A and 12B  show a fluid management system  400  with only two pumps  405 A and  405 B but that is configured to operate in first and second modes to provide the functionality of four pumps, that is and infusion (inflow) and suction (outflow) pump for each working space  380  and  385  in  FIG. 11 . The system  400  and controller  420  provides the first and second operating modes by selectively operating both of the pumps in a first rotational directions or in a second opposing rotational directions. The two pumping operating modes are enabled by a series of one-way valves with branching or split tubing lines, e.g. lines having a single inlet connected by a Y-connector. 
         [0063]      FIG. 12A  illustrates the system operating in the first mode with the pumps operating in a first rotational direction (counter-clockwise when viewed from front). It can be seen that when the system is actuated, rotation of infusion pump  405 A draws fluid from source  410  through open one-way valve  422   a  and pumps fluid through open valve  422   b  to flow through the flow channel  428   a  in the endoscope into space  380  (see  FIG. 11 ).  FIG. 12A  further shows the rotation of suction pump  405 B which draws fluid from the space  380  through flow channel  428   b  in the endoscope and through open one-way valve  424   a  and pumps fluid through open valve  424   b  into the collection container  440 . While the pumps operate in this first direction, the other one-way valves  432   a ,  432   b ,  434   a  and  434   b  are maintained in the closed position by fluid pressures resulting from the pressure of the fluid flows. 
         [0064]      FIG. 12B  illustrates the system  400  operating in the second mode with the pumps operating in a second rotational direction (clockwise when viewed from front). When the fluid management system  400  is actuated in this mode, rotation of infusion pump  405 A draws fluid from source  410  through open one-way valve  432   a  and pumps fluid through open valve  432   b  to flow to the inflow channel of the resection device  100  and through working end  140  to working space  385  (see  FIG. 11 ).  FIG. 12B  further shows the clockwise rotation of suction pump  405 B which draws fluid from space  385  through the extraction channel  132  of the resection device and through open one-way valve  434   a  and pumps fluid through open valve  434   b  into the collection container  440 . While the pumps operate in this second (clockwise) direction, the other one-way valves  422   a ,  422   b ,  424   a  and  424   b  are maintained in the closed position by fluid pressures resulting from the fluid flows. 
         [0065]    During operation, the controller  420  can use algorithms to automatically switch between the first and second modes. For example, the system can monitor a parameter in the first working space  380  (e.g., fluid pressure) with a pressure sensor system, and operate in the first mode to maintain the pressure within a pre-determined range. Typically, the pumps only operate intermittently to maintain a set pressure in space  380 , so that there are time intervals in which the pumps may operate in the second mode. 
         [0066]    During an interval of resecting tissue, the controller  420  can use algorithms to automatically switch to the second mode from the first mode when the resection device  100  is actuated and saline flows to the space  385  are needed. 
         [0067]    As can be understood, the controller algorithms can provide for priorities as to whether the first or second mode is needed during any time interval based on feedback from operating parameters or site parameters. Typically, when the resection device  100  is resecting tissue, the controller would continuously provide at least some, e.g. at least a low volume of, saline flow to the working end in the prostate or other solid tissue which would take priority over flow to space  380  in the urethra or other body lumen or cavity. When, the resection device  100  is not activated, typically the first mode would have priority to provide a sufficient saline flow to maintain an open space in the urethra or other body lumen or cavity. 
         [0068]    In another embodiment, as illustrated in  FIGS. 13A and 13B , a system  500  uses powered three-way control valves  502  and  504 , such as solenoid valves, controlled by controller  520  to direct fluid flow in either of the two paths shown in  FIG. 11  with the pumps then only operating in one direction. Infusion control valve  502  can be placed in a first position, as shown in  FIG. 13A , to direct saline or other infusate from source  510  through an infusion pump  506  to the resection device  100 . Similarly. The aspiration control valve  504  can be positioned by the controller  520  to direct the outflow of fluid from the resection device  100  through outflow pump  508  to a collection continent  540 . 
         [0069]    When it is desired to redirect the infusate to the endoscope or cystoscope  194 , the controller  510  can reposition the three-way control valve  506  to deliver the infusate to the endoscope and the three-way control valve  508  to collect the outflow of fluid from the endoscope or cystoscope  194 , as illustrated in  FIG. 13B . In contrast to the embodiment of  FIGS. 12A and 12B , the direction of the pumps does not need to be changed 
         [0070]    Methods according to the present invention could utilize either of the one-way valve systems of  FIGS. 12 a    and  12 B or the powered on-off valve systems of  FIGS. 13A and 13B .