Patent Description:
Uterine fibroids are non-cancerous tumors that develop in the wall of uterus. Such fibroids occur in a large percentage of the female population, with some studies indicating up to <NUM> percent of all women have fibroids. Uterine fibroids can grow over time to be several centimeters in diameter and symptoms can include menorrhagia, reproductive dysfunction, pelvic pressure and pain.

One current treatment of fibroids is hysteroscopic resection or myomectomy which involves transcervical access to the uterus with a hysteroscope together with insertion of a cutting instrument through a working channel in the hysteroscope. The cutting instrument may be a mechanical tissue cutter or an electrosurgical resection device such as a cutting loop. Mechanical cutting devices are disclosed in <CIT>; <CIT> and <CIT> and <CIT>. An electrosurgical cutting device is disclosed in <CIT>.

Moreover, document <CIT> describes a system for insufflation and recirculation of insufflation fluid in a surgical procedure. The system includes a control unit having a fluid pump, a supply conduit, a return fluid conduit and a pressure-controlled valve. The fluid pump is adapted and configured to circulate insufflation fluid through the system. The supply conduit is in fluid communication with an output of the fluid pump and configured and adapted for delivering pressurized insufflation fluid to an output port of the control unit. The return conduit is in fluid communication with an input of the fluid pump for delivering insufflation fluid to the fluid pump and is configured and adapted for returning insufflation fluid from an input port of the control unit. The pressure-controlled valve is in fluid communication with the supply conduit and the return conduit, and is adapted and configured to receive a control signal and respond to the control signal by opening, thereby fluidly connecting the supply conduit and the return conduit with one another.

In a myomectomy or hysteroscopic resection, the initial step of the procedure includes distention of the uterine cavity to create a working space for assisting viewing through the hysteroscope. In a relaxed state, the uterine cavity collapses with the uterine walls in contact with one another. A fluid management system is used to distend the uterus to provide a working space wherein a fluid is administered through a passageway in the hysteroscope under sufficient pressure to expand or distend the uterine cavity. The fluids used to distend the uterus are typically liquid aqueous solutions such as a saline solution or a sugar-based aqueous solution.

In some RF electrosurgical resection procedures, the distending fluid is a non-conductive aqueous solution to limit RF current conduction.

One particular concern is the fact that fluid management systems typically administer the fluid under a pressure of up to <NUM> Hg or more which results in a significant risk that the distending fluid may be taken up by a cut blood vessel exposed in the uterine cavity. Such unwanted fluid uptake is known as intravasation, which can lead to serious complications and even death. For this reason, fluid management systems have been developed to monitor the patient's fluid uptake on a continuous basis during a procedure, typically using complicated systems that capture, collect and weigh distending fluids that flow through the uterine cavity.

For these reasons, it would be desirable to provide improved fluid management systems for their use for performing hysteroscopic fibroid resection, myomectomy, or other similar procedures which require fluid distension. The systems preferably utilize a limited volume of distending fluid and will provide for an alarm and/or system shut down when it appears that excessive fluid has been lost from the system.

At least some of these objectives will be met by the invention described herein below.

Aspects, embodiments and examples of the present disclosure which do not fall under the scope of the appended claims do not form part of the claimed invention and are merely provided for illustrative purposes. In particular, any methods described herein are provided for illustrative purposes only.

The present disclosure provides improved fluid management systems and merely illustrative methods for use in performing hysteroscopic fibroid resection, myomectomy, and a variety of other merely illustrative tissue removal procedures performed in a re-circulating distension fluid environment. The fluid management systems of the present disclosure are adapted to utilize an initial volume of distending fluid which is recovered, filtered, and re-circulated to the patient. Thus, by limiting the initial volume of distending fluid used in the system, the risk of excess fluid uptake by the patient can be reduced. The systems and merely illustrative methods also provide for convenient and reliable detection of fluid loss to alert the user and/or automatically shut down the system.

In accordance with the invention, a fluid management system is provided for use with a fluid reservoir and a probe. The fluid reservoir may be a conventional fluid drip bag which is adapted to receive the return of a filtered, re-circulating distending fluid from the patient. The probe will typically be adapted for tissue resection, including cutting blades, radiofrequency (RF) ablation electrodes or elements, rotating burrs, drills, or the like. An exemplary fluid removal probe includes an outer sleeve and an inner cutting sleeve which is reciprocatably mounted in the outer sleeve. The outer sleeve has a cutting window which can be engaged against fibroid or other tissue to be resected. By pressing the window against the tissue, the fibroid or the tissue intrudes into the window, and the inner cutting sleeve can be distally advanced to severe the tissue.

The fluid management systems of the present invention will be connectable both to the fluid reservoir and to the probe, where the probe will typically have lumens both for delivering the distending fluid and to a body space or potential space having the tissue to be resected, such as a uterus having fibroids. An inflow pump is connectable to an inflow fluid lumen of the probe for providing an inflow of the distending fluid to the body space or potential space. An outflow pump of the system is connectable to a fluid outflow lumen of the probe for removing fluid from the space and returning the removed fluid to the reservoir. The system further includes a filter arrangement for removing waste from the removed fluid before returning the removed fluid to the reservoir. A controller is also provided for adjusting the flow rates of the inflow pump and of the outflow pump. By properly controlling and adjusting these flow rates, a controller can maintain a pre-selected distended fluid pressure and/or fluid volume in the body space or potential space.

In a first exemplary embodiment, the controller is configured to control the inflow and outflow of the first and second pumps, which are typically positive displacement pumps, to maintain a target pressure within the body space or potential space. For fibroid resection in a uterus, the pressure will typically be in the range from <NUM> mmHg to <NUM> mmHg. More generally, the range may be from <NUM> mmHg to <NUM> mmHg for other treatment modalities.

Alternatively, the controller may be configured in a flow control mode, wherein the first and second pumps cooperate to deliver fluid to the space within flow rates selected to control the volume of fluid accumulating in the body space or potential space. For treatment of fibroids or other conditions within the uterus, the flow rate of fluid, typically saline, will typically be from <NUM>/min to <NUM>/min.

When controlling body space pressure, the system further includes at least two pressure sensors each capable of providing a pressure signal indicating fluid pressure in the space or potential space. For example, one of the pressure sensors could be located in the fluid input lumen of the probe, preferably near a distal tip of the lumen. To maintain a desired volume of fluid in the body space or potential space, the system will typically include flow measurement sensors for both the inflow flow rate and the outflow flow rate, where the flow rates over time can be integrated to calculate the total fluid volume in and the total fluid volume out over time.

In a still further alternate embodiment, the fluid management system may be configured to further monitor both inflow pump pressure and outflow pump pressure. If the inflow pressure and outflow pressure are found to differ by more than a pre-determined minimum amount, there may be blockages or other malfunctions of the system. In such cases, the system can alert the user and/or automatically shut down the system.

In an embodiment, the controller may periodically or continuously calculate a difference between a fluid volume delivered to the space or potential space and a fluid volume recovered from the space or potential space, wherein the controller can alert the user and/or shut down at least the inflow pump if the difference exceeds a predetermined limit.

In a further embodiment, the fluid management the controller may continuously or periodically compare an inflow pressure from the inflow pump and an outflow pressure at the outflow pump. The controller may be further configured to stop at least the inflow pump if two pressure signals differ by more than a predetermined minimum amount.

The system may have other components and features, for example, the system may further comprise a probe and optionally a disposable tubing set for delivering fluid to the probe, where the tubing set includes at least one pulse dampener. The tubing set will typically also include tubes and connectors for recovering fluid from the probe and returning the fluid to the reservoir. The probe may comprise a windowed outer sleeve and a reciprocating inner cutting sleeve. The reciprocation may be configured to move the probe between window-open and window-closed configurations.

The systems of the present invention may still further comprise a window-closing mechanism on the probe converts to its window-closed configuration in response to idling or other cessation of the reciprocation of the inner cutting tube.

In a still further aspect of the present disclosure, methods are provided for illustration only, the methods being for monitoring delivery and recovery of a distending fluid to a body or potential space to detect loss of that fluid beyond an expected loss. Additionally, a reference volume of the distending fluid within a supply container is recorded. The distending fluid is then directed into the body space or potential space, and an outflow of the fluid volume from the space is recovered. The recovered fluid is filtered and re-circulated to the supply container to provide a replenished volume. A fluid deficit may be then calculated by subtracting the replenished fluid volume from the initial reference volume. While at the beginning of a treatment, the replenished volume will be expected to be significantly lower than the initial volume, after some time a steady state will be reached in which a smaller, generally constant fluid deficit is found. The fluid deficit results, of course, from fluid present within the system as well as fluid present within the body space or the potential space. Thus, the methods of the present disclosure are all optionally comprise determining and recording both the system capacity volumes and the volumes of the potential space. By taking those volumes into account, the difference between the referenced volume and the replenished volume will be further reduced. The system volume may be determined, for example, by priming the supply tubing set and a probe or other surgical device with the distending fluid. The volume of the body or potential space may be determined by introducing a distending fluid into the body space and measuring the volume of the introduced fluid. Alternatively, the volume of the body space could be determined by imaging means.

In further examples provided for illustrative purposes only, the methods of the present disclosure may comprise sealing an access to the body space, for example the cervix when treating a uterus, to prevent the loss of distending fluid from the body cavity or space. Alternatively, fluid which is lost through the access to the body space may be captured and measured in order to account for it by adding that fluid volume to the replenished fluid volume. The methods further provide for monitoring and signaling a fluid deficit which has become excessive, either on an intermittent or continuous basis, where the signal may be at least one of visual, aural and tactile.

<FIG> illustrates an assembly that is provided for comparison only and which comprises an endoscope <NUM> used for hysteroscopy together with a tissue-extraction device <NUM> extending through a working channel <NUM> of the endoscope. The endoscope or hysteroscope <NUM> has a handle <NUM> coupled to an elongated shaft <NUM> having a diameter of <NUM> to <NUM>. The working channel <NUM> therein may be round, D-shaped or any other suitable shape. The endoscope shaft <NUM> is further configured with an optics channel <NUM> and one or more fluid inflow/outflow channels 108a, 108b (<FIG>) that communicate with valve-connectors 110a, 110b configured for coupling to a fluid inflow source <NUM> thereto, or optionally a negative pressure source <NUM> (<FIG>). The fluid inflow source <NUM> is a component of a fluid management system <NUM> as is known in the art (<FIG>) which comprises a fluid container <NUM> and pump mechanism <NUM> which pumps fluid through the hysteroscope <NUM> into the uterine cavity. As can be seen in <FIG>, the fluid management system <NUM> further includes the negative pressure source <NUM> (which can comprise an operating room wall suction source) coupled to the tissue-cutting device <NUM>. The handle <NUM> of the endoscope includes the angled extension portion <NUM> with optics to which a videoscopic camera <NUM> can be operatively coupled. A light source <NUM> also is coupled to light coupling <NUM> on the handle of the hysteroscope <NUM>. The working channel <NUM> of the hysteroscope is configured for insertion and manipulation of the tissue-cutting and extracting device <NUM>, for example to treat and remove fibroid tissue. In one embodiment, the hysteroscope shaft <NUM> has an axial length of <NUM>, and can comprise a <NUM>° scope, or <NUM>° to <NUM>° scope.

Still referring to <FIG>, the tissue-cutting device <NUM> has a highly elongated shaft assembly <NUM> configured to extend through the working channel <NUM> in the hysteroscope. A handle <NUM> of the tissue-cutting device <NUM> is adapted for manipulating the electrosurgical working end <NUM> of the device. In use, the handle <NUM> can be manipulated both rotationally and axially, for example, to orient the working end <NUM> to cut targeted fibroid tissue. The tissue-cutting device <NUM> has subsystems coupled to its handle <NUM> to enable electrosurgical cutting of targeted tissue. A radio frequency generator or RF source <NUM> and controller <NUM> are coupled to at least one RF electrode carried by the working end <NUM> as will be described in detail below. In one embodiment shown in <FIG>, an electrical cable <NUM> and negative pressure source <NUM> are operatively coupled to a connector <NUM> in handle <NUM>. The electrical cable couples the RF source <NUM> to the electrosurgical working end <NUM>. The negative pressure source <NUM> communicates with a tissue-extraction channel <NUM> in the shaft assembly <NUM> of the tissue extraction device <NUM> (<FIG>).

<FIG> further illustrates a seal housing <NUM> that carries a flexible seal <NUM> carried by the hysteroscope handle <NUM> for sealing the shaft <NUM> of the tissue-cutting device <NUM> in the working channel <NUM> to prevent distending fluid from escaping from a uterine cavity.

In one embodiment as shown in <FIG>, the handle <NUM> of tissue-cutting device <NUM> includes a motor drive <NUM> for reciprocating or otherwise moving a cutting component of the electrosurgical working end <NUM> as will be described below. The handle <NUM> optionally includes one or more actuator buttons <NUM> for actuating the device. In another embodiment, a footswitch can be used to operate the device. In one embodiment, the system includes a switch or control mechanism to provide a plurality of reciprocation speeds, for example <NUM>, <NUM> , <NUM>, <NUM> and up to <NUM>. Further, the system can include a mechanism for moving and locking the reciprocating cutting sleeve in a non-extended position and in an extended position. Further, the system can include a mechanism for actuating a single reciprocating stroke.

Referring to <FIG> and <FIG>, an electrosurgical tissue-cutting device has an elongate shaft assembly <NUM> extending about longitudinal axis <NUM> comprising an exterior or first outer sleeve <NUM> with passageway or lumen <NUM> therein that accommodates a second or inner sleeve <NUM> that can reciprocate (and optionally rotate or oscillate) in lumen <NUM> to cut tissue as is known in that art of such tubular cutters. In one embodiment, the tissue-receiving window <NUM> in the outer sleeve <NUM> has an axial length ranging between <NUM> and <NUM> and extends in a radial angle about outer sleeve <NUM> from about <NUM>° to <NUM>° relative to axis <NUM> of the sleeve. The outer and inner sleeves <NUM> and <NUM> can comprise a thin-wall stainless steel material and function as opposing polarity electrodes as will be described in detail below. <FIG> illustrate insulative layers carried by the outer and inner sleeves <NUM> and <NUM> to limits, control and/or prevent unwanted electrical current flows between certain portions go the sleeve. In one embodiment, a stainless steel outer sleeve <NUM> has an O. of <NUM>" with an I. of <NUM>" and with an inner insulative layer (described below) the sleeve has a nominal I. In this embodiment, the stainless steel inner sleeve <NUM> has an O. of <NUM>" with an I. The inner sleeve <NUM> with an outer insulative layer has a nominal O. of about <NUM>" to <NUM>" to reciprocate in lumen <NUM>. In other embodiments, outer and or inner sleeves can be fabricated of metal, plastic, ceramic of a combination thereof. The cross-section of the sleeves can be round, oval or any other suitable shape.

As can be seen in <FIG>, the distal end <NUM> of inner sleeve <NUM> comprises a first polarity electrode with distal cutting electrode edge <NUM> about which plasma can be generated. The electrode edge <NUM> also can be described as an active electrode during tissue cutting since the electrode edge <NUM> then has a substantially smaller surface area than the opposing polarity or return electrode. In one embodiment in <FIG>, the exposed surfaces of outer sleeve <NUM> comprises the second polarity electrode <NUM>, which thus can be described as the return electrode since during use such an electrode surface has a substantially larger surface area compared to the functionally exposed surface area of the active electrode edge <NUM>.

In one aspect of the present disclosure, the inner sleeve or cutting sleeve <NUM> has an interior tissue extraction lumen <NUM> with first and second interior diameters that are adapted to electro surgically cut tissue volumes rapidly-and thereafter consistently extract the cut tissue strips through the highly elongated lumen <NUM> without clogging. Now referring to <FIG> and <FIG>, it can be seen that the inner sleeve <NUM> has a first diameter portion 190A that extends from the handle <NUM> (<FIG>) to a distal region <NUM> of the sleeve <NUM> wherein the tissue extraction lumen transitions to a smaller second diameter lumen 190B with a reduced diameter indicated at B which is defined by the electrode sleeve element <NUM> that provides cutting electrode edge <NUM>. The axial length C of the reduced cross-section lumen 190B can range from about <NUM> to <NUM>. In one embodiment, the first diameter A is <NUM>" and the second reduced diameter B is <NUM>". As shown in <FIG>, the inner sleeve <NUM> can be an electrically conductive stainless steel and the reduced diameter electrode portion also can comprise a stainless steel electrode sleeve element <NUM> that is welded in place by weld <NUM> (<FIG>). In another alternative embodiment, the electrode and reduced diameter electrode sleeve element <NUM> comprises a tungsten tube that can be press fit into the distal end <NUM> of inner sleeve <NUM>. <FIG> and <FIG> further illustrates the interfacing insulation layers <NUM> and <NUM> carried by the first and second sleeves <NUM>, <NUM>, respectively. In <FIG>, the outer sleeve <NUM> is lined with a thin-wall insulative material <NUM>, such as PFA, or another material described below. Similarly, the inner sleeve <NUM> has an exterior insulative layer <NUM>. These coating materials can be lubricious as well as electrically insulative to reduce friction during reciprocation of the inner sleeve <NUM>.

The insulative layers <NUM> and <NUM> described above can comprise a lubricious, hydrophobic or hydrophilic polymeric material. For example, the material can comprise a biocompatible material such as PFA, TEFLON®, polytetrafluroethylene (PTFE), FEP (Fluorinated ethylenepropylene), polyethylene, polyamide, ECTFE (Ethylenechlorotrifluoro-ethylene), ETFE, PVDF, polyvinyl chloride or silicone.

Now turning to <FIG>, another variation of inner sleeve <NUM> is illustrated in a schematic view together with a tissue volume being resected with the plasma electrode edge <NUM>. In this embodiment, as in other embodiments in this disclosure, the RF source operates at selected operational parameters to create a plasma around the electrode edge <NUM> of electrode sleeve <NUM> as is known in the art. Thus, the plasma generated at electrode edge <NUM> can cut and ablate a path P in the tissue <NUM>, and is suited for cutting fibroid tissue and other abnormal uterine tissue. In <FIG>, the distal portion of the cutting sleeve <NUM> includes a ceramic collar <NUM> which is adjacent the distal edge <NUM> of the electrode sleeve <NUM>. The ceramic <NUM> collar functions to confine plasma formation about the distal electrode edge <NUM> and functions further to prevent plasma from contacting and damaging the polymer insulative layer <NUM> on the cutting sleeve <NUM> during operation. In one aspect of the present disclosure, the path P cut in the tissue <NUM> with the plasma at electrode edge <NUM> provides a path P having an ablated width indicated at W, wherein such path width W is substantially wide due to tissue vaporization. This removal and vaporization of tissue in path P is substantially different than the effect of cutting similar tissue with a sharp blade edge, as in various prior art devices. A sharp blade edge can divide tissue (without cauterization) but applies mechanical force to the tissue and may prevent a large cross section slug of tissue from being cut. In contrast, the plasma at the electrode edge <NUM> can vaporize a path P in tissue without applying any substantial force on the tissue to thus cut larger cross sections or slugs strips of tissue. Further, the plasma cutting effect reduces the cross section of tissue strip <NUM> received in the tissue-extraction lumen 190B. <FIG> depicts a tissue strip to <NUM> entering lumen 190B which has such a smaller cross-section than the lumen due to the vaporization of tissue. Further, the cross section of tissue <NUM> as it enters the larger cross-section lumen 190A results in even greater free space <NUM> around the tissue strip <NUM>. Thus, the resection of tissue with the plasma electrode edge <NUM>, together with the lumen transition from the smaller cross-section (190B) to the larger cross-section (190A) of the tissue-extraction lumen <NUM> can significantly reduce or eliminate the potential for successive resected tissue strips <NUM> to clog the lumen. Prior art resection devices with such small diameter tissue-extraction lumen typically have problems with tissue clogging.

In another aspect of the present disclosure, the negative pressure source <NUM> coupled to the proximal end of tissue-extraction lumen <NUM> (see <FIG> and <FIG>) also assists in aspirating and moving tissue strips <NUM> in the proximal direction to a collection reservoir (not shown) outside the handle <NUM> of the device.

<FIG> illustrate the change in lumen diameter of cutting sleeve <NUM> of <FIG>. <FIG> illustrates the distal end of a variation of cutting sleeve <NUM>' which is configured with an electrode cutting element <NUM>' that is partially tubular in contrast to the previously described tubular electrode element <NUM> (<FIG> and <FIG>). <FIG> again illustrate the change in cross-section of the tissue- extraction lumen between reduced cross-section region 190B' and the increased cross-section region 190A' of the cutting sleeve <NUM>' of <FIG>. Thus, the functionality remains the same whether the cutting electrode element <NUM>' is tubular or partly tubular. 8A, the ceramic collar <NUM>' is shown, in one variation, as extending only partially around sleeve <NUM> to cooperate with the radial angle of cutting electrode element <NUM>'. Further, the variation of <FIG> illustrates that the ceramic collar <NUM>' has a larger outside diameter than insulative layer <NUM>. Thus, friction may be reduced since the short axial length of the ceramic collar <NUM>' interfaces and slides against the interfacing insulative layer <NUM> about the inner surface of lumen <NUM> of outer sleeve <NUM>.

In general, one aspect of the present disclosure comprises a tissue cutting and extracting device (<FIG>) that includes first and second concentric sleeves having an axis and wherein the second (inner) sleeve <NUM> has an axially-extending tissue-extraction lumen therein, and wherein the second sleeve <NUM> is moveable between axially non-extended and extended positions relative to a tissue-receiving window <NUM> in first sleeve <NUM> to resect tissue, and wherein the tissue extraction lumen <NUM> has first and second cross-sections. The second sleeve <NUM> has a distal end configured as a plasma electrode edge <NUM> to resect tissue disposed in tissue-receiving window <NUM> of the first sleeve <NUM>. Further, the distal end of the second sleeve, and more particularly, the electrode edge <NUM> is configured for plasma ablation of a substantially wide path in the tissue. In general, the tissue-extraction device is configured with a tissue extraction lumen <NUM> having a distal end portion with a reduced cross-section that is smaller than a cross-section of medial and proximal portions of the lumen <NUM>.

In one aspect of the present disclosure, referring to <FIG> and <FIG>, the tissue-extraction lumen <NUM> has a reduced cross-sectional area in lumen region 190A proximate the plasma cutting tip or electrode edge <NUM> wherein said reduced cross section is less that <NUM>%, <NUM>%, <NUM>% or <NUM>% than the cross sectional area of medial and proximal portions 190B of the tissue-extraction lumen, and wherein the axial length of the tissue-extraction lumen is at least <NUM>, <NUM>, <NUM> or <NUM>. In one embodiment of tissue-cutting device <NUM> for hysteroscopic fibroid cutting and extraction (<FIG>), the shaft assembly <NUM> of the tissue-cutting device is <NUM> in length.

<FIG> illustrate the working end <NUM> of the tissue-cutting device <NUM> with the reciprocating cutting sleeve or inner sleeve <NUM> in three different axial positions relative to the tissue receiving window <NUM> in outer sleeve <NUM>. In <FIG>, the cutting sleeve <NUM> is shown in a retracted or non-extended position in which the sleeve <NUM> is at it proximal limit of motion and is prepared to advance distally to an extended position to thereby electrosurgically cut tissue positioned in and/or suctioned into in window <NUM>. <FIG> shows the cutting sleeve <NUM> moved and advanced distally to a partially advanced or medial position relative to tissue cutting window <NUM>. <FIG> illustrates the cutting sleeve <NUM> fully advanced and extended to the distal limit of its motion wherein the plasma cutting electrode <NUM> has extended past the distal end <NUM> of tissue-receiving window <NUM> at which moment the resected tissue strip <NUM> in excised from tissue volume <NUM> and captured in reduced cross-sectional lumen region 190A.

Now referring to <FIG> and <FIG>, another aspect of the present disclosure comprises "tissue displacement" mechanisms provided by multiple elements and processes to "displace" and move tissue strips <NUM> in the proximal direction in lumen <NUM> of cutting sleeve <NUM> to thus ensure that tissue does not clog the lumen of the inner sleeve <NUM>. As can seen in <FIG> and the enlarged views of <FIG>, one tissue displacement mechanism comprises a projecting element <NUM> that extends proximally from distal tip <NUM> which is fixedly attached to outer sleeve <NUM>. The projecting element <NUM> extends proximally along central axis <NUM> in a distal chamber <NUM> defined by outer sleeve <NUM> and distal tip <NUM>. In one embodiment depicted in <FIG>, the shaft-like projecting element <NUM>, in a first functional aspect, comprises a mechanical pusher that functions to push a captured tissue strip <NUM> proximally from the small cross-section lumen 190B of cutting sleeve <NUM> as the cutting sleeve <NUM> moves to its fully advanced or extended position. In a second functional aspect, the chamber <NUM> in the distal end of sleeve <NUM> is configured to capture a volume of saline distending fluid <NUM> from the working space, and wherein the existing RF electrodes of the working end <NUM> are further configured to explosively vaporize the captured fluid <NUM> to generate proximally-directed forces on tissue strips <NUM> resected and disposed in lumen <NUM> of the cutting sleeve <NUM>. Both of these two functional elements and processes (tissue displacement mechanisms) can apply a substantial mechanical force on the captured tissue strips <NUM> by means of the explosive vaporization of liquid in chamber <NUM> and can function to move tissue strips <NUM> in the proximal direction in the tissue-extraction lumen <NUM>. It has been found that using the combination of multiple functional elements and processes can virtually eliminate the potential for tissue clogging the tissue extraction lumen <NUM>.

More in particular, <FIG> illustrate sequentially the functional aspects of the tissue displacement mechanisms and the explosive vaporization of fluid captured in chamber <NUM>. In <FIG>, the reciprocating cutting sleeve <NUM> is shown in a medial position advancing distally wherein plasma at the cutting electrode edge <NUM> is cutting a tissue strip <NUM> that is disposed within lumen <NUM> of the cutting sleeve <NUM>. In <FIG>, it can be seen that the system operates in first and second electrosurgical modes corresponding to the reciprocation and axial range of motion of cutting sleeve <NUM> relative to the tissue-receiving window <NUM>. As used herein, the term "electrosurgical mode" refers to which electrode of the two opposing polarity electrodes functions as an "active electrode" and which electrode functions as a "return electrode". The terms "active electrode" and "return electrode" are used in accordance with convention in the art-wherein an active electrode has a smaller surface area than the return electrode which thus focuses RF energy density about such an active electrode. In the working end <NUM> of <FIG>, the cutting electrode element <NUM> and its cutting electrode edge <NUM> must comprise the active electrode to focus energy about the electrode to generate the plasma for tissue cutting. Such a high-intensity, energetic plasma at the electrode edge <NUM> is needed throughout stroke X indicated in <FIG> to cut tissue. The first mode occurs over an axial length of travel of inner cutting sleeve <NUM> as it crosses the tissue-receiving window <NUM>, at which time the entire exterior surface of outer sleeve <NUM> comprises the return electrode indicated at <NUM>. The electrical fields EF of the first RF mode are indicated generally in <FIG>.

<FIG> illustrates the moment in time at which the distal advancement or extension of inner cutting sleeve <NUM> entirely crossed the tissue-receiving window <NUM>. At this time, the electrode sleeve <NUM> and its electrode edge <NUM> are confined within the mostly insulated-wall chamber <NUM> defined by the outer sleeve <NUM> and distal tip <NUM>. At this moment, the system is configured to switch to the second RF mode in which the electric fields EF switch from those described previously in the first RF mode. As can be seen in <FIG>, in this second mode, the limited interior surface area <NUM> of distal tip <NUM> that interfaces chamber <NUM> functions as an active electrode and the distal end portion of cutting sleeve <NUM> exposed to chamber <NUM> acts as a return electrode. In this mode, very high energy densities occur about surface <NUM> and such a contained electric field EF can explosively and instantly vaporize the fluid <NUM> captured in chamber <NUM>. The expansion of water vapor can be dramatic and can thus apply tremendous mechanical forces and fluid pressure on the tissue strip <NUM> to move the tissue strip in the proximal direction in the tissue extraction lumen <NUM>. <FIG> illustrates such explosive or expansive vaporization of the distention fluid <NUM> captured in chamber <NUM> and further shows the tissue strip <NUM> being expelled in the proximal direction the lumen <NUM> of inner cutting sleeve <NUM>. <FIG> further shows the relative surface areas of the active and return electrodes at the extended range of motion of the cutting sleeve <NUM>, again illustrating that the surface area of the non-insulated distal end surface <NUM> is small compared to surface <NUM> of electrode sleeve which comprises the return electrode.

Still referring to <FIG>, it has been found that a single power setting on the RF source <NUM> and controller <NUM> can be configured both (i) to create plasma at the electrode cutting edge <NUM> of electrode sleeve <NUM> to cut tissue in the first mode, and (ii) to explosively vaporize the captured distention fluid <NUM> in the second mode. Further, it has been found that the system can function with RF mode-switching automatically at suitable reciprocation rates ranging from <NUM> cycles per second to <NUM> or <NUM> cycles per second. In bench testing, it has been found that the tissue-cutting device described above can cut and extract tissue at the rate of from <NUM> grams/min to <NUM> grams/min without any potential for tissue strips <NUM> clogging the tissue-extraction lumen <NUM>. In these embodiments, the negative pressure source <NUM> also is coupled to the tissue-extraction lumen <NUM> to assist in applying forces for tissue extraction.

Of particular interest, the fluid-capture chamber <NUM> defined by sleeve <NUM> and distal tip <NUM> can be designed to have a selected volume, exposed electrode surface area, length and geometry to optimize the application of expelling forces to resected tissue strips <NUM>. In one embodiment, the diameter of the chamber is <NUM> and the length is <NUM> which taking into account the projecting element <NUM>, provided a captured fluid volume of approximately <NUM>. In other variations, the captured fluid volume can range from <NUM> to <NUM>.

In one example, a chamber <NUM> with a captured liquid volume of <NUM> together with <NUM>% conversion efficiency in and instantaneous vaporization would require <NUM> Joules to heat the liquid from room temperature to water vapor. In operation, since a Joule is a W*s, and the system reciprocate at <NUM>, the power required would be on the order of <NUM> W for full, instantaneous conversion to water vapor. A corresponding theoretical expansion of 1700x would occur in the phase transition, which would results in up to <NUM>,<NUM> psi instantaneously (<NUM>. 7psi x <NUM>), although due to losses in efficiency and non-instantaneous expansion, the actual pressures would be much less. In any event, the pressures are substantial and can apply significant expelling forces to the captured tissue strips <NUM>.

Referring to <FIG>, the interior chamber <NUM> can have an axial length from about <NUM> to <NUM> to capture a liquid volume ranging from about <NUM> <NUM>. It can be understood in <FIG>, that the interior wall of chamber <NUM> has an insulator layer <NUM> which thus limits the electrode surface area <NUM> exposed to chamber <NUM>. In one embodiment, the distal tip <NUM> is stainless steel and is welded to outer sleeve <NUM>. The post element <NUM> is welded to tip <NUM> or machined as a feature thereof. The projecting element <NUM> in this embodiment is a non-conductive ceramic. <FIG> shows the cross-section of the ceramic projecting element <NUM> which is fluted, which in one embodiment has three flute elements <NUM> in three corresponding axial grooves <NUM> in its surface. Any number of flutes, channels or the like is possible, for example from <NUM> to about <NUM>. The purpose of this design is to provide a significant cross-sectional area at the proximal end of the projecting element <NUM> to push the tissue strip <NUM>, while at the same time the three grooves <NUM> permit the proximally-directed jetting of water vapor to impact the tissue exposed to the grooves <NUM>. In one embodiment, the axial length D of the projecting element <NUM> is configured to push tissue entirely out of the reduced cross-sectional region 190B of the electrode sleeve element <NUM>. In another embodiment, the volume of the chamber <NUM> is configured to capture liquid that when explosively vaporized provided a gas (water vapor) volume sufficient to expand into and occupy at least the volume defined by a <NUM>% of the total length of extraction channel <NUM> in the device, at least <NUM>% of the extraction channel <NUM>, at least <NUM>% of the extraction channel <NUM>, at least <NUM>% of the extraction channel <NUM>, at least <NUM>% of the extraction channel <NUM> or at least <NUM>% of the extraction channel <NUM>.

As can be understood from <FIG>, the distending fluid <NUM> in the working space replenishes the captured fluid in chamber <NUM> as the cutting sleeve <NUM> moves in the proximal direction or towards its non-extended position. Thus, when the cutting sleeve <NUM> again moves in the distal direction to cut tissue, the interior chamber <NUM> is filled with fluid <NUM> which is then again contained and is then available for explosive vaporization as described above when the cutting sleeve <NUM> closes the tissue-receiving window <NUM>. In another embodiment, a one-way valve can be provided in the distal tip <NUM> to draw fluid directly into interior chamber <NUM> without the need for fluid to migrate through window <NUM>.

<FIG> illustrates another variation in which the active electrode surface area <NUM>' in the second mode comprises a projecting element <NUM> with conductive regions and non-conductive regions <NUM> which can have the effect of distributing the focused RF energy delivery over a plurality of discrete regions each in contact with the captured fluid <NUM>. This configuration can more efficiently vaporize the captured fluid volume in chamber <NUM>. In one embodiment, the conductive regions <NUM>' can comprise metal discs or washers on post <NUM>. In other variation (not shown) the conductive regions <NUM>' can comprise holes, ports or pores in a ceramic material <NUM> fixed over an electrically conductive post <NUM>.

In another embodiment, the RF source <NUM> and controller <NUM> can be programmed to modulate energy delivery parameters during stroke X and stroke Y in <FIG> to provide the optimal energy (i) for plasma cutting with electrode edge <NUM>, and (ii) for explosively vaporizing the captured fluid in chamber <NUM>.

It should be appreciated that while an RF source is suitable for causing explosive vaporization of the captured fluid volume, any other energy source can be used and falls within the present disclosure, such as an ultrasound tranducer, HIFU, a laser or light energy source, a microwave or a resistive heat source.

In another embodiment, the probe can be configured with a lumen in communication with a remote liquid source to deliver fluid to the interior chamber <NUM>.

<FIG> illustrates an embodiment of a hysteroscopic system <NUM> for fibroid cutting and extraction that comprises a hysteroscope <NUM> and cutting tool <NUM> as describe above together with an integrated fluid management system <NUM>. The fluid management system is integrated with controller <NUM> which controls the positive pressure source <NUM> and the negative pressure source <NUM> for controlling all inflows of distending fluid and outflows of distending fluid. It has been found that the probe <NUM> and internal RF cutting sleeve <NUM> can be extremely efficient in cutting tissue slugs or strips when engaging tissue under suitable slight contacting pressure. In use, the system can cut tissue on each extending stroke that can approximate the theoretical maximum "cut volume"-which term I used herein to describe the cylindrical tissue volume defined by the inner diameter of reduced cross section 190B of RF sleeve <NUM> and the length of the stroke (or longitudinal window dimension) and is depicted in <FIG>. In other words, <FIG> illustrates the potential tissue volume that can be cut in a single extending stroke of the cutting sleeve <NUM>. In one embodiment, the cut volume can comprise <NUM><NUM> wherein the inner bore of lumen 190B is <NUM>" and the window <NUM> is <NUM> in length Z. In other embodiments which still maintain the O. of the outer sleeve <NUM> at <NUM>" or less, and by providing a larger lumen 190B, the cut volume can be at least <NUM><NUM>, <NUM><NUM> or <NUM><NUM>. The definition of cut volume does not separately distinguish the slight thickness of tissue that is cut by the RF plasma-which is vaporized altogether.

In actual operation, the efficiency has been found to be very high, wherein the efficiency is defined as the percentage of maximum cut volume that is cut per stroke. For example, the probe's efficiency can be <NUM>%, <NUM>% or <NUM>% on each extending stroke after which the tissue is then extracted by means described above after extension of the cutting sleeve <NUM> past the window <NUM>.

It can be easily understood that if the cutting efficiency is very high as described above, the reduced cross section lumen 190B and extraction lumen <NUM> will be substantially occupied by tissue during operation and thus leave little room for distending fluid to be extracted with the tissue strips or slugs. This aspect of the present disclosure is highly advantageous as the risk of intravasation can be reduced, the fluid management system can be simplified and the fluid management system can be more compact and potential well-suited for office-based procedures instead of hospital operating rooms.

Referring to <FIG>, in one system embodiment with lumen dimensions described above, if the system is left "open" with the ablation probe's working end <NUM> disposed in a sealed and distended cavity <NUM> (e.g. a uterine cavity) and the negative pressure source operated at a level of approximately <NUM> mmHg, when a suitable pressure is applied to distend the cavity-then a flow rate will range from about <NUM>/min to <NUM>/min flowing through the open system. In actual operation, it has been found that the efficiency of the RF cutting system can reduce the inflows to less <NUM>/min, less than <NUM>/min and as low as <NUM>/min. In this system, a cervical seal <NUM> is used to prevent leakage of distending fluid from the cavity <NUM>.

In general, a method (here provided for illustrative purposes only) of the present disclosure for cutting and extracting tissue from a body cavity comprises distending a body cavity with distending fluid inflow, cutting tissue with a reciprocating RF cutting sleeve configured to reciprocate and capture tissue strips in a distal portion of an extraction lumen of an elongate probe, extracting the tissue strips and distending fluid at least in part by applying negative pressure to the extraction lumen thereby causing a distending fluid outflow, and managing the fluid inflows and outflows with a controller to limit distending fluid inflows to less than <NUM>/min.

In such a merely illustrative method, the probe can have an extraction lumen <NUM> that has a mean diameter of at least <NUM>", at least <NUM>", at least <NUM>" or at least <NUM>", wherein the larger lumens obviously increase the difficulty in lowering fluid inflow rates. The method includes operating the RF cutting sleeve in a reciprocation range of <NUM> to <NUM>. The method allows the RF cutting sleeve to cuts tissue at the rate of at least <NUM> grams/min, at least <NUM> grams/min or at least <NUM> grams/min. In this method, the controller can further limit the fluid inflows to less than <NUM>/min, less than <NUM>/min or less than <NUM>/min.

In another variation for reducing the inflows of distending fluids, the controller <NUM> can modulates inflows and/or outflows depending on which portion or position of the stroke of the RF cutting sleeve <NUM>. For example, the controller can use maximum suction for only a selected initial portion of the extending stroke (e.g., <NUM>%, <NUM>%, <NUM>%, <NUM>% or <NUM>%) after which time the tissue that was suctioned into the window <NUM> will not have time to rebound outwardly before being cut. Further, when the sleeve <NUM> is in its retraction stroke, the negative pressure can be reduced since the movement of the sleeve itself is moving the tissue proximally in the extraction lumen <NUM>. In another variation, the negative pressure can be pulsed.

In another variation for reducing the inflows of distending fluids into the body cavity, the controller <NUM> can modulate inflows and/or outflows in response to measured fluid pressure in the body cavity. The probe <NUM> can carry a pressure sensor, or pressure sensor can be introduced through the hysteroscope. In another variation, the controller can modulate inflows and/or outflows at least in part in response to a measured negative pressure in communication with the extraction lumen. In another method, provided for illustrative purposes only, the controller <NUM> can compare intracavity pressure and applied negative pressure and modulate either inflows or outflow negative pressure.

In general, a merely illustrative method of cutting and extracting tissue from a body cavity comprises distending a body cavity with distending fluid inflow, cutting tissue with a reciprocating RF cutting sleeve configured to reciprocate and capture tissue strips in a distal portion of an extraction lumen of an elongate probe, extracting the tissue strips and distending fluid at least in part by applying negative pressure to the extraction lumen thereby causing a distending fluid outflow, and modulating at least one of an inflow rate or an outflow rate in response to feedback from a sensor system. The sensor can be configured to measure pressure in the body cavity, to measure negative pressure coupled to the extraction lumen, or to compare pressure in the body cavity and the negative pressure coupled to the extraction lumen.

In another aspect of the present disclosure, a method, provided for illustrative purposes only, of cutting and extracting tissue from a body cavity comprises distending a body cavity with distending fluid inflow, cutting tissue with a reciprocating RF cutting sleeve configured to reciprocate and capture tissue strips in a distal portion of an extraction lumen of an elongate probe, extracting the tissue strips and distending fluid at least in part by applying negative pressure to the extraction lumen thereby causing a distending fluid outflow; and modulating at least one operational parameter in response to feedback signals from sensors coupled to a controller. The operational parameters can be selected from the group consisting of applied RF power, fluid inflow rate, fluid inflow pressure, reciprocation rate and negative pressure coupled to the extraction lumen. The feedback signals can be selected from the group consisting of impedance, capacitance of compositions in the extraction lumen, fluid pressure level in the body cavity, reciprocation rate and negative pressure level in the extraction lumen.

In another aspect of the present disclosure, referring to <FIG>, a medical system for cutting and extracting tissue form a body cavity comprises a probe comprising a windowed outer sleeve and a concentric inner RF cutting sleeve that defines a per stroke cutting volume of at least <NUM><NUM>, and a fluid management system comprising a distending fluid source, a pump mechanism and a controller for controlling inflows and outflows of a distending fluid from the body cavity, wherein the fluid management system is configured to deliver a distension fluid volume of less than <NUM>/min, less than <NUM>/min or less than <NUM>/min. In another variation, the RF cutting sleeve defines a per stroke cutting volume of at least <NUM><NUM>, <NUM><NUM>, <NUM><NUM> or <NUM><NUM>. The reciprocation of the RF cutting sleeve can be in the range of <NUM> to <NUM>.

In general, a medical system of the invention for cutting and extracting tissue form a body cavity comprises a probe comprising a windowed outer sleeve and a concentric inner RF cutting sleeve configured to cut tissue at a rate of at least <NUM> grams/min, and a fluid management system comprising a distending fluid source, a pump mechanism and a controller for controlling inflows and outflows of a distending fluid from the body cavity, wherein the fluid management system is configured to deliver a distension fluid volume of less than <NUM>/min, less than <NUM>/min or less than <NUM>/min.

<FIG> illustrate a fluid management system <NUM> that can be used when treating tissue in a body space, cavity or potential space, and is depicted schematically in a hysteroscopic system embodiment for cutting and extraction of fibroids or other abnormal intra-uterine tissue. A body cavity or uterine cavity <NUM> is shown with a cervical seal <NUM> positioned in the external cervical os and cervical canal. The fluid management system <NUM> again is integrated with a controller <NUM> that is configured to control the positive pressure source <NUM> (or pump <NUM>') and the negative pressure source <NUM> (or pump <NUM>') for controlling inflows of distending fluid from source <NUM> and outflows of such distending fluid. In this embodiment, a probe <NUM> is shown with the working end <NUM> disposed in the uterine cavity <NUM>.

Referring to <FIG>, in general, the fluid management system <NUM> of the invention comprises a source or container <NUM> of distending fluid, a pumping system for maintaining the distension of a body cavity, a filter system <NUM> for filtering distending fluid that is recovered from the body cavity and a further subsystem for returning the filtered fluid to the source <NUM>. The use of such recovered and filtered fluid and the replenishment of the fluid supply <NUM> is advantageous because (i) the closed-loop fluid management system <NUM> system can effectively measure fluid deficit to thereby monitor intravasation to thereby insure patient safety, (ii) the system can be set up and operated in a much more time-efficient manner that prior art fluid deficit monitoring systems, and (ii) the system can be very compact and less expensive to enable office-based procedures.

<FIG> illustrates the fluid management system <NUM> in more detail wherein a first pump <NUM>' provides an inflow of a distending fluid from fluid source <NUM> into the body cavity or potential space <NUM> at a suitable rate, e.g., ranging from <NUM>/min to <NUM>/min. The system has a second pump <NUM>' to assist in removing and recovering fluid removed from space <NUM>. A tissue collection reservoir <NUM> collects resected tissue strips. Thereafter, the recovered fluid is moved by pump <NUM>' into the filter system <NUM>. More in particular, the filter system <NUM> comprises a first filter <NUM> or macro filter that accommodates high flows from about <NUM>/min to <NUM>/min and is adapted for removing cells and particulate matter from the fluid flow. In one variation, the first filter <NUM> has pore size of about <NUM> microns, <NUM> microns or <NUM> micron. As can be seen in <FIG>, the second filter or micro filter <NUM> is a low volume filter for use in ultra-filtration of fluids as is known in the art and is adapted for the removal of molecules having a weight greater than <NUM> kD or <NUM> kD. The debris or blood constituents filtered from the microfilter is collected in blood collection reservoir <NUM> (<FIG>). In one variation, a pump <NUM> is provided for a looped flow through the microfilter <NUM> to cleanse the distending fluid for subsequent return to the fluid source or container <NUM>.

In general, the fluid management system <NUM> corresponding to the invention comprises a first pump for providing an inflow of a distending fluid from fluid source <NUM> to the body cavity or potential space, a second pump for removing and recovering fluid removed from the space and a controller and filter system for filtering recovered fluid and thereafter re-circulating the filtered fluid to the fluid source <NUM>.

In one embodiment, the fluid management system <NUM> has a controller configured for operation in a pressure control mode wherein the first and second pumps cooperate to deliver fluid to the space or cavity <NUM> (<FIG>) and maintain pressure therein within a predetermined pressure range. In another variation, the fluid management system has a controller configured for operation in a flow control mode wherein the first and second pumps cooperate to deliver fluid to the space within a predetermined flow rate range.

The fluid management system <NUM> of <FIG> can utilize at least one pressure sensor capable of providing a pressure signal indicating fluid pressure in the space <NUM> to enable or assist in operating in various modes, for example, the pressure mode or the flow control mode. The pressure sensor can be disposed in an inflow lumen that delivers the distending fluid inflow. In another variation, the pressure sensor can be disposed in a lumen that receives the distending fluid outflow.

In one embodiment, the fluid management system has a controller <NUM> configured for calculation of a fluid deficit that is measured as a difference between a fluid volume delivered to the space <NUM> and a fluid volume recovered from the space (see <FIG>). The controller <NUM> can be configured to compare pressure signals from at least two pressure sensors, wherein the controller is further configured to terminate or stop the pump if two pressure signals differ by a predetermined minimum amount.

In another embodiment, the fluid management system includes a disposable tubing set for delivering fluid to a probe or hysteroscope introduced into the space <NUM>, wherein the tubing set includes at least one pulse dampener for use with a peristaltic or other pump (not shown).

In another aspect of the present disclosure, a method, provided for illustrative purposes only, of monitoring a fluid deficit is provided in the use of a fluid management system in a treatment in a body space which comprises (i) recording an initial reference volume comprising a volume of distending fluid contained within a supply container, a system capacity volume, and a volume of the space, (ii) inflowing distending fluid into the space, recovering a fluid volume in an outflow from the space and re-circulating the recovered fluid to the supply container to provide a replenished volume, and (iii) calculating the fluid deficit by subtracting the replenished volume from the initial reference volume. The recording step can include priming a supply tubing set and a surgical device with the distending fluid. In another variation, the recording step includes inflowing distending fluid into the body space <NUM>, and/or calculating the volume of the body space by imaging means. The method can further comprises sealing an access to the body space <NUM> to prevent the loss of distending fluid into the environment, such as in the use of a cervical seal. In another variation, the method can capture fluid loss through the access to the body space, measure such lost fluid volume, and calculate the fluid deficit taking into account the lost fluid volume. A user interface is provided in the controller <NUM> to monitor and signal one or more fluid deficit parameters on an intermittent or continuous basis-wherein the signal can be at least one of visual, aural and tactile.

Referring again to <FIG>, a method, provided for illustrative purposes only, of using a fluid management system in a treatment in a body cavity comprises actuating a first pump to deliver a distending fluid volume from a fluid source into the cavity, actuating a second pump to remove and recover fluid from the cavity, filtering the recovered fluid and re-circulating filtered fluid to the fluid source. The controller is adapted to operate in a first mode for maintaining distension of the cavity wherein fluid pressure is maintained in the cavity <NUM> in a predetermined range. In one variation, the predetermined range is between <NUM> mmHg and <NUM> mmHg. In another method, provided for illustrative purposes only, the controller operates in second mode configured to maintain an inflow rate in a predetermined range, wherein the range is between <NUM>/min and <NUM>/min. In one variation, the filtering step includes flowing the recovered fluid through a first filter mechanism to remove matter having mean cross section of <NUM> micron and larger. The filtering step further includes flowing the recovered fluid through at least a second filter mechanism to remove molecules having a weight greater than <NUM> kD. A pump <NUM> can be provided to generate a pressure of at least <NUM> psi, <NUM> psi, <NUM> psi or <NUM> psi for re-circulating a portion of the fluid outflow through the at least one second filter mechanism. In one variation, the system can return filtered fluid to the distending fluid source <NUM> with a fluid recovery rate of at least <NUM>/min, <NUM>/min, <NUM>/min, <NUM>/min or <NUM>/min.

In one embodiment, the fluid management system <NUM> of <FIG> comprises a first pump for delivering a distending fluid to a body space through a probe, a second pump for providing fluid outflows from the space through a probe extraction lumen, and a controller operatively connected to the first and second pumps and the probe wherein the controller is configured to modulate the pumps to maintain a fluid pressure in the space in response to an indicator signal that indicates the extraction lumen is in an open, partly open or closed configuration. In this embodiment, the probe includes a windowed outer sleeve and a concentric reciprocating inner cutting sleeve wherein reciprocation of the cutting sleeve adjusts the extraction lumen between the open, partly open or closed configurations. Thus, the controller can reduce needed flows through the system by reducing at least one flow pressure (at pump <NUM>' or <NUM>' in <FIG>) when the window is open and increasing at least one flow pressure when the window is closed. In another variation, the flow from either pump <NUM>' or <NUM>' can be pulsed.

In another variation of fluid management system, the system can comprise at least one pump for delivering a distending fluid to a body space through a probe and for providing fluid outflows from the space through a probe extraction lumen, wherein the probe comprises a windowed outer sleeve <NUM> and a reciprocating inner cutting sleeve <NUM> (<FIG>) wherein such reciprocation moves the probe between window-open and window-closed configurations and wherein a window-closing mechanism is provided to move the probe to the window-closed configuration in response to idling the reciprocation. This system will assist in maintaining distension of the body cavity while at the same time reducing the total volume of new fluid used in a procedure. In another variation, the window-closing mechanism includes a stroke sensing mechanism operatively connected to the cutting sleeve <NUM> for determining the stage of a reciprocating stroke of the cutting sleeve.

In another variation, the probe working end comprises a windowed outer sleeve and a reciprocating inner cutting sleeve wherein such reciprocation moves the probe between window-open and window-closed configurations and a controller and sensor system configured to signal if the probe working end is engaging tissue, and a controller algorithm configured to modulate the at least one pump in response to the signal. In one variation shown in <FIG>, the sensor system comprises at least one capacitance sensor <NUM> at the edge of the window <NUM> on sleeve <NUM> which can measure a change in capacitance and compare capacitance against a stored library of values to determine whether the working end <NUM> is engaging tissue or is only submersed in the distending fluid. In response to the signal, the fluid management system can modulate and/or reduce flow pressures when the working end is not engaging and cutting tissue. In another variation, the capacitance sensor(s) could be positioned on the cutting sleeve <NUM>. In other embodiments, the sensor system can be configured to function as described above, wherein the sensor system can be configured to measure impedance associated with at RF cutting sleeve, can be configured to measure pressure of compare pressures, or can be configured to measure loads on the cutting sleeve with a load sensor.

Claim 1:
A fluid management system connectable to a probe (<NUM>) and for use with a fluid reservoir to re-circulate a distending fluid in a body space or potential space, said system comprising:
an inflow pump (<NUM>) connectable to a fluid inflow lumen for providing an inflow of the distending fluid from the fluid reservoir to the body space or potential space;
an outflow pump (<NUM>) connectable to a fluid outflow lumen of the probe (<NUM>) for removing fluid from the body space or potential space;
at least two pressure sensors each capable of providing a pressure signal indicating fluid pressure in the body space or potential space;
a controller (<NUM>) configured to compare pressure signals from the at least two pressure sensors; and
a filter system for filtering removed distending fluid before returning the removed distending fluid to the fluid reservoir;
wherein the controller (<NUM>) is configured for operation in a pressure control mode wherein the inflow pump (<NUM>) and the outflow pump (<NUM>) cooperate to deliver fluid to the body space or potential space and maintain the fluid pressure in the body space or potential space within a predetermined pressure range.