Fluid management system

Abstract

To provide a fluid management system maintaining a body cavity internal pressure.SOLUTION: A management system (500) includes: a controller (545); a pump (546A) operated by the controller and configured to provide fluid inflow to a target site; and a controller algorithm. The algorithm of the controller is configured to monitor current supplied for a motor driving the pump and measured and to automatically deactivate the pump so as to block a medical procedure in the target part when the current is over a predetermined level beyond a pre-selected time interval.SELECTED DRAWING: Figure 21

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority from U.S. Provisional Patent Application No. 61 / 809,681, filed April 8, 2013 (Attorney Docket No. 41878-722.101), the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to a surgical fluid management system and method for use in distending the uterine cavity to allow for the resection and extraction of abnormal uterine tissue, such as, for example, uterine fibroids and polyps. [Background technology]

[0003] Uterine fibroids are non-cancerous tumors that grow in the wall of the uterus. Such fibroids occur in a large percentage of the female population, with some studies indicating that up to 40 percent of all women have fibroids. Fibroids can grow over time to several centimeters in diameter, and symptoms can include menorrhagia, reproductive dysfunction, pelvic pressure, and pain.

[0004] One current treatment for uterine fibroids is hysteroscopic resection or myomectomy, which involves transcervical access to the uterus using a hysteroscope with insertion of a resection instrument through the working channel of the hysteroscope. The resection instrument may be a mechanical tissue cutter or an electrosurgical resection device such as a cutting loop. Mechanical cutting devices are disclosed in U.S. Patent Nos. 5,393, 5,639, 5,743, 5,750, 5,763, 5,894, 6,971, 6,103, 6,111, 6,122, 6,136, 6,143, 6,152, 6,166, 6,171, 6,182, 6,197, 7,198, 8,199, 9,103, 9,116, 9,122, 9,136, 9,142, 9,152, 9,166, 9,177, 9,182, 9,199, 10,199, 10,199, 11,102, 12,136, 13,142, 14,152, 15,166, 16,177, 17,182, 17,199, 18,199, 19,199, 19,199, 20,203, 20,204, 20,205, 20,206, 20,207, 20,209, 20,211, 20,212, 20,221, 20,237, 20,241, 20,252, 20,263,

[0005] In a myomectomy or hysteroscopic resection, the initial stage of the procedure involves distension of the uterine cavity to create a working space to aid in viewing through the hysteroscope. In a relaxed state, the uterine cavity is collapsed and the uterine walls are in contact with one another. A fluid management system is used to distend the uterus and administer fluid under sufficient pressure through a passageway in the hysteroscope to provide a working space to expand or distend the uterine cavity. The fluid used to distend the uterus is typically a liquid aqueous solution, such as saline or a sugar-based aqueous solution.

[0006] In some RF electrosurgical ablation procedures, the inflation fluid is a non-conductive aqueous solution to limit RF current transmission.

[0007] One particular concern is the fact that fluid management systems typically administer fluid under pressure, up to 100 mmHg or higher, which poses a significant risk that the distension fluid may be taken up by cut blood vessels exposed to the uterine cavity. Such unwanted fluid intake is known as intravascular entry, which can lead to serious complications and even death. For this reason, fluid management systems have typically been developed to monitor the patient's fluid intake continuously during the procedure using complex systems that capture, collect, and meter the distension fluid flowing through the uterine cavity. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] U.S. Patent No. 7,226,459 [Patent Document 2] U.S. Patent No. 6,032,673 [Patent Document 3] U.S. Patent No. 5,730,752 [Patent Document 4] U.S. Published Patent Application No. 2009 / 0270898 [Patent Document 5] U.S. Pat. No. 5,906,615 Summary of the Invention [Problem to be solved by the invention]

[0009] Hysteroscopic resection can be effective in removing uterine fibroids, but many commercially available instruments are too large in diameter and therefore require anesthesia in an operating room environment. Conventional resecting endoscopes require a cervical diameter of up to approximately 9 mm. What is needed is a system that can effectively resect and remove uterine fibroid tissue through a small diameter hysteroscope. [Means for solving the problem]

[0010] In a first aspect of the present invention, a uterine fibroid treatment system includes a controller, an inflow pump operated by the controller and configured to effect fluid inflow through a flow path to a patient's uterine cavity, an outflow pump operated by the controller and configured to effect fluid outflow through a flow path to the uterine cavity, and a motor-driven ablation device operated by the controller. The ablation device includes an elongated inducer member having a diameter not less than 2.4 mm and a tissue extraction channel therein, and an outer sleeve having a diameter not greater than 3.8 mm. Furthermore, the ablation device is adapted to remove uterine fibroid tissue at a rate of at least 2 gm / min. In one variation, the controller can be configured to operate the inflow pump and the outflow pump in response to a signal of fluid pressure in the uterine cavity and maintain a target pressure, as described above. In addition, the signal of fluid pressure can be provided by a pressure sensor coupled to a stationary fluid column communicating with the uterine cavity. In another variation, the controller can be configured to operate the ablation device in response to at least one parameter selected from the group consisting of an inflow pump speed, an outflow pump speed, and a signal of fluid pressure in the uterine cavity, as further described below.

[0011] In a second aspect of the invention, a fluid management system includes a controller. A first pump is operated by the controller and configured to provide an inflow of fluid to a site within the patient's body. A second pump is also operated by the controller and configured to provide an outflow of fluid from a site within the patient's body. The controller is configured to maintain at least one operating parameter selected from the group consisting of a first pump speed, a fluid inflow rate, a second pump speed, and a fluid outflow rate or flow rate, and the controller is configured to provide a fluid loss warning if the first pump speed exceeds a predetermined level for a preselected time interval.

[0012] In an exemplary embodiment of the second aspect, the preselected time interval can be at least 1 second, at least 5 seconds, or at least 10 seconds. The controller can be further configured to deactivate at least one pump if the first pump speed exceeds a predetermined level for the preselected time interval, and the controller can be further configured to deactivate a powered ablation device positioned at the site if the first pump speed exceeds a predetermined level for the preselected time interval.

[0013] In a third aspect of the invention, a fluid management system includes a controller. An inflow pump is operated by the controller and is adapted to effect an inflow of fluid to a site within the patient's body through a flow path. An outflow pump is also operated by the controller and is adapted to effect an outflow of fluid from a site within the patient's body through a flow path. The controller is configured to maintain at least one operating parameter selected from the group consisting of a first pump speed, a fluid inflow rate, a second pump speed, and a fluid outflow rate or outflow flow rate, and the controller is configured to provide a flow interruption warning if the calculated power to drive the inflow pump exceeds a predetermined level for a preselected time interval.

[0014] In an exemplary embodiment of the third aspect of the present invention, the controller may be further configured to deactivate at least one pump if the calculated power to drive the inflow pump exceeds a predetermined level for a preselected time interval. The controller may be further configured to deactivate a powered ablation device positioned at the site if the calculated power to drive the inflow pump exceeds a predetermined level for a preselected time interval.

[0015] In a fourth aspect of the invention, a fluid management system includes a controller. A first pump is operated by the controller and configured to effect an inflow of fluid to a site within a patient's body. A second pump is also operated by the controller and configured to effect an outflow of fluid from a site within the patient's body. The controller is configured to maintain at least one operating parameter selected from the group consisting of a first pump speed, a fluid inflow rate, a second pump speed, and a fluid outflow rate or outflow flow rate, the controller being further configured to provide a flow interruption warning if an input voltage to the inflow pump motor is below a predetermined threshold voltage for a preselected time interval.

[0016] In an exemplary embodiment of the fourth aspect of the invention, the preselected time interval may range from 5 seconds to 120 seconds. The controller may be further configured to deactivate at least one pump if the input voltage to the inflow pump falls below a predetermined level for the preselected time interval, and the controller may be further configured to deactivate a powered ablation device positioned at the site if the voltage to the inflow pump motor exceeds a predetermined level for the preselected time interval.

[0017] In a fifth aspect of the invention, a fluid management system includes a controller. An inflow pump is operated by the controller and configured to effect an inflow of fluid to a site within the patient's body through a flow path. An outflow pump is also operated by the controller and configured to effect an outflow of fluid from a site within the patient's body through a flow path. The controller is configured to maintain at least one operating parameter selected from the group consisting of a first pump speed, a fluid inflow rate, a second pump speed, and a fluid outflow rate or outflow flow rate, the controller being further configured to provide a flow interruption warning if a measured current to the outflow pump exceeds a predetermined threshold voltage for a preselected time interval.

[0018] In a sixth aspect of the invention, a fluid management system for use in a tissue ablation procedure includes a controller. An inflow pump is configured to be operated by the controller and to effect an inflow of fluid to a site within the patient's body through a flow path. An outflow pump is also configured to be operated by the controller and to effect an outflow of fluid from a site within the patient's body through a flow path. A motorized ablation device for ablating tissue at the site is also provided. The controller is configured to actuate the inflow pump and the outflow pump, respectively, in response to a signal of an actual pressure at the site within the patient's body to effect an inflow of fluid and an outflow of fluid to maintain a target pressure at the site, and the controller is further configured to deactivate the motorized ablation device upon sensing that the actual pressure at the site falls below a predetermined threshold pressure level.

[0019] In an exemplary embodiment of the sixth aspect of the present invention, the controller may be further configured to deactivate a motor in the motorized ablation device when the actual pressure in the site falls below a predetermined threshold pressure level. The controller may alternatively be configured to deactivate at least one tissue ablation electrode in the motorized tissue ablation device when the actual pressure in the site falls below a predetermined threshold pressure level. The threshold pressure level may be less than 100 mmHg, less than 50 mmHg, or less than 25 mmHg.

[0020] In a seventh aspect of the invention, a fluid management system for use in tissue ablation includes a controller configured to (a) operate an inflow pump and an outflow pump, respectively, in response to a signal of actual pressure within a site within a patient's body, thereby causing fluid inflow and fluid outflow to maintain a target pressure at the site, (b) send a tissue engagement signal to the controller after sensing a predetermined increase in actual pressure within a preselected interval resulting from the ablation tool engaging a target tissue within the site, (c) send a tissue disengagement signal to the controller after sensing a predetermined decrease in actual pressure within a preselected interval resulting from the ablation tool subsequently disengaging from the tissue, and (d) adjust operating parameters of the fluid management system in response to the tissue engagement signal or the tissue disengagement signal.

[0021] In an exemplary embodiment of the seventh aspect of the invention, the controller may be further configured to place the inflow pump in a standby state to provide the selected high inflow rate in response to a tissue engagement signal. The controller may also be configured to activate the inflow pump to provide the selected high inflow rate in response to a tissue disengagement signal. [Brief description of the drawings]

[0022] [Figure 1] FIG. 2 is a plan view of an assembly including a hysteroscope and a tissue resection device according to the present invention inserted through the working channel of the hysteroscope. [Diagram 2] FIG. 1 is a schematic perspective view of a fluid management system used to distend the uterus to assist in electrosurgical tissue ablation and extraction. [Diagram 3] FIG. 2 is a cross-sectional view of the shaft of the hysteroscope of FIG. 1 showing the various channels therein. [Figure 4] 2 is a schematic side view of the working end of the electrosurgical tissue ablation device of FIG. 1 showing the outer sleeve and reciprocating inner sleeve, and electrode arrangement. [Diagram 5] 5 is a schematic perspective view of the working end of the inner sleeve of FIG. 4 showing its electrode edge. FIG. [Figure 6A] 1 is a schematic cutaway view of an outer sleeve, an inner RF ablation sleeve, and a portion of a tissue receiving window of the outer sleeve. [Figure 6B] 13 is a schematic diagram of a distal end portion of another embodiment of an inner RF ablation sleeve. [Figure 7A] 7A is a cross-sectional view of the inner RF ablation sleeve of FIG. 6B taken along line 7A-7A of FIG. 6B. [Figure 7B] 7B is another cross-sectional view of the inner RF ablation sleeve of FIG. 6B taken along line 7B-7B of FIG. 6B. [Figure 8] 13 is a schematic diagram of a distal end portion of another embodiment of an inner RF ablation sleeve. [Figure 9A] 9A is a cross-sectional view of the RF ablation sleeve of FIG. 8 taken along line 9A-9A of FIG. 8B. [Figure 9B] 9B is a cross-sectional view of the RF ablation sleeve of FIG. 8 taken along line 9B-9B of FIG. 8B. [Figure 10A] 2 is a perspective view of the working end of the tissue excision device of FIG. 1 with the reciprocating RF ablation sleeve in an unextended position. [Figure 10B] 2 is a perspective view of the tissue ablation device of FIG. 1 with the reciprocating RF ablation sleeve in a partially extended position. [Figure 10C] 2 is a perspective view of the tissue ablation device of FIG. 1 with the reciprocating RF ablation sleeve in a fully extended position across the tissue receiving window. [Figure 11A] 10B is a cross-sectional view of the working end of the tissue ablation device of FIG. 10A with the reciprocating RF ablation sleeve in an unextended position. [Figure 11B]FIG. 10C is a cross-sectional view of the working end of FIG. 10B with the reciprocating RF ablation sleeve in a partially expanded position. [Figure 11C] FIG. 10D is a cross-sectional view of the working end of FIG. 10C with the reciprocating RF ablation sleeve in a fully extended position. [Figure 12A] FIG. 11C is an enlarged cross-sectional view of the working end of the tissue ablation device of FIG. 11B with the reciprocating RF ablation sleeve in a partially extended position illustrating the RF field of the first RF mode and plasma ablating tissue. [Figure 12B] 11D is an enlarged cross-sectional view of the working end of FIG. 11C showing the RF field with the reciprocating RF ablation sleeve almost fully expanded, switching from the first RF mode shown in FIG. 12 to the second RF mode. [Figure 12C] FIG. 11D is an enlarged cross-sectional view of the working end of FIG. 11C with the reciprocating RF ablation sleeve again nearly fully expanded, showing explosive evaporation of the trapped liquid volume expelling the ablated tissue in the proximal direction. [Figure 13] FIG. 12D is an enlarged perspective view of a portion of the working end of FIG. 12C showing the internal chamber and grooved firing element. [Figure 14] 12D is a cross-sectional view of the working end of FIG. 12C illustrating deformation of the internal chamber and firing element. [Figure 15] 12D is a cross-sectional view of the working end of FIG. 12C showing a variation of a firing element configured to explosively vaporize the internal chamber and the captured liquid volume. [Figure 16] FIG. 1 is a schematic diagram of a system for uterine fibroid removal including a fluid management system. [Figure 17] FIG. 17 is a schematic diagram of the fluid management system of FIG. 16 together with an enlarged view of the working end of a tissue removal probe as generally described in FIGS. 1-12C in position to resect and extract uterine fibroid tissue. [Figure 18] FIG. 18 is a schematic diagram of a pressure sensor component of the fluid management system of FIGS. 16-17. [Figure 19] FIG. 18 is a cut-away schematic view of a filter module of the fluid management system of FIGS. 16-17. [Figure 20] FIG. 1 is a schematic diagram of an endoscope and fluid management system used in a diagnostic mode. [Figure 21]FIG. 21 is a schematic diagram of the endoscope and fluid management system of FIG. 20 together with an ablation probe when the assembly is used in a non-diagnostic or therapeutic mode. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] FIG. 1 shows an assembly including an endoscope 50 for use with a hysteroscope with a tissue resection device 100 extending through a working channel 102 of the endoscope. The endoscope or hysteroscope 50 has a handle 104 coupled to an elongated shaft 105 having a diameter of 5 mm to 7 mm. The working channel 102 therein can be circular, D-shaped or any other suitable shape. The endoscope shaft 105 is further configured with an optics channel 106 and one or more fluid inflow / outflow channels 108a, 108b (FIG. 3) in communication with a valve connector 110a, 110b configured to couple to a fluid inflow source 120 or, optionally, a negative pressure source 125 (FIGS. 1-2). The fluid inflow source 120 is a component of a fluid management system 126 as known in the art (FIG. 2), which includes a fluid container 128 and a pump mechanism 130 that pump fluid through the hysteroscope 50 and into the uterine cavity. 2, the fluid management system 126 further includes a negative pressure source 125 (which may include a room wall suction source) coupled to the tissue resection device 100. The handle 104 of the endoscope includes an angled extension 132 having optics to which a video camera 135 may be operatively coupled. A light source 136 is also coupled to an optical coupling 138 on the handle of the hysteroscope 50. The working channel 102 of the hysteroscope is configured for insertion and manipulation of the tissue resection and extraction device 100, for example, to treat and remove uterine fibroid tissue. In one embodiment, the hysteroscope shaft 105 has an axial length of 21 cm and may include a 0° scope or a 15°-30° scope.

[0024] Still referring to FIG. 1, the tissue resection device 100 has a highly elongated shaft assembly 140 configured to extend through a working channel 102 in a hysteroscope. A handle 142 of the tissue resection device 100 is adapted to manipulate an electrosurgical working end 145 of the device. In use, the handle 142 can be manipulated both rotationally and axially to orient the working end 145 to resect target fibroid tissue, for example. The tissue resection device 100 has a subsystem coupled to its handle 142 to enable electrosurgical resection of the target tissue. A radio frequency generator or RF source 150 and a controller 155 are coupled to at least one RF electrode carried by the working end 145, as described in detail below. In one embodiment shown in FIG. 1, an electrical cable 156 and a negative pressure source 125 are operatively coupled to a connector 158 of the handle 142. The electrical cable couples the RF source 150 to the electrosurgical working end 145. The negative pressure source 125 communicates with a tissue extraction channel 160 in the shaft assembly 140 of the tissue extraction device 100 (FIG. 4).

[0025] FIG. 1 further shows a sealing housing 162 carrying a flexible seal 164 carried by the hysteroscope handle 104 to seal the shaft 140 of the tissue resection device 100 in the working channel 102 to prevent inflation fluid from escaping the uterine cavity.

[0026] In one embodiment shown in FIG. 1, the handle 142 of the tissue resection device 100 includes a motor drive 165 for reciprocating or otherwise moving the cutting component of the electrosurgical working end 145, as described below. The handle 142 optionally includes one or more actuator buttons 166 for actuating the device. In another embodiment, a foot switch can be used to actuate the device. In one embodiment, the system includes a switch or control mechanism to provide multiple reciprocating speeds, for example, 1 Hz, 2 Hz, 3 Hz, 4 Hz, and up to 8 Hz. Additionally, the system can include mechanisms for moving and locking the reciprocating resection sleeve in unextended and extended positions. Additionally, the system can include a mechanism for actuating a single reciprocating stroke.

[0027] 1 and 4, the electrosurgical tissue resection device includes an elongated shaft assembly 140 extending about a longitudinal axis 168 including an outer or first outer sleeve 170 having a passageway or lumen 172 that accommodates a second or inner sleeve 175 that reciprocates (and optionally rotates or oscillates) in the lumen 172 to resect tissue as known in the art for tubular cutters. In one embodiment, the tissue receiving window 176 of the outer sleeve 170 has an axial length ranging from 10 mm to 30 mm and extends at a radial angle of about 45° to 210° about the outer sleeve 170 relative to the sleeve axis 168. The outer and inner sleeves 170 and 175 can comprise a thin walled stainless steel material and function as opposing multiple electrodes, as described in detail below. FIGS. 6A-8 show an insulating layer carried by the outer and inner sleeves 170 and 175 to limit, control, and / or prevent unwanted current flow between certain portions toward the sleeve. In one embodiment, the stainless steel outer sleeve 170 has an OD (outer diameter) of 3.6 mm to 3.8 mm, an ID (inner diameter) of 3.38 mm to 3.5 mm, and has an inner insulating layer (described below), with the sleeve having a nominal ID of about 3.175 mm''. In this embodiment, the stainless steel inner sleeve 175 has an OD of about 3.05 mm, and an ID of about 2.84 mm''. The inner sleeve 175 with the outer insulating layer has a nominal OD of about 3.12 mm'' to reciprocate in the lumen 172. The inner diameter of the inner sleeve portion is described below. As seen in FIG. 4, the distal end 177 of the inner sleeve 175 includes a first polarity electrode having a distal ablation electrode edge 180 capable of generating a plasma. The electrode edge 180 can also be described as the active electrode during tissue ablation, as the electrode edge 180 thus has a substantially smaller surface area than the opposing polarity or return electrode. In one embodiment of FIG. 4 , the exposed surface of the outer sleeve 170 includes a second polarity electrode 185 which may therefore be described as a return electrode, as such electrode surface has a substantially larger surface area than the functional exposed surface area of ​​the active electrode edge 180 during use.

[0028] In one aspect of the invention, the inner sleeve or resection sleeve 175 has an internal tissue extraction lumen 160 having first and second inner diameters configured to electrosurgically resect a tissue volume rapidly and then consistently extract the resected tissue strip through the highly elongated lumen 160 without clogging. Referring now to Figures 5 and 6A, the inner sleeve 175 can be seen to have a first diameter portion 190A extending from the handle 142 (Figure 1) of the sleeve 175 to a distal region 192, where the tissue extraction lumen transitions to a smaller second diameter lumen 190B having a minor diameter indicated at B defined by an electrode sleeve element 195 providing the resection electrode edge 180. The axial length C of the reduced cross-section lumen 190B can range from about 2 mm to 20 mm. In one embodiment, the first diameter A is 2.8 mm to 2.9 mm and the second diameter B is 2.4 mm to 2.5 mm. As shown in FIG. 5, the inner sleeve 175 can be conductive stainless steel, and the small diameter electrode portion can also include a stainless steel electrode sleeve element 195 welded to a preset position by a weld 196 (FIG. 6A). In another alternative embodiment, the electrode and small diameter electrode sleeve element 195 include a tungsten tube that can be press-fitted into the distal end 198 of the inner sleeve 175. FIGS. 5 and 6A further show connecting insulation layers 202 and 204 carried by the first and second sleeves 170, 175, respectively. In FIG. 6A, the outer sleeve 170 is lined with a thin-walled insulating material 200, such as PFA, or another material described below. Similarly, the inner sleeve 175 has an outer insulating layer 202. These coating materials can be lubricious and electrically insulating at the same time to reduce friction during the reciprocation of the inner sleeve 175.

[0029] The insulating layers 200 and 202 described above can include lubricious hydrophobic or hydrophilic polymeric materials. For example, the materials can include biocompatible materials such as PFA, TEFLON, polytetrafluoroethylene (PTFE), FEP (fluorinated ethylene propylene), polyethylene, polyamide, ECTFE (ethylene chlorotrifluoroethylene), ETFE, PVDF, polyvinyl chloride, or silicone.

[0030] Returning now to FIG. 6B, another variation of the inner sleeve 175 is shown in a schematic diagram in which a tissue volume has been ablated with the plasma electrode edge 180. In this embodiment, as in other embodiments of the present disclosure, the RF source is operated at selected operating parameters to generate a plasma around the electrode edge 180 of the electrode sleeve 195, as known in the art. The plasma generated at the electrode edge 180 can thus ablate and ablate a pathway P in the tissue 220, suitable for ablating fibroid tissue and other abnormal uterine tissue. In FIG. 6B, the distal portion of the ablation sleeve 175 includes a ceramic collar 222 adjacent the distal edge 180 of the electrode sleeve 195. The ceramic 222 collar functions to confine plasma formation around the distal electrode edge 180 and further prevents the plasma from contacting and damaging the polymeric insulating layer 202 on the ablation sleeve 175 during operation. In one embodiment of the present invention, a path P cut in tissue 220 with plasma at electrode edge 180 provides a path P having an ablation width shown at W, such path width W being substantially wider due to tissue vaporization. The removal and vaporization of tissue at path P is substantially different than the effect of cutting similar tissue with a sharp cutting edge as in various prior art devices. A sharp cutting edge can separate tissue (without cauterizing) but prevent the application of mechanical forces to the tissue from cutting a large cross-sectional slug of tissue. In contrast, plasma at electrode edge 180 vaporizes tissue path P without applying any substantial force to the tissue, thus ablating a larger cross-sectional or slug strip of tissue. Additionally, the plasma ablation effect reduces the cross-section of tissue strip 225 received by tissue extraction lumen 190B. FIG. 6B shows tissue strip 225 entering lumen 190B having such a cross-section smaller than the lumen due to tissue vaporization. Additionally, the cross-section of the tissue 225 provides a larger free space 196 around the tissue strip 225 as it enters the larger cross-section lumen 190A.Thus, ablating tissue with the plasma electrode edge 180, along with the lumen transition from the smaller cross-section (190B) to the larger cross-section (190A) of the tissue extraction lumen 160, can significantly reduce or eliminate the possibility of the continuous ablated tissue strip 225 clogging the lumen. Prior art ablation devices having such small diameter tissue extraction lumens have problems typically associated with tissue clogging.

[0031] In another embodiment of the invention, a negative pressure source 225 coupled to the proximal end of the tissue extraction lumen 160 (see Figures 1 and 4) also assists in aspirating and moving the tissue strip 225 proximally to a collection reservoir (not shown) outside the handle 142 of the device.

[0032] 7A-7B show the change in lumen diameter of the cutting sleeve 175 of FIG. 6B. FIG. 8 shows the distal end of a variety of cutting sleeves 175' constructed with an electrode cutting element 195' that is partially tubular as opposed to the tubular electrode element 195 (FIGS. 5 and 6A) described above. FIGS. 9A-9B again show the change in cross section of the tissue extraction lumen between the reduced cross-sectional area 190B' and the increased cross-sectional area 190A' of the cutting sleeve 175' of FIG. 8. Thus, functionality remains the same whether the cutting electrode element 195' is tubular or partially tubular. In FIG. 8A, the ceramic collar 222' is shown to extend only partially around the sleeve 175 to cooperate with the radial angle of the cutting electrode element 195' in one variation. Additionally, the variation of FIG. 8 shows that the ceramic collar 222' has a larger outer diameter than the insulating layer 202. Thus, the short axial length of the ceramic collar 222' engages and slides against the insulating layer 200 which engages around the inner surface of the bore 172 of the outer sleeve 170, and thus friction can be reduced.

[0033] In general, one embodiment of the invention includes a tissue resection and extraction device (FIGS. 10-11C) including first and second concentric sleeves having an axis, the second (inner) sleeve 175 having a tissue extraction lumen extending axially therethrough, the second sleeve 175 being movable between axially unextended and extended positions relative to a tissue receiving window 176 in the first sleeve 170 to resect tissue, and the tissue extraction lumen 160 having first and second cross-sections. The second sleeve 175 has a distal end configured as a plasma electrode edge 180 to resect tissue disposed in the tissue receiving window 176 of the first sleeve 170. Additionally, the distal end of the second sleeve, and in particular the electrode edge 180, is configured for plasma ablation of a substantially wide tissue passage. In general, the tissue extraction device is configured with a tissue extraction lumen 160 having a distal end portion having a reduced cross-section that is smaller than the cross-sections of the inner and proximal portions of the lumen 160.

[0034] 7A-7B and 9A-9B, in one aspect of the invention, the tissue extraction lumen 160 has a reduced cross-sectional area in a lumen region 190A proximal to the plasma ablation tip or electrode edge 180 that is 95%, 90%, 85%, or 80% less than the cross-sectional area of ​​the inner and proximal portion 190B of the tissue extraction lumen, and the axial length of the tissue extraction lumen is at least 10 cm, 20 cm, 30 cm, or 40 cm. In one embodiment of a tissue excision device 100 for hysteroscopic uterine myoma resection and extraction (FIG. 1), the tissue excision device shaft assembly 140 is 35 cm in length.

[0035] 10A-10C show the working end 145 of the tissue resection device 100 having a reciprocating cutting sleeve or inner sleeve 175 in three different axial positions relative to the tissue receiving window 176 of the outer sleeve 170. In FIG. 10A, the cutting sleeve 175 is shown in a retracted or unextended position, where the sleeve 175 is at its proximal limit of motion and ready to be advanced distally to an extended position, thereby electrosurgically resecting tissue positioned and / or aspirated within the window 176. FIG. 10B shows the advanced cutting sleeve 175 partially advanced or moved distally to an intermediate position relative to the tissue resection window 176. FIG. 10C shows the advanced cutting sleeve 175 fully advanced to its distal limit of motion, with the plasma ablation electrode 180 extending past the distal end 226 of the tissue receiving window 176, at which point a strip of excised tissue 225 is cut from the tissue volume 220 and captured in the reduced cross-sectional lumen area 190A.

[0036] 10A-10C and 11A-11C, another embodiment of the present invention includes a "tissue displacement" mechanism provided by a number of elements and processes that "displace" and move the tissue strip 225 proximally of the lumen 160 of the resection sleeve 175, thus ensuring that the tissue does not clog the lumen of the inner sleeve 175. As can be seen in the enlarged views of FIGS. 10A and 11A-11C, one tissue displacement mechanism includes a firing element 230 that extends proximally from a distal tip 232 fixedly attached to the outer sleeve 170. The firing element 230 extends proximally along a central axis 168 of a distal chamber 240 predetermined by the outer sleeve 170 and the distal tip 232. In one embodiment shown in FIG. 11A, the shaft-like firing element 230 includes a mechanical pusher that functions in a first functional aspect to push the captured tissue strip 225 proximally out of the small cross-sectional lumen 190B of the resection sleeve 175 as the resection sleeve 175 moves to its fully advanced or extended position. In a second functional aspect, a chamber 240 at the distal end of the sleeve 170 is configured to capture a volume of saline inflation fluid 244 from the working space, and an existing RF electrode at the working end 145 is further configured to explosively vaporize the captured fluid 244 and generate a proximal force on the resected and positioned tissue strip 225 in the lumen 160 of the resection sleeve 175. Both of these two functional elements and processes (tissue displacement mechanisms) can use the explosive vaporization of the liquid in the chamber 240 to apply a substantial mechanical force on the captured tissue strip 225 and can function to move the tissue strip 225 in a proximal direction in the tissue extraction lumen 160. It has been discovered that by using a combination of multiple functional elements and processes, the possibility of tissue clogging the tissue extraction lumen 160 can be virtually eliminated.

[0037] In particular, Figures 12A-12C sequentially illustrate the functional aspects of the tissue displacement mechanism and explosive vaporization of fluid trapped in chamber 240. In Figure 12A, the reciprocating cutting sleeve 175 is shown in an intermediate distally advanced position, with plasma at the cutting electrode edge 180 ablating a tissue strip 225 disposed within the lumen 160 of the cutting sleeve 175. In Figures 12A-12C, the system can be seen to operate in first and second electrosurgical modes corresponding to the reciprocating and axial ranges of motion of the cutting sleeve 175 relative to the tissue receiving window 176. As used herein, the term "electrosurgical mode" refers to which of the two opposing polarity electrodes functions as the "active electrode" and which electrode functions as the "return electrode." The terms "active electrode" and "return electrode" are used according to convention in the art, with the active electrode having a smaller surface area than the return electrode, and thus the active electrode focuses the RF energy density around such active electrode. In the working end 145 of Figures 10A-11C, the ablation electrode element 195 and its ablation electrode edge 180 must comprise the active electrode to concentrate energy around the electrode to generate a plasma for tissue ablation. Such a high density energy plasma at the electrode edge 180 is necessary to ablate tissue throughout the entire stroke X shown in Figures 12A-12B. The first mode occurs over the axial length of travel of the inner ablation sleeve 175 as the sleeve crosses the tissue receiving window 176, at which point the entire exterior surface of the outer sleeve 170 includes the return electrode, shown at 185. The electric field EF of the first RF mode is generally shown in Figure 12A.

[0038] FIG. 12B illustrates the moment when the distal progression or expansion of the inner cutting sleeve 175 completely crosses the tissue receiving window 176. At this point, the electrode sleeve 195 and its electrode edge 180 are confined within the mostly insulated wall chamber 240 defined by the outer sleeve 170 and the distal tip 232. At this time, the system is configured to switch to a second RF mode, in which the electric field EF switches from that described above in the first RF mode. As can be seen in FIG. 12B, in this second mode, the limited inner area 250 of the distal tip 232 that connects to the chamber 240 functions as the active electrode, and the distal end portion of the cutting sleeve 175 exposed to the chamber 240 acts as the return electrode. In this mode, a very high energy density occurs per surface 250, and the electric field EF so contained can explosively and instantaneously vaporize the fluid 244 trapped in the chamber 240. The expansion of the water vapor is dramatic and therefore can apply tremendous mechanical and fluid forces to the tissue strip 225, moving it proximally in the tissue extraction lumen 160. Figure 12C illustrates such explosive or expansive evaporation of the expansion fluid 244 trapped in the chamber 240, further showing the tissue strip 225 expelling proximally out the lumen of the inner cutting sleeve 175. Figure 14 further illustrates the relative surface areas of the active and return electrodes at the extended range of motion of the cutting sleeve 175, again showing that the surface area of ​​the uninsulated distal end face 250 is small compared to the surface 255 of the electrode sleeve including the return electrode.

[0039] Still referring to Figures 12-12C, it has been found that a single power setting for the RF source 150 and controller 155 can be configured to (i) generate plasma at the electrode cutting edge 180 of the electrode sleeve 195 to ablate tissue in a first mode, and (ii) explosively vaporize the trapped expansion fluid 244 in a second mode. Furthermore, it has been found that the system can function with automatic RF mode switching at preferred reciprocation rates ranging from 0.5 cycles per second to 8 or 10 cycles per second. Testing, it has been found that the tissue ablation device described above can ablate and extract tissue at a rate of 2 grams / minute to 8 grams / minute without any possibility for the tissue strip 225 to clog the tissue extraction lumen 160. In one embodiment, a negative pressure source 125 can be coupled to the tissue extraction lumen 160 to apply a tissue extraction force to the tissue strip in the lumen.

[0040] Of particular interest, the fluid capture chamber 240 defined by the sleeve 170 and distal tip 232 can be designed to have a selected volume, exposed electrode surface area, length, and shape to optimize the application of ejection force to the excised tissue strip 225. In one embodiment, the chamber has a diameter of 3.175 mm and a length of 5.0 mm, a diameter that allows for the firing element 230 to provide a captured fluid volume of approximately 0.040 mL. In other variations, the captured liquid volume can range from 0.004 to 0.080 mL.

[0041] In one embodiment, a chamber 240 having a captured liquid volume of 0.040 mL with 100% conversion efficiency of instant vaporization would require 10 Joules to heat the liquid from room temperature to water vapor. In operation, Joules are expressed as W *s and the system cycles at 3 Hz, therefore the power required is believed to be approximately 311 W for complete instantaneous conversion to water vapor. A corresponding theoretical expansion of 1700x is believed to occur at a phase transition which would instantaneously provide up to 25,000 psi (172.3 MPa) (14.7 psi x 1700 or 101.3 KP ax 1700), although losses in efficiency and non-instantaneous expansion would result in a smaller actual pressure. In either case, the pressure is significant and sufficient ejection force can be applied to eject the captured tissue strip 225 down the length of the extraction channel in the probe.

[0042] Referring to FIG. 12A, the interior chamber 240 has an axial length of about 0.5 mm to 10 mm and can capture a liquid volume ranging from about 0.004 mL to 0.010 mL. It can be seen in FIG. 12A that the interior wall of the chamber 240 has an insulating layer 200 which thus limits the electrode surface area 250 exposed to the chamber 240. In one embodiment, the distal tip 232 is stainless steel and is welded to the outer sleeve 170. The post element 248 is welded to the tip 232 or machined as a feature thereon. The firing element 230 in this embodiment is a non-conductive ceramic. FIG. 13 shows a cross section of a ceramic firing element 230 which is grooved, and which in one embodiment has three grooved elements 260 with three corresponding axial grooves 262 on its surface. There can be several grooved channels, for example, 2 to about 20. The purpose of this design is to provide a significant cross-sectional area at the proximal end of the firing element 230 to press against the tissue strip 225, while the three grooves 262 allow the proximal jet of water vapor to impact tissue exposed to the grooves 262. In one embodiment, the axial length D of the firing element 230 is configured to push tissue completely out of the reduced cross-sectional area 190B of the electrode sleeve element 195. In another embodiment, the volume of the chamber 240 is configured to capture liquid that, upon explosive vaporization, provides a sufficient amount of gas (water vapor) to expand to and occupy at least the amount defined by 10% of the total length of the extraction channel 160 of the device, at least 20% of the extraction channel 160, at least 40% of the extraction channel 160, at least 60% of the extraction channel 160, at least 80% of the extraction channel 160, or at least 100% of the extraction channel 160.

[0043] 12A-12C, the inflation fluid 244 in the working space replenishes the trapped fluid in the chamber 240 as the cutting sleeve 175 moves proximally, or toward its unextended position. Thus, when the cutting sleeve 175 again moves distally relative to the resected tissue, the internal chamber 240 then again fills with the contained fluid 244, which is then available for explosive vaporization as described above when the cutting sleeve 175 closes the tissue-receiving window 176. In another embodiment, a one-way valve can be provided at the distal tip 232 to draw fluid directly into the internal chamber 240 without the fluid having to travel through the window 176.

[0044] 15 illustrates another variation in which the second mode active electrode surface area 250' includes a firing element 230 having conductive and non-conductive regions 260 that can have the effect of distributing a focused RF energy delivery onto each of a plurality of discrete regions in contact with the trapped fluid 244. This configuration can more efficiently evaporate the trapped fluid volume in the chamber 240. In one embodiment, the conductive regions 250' can include metal disks or washers on the posts 248. In another variation (not shown), the conductive regions 250' can include holes, ports, or porosity in a ceramic material 260 secured onto the conductive posts 248.

[0045] In another embodiment, RF source 150 and controller 155 can be programmed to adjust energy delivery parameters during stroke X and stroke Y of Figures 12A-12C to provide optimal energy for (i) plasma ablation by electrode edge 180 and (ii) explosive vaporization of trapped fluid in chamber 240. In one variation, controller 155 can deliver RF energy to the working end as cutting sleeve 175 moves distally toward its extended position to ablate tissue, but terminate RF energy delivery to the working end as cutting sleeve 175 moves proximally toward its unextended position. Terminating RF energy delivery during the proximal stroke of cutting sleeve 175 precludes energy delivery to electrode edge 180 when not ablating tissue, thus preventing unwanted heating of the expanding fluid that would occur when delivering RF energy during both the forward and rearward strokes of the cutting sleeve.

[0046] 16-18 show a fluid management system 500 that can be used when treating tissue in a body cavity, space, or potential space 502 (FIG. 17). The fluid management system 500 is depicted generally in a hysteroscopic tissue ablation system 510 adapted for the ablation and extraction of uterine fibroids or other abnormal intrauterine tissue using an endoscope or hysteroscope 512 and a tissue ablation probe 515, which may be similar to those described above. FIG. 16 shows the tissue ablation probe 515 having a handle 516 and an extension member including an outer sleeve 518 having a working end 520 (FIG. 17) that can be introduced through a working channel 522 extending through the body 523 and shaft 524 of the hysteroscope 512. FIG. 16 further shows a module 525 of the tissue ablation probe handle 516 coupled to a controller and power source by a power cable 526. FIG. 17 shows the working end 520 of the ablation probe 515 in the uterine cavity proximate to a target uterine fibroid 530.

[0047] 16-17, generally, the fluid management system 500 includes a fluid source or reservoir 535 of inflation fluid 244, a controller, and a pump system to provide inflow and outflow of fluid configured to maintain inflation of the body cavity, as well as a filter system 540 for filtering inflation fluid 244 that is removed from the body cavity and then returned to the fluid source 535. The use of recovered and filtered fluid 244, as well as refilling of the fluid source 535, is advantageous because (i) the closed loop fluid management system can substantially measure fluid deficits, thereby monitoring intravascular foreign body entry to ensure patient safety, (ii) the system can be set up and operated in a very time-efficient manner, and (iii) the system is small and inexpensive, thereby helping to enable office-based procedures.

[0048] The fluid management system 500 (FIG. 16) includes a computer control system integrated with an RF control system of an integrated controller 545. The controller 545 is adapted to control first and second peristaltic pumps 546A and 546B to provide an inflow and outflow of inflation fluid 244, such as a saline solution, from a source 535 for purposes of inflating the body cavity. The first peristaltic pump may also be referred to herein as an inflow pump or an infusion pump. The second peristaltic pump may also be referred to herein as an outflow pump or an aspiration pump. The controller 545 and control algorithms are adapted to control intracavity pressure during tissue resection and extraction procedures, as shown in FIG. 17. In one embodiment shown in FIGS. 16-18, the controller 545 controls the inflow pump 546A to provide positive pressure at the outflow side 548 of the pump (FIG. 17) and provide an inflow of inflation fluid 244 through an inflow conduit 550 in communication with an attachment 561 and a fluid inflow channel 108a in the hysteroscope 515. The flow path 108a has been described above in previous embodiments and is shown in FIG. 3 above. The controller 545 further controls the outflow pump 546B to provide negative pressure at the inflow side 552 of the pump (FIG. 17) to the outflow line 555 to provide outflow of the inflation fluid 244 from the body cavity 502. As described above, explosive vaporization of fluid at the working end 525 of the ablation probe 515 functions to expel the tissue strip 225 proximal to the extraction channel 160 of the cutting sleeve 175, which can be operated with the negative pressure in the line 555 provided by the pump 546B. During operation, the outflow pump 546B also operates to provide positive pressure to the outflow side 556 of the pump 546B of the second outflow line member 555′ to pump the outflow of the inflation fluid 244 through the filter system 540 and back to the fluid source 535.

[0049] In one system embodiment, the controller 545 operates to control the pressure in the body cavity 502 by a pressure signal from a pressure sensor 560 coupled to an attachment 562 in the hysteroscope 512 that communicates with a flow path 108b (see FIG. 16) extending through the hysteroscope. In one embodiment, the flow path 108b has a diameter of at least 1.0 mm, allowing for highly accurate sensing of the intracavity pressure. In prior art commercially available fluid management systems, intracavity pressure is typically estimated by various calculations using a known flow rate through a pump or a remote pressure sensor in the fluid inlet line where counter pressure can be measured. Such prior art fluid management systems are stand-alone systems and are intended for use with a wide range of hysteroscopes and endoscopes, most of which do not have a dedicated flow path to communicate with a pressure sensor. For this reason, prior art fluid management systems only rely on algorithms and calculations to estimate intracavity pressure.

[0050] In one embodiment, as shown in FIG. 16, the pressure sensor 560 is disposable and removably coupled to the endoscope 512 and in fluid communication with the body cavity through the endoscope's flow channel 108b. The pressure sensor 560 is operatively coupled to the controller 545 by a cable 564. The pressure sensor may be a biocompatible piezoelectric silicon sensor of the type used in invasive blood pressure monitors. For example, the sensor may be a piezoelectric silicon pressure sensor Model No. 1620 available from Measurement Specialities, Ltd., 45738 Northport Loop West, Fremont, CA 94538. The sensor is designed with a pressure sensing element mounted on a ceramic substrate. A dielectric material gel may be placed over the sensor element to provide electrical and fluidic isolation. The sensor housing may have a "luer" connection to couple to the endoscope 512. Additionally, the sensor body may have a pressure relief valve for redundant overpressure protection (not shown).

[0051] As can be seen from Figs. 16 and 17, the pressure sensor 560 is attached to the endoscope 512 and communicates with a fluid channel that extends through the endoscope shaft to the body cavity. The fluid channel or sensor channel 108b used by the pressure sensor 560 is independent of the flow path 108a used for the inflow of inflation fluid to the body cavity. In the absence of fluid flow in the sensor channel 108b, the fluid in the channel 108b forms a stationary column of incompressible fluid whose pressure changes when the pressure in the body cavity changes. With a sensor channel cross section of 1 mm or larger, the pressure in the pressure channel column and the pressure in the body cavity are equivalent. Thus, the pressure sensor 560 can directly measure the pressure in the body cavity. In another variation, shown diagrammatically in Fig. 18, the pressure sensor 560 as shown in Fig. 16 can be composed of two independent sensing elements 560' and 560'' that both connect with the fluid extending from a single fluid channel 108b into the sensor 560. Sensing elements 560' and 560'' transmit pressure signals through cables 564' and 564'' (FIG. 18) to controller 545. At the start of a procedure or during a procedure, the controller can then be configured to monitor or compare the pressure signals from the independent sensing elements 560' and 560''. If the pressure signals of the two sensors are not within a preselected range of each other, the controller 545 can provide a sensor malfunction warning and / or terminate or adjust any ongoing operation of the fluid management system or ablation device.

[0052] FIG. 17 shows a schematic of the fluid management system 500 in operation. The uterine cavity 502 is a potential space that needs to be inflated to allow for hysteroscopic observation. The selected pressure can be set on the controller 545, for example, through a touch screen 565 that the physician knows from experience is suitable for inflating the cavity 502 and / or performing the procedure. In one embodiment, the selected pressure can be any pressure between 0 and 150 mmHg. In one system embodiment, the inflow pump 546A can be operated as a variable speed pump operated to provide a rate of up to 850 milliliters per minute through the first or inflow conduit 550. In this embodiment, the outflow pump 546B can be operated at a fixed speed to move fluid in the second or outflow conduit 555. In use, the controller 545 can operate the pumps 546A and 546B at selected matched or mismatched speeds to increase, decrease, or maintain the amount of distension fluid 244 in the uterine cavity 502. Thus, by independent control of the pumping flow rates of the inflow and outflow pumps 546A and 546B, a selected set temperature in the body cavity can be achieved and maintained in response to the intracavity pressure signal provided by sensor 560.

[0053] 17 and 19, the fluid management system 500 includes a filter module or system 540 that may include a first filter or tissue capture filter 570 configured to capture the tissue strip 225 being extracted and excised from the body cavity 502. A second filter or molecular filter 575, typically a hollow fiber filter, is provided over the first filter 570, the molecular filter 575 adapted to remove blood and other biological material from the inflation fluid 244. In particular, the molecular filter 575 may remove red blood cells, hemoglobin, particulate matter, proteins, bacteria, viruses, etc. from the inflation fluid 244 such that the endoscopic view of the body cavity is not obscured or clouded by any such blood components or other contaminants. As can be seen from Figures 16-19, the outlet pump 546B on its outlet side 556 provides positive pressure for fluid flow within the filter module 540, moving the inflation fluid 244 and body media through the first and second filters 570 and 575 and back to the fluid source 535 in a circulating flow.

[0054] Referring to FIG. 19, in an embodiment, the first filter 570 includes a container portion or vial 576 having a removable cap 577. The inflow of inflation fluid 244 and body media flows through the conduit portion 555 and through fitting 578 into a mesh sac or perforated structure 580 disposed in an interior chamber 582 of the vial 576. The pore size of the perforated structure 580 can range from about 200 microns to 10 microns. The lumen diameter of the hollow fibers 585 in the second filter 575 can be about 400 microns to 20 microns. Generally, the pore size of the perforated structure 580 in the first filter 570 is less than the diameter of the lumen of the hollow fibers 585 in the second filter 575. In one embodiment, the pore size of the perforated structure 580 is 100 microns and the lumen size of the hollow fibers 585 in the molecular filter 575 is 200 microns. In one embodiment, molecular filter 575 is a Nephros DSU filter available from Nephros, Inc., 41 Grand Ave., River Edge, NJ 07661. In one variation, filter 575 is constructed of hollow fibers having a nominal molecular weight limit (NMWL) of less than 50 kDa, 30 kDa, or 20 kDa.

[0055] In another aspect of the invention, molecular filter 575 is configured to filter a large volume of inflation fluid as the fluid flow is circulating. Additionally, molecular filter 575 is configured to filter a significant amount of potential inflation fluid that may be contaminated with blood, blood products, etc. that may become mixed with the fluid. In one embodiment, molecular filter 575 is configured to filter a large volume of ... 2 , 0.8m 2 , 1.0m 2 , 1.2m 2 , and 1.4m 2, where the membrane surface area is defined as the total surface area of ​​the lumens of the hollow fibers 585 in the molecular filter 575. In another aspect of the invention, a method of fluid management can include inflating the body space and then maintaining a rate of up to 850 ml / min of inflation fluid flow into and out of the body space through a filter system 540 capable of removing at least 20 ml, 40 ml, or 60 ml of blood from the inflation fluid 244.

[0056] 19, it can be seen that the filter module 540 includes removable connections between the various fluid flow lines, allowing for quick coupling and decoupling of the filters and flow lines. In particular, a flow line 555 extending from the tissue ablation probe 515 has a connector portion 592 that connects to an inlet fitting 578 at the first filter 546A. A flow line portion 555' intermediate filters 546A and 546B has a connector portion 596a that connects to an outlet fitting 596b at the first filter 542A. An outlet end of the flow line 555' has a connector 598a that connects to an inlet fitting 598b of the second filter 546B. A return flow line 600 intermediate the second filter 546B and the fluid source 535 has a connector portion 602a that connects to an outlet fitting 602b of the second filter 546B. In one embodiment, at least one check valve 605 is provided in the flow path intermediate the filters 546A, 546B, which can be, for example, the conduit 555', the connectors 596a, 598a, or the fittings 596b, 598b. In FIG. 19, the check valve 605 is integrated with the inlet end 608 of the second filter 546B. During use, operation of the system will result in significant fluid pressure within the second filter, and the check valve 605 allows for disconnection of the first filter without pressure relief and release of fluid media into the environment, for example, when the tissue ablation procedure is completed and a doctor or nurse wishes to transport the vial 576 and tissue strip 225 therein to a different site for biopsy purposes. In general, a one-way valve, such as the check valve 605, can be provided at one or more locations in the flow conduits 555 and 555' to prevent backflow of pressure through the conduit 555 to the ablation device 515. For example, a one-way valve 605', such as a float valve, can be provided at one or more locations in the line 555 or in the fitting 578, as shown by the dashed lines in Figure 19 (see also Figures 20-21). A float valve 605'' can also be provided in the line 550 proximate the saline source 535.

[0057] In one embodiment, the fluid management system includes a first fluid line 550 configured to transport inflation fluid 224 from a fluid source 535 to the body space, second fluid lines 55, 555', and 560 configured to transport fluid from the body space to a first filter 570, then to a second filter 575, and then back to the fluid source 535, an outflow pump operatively coupled to the second fluid line, and at least one check valve 605 in the second fluid line intermediate the first and second filters 570 and 575.

[0058] In one embodiment, the controller 545 of the fluid management system 500 is configured for calculation of fluid deficit measured as the difference between the volume of fluid delivered to the body space 502 and the volume of fluid withdrawn from the body space during a medical treatment such as uterine fibroid removal (see FIGS. 16-19). A method of fluid management in a hysteroscopic procedure includes providing an inflation fluid source 535 (FIG. 17) having a predetermined volume, and introducing fluid (e.g., saline) from the source 535 through a first or inflow conduit 550 into the uterine cavity, from the body cavity through a second or outflow conduit 555 into the filter module 540, and back to the fluid source 535 through another portion 600 of the second flow conduit, the internal volume of the first and second flow conduits, and the filter module being equal to or less than 2.5 liters upon removal from the source 535 of the predetermined volume. The instructions for use may then include a requirement that only a single 3 liter saline bag may be used for any fibroid or polyp removal procedure, which in turn would ensure that saline intravasation never exceeds 2.5 liters. In this variation, the predetermined volume source 535 may be 3.0 liters, as in a standard 3 liter saline bag, and the volume of the internal system may be at least 0.5 liters.

[0059] 20 and 21 are schematic diagrams associated with the integrated operation of an RF tissue ablation probe 515 of the type described above and a fluid management system 500 of the type described above. In general, controller 545, RF generator 670, and fluid management system 500 are adapted to control the flow of inflation fluid into and out of body cavity 502 while maintaining a target pressure within the body cavity and simultaneously delivering RF energy to the ablation probe with the fluid flow. In one system embodiment, the system can be operated in three different modes, all controlled by controller 545: (i) a diagnostic mode for hysteroscopy, (ii) an ablation treatment mode for tissue ablation and extraction, and (iii) a coagulation treatment mode for tissue coagulation.

[0060] Referring to FIG. 20, in diagnostic mode, the inflow or infusion pump 546A, the outflow or suction pump 546B, and the pressure sensor 560, as well as the monitoring system, are all activated. In one embodiment, a touch screen 565 on the controller 545 has a graphical user interface (GUI) with fluid control settings that can be adjusted by the physician (FIG. 16). The inflow pump 546A can be turned on / off by touching an inflow pump button on the GUI. A target intracavity pressure can be set on the touch screen 565, for example, from 0 to 150 mmHg or more (FIG. 16).

[0061] In a method of operation as shown in FIG. 20, the physician sets a target intracavity pressure on the GUI and then activates the inflow pump 546A which causes a flow of inflation fluid 244 into the body cavity 502 through the inflow or injection line 550 and the endoscope 512. In one embodiment, the inflow pump 546A in diagnostic mode can be activated against the touch screen 565. In diagnostic mode, the controller 545 is configured not to activate the outflow pump 546B until the set pressure is achieved or an overpressure condition exists. Thereafter, in one variation, the outflow pump 546A will then be operated at a fixed speed and the inflow pump speed can be adjusted in response to a signal from the pressure sensor to stabilize the pressure per the target intracavity pressure. The intracavity pressure measured by the pressure sensor 560 can be displayed on the controller GUI (FIG. 16).

[0062] To stabilize the fluid pressure in the body cavity, the controller 545 includes a pressure control algorithm configured as a feedback control loop. The controller microprocessor reads both the intracavity pressure setpoint and the body cavity pressure based on the signal from the pressure sensor 560. In response to these two parameters, the algorithm calculates a delta value signal based on a general proportional-integral (PI) control algorithm. The delta value is sent to a digital-to-analog converter and fed into a motor amplifier that drives the inflow pump 546A. The controller algorithm then minimizes the difference between the setpoint pressure and the actual pressure by adjusting the speed of the inflow (infusion) pump 546A.

[0063] In one embodiment, the system further includes an actuator and algorithm to provide rapid fluid inflow and outflow to flush the cavity 502, which may be, for example, an actuator button 672 on the foot switch assembly 675. In this flushing method, the outflow (aspiration) pump 546B is activated to provide an increased level of outflow, and then the pressure algorithm adjusts the speed of the inflow (infusion) pump 546A to maintain the target pressure in the cavity. Thus, in a diagnostic mode, the system may be activated to rapidly flush the cavity with fluid inflow and outflow, while the controller algorithm maintains the intracavity pressure as described above. The flow rate through the system and cavity may be preset at 100 ml / min or more, for example, 200 ml / min or 300 ml / min. In another embodiment, the physician may select a rapid flow rate on the touch screen between 200 ml / min and 800 ml / min.

[0064] In a non-diagnostic or therapeutic ablation mode for ablating tissue, referring to FIGURE 21, controller 545 delivers radio frequency energy to the bipolar electrode arrangement of probe 515 (see FIGS. 12A-12C) to ablate tissue and also operates the two pumps to provide fluid inflow and outflow as described above. To operate in the ablation mode, the physician uses touch screen 565 (FIGURE 16) to enter a non-diagnostic (therapeutic) mode of operation. A first pedal 677a on foot switch 675 can then be used to operate the system in the ablation mode to ablate tissue. Actuation of the first pedal 677a simultaneously causes the controller to (i) activate the outflow pump 546B at a fixed speed to provide outflow at a rate of 400 ml / min to 850 ml / min, (ii) activate the inflow pump 564A having a rotational speed controlled and adjusted by the controller 545 as described above to maintain a target pressure in the body cavity, (iii) deliver a DC voltage to the motor 525 of the ablation probe 515 to reciprocate the ablation sleeve 175, and (iv) deliver RF energy to the bipolar electrode arrangement of the ablation probe 515. In one embodiment, the RF generator 670 and controller 545 provide a variable DC voltage of 5 to 20 volts, 200 watts peak RF power, and 240 volts peak RF voltage at a 148 kHz frequency to the ablation probe motor 525.

[0065] In the ablation mode, the pressure algorithm of the controller operates under dynamic flow conditions, and the outflow of inflation fluid 244 from the body cavity 502 varies as it depends on the flow rate of tissue ablation and the speed at which the ablated tissue strips 225 and fluid 244 can move through the extraction channel 160. The intracavity pressure is maintained at a set pressure by a feedback loop that operates in a manner similar to that described above when the system operates in the diagnostic mode. The ablated tissue strips 225 move through the system as described above and are extracted from the body cavity and probe through the outflow line 555. The outflow of fluid carries the ablated tissue, blood, and other fluids into the first filter 570 and then into the second filter 575, as seen in FIG. 21. When the physician releases pressure on the first pedal 677a, the ablation probe 515 is then stopped and only the inflow 546A will remain active to control the intracavity pressure as described above.

[0066] In the coagulation mode, the controller 545 and controller algorithms activate the bipolar electrode arrangement of the probe 515 to coagulate tissue and also intermittently activate the fluid flow function, as described above. The motor 525 in the probe handle is not activated and the cutting sleeve 175 is positioned at the midpoint of the window 517 in the outer sleeve 518 (see FIG. 12A). The midpoint of the cutting sleeve 175 at the window 517 is the initial position that occurs every time the DC current to the probe motor 525 is terminated.

[0067] To initiate operation under the coagulation mode, it is assumed that the physician has preselected a non-diagnostic (therapeutic) mode of operation using the touch screen 565. The physician can then actuate the second pedal 677b on the foot switch 675 to coagulate tissue. Actuation of the second pedal 677b simultaneously causes the controller to (i) deliver RF energy to the bipolar electrode arrangement of the ablation probe 515, and (ii) intermittently activate the inflow and outflow pumps 546A and 546B to induce circulatory fluid flow while maintaining intracavity pressure as described above. In one embodiment, the dual pumps are activated for 1-8 seconds after successive intervals of RF energy delivery for 10 seconds or more. The fluid flow rate can be 100-600 milliliters per minute. Additionally, the inflow and outflow pumps 546A and 546B can be activated for 1-10 seconds each time the physician terminates RF energy delivery. The intermittent circulatory flow in coagulation mode aids in visualization and also prevents heating of the inflation fluid 244 in the body cavity 502 as a result of RF energy application. In one embodiment, the RF generator 670 and controller 545 provides bipolar radio frequency output for coagulation at 110 watts peak RF power and 200 volts peak voltage at 148 kHz frequency.

[0068] When operating the system in any diagnostic or therapeutic mode, the controller 545 has an overpressure protection algorithm in the event that the pressure exceeds the target intracavity set pressure. In one embodiment, if the intracavity pressure exceeds the set pressure by a pre-determined volume for a pre-selected period of time, the controller 545 can activate the outflow pump 546B at a higher pumping rate than the inflow pump 546A until the measured fluid pressure in the cavity is less than the set pressure. Optionally, the controller 545 can slow or disable the inflow pump 546A until the intracavity pressure drops to a target level. In one variation, a pump or pumps can be activated to reduce intracavity pressure if the measured pressure exceeds the set pressure by 5 mmHg for 1, 2, or 5 seconds or more.

[0069] Another mechanism for overpressure protection is provided in the form of a pressure relief valve 680 as shown in FIG. 18. In one variation, the pressure relief valve 680 is coupled to the housing 682 of the sensor 560 and communicates with the flow path 108b' in the sensor 560 to allow fluid drainage and pressure relief through the sensor body. The pressure relief valve 680 can relieve pressure at an appropriate pressure of 100 mmHg or greater, for example, 100 mmHg, 125 mmHg, 150 mmHg, or another predetermined pressure. Thus, if the intracavity pressure exceeds a target maximum level, the controller 545 provides an algorithm-based pressure relief mechanism by adjusting the pump, while the check valve 680 provides a backup form of pressure relief (FIG. 18). Additionally, the system can include a manual pressure relief valve 688 on the disposable accessory 712 coupled to the endoscope for additional safety redundancy (FIG. 20).

[0070] In another aspect of the invention, the controller 545 includes an algorithm configured to deactivate the powered ablation device when the actual pressure within the treatment site is below a predetermined threshold level. The controller 545 is provided with a continuous signal of the actual pressure within the site from a pressure sensor assembly 560 (FIG. 18). In one variation, the controller algorithm can automatically deactivate the motor driving the reciprocating or rotating ablation member when the actual pressure within the site falls below an acceptable threshold pressure level. In another variation, the controller algorithm can deactivate RF energy delivery to the working end of the ablation device 515, as shown in FIGS. 16-17. In this variation of deactivating RF energy delivery, the algorithm can allow continued movement of the ablation sleeve 175 for a selected interval, and then RF can be reactivated after the intracavity pressure level increases above a predetermined threshold, either instantaneously or when such pressure exceeds the threshold level for a selected interval, e.g., 1-10 seconds. In another variation, the controller algorithm can disable both the motor drive and RF delivery as a result of a pressure drop below a threshold pressure level, which can be any predetermined pressure, for example, 100 mmHg or less, 50 mmHg or less, or 25 mmHg or less.

[0071] In one aspect of the invention relating to treating tissue and directly sensing pressure in a body space, the method includes (i) accessing the body space or potential body space with at least one system component including an electrosurgical tissue ablation probe configured to provide an inflow of inflation fluid 244 into the space and an outflow of fluid from the space, (ii) providing a pressure sensor coupled to one or more components configured to measure an actual pressure in the space, (iii) sensing pressure in the space in response to the sensed pressure and adjusting the inflow and outflow rates to achieve or maintain a pressure setpoint in the space, and (iv) operating the electrosurgical probe with first RF parameters to ablate tissue. The probe can be operated with second RF parameters to coagulate tissue. Adjusting the inflow rate can provide an inflow of 0 milliliters / minute to 800 milliliters / minute. The pressure setpoint can be 30 mmHg to 200 mmHg. As discussed above, sensing pressure is accomplished by a sensor coupled to an independent fluid channel separate from the flow paths carrying the inflow and outflow of inflation fluid.

[0072] In general, a uterine fibroid treatment system according to the present invention includes a controller, an inflow pump operated by the controller and configured to effect fluid inflow through a flow path to the uterine cavity of the patient, an outflow pump operated by the controller and configured to effect fluid outflow through a flow path to the uterine cavity of the patient, and a motor-driven ablation device operated by the controller. The ablation device includes an elongated transducer having a tissue extraction channel (190A, 190B in FIG. 6A) therein having a diameter not smaller than 2.4 mm, and an outer sleeve 170 having a diameter not larger than 3.8 mm. The ablation device is adapted to remove uterine fibroid tissue at a rate of at least 2 gm / min. In this variation, the controller can be configured to operate the inflow pump and outflow pump in response to a signal of fluid pressure in the uterine cavity to maintain a target pressure, as described above. In particular, the signal of fluid pressure can be provided by a pressure sensor coupled to a stationary fluid column communicating with the uterine cavity. In another variation, the controller can be configured to operate the ablation device in response to at least one parameter selected from the group consisting of an inflow pump speed, an outflow pump speed, and a signal of fluid pressure in the uterine cavity, as further described below. In another aspect of the invention, a fluid management system 500 and a cooperating electrosurgical probe are provided, including an inflow pump 546A configured to provide an inflow of inflation fluid into a site within a patient's body, and a control system configured for operator selection of at least a first and a second flow control mode, the first flow control mode being configured for tissue ablation and activating the inflow pump to provide a first peak inflow rate, and the second flow control mode being configured for tissue coagulation and activating the inflow pump to provide a second peak inflow rate. Typically, the first peak inflow rate is greater than the second peak inflow rate. In one variation, the first peak inflow is 1,000 milliliters / minute, 800 milliliters / minute, 600 milliliters / minute, or 500 milliliters / minute. The fluid management and procedure system includes a control system configured for operator selection of pressure set points at the site.As described above, the fluid management system and controller are configured to operate the inflow pump and the outflow pump to provide outflow of inflation fluid from the site to achieve or maintain a pressure set point in both the first and second flow control modes.

[0073] 16-21, a fluid management system 500 of the present invention includes an inflow pump 546A configured to provide an inflow of inflation fluid 244 into a site within a patient's body, an outflow pump 546B configured to provide an outflow of fluid from the site, and a controller 545 configured for operator selection of first, second, and third flow control modes, the first flow control mode configured for diagnostic procedures and providing an inflow rate of up to 800 milliliters / minute, the second flow control mode configured for tissue ablation procedures and providing an inflow rate of up to 1000 milliliters / minute, and the third flow control mode configured for tissue coagulation procedures and providing an inflow rate of up to 800 milliliters / minute with intermittent outflow at preselected time intervals.

[0074] 16-21, a fluid management and ablation system consistent with the present invention includes an elongated assembly configured to access a site within a patient's body to perform a procedure, the system components including an endoscope, a tissue ablation probe, a fluid source and tubing set, an inflow pump and an outflow pump, and a controller, the inflow pump configured to provide an inflow of fluid from the fluid source to the site through a first channel in the assembly and the outflow pump configured to provide an outflow of fluid from the site through a second channel in the assembly, the controller configured to operate to provide and maintain an operator-selected pressure set point at the site, and for simultaneous control of the probe in at least one of the inflow and outflow pump modes.

[0075] The system further includes a disposable pressure sensor removably coupled to the system components, and in one variation, the pressure sensor is operatively coupled to a third channel in the system, typically within the endoscope. In another variation, the pressure sensor is operatively coupled to the tubing set. Typically, the first channel described above is within the endoscope shaft 524 and the second channel is within the tissue ablation probe 515.

[0076] In another embodiment of the invention, with reference to FIGS. 20-21 , a fluid management system includes a fluid source 535, typically a saline bag, having a sealed outflow port 702 and inflow line tubing 550 having a connector end 705 including at least one arrowhead feature configured to allow the connector end 705 to advance into and spike the outflow port 702, but to prevent retraction of said connector end 705 from the outflow port 702.

[0077] In another aspect of the invention, the fluid management system 500 (FIGS. 16-17) includes a controller algorithm configured to detect significant fluid leakage or loss within the system upon deployment and during use for diagnostic or therapeutic procedures. Such leakage may consist of fluid loss anywhere within the fluid passageway, such as in the inflow or outflow lines (550, 555) or through the cervical canal around the elongated shaft 524 of the endoscope 512 (see FIG. 17).

[0078] To determine leakage or fluid loss, the controller algorithm constantly monitors the input voltage to the inflow or infusion pump 546A, which directly corresponds to the pump speed and therefore to the inflow rate. The algorithm also constantly monitors the input voltage to the motor of the outflow or aspiration pump 546B, which directly corresponds to the outflow rate or outflow flow rate of fluid. During such continuous monitoring, if the algorithm determines that the inflow pump motor is operating at an input voltage (inflow rate) that exceeds a predetermined threshold voltage level, the threshold voltage level is a function of the set pressure, the intraluminal pressure, and which operating mode (diagnostic mode, ablation mode, etc.) is operating at the time. In each of the operating modes, the input voltage (outflow rate) of the outflow pump that achieves the purpose of each mode is different. Thus, for each different mode and corresponding outflow rate, a different threshold voltage, inflow rate of fluid, and time interval are used to determine whether there is an unwanted fluid loss. In another variation, the controller algorithm can detect leakage or fluid loss in the system using a linear fit curve that relates the infusion motor voltage to the elapsed time interval to signal leakage or fluid loss. This type of algorithm allows for faster detection of fluid loss in operating modes where the inflow pump motor operates at a faster rate, such as in an ablation mode. In other words, fluid loss can be detected faster if there is a faster rate of loss. Test data can be collected and fluid loss measured at different motor speeds over a time interval, and such a linear fit curve can be created.

[0079] If the timer exceeds a preselected time interval while the input voltage of the inflow pump motor exceeds a predetermined voltage threshold, the controller will display a notification alert and / or an audible or visual alarm to indicate a leak or fluid loss. The length of the preselected interval may also vary depending on the inflow rate in any of the system's operating modes, i.e., the severity of the input voltage to the inflow pump motor. When the inflow rate increases above the nominal inflow rate in any of the modes, the time interval preceding the fluid loss alert or alarm is shortened. In one variation, the predetermined voltage threshold level may correspond to an inflow rate of at least 25 ml / min, at least 50 ml / min, or at least 100 ml / min, and the preselected time interval may be at least 1 second, at least 5 seconds, or at least 10 seconds.

[0080] In another aspect of the invention, the controller 545 includes an algorithm configured to detect kinks or clogs in the inlet tubing of the inlet line 550 or the suction tubing of the outlet line 555. The flexible tubing of either the inlet line 550 or the outlet line 555 may kink, which may remain temporarily unnoticed by the physician or nursing staff. If the inlet line 550 is kinked, the reduced flow of fluid into the treatment site will result in a loss of pressure at the site and the working space may collapse. A kink in the outlet line 555 may result in an unwanted increase in fluid pressure at the treatment site.

[0081] To quickly detect kinks in the inlet line 550 on the positive pressure side of the inlet pump 564A, the controller algorithm provides a kinked piping warning if the calculated power driving the inlet pump motor exceeds a predetermined value for a preselected time interval. Such predetermined value depends on the motor, gearbox, pump head, and predetermined pressure limits. As can be understood from the above description of the dual pump system, the motor power directly corresponds to the pressure applied to the positive pressure side of the inlet pump 564A. If the pressure in the inlet piping increases as a result of a kink or clog in the piping, the hydraulic load on the pump rollers from the piping will increase, which transfers load to the inlet pump motor. This increased load on the motor then results in an increase in the current required to drive the pump motor at the target speed. The controller 545 includes algorithms for maintaining the pump speed (and corresponding flow rate) at a predetermined level, even under load, during use of the fluid management system in its various modes. The power value is measured by the controller algorithm and at predetermined limits, the algorithm may (i) display a warning of a fluid flow blockage associated with kinked tubing or clogging of the flow path or filter 575, (ii) display a message or warning that the molecular filter 575 may be clogged, or (iii) display a message to replace the filter 575. The algorithm may further shut down the procedure by deactivating the pumps 546A, 546B and / or by deactivating power to any tissue ablation devices 515 when in use.

[0082] The fluid management system 500 further includes a controller algorithm for detecting kinks or clogging in the outflow line 555 on the negative pressure side of the outflow pump 546B. This kink detection is accomplished by monitoring the motor voltages of both pump motors. When the system is operating in either the ablation or diagnostic mode, the algorithm first checks to determine if the outflow pump 546B is on and then checks that voltage is applied to the inflow pump 546A. If the inflow pump 546A motor is operating at a voltage less than a predetermined threshold level, a timer is started. The predetermined voltage threshold for the inflow pump motor is selected based on the expected input motor voltage during the ablation and diagnostic modes. A typical fluid outflow rate or outflow flow rate from the uterine cavity during the ablation and diagnostic modes is 250-500 milliliters per minute, a flow rate that requires a minimum motor voltage input to the inflow pump motor to maintain pressure. When outflow from the uterine cavity is reduced or deactivated as a result of a kink in the outflow line 555, the intraluminal pressure will remain at a relatively quiescent level. In this quiescent condition, the input voltage to the inflow pump motor will fall below a predetermined threshold input voltage, thus initiating a kink detection timer. When the timer exceeds a preselected time interval ranging from 5 seconds to 120 seconds, an algorithm is applied to provide a kink piping warning. Additionally, the algorithm can shut down the procedure by deactivating the pumps (546A, 546B) and / or deactivating power to any of the resection devices 515 during use.

[0083] The fluid management system 500 further includes a controller algorithm for detecting a kink in the piping of the outlet line 555 on the positive pressure side of the outlet pump 546B. The controller algorithm detects such a kink in the outlet line 555 when the measured motor current of the motor driving the outlet pump 546B exceeds a predetermined level. The predetermined level again depends on the motor, gearbox, pump head, and predetermined pressure limits. The motor current directly corresponds to the pressure on the positive pressure side of the pump 546B. As the pressure in the piping increases (as a result of kinks in the piping or a clogged filter), the hydraulic load on the pump rollers from the piping increases, which transfers load to the motor. This increased load on the motor increases the current required to drive the motor at the target speed and flow rate. As described above, the controller 545 includes algorithms to maintain the pump speed at a predetermined level during use of the fluid management system in various modes. Thus, the kinks detection algorithm measures the current driving the outflow pump motor, and at a predetermined current limit over a preselected time interval, the algorithm can (i) display a kinked tubing warning, (ii) display a message or warning that the molecular filter 575 is clogged, or (iii) display a message to replace the filter 575. Additionally, the algorithm can automatically shut down the procedure by disabling the pumps (546A, 546B) and / or by disabling power to any ablation devices 515 in use in response to detecting kinked tubing or clogged flow paths.

[0084] In another embodiment of the invention, the controller 545 includes an algorithm configured to further control and optimize the fluid pressure within the site during the tissue ablation interval to maintain the target set pressure using a feedback control loop. The feedback control loop consists of utilizing a pressure sensor 560 to monitor the actual pressure at the site, and then utilizing a controller algorithm to adjust the speed of both the inflow pump 546A and the outflow pump 546B (FIG. 21). In particular, when the physician initiates tissue ablation with the tissue ablation device 515 as shown in FIGS. 16-17 and 21, the tissue volume in communication with the window 517 (FIG. 21) will at least partially block the window, thus beginning to slow the outflow of fluid through the extraction channel 160 in the inner sleeve 175. As a result of the reduced outflow, the signal from the pressure sensor 560 to the controller 545 will indicate an increase in the actual pressure within the site, which in turn, under the above-described algorithm, will result in a reduction in the input voltage at the inflow pump motor thus slowing the inflow rate. If the state of reduced outflow continues for a first preselected time interval, the controller algorithm will recognize that the ablation device is ablating tissue and will send a tissue engagement signal to the controller. After a subsequent or second preselected time interval, the algorithm will allow the controller 545 to reduce the input voltage to the outflow pump motor (and thus the outflow rate or flow rate of fluid) from a higher voltage level (e.g., in the 15-30 volt range) to a lower voltage (e.g., in the 5-12 volt range) while placing the inflow pump in a "standby" state. In this standby state, if a sudden decrease in actual pressure in the site were signaled by the pressure sensor 560, the algorithm would cause the delivery of maximum voltage (e.g., 30 volts rather than the nominal voltage) to the inflow pump motor, and thus maximum fluid inflow into the site. As a result of such a sudden decrease in pressure, the algorithm will then send a tissue detachment signal to the controller, which will operate the inflow pump at maximum voltage as described above. Under normal operating conditions, the nominal inflow pump voltage would be in the 10-20 volt voltage range.The purpose of this pressure maintenance algorithm is to anticipate a sudden decrease in pressure at the site when tissue is removed from the ablation device window 517 while the ablation device is activated, or when a tissue tip is removed through the extraction channel 160, which in turn results in a rapid increase in outflow. The ongoing reduction in outflow pump voltage will then also reduce the outflow rate, and the "standby" state of the inflow pump will ensure that when a sudden tissue removal condition (tissue withdrawal signal) occurs, the inflow pump 546A will be activated at its maximum voltage and inflow rate that matches or exceeds the outflow rate, which in turn prevents any drop in the actual pressure within the site. The maximum inflow rate and reduced outflow rate will continue until the target set pressure is maintained for a preselected interval that may range from 0.1 seconds to 10 seconds.

[0085] Another method of operating the fluid management system and RF ablation probe as shown in Figures 16-21 includes the steps of: (i) accessing a site within a patient's body with a distal end of an endoscope and a working end of an electrosurgical probe; (ii) delivering RF energy to the working end to apply energy to tissue at the site; (iii) simultaneously operating the fluid management system to provide a selected inflow rate to the site and an outflow rate or flow rate of fluid from the site; and (iv) detecting a change in a signal of an electrical parameter of the probe during operation and, in response to detecting the change, switching at least one operating parameter of the fluid management system described above. Typically, the electrical parameter includes at least one of an impedance level, a power level, a voltage level, and a current level. The operating parameters of the fluid management system that can be adjusted include at least one of an inflow rate to the site, an outflow rate or flow rate of fluid from the site through a system outflow channel, a positive pressure level communicating with a fluid inflow channel, a negative pressure level communicating with a fluid outflow channel, a target pressure set point at the site, and a rate of change of any of the above. In another variation, the at least one operating parameter can include an algorithm for operating a pressure sensing system configured to determine a fluid pressure at the site. In the above-described methods, the applied energy can be adapted to ablate and remove tissue or to coagulate tissue.

[0086] While certain embodiments of the present invention have been described above in detail, it will be understood that this is for illustrative purposes only and that the above description of the present invention is not exhaustive. Certain features of the present invention are shown in some drawings and not in others, and this is for convenience only, as any feature may be combined with another in accordance with the present invention. Several modifications and alternatives will be apparent to those skilled in the art. Such alternatives and modifications are intended to be included within the scope of the claims. Certain features presented in dependent claims may be combined to fall within the scope of the present invention. The present invention also encompasses embodiments as if the dependent claims were instead written in a multiple dependent claim format with reference to other independent claims. [Explanation of symbols]

[0087] 500 Fluid Management System 502 Uterine cavity (body cavity) 512 Endoscope 515 Tissue ablation probe 545 Controller 546A Inflow Pump 546B Outflow Pump 560 Pressure Sensor 560', 560'' sensing element

Claims

1. A uterine fibroid treatment system, comprising: A controller; an inflow pump operated by the controller and configured to direct the inflow of fluid through a flow path to the patient's uterine cavity; an outflow pump operated by the controller and configured to effect outflow of fluid through a flow path to the uterine cavity; a motorized ablation device operated by the controller; the resection device includes an elongated introducer, the introducer having (i) a tissue extraction channel located therein and having a diameter not less than 2.4 mm, and (ii) an outer diameter not greater than 3.8 mm, such that the resection device is configured to remove uterine fibroid tissue at a rate of at least 2 gm / min; A uterine fibroid treatment system, wherein the controller is configured to operate the inflow pump and the outflow pump in response to a signal of fluid pressure within the uterine cavity to maintain a target pressure within the uterine cavity.

2. 2. The uterine fibroid treatment system of claim 1, wherein the controller is configured to operate the ablation device in response to at least one parameter selected from the group consisting of an inflow pump speed, an outflow pump speed, and a signal of fluid pressure within the uterine cavity.

3. The uterine fibroid treatment system of claim 1 , wherein the signal of fluid pressure within the site is provided by a pressure sensor coupled to a stationary fluid column in communication with the uterine cavity.

4. The uterine fibroid treatment system of claim 1 , wherein the controller is configured to provide a fluid loss signal in response to at least one parameter selected from the group consisting of an inflow pump speed, an outflow pump speed, and a signal of fluid pressure within the uterine cavity.

5. 1. A fluid management system comprising: A controller; a first pump operated by the controller and configured to pump fluid to a site within a patient's body; a second pump operated by the controller and configured to effect an outflow of fluid from the site within the patient's body; the controller is configured to provide at least one operating parameter selected from the group consisting of a first pump speed, a second pump speed, and a target pressure within the site rate; The fluid management system, wherein the controller is configured to provide a fluid loss warning if the first pump speed exceeds a predetermined level for a preselected time interval.

6. 6. The fluid management system of claim 5, wherein the first pump speed provides a fluid loss warning at a first predetermined level when operating in an ablation mode of operation and provides a fluid loss warning at a second predetermined level when operating in a non-ablative mode of operation.

7. The fluid management system of claim 6 , wherein the preselected time interval is at least 1 second.

8. The fluid management system of claim 6 , wherein the preselected time interval is at least 5 seconds.

9. The fluid management system of claim 6 , wherein the preselected time interval is at least 10 seconds.

10. The fluid management system of claim 6 , wherein the controller is further configured to disable at least one pump if the first pump speed exceeds the predetermined level for the preselected time interval.

11. 7. The fluid management system of claim 6, wherein the controller is further configured to deactivate a powered ablation device positioned within the site if the first pump speed exceeds the predetermined level for the preselected time interval.

12. 1. A fluid management system comprising: A controller; an inflow pump operated by the controller and configured to direct the inflow of fluid through a flow path to a site within a patient's body; an outflow pump operated by the controller and configured to effect outflow of fluid through a flow path from the site within the patient's body; the controller is configured to provide at least one operating parameter selected from the group consisting of a first pump speed, a second pump speed, and a target pressure within the site; The fluid management system, wherein the controller is configured to provide a flow interruption warning if the calculated power to drive the inflow pump exceeds a predetermined level for a preselected time interval.

13. 13. The fluid management system of claim 12, wherein the controller is further configured to disable at least one pump if the calculated power to drive the inflow pump exceeds the predetermined level for the preselected time interval.

14. 13. The fluid management system of claim 12, wherein the controller is further configured to shut down a powered ablation device positioned at the site if the calculated power to drive the inflow pump exceeds the predetermined level for the preselected time interval.

15. 1. A fluid management system comprising: A controller; a first pump operated by the controller and configured to pump fluid to a site within a patient's body; a second pump operated by the controller and configured to effect the outflow of fluid from the site within the patient's body; the controller is configured to provide at least one operating parameter selected from the group consisting of a first pump speed, a second pump speed, and a target pressure within the site; The fluid management system, wherein the controller is configured to provide a flow interruption warning if an input voltage to a motor of the inflow pump is below a predetermined threshold voltage for a preselected time interval during which the outflow pump is operating.

16. The fluid management system of claim 15, wherein the preselected time interval is within a range of 5 seconds to 120 seconds.

17. 16. The fluid management system of claim 15, wherein the controller is further configured to disable at least one pump when an input voltage to the inflow pump falls below the predetermined level for the preselected time interval.

18. 16. The fluid management system of claim 15, wherein the controller is further configured to deactivate the powered ablation device positioned within the site if an input voltage to the inflow pump motor exceeds the predetermined level for the preselected time interval.

19. 1. A fluid management system comprising: A controller; an inflow pump operated by the controller and configured to direct the inflow of fluid through a flow path to a site within a patient's body; an outflow pump operated by the controller and configured to effect outflow of fluid through a flow path from the site within the patient's body; the controller is configured to maintain at least one operating parameter selected from the group consisting of a first pump speed, a fluid inflow rate, a second pump speed, and a fluid outflow rate or outflow flow rate; The fluid management system, wherein the controller is further configured to provide a flow interruption warning if a measured current to the outflow pump exceeds a predetermined threshold voltage for a preselected time interval.

20. 1. A fluid management system for use in a tissue ablation procedure, comprising: A controller; an inflow pump operated by the controller and configured to direct the inflow of fluid through a flow path to a site within a patient's body; an outflow pump operated by the controller and configured to effect outflow of fluid through a flow path from the site within the patient's body; a motorized ablation device for ablating tissue at the site; the controller is configured to operate the inflow pump and the outflow pump to respectively pump fluid in and out of the patient's body in response to a signal of an actual pressure at the site to maintain a target pressure at the site; The fluid management system, wherein the controller is configured to deactivate the motorized ablation device when it senses that the actual pressure within the site falls below a predetermined threshold pressure level.

21. The fluid management system of claim 20, wherein the controller is further configured to deactivate a motor driving the ablation device when the actual pressure within the site falls below a predetermined threshold pressure level.

22. 21. The fluid management system of claim 20, wherein the controller is further configured to deactivate at least one tissue ablation electrode when the actual pressure within the site falls below a predetermined threshold pressure level.

23. The fluid management system of claim 20, wherein the threshold pressure level is less than 100 mmHg.

24. The fluid management system of claim 20, wherein the threshold pressure level is less than 50 mmHg.

25. The fluid management system of claim 20, wherein the threshold pressure level is less than 25 mmHg.

26. 1. A fluid management system for use in tissue ablation, comprising: a controller, the controller comprising: (a) actuating an inflow pump and an outflow pump to respectively pump fluid in and out of the patient's body in response to signals of an actual pressure in a site within the patient's body to maintain a target pressure at the site; (b) transmitting a tissue engagement signal to the controller upon sensing a predetermined steady-state pressure condition within a preselected interval resulting from the ablation tool engaging target tissue within the site; (c) transmitting a tissue disengagement signal to the controller upon sensing a predetermined change in the actual pressure within a preselected interval resulting from the ablation tool subsequently disengaging from the tissue; (d) a fluid management system configured to adjust an operating parameter of the fluid management system in response to a tissue engagement signal or a tissue disengagement signal.

27. 27. The fluid management system of claim 26, wherein the controller is further configured to, in response to a tissue engagement signal, place the inflow pump in a standby state providing a selected high inflow rate.

28. 27. The fluid management system of claim 26, wherein the controller is further configured to reduce a speed of the inflow pump in response to a tissue engagement signal.

29. 27. The fluid management system of claim 26, wherein the controller is further configured to operate the inflow pump to provide a selected high inflow rate in response to a tissue detachment signal.

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