FLUID MANAGEMENT SYSTEM

Fluid management systems used, for example, in endoscopic procedures.

BACKGROUND OF THE INVENTION

Field of the Invention The present invention relates to a fluid management system of the type used, for example, in endoscopic procedures.

Surgical fluid management systems typically deliver a fluid, such as saline, to a targeted working space or body cavity to provide access and visibility to the physician performing a procedure in the space. The fluid usually provides pressure sufficient to “open” the space (i.e., create a working space for the procedure) and additionally will usually flush blood and debris from the space. Typically, the fluid management system includes a control system for maintaining a preset fluid pressure in a working space.

Surgical fluid management systems are often inconvenient to use and difficult to monitor. Further, fluid management systems often have control systems that are unable to accurately measure pressure in a working space when the patient and the fluid management console are at different elevations. It would therefore be beneficial to provide improved surgical fluid management systems that overcome at least some of these shortcomings.

SUMMARY OF THE INVENTION

In general, the fluid management system includes a roll stand carrying a control unit and controller, a disposable or multiple-use cassette that is adapted to pressurize a pressure cuff carrying a saline bag, a drape pump, a collection reservoir, and a display for displaying operating parameters of the fluid management system. During operation, the system can calculate pressure in the working space based on fluid pressure in the cassette tubing and provide for inflow and outflow control to maintain a desired pressure in the working space or adjust other operating parameters. Other features, objects, and advantages will be apparent from the description and drawings and from the claims.

The present invention provides improved fluid management systems and methods for their use. In particular, the present invention provides a disposable or multiple-use cassette, with first and second flexible tubing loops therein for coupling to first and second roller pumps. The first tubing loop is used for pressurizing a pressure cuff for delivering fluid from a fluid source to a patient. The second tubing loop may be used for regulating fluid outflows from the patient and delivering the fluid outflows to a disposal waste reservoir. The fluid management systems may also be configured to alert the user when the cassette has been successfully loaded or, conversely, when the cassette has not been successfully loaded. Further capabilities include sensing conditions of the fluid, in particular, positive pressures in the first tubing loop in the cassette. Automatic locking capabilities for locking the cassette in place may also be provided by a motor and control mechanism carried by the control unit.

In other specific embodiments, the cassette may further comprise a flexible membrane on a sensing window on at least one of the first and second tubing loops. The at least one sensing window will usually be positioned to align with a pressure or force sensor on the control unit the cassette is locked into place on the control unit. In an exemplary embodiment, the membrane of the sensing window comprises a thin resilient element overlying an interior chamber in a housing that communicates with the lumen in a tubing loop carried by the cassette.

DETAILED DESCRIPTION OF THE INVENTION

FIG.1illustrates a fluid management system100of the invention, which includes a control unit102and video display104mounted on a roll stand105. The fluid management system100is used in endoscopic procedures, which can be a gynecology procedure, a urology surgery or an arthroscopic surgery, to provide inflows and outflows of a pressurized fluid to and from a working space or body cavity. The fluid is typically saline solution and can be delivered through an endoscope or other device to provide and maintain a preset pressure level within the working space. In the system shown inFIG.1, the fluid is delivered from a fluid source comprising a flexible saline bag106, which is carried within a pressure cuff110as is known in the art. The pressure cuff110consists of a flexible structure with an inflatable chamber that surrounds the saline bag106where inflation of the pressure cuff110compresses the saline bag106to cause a fluid flow therefrom through an inflow tubing112that is typically coupled to an endoscope114.

As also can be understood from inFIGS.1and5, the roll stand105further carries a waste collection reservoir115, which is adapted to receive outflows from the working space WS through outflow tubing116(FIG.5) that is coupled to an endoscope or other device. Further, the roll stand105carries an independent drape pump118(seeFIG.1) for removing fluid from a surgical drape120that may be used in a surgical procedure. The drape pump118carries fluid from the drape120through waste tubing122to the waste collection reservoir115(FIG.5). As will be described below, a processor or controller125(FIG.5) in the control unit102is configured to sense the weight of fluid in the collection reservoir115from which fluid deficits can be calculated and which is important for certain surgical procedures.

InFIG.1, one variation of a control unit102is coupled to a type of video display104that comprises a touch screen. In this variation, various icons126on the touch screen display104are adapted for selecting a target pressure in the working space, a fluid inflow rate, flush, image capture with the endoscope, light intensity of LEDs carried by the endoscope, and/or other modes of operation. It should be appreciated that a smaller touchscreen can be integrated into the control unit102itself. Alternatively, an endoscope coupled to the control unit102has a control pad with controls buttons for adjusting any operating parameter of the system, such as set pressure, inflow rate, image capture, light intensity, flush, and the like. The touch screen or an actuator on the control unit102can be used to unlock or lock the cassette on the control unit as will be described further below.

The video display104also is configured to receive data from the controller125to continuously display the pressure in the working space, the fluid deficit as will be further described below, the volume of saline remaining in the saline bag106, the fluid inflow rate. In some variations, the endoscope114may be coupled to the controller, and LED light intensity may be displayed on the video display104as well as other operating parameters of the endoscope. The endoscope114can be coupled to the control unit at connector126in the control unit102.

Now referring toFIGS.1and2, the control unit102has a front surface130that carries first and second peristaltic roller pumps132A and132B with corresponding motors134A and134B in the interior of the control unit102(seeFIG.2). The peristaltic roller pumps132A and132B extend through a slidable base plate135in the front surface130of the control unit102. As can be seen inFIG.1, a removable cassette140is provided that is adapted for looking in position in the base plate135(FIG.2) to be engaged by the first and second roller pumps132A and132B.

Referring toFIGS.3-4, the cassette140includes a plastic molded housing or body142that carries portions of a tubing set, and more particularly two loops of a flexible tubing144A and144B as in known in the art. The tubing loops are typically a flexible polymer material having a diameter ranging between about ¼″ to ½″ and are adapted to cooperate with the first and second pumps132A and132B (seeFIGS.1and2). The tubing loops144A and144B in the cassette140(seeFIG.4) extend in a semicircular arc of at least 90° or at least 120° in the plane of the cassette, where the plane of the cassette is adapted to align with the first and second roller pumps132A and132B. As can be understood fromFIGS.2and4, the plane of the tubing loops is perpendicular to the axis of each shaft148of the pump motors134A and134B.

The system100and control unit102includes a mechanism for locking the cassette140in place. Referring toFIGS.2and4, it can be understood that the tubing loops144A and144B within the cassette140are adapted to be inserted between the roller pumps132A and132B and the arcuate structure or eyebrows150A and150B (FIG.2). As can be seen inFIG.2, the slidable base plate135carries the eyebrows150A and150B that are adapted to contact and press the tubing loops144A and144B against the first and second roller pumps132A and132B. Referring toFIGS.3and4, it can be seen that the cassette140has four short leg elements152a-152dextending away from the front face154of the cassette140. InFIG.2, it can be seen that two sensor boards155aand155bare provided on either side of the base plate135of the control unit102. Each sensor board155aand155bcarries optical sensors (not shown) that sense reflectance of the legs152a-152dof the cassette140when pushed into place against the base plate135. In other words, as the cassette140is pushed inwardly to contact the front surface of the base plate, the four optical sensors detect reflectance of the four legs152a-152dwhich then activates a locking motor160, which in turn moves the base plate135in a downward direction to press the eyebrows150A and150B against the tubing loops144A and144B so that the first and second roller pumps132A and132B properly engage the tubing loops. The downward movement of the base plate135and eyebrows150A and150B then reach a stop position to lock the cassette140in place.

As described above, the system allows for precise control of fluid flows and fluid pressure in the working space, which is next described in more detail. Referring again toFIG.2, it can be seen that the front surface130of the control unit102carries a pressure sensor mechanism170which in a variation includes two pressure sensors172aand172b. The first and second pressure sensors172aand172bare provided for redundancy. The sensor mechanism170is adapted to contact a flexible membrane175carried by the cassette140(seeFIG.4). It can be understood fromFIGS.2and4that the cassette sensor membrane175is disposed on a side of an air chamber176in the cassette140that communicates with pressure cuff tubing177. The membrane175is adapted to flex inwardly and outwardly depending on pressure of the air in the chamber176and the lumen of the tubing loop144A. Referring toFIGS.2-4, actuation of the first pump132A causes air to be suctioned through port178ain the cassette140, which communicates with tubing loop144A, air chamber176, and the port178b, which in turn is coupled to the pressure cuff tubing177, which extends to the pressure cuff110. The sensor mechanism170can then sense pressure in the pressure cuff tubing177, which in turn measures pressure in the pressure cuff110, the saline bag106and the working space WS, which are all correlated. The controller125then can use algorithms to calculate the fluid pressure in the working space WS and then can maintain or modulate pressure in the pressure cuff110and working space WS by controlling roller pump132A.

In one variation, the fluid management system100has a controller125that is adapted to alter the pressure applied to the pressure cuff110that is dependent on the volume of saline remaining in the saline bag106. It can be understood that as the saline in the bag106has a greatly reduced volume, pressure in the cuff110may not cause the same saline inflow rate as when the saline bag has a full volume. Therefore, the controller125can use a look-up table or similar mechanism to correlate pressure provided by the roller pump with the volume of saline in the saline bag. The pressure cuff110can be configured with a sensor mechanism coupled to the controller125for sensing the volume of fluid in the saline bag106, wherein the sensor system comprises at least one of a weight sensor, an ultrasound sensor, an optical sensor or an electrical sensor wherein the controller125is responsive to signals from such a sensor mechanism to adjust operation of the roller pump to provide a flow of air into the cuff110the volume of saline is at any particular level. As described above, the positive pressure in the cuff110is used to provide fluid flows into a working space WS from the saline bag106. The roller pump132A can apply negative pressure to collapse the pressure cuff110, for example, to change the saline bags or too rapidly reduce pressure in the working space WS.

In another aspect, the system100and controller125provides a mechanism or flow regulator for controlling fluid outflows from the working space WS. Referring toFIGS.2,3and4, the second peristaltic roller pump132B engages the second tubing loop144B in the cassette140. Actuation of second roller pump132B causes air to be suctioned through port182ain the cassette140, which communicates with tubing loop144B with the air exiting the tubing loop144B through port182binto clamp tubing184, which in turn is coupled to the clamp valve185as shown inFIGS.2and5. The pump132B then can be used to actuate an actuator in the clamp valve185to pinch the outflow tubing116that is clamped into the clamp valve185. The controller125is adapted to control the second roller pump132B to apply positive or negative pressure to the clamp valve to decrease or increase flows through the outflow tubing116.

In one variation shown inFIG.6, the clamp valve185includes internal bladder186, which when expanded by airflow through tubing184is adapted to move a sliding pinch element188into the flexible outflow tubing116. It can be understood that the pinch element188applies pressure to the exterior of the flexible outflow tubing116and can thereby control to the fluid outflow rate. Thus, the controller125can thus control both roller pumps132A and132B in response to signals from the pressure sensor mechanism170to vary the inflows and/or outflows to maintain a targeted set pressure in the working space or a targeted pressure in combination with a selected inflow or outflow rate.

In another aspect, the system100and controller125are capable of determining fluid deficit, which is important is some surgical procedures, such as gynecology. As can be understood fromFIGS.1and5, the roll stand105and control unit102carry a load sensor195that provides a signal to the controller125of the weight of saline collected in collection reservoir115, which is collected from fluid outflows and well as collected from the drape120. The fluid deficit monitoring system is calibrated at the start of a procedure by providing the controller125with the known volume of saline in the saline bag106. Another load sensor optionally could be used to monitor the weight of the saline bag106and pressure cuff110. The controller125then is configured to calculate the volume of saline inflows to the working space WS and the volume of saline collected in the collection reservoir115from which the fluid deficit then is known. In one variation, the fluid deficit is continuously calculated and shown on the display104. The system100further can include audio and/or visual alarms when the fluid deficit reaches a preselected level, and the system can include a shut-down mechanism when the fluid deficit reaches a preselected level.

In another aspect of the invention, referring toFIG.3, the cassette140with tubing loops144A and144B can be configured for limited re-use since only air flows through the tubing loops within the cassette140. InFIG.3, it can be seen that the front surface154of the cassette140carries a housing194that houses a mechanical counter mechanism195that automatically advances the counter each time the cassette is pushed into contact with the front surface130of the control unit102. In another variation, the cassette140can carry an identifier such as an RFID identifier that the controller125can sense and monitor for the number of uses. In such a variation, the controller125then would not operate after a selected number of uses, for example, ten or twelve uses.

Although particular embodiments of the present invention have been described above in detail, it will be understood that this description is merely for purposes of illustration and the above description of the invention is not exhaustive. Specific features of the invention are shown in some drawings and not in others, and this is for convenience only, and any feature may be combined with another in accordance with the invention. A number of variations and alternatives will be apparent to one having ordinary skills in the art. Such alternatives and variations are intended to be included within the scope of the claims. Particular features that are presented in dependent claims can be combined and fall within the scope of the invention. The invention also encompasses embodiments as if dependent claims were alternatively written in a multiple dependent claim format with reference to other independent claims.