Patent Publication Number: US-2021178033-A1

Title: Cassette design and systems and methods thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 62/949,431, filed Dec. 17, 2019, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of Technology 
     The present invention relates generally to a system for distributing fluid in a surgical cassette, comprising a cassette for use with a surgical console, further comprising a first set of fluid channels having a first set of ports, a second set of fluid channels having a second set of ports, at least one rotary valve in fluid communication with the first set of fluid channels, at least one rotary valve in fluid communication with the second set of fluid channels, and a plurality of deformable channels, wherein the deformable channels are fluidly connected to ones of the first set of ports and second set of ports. 
     Description of the Background 
     The optical elements of the eye include both a cornea (at the front of the eye) and a lens within the eye. The lens and cornea work together to focus light onto the retina at the back of the eye. The lens also changes in shape, adjusting the focus of the eye to vary between viewing near objects and far objects. The lens is found just behind the pupil and within a capsular bag, the capsular bag being a thin, relatively delicate structure which separates the eye into anterior and posterior chambers. 
     With age, clouding of the lens or cataracts is fairly common. Cataracts may form in the hard central nucleus of the lens, in the softer peripheral cortical portion of the lens, or at the back of the lens near the capsular bag. Cataracts can be treated by the replacement of the cloudy lens with an artificial lens. Phacoemulsification systems often use ultrasound energy to fragment the lens and aspirate the lens material from within the capsular bag. This may allow the capsular bag to be used for positioning of the artificial lens and maintains the separation between the anterior portion of the eye and the vitreous humor in the posterior chamber of the eye. 
     During cataract surgery and other therapies of the eye, accurate control over the volume of fluid within the eye is highly beneficial. For example, while ultrasound energy breaks up the lens and allows it to be drawn into a treatment probe with an aspiration flow, a corresponding irrigation flow may be introduced into the eye so that the total volume of fluid in the eye does not change excessively. If the total volume of fluid in the eye is allowed to get too low at any time during the procedure, the eye may collapse and cause significant tissue damage. Similarly, excessive pressure within the eye may strain and injure tissues of the eye. 
     While a variety of specific fluid transport mechanisms may be used in phacoemulsification and other treatment systems for the eyes, aspiration flow systems can generally be classified in two categories: 1) volumetric based aspiration flow systems using positive displacement pumps (e.g. peristaltic); and 2) vacuum-based aspiration systems using a vacuum source, typically applied to the aspiration flow through an air-liquid interface within a reservoir (e.g. Venturi). Both systems may be incorporated into one treatment system and/or cassette. Cassette (“pack”) systems can be used to couple peristaltic pump drive rotors and/or vacuum systems of the surgical consoles to an eye treatment handpiece, with the flow network conduit of the cassette being disposable to avoid cross-contamination between different patients. 
     To mitigate any such occurrences of cross-contamination between different patients, staff operating a system typically begin each procedure with afresh cassette and irrigation source prior to each case and monitor the fluid visually throughout surgery. However, conventional configurations do not efficiently provide for easily exchangeable cassettes which can optimally perform certain intended functions. As such, improvements are needed in the art to address these issues. 
     SUMMARY 
     A surgical system is disclosed, comprising a cassette for use with a surgical console, further comprising a first set of fluid channels having a first set of ports, a second set of fluid channels having a second set of ports, at least one rotary valve in fluid communication with the first set of fluid channels, at least one rotary valve in fluid communication with the second set of fluid channels, and a plurality of deformable channels, wherein the deformable channels are fluidly connected to ones of the first set of ports and second set of ports. 
     Under another exemplary embodiment, a cassette for distributing fluid during a surgical procedure is disclosed, comprising a plurality of rigid fluid channels, at least two rotary valves, a plurality of pressure sensing devices, and at least one level sensing device associated with at least one fluid tank, wherein at least one of the plurality of fluid channels is in fluid communication with at least one of the plurality of pressure sensing devices. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification. The drawings illustrate disclosed embodiments and/or aspects and, together with the description, serve to explain the principles of the invention, the scope of which is determined by the claims. 
         FIG. 1A  is a schematic illustrating an eye treatment system in which a cassette is coupled to an eye treatment probe with an eye treatment console under one embodiment; 
         FIG. 1B  is a schematic illustrating a surgical eye treatment console under another exemplary embodiment; 
         FIG. 2  is a functional block diagram of an exemplary cassette system for an eye treatment system under one embodiment; 
         FIG. 3  is a schematic illustrating a cassette under another exemplary embodiment; 
         FIG. 4  is a schematic illustrating a cassette under another exemplary embodiment; 
         FIG. 5A  is a schematic illustrating a cassette under another exemplary embodiment; 
         FIG. 5B  is a schematic illustrating a portion of a cassette under another exemplary embodiment; 
         FIG. 5C  is a schematic illustrating side view of a portion of a cassette under another exemplary embodiment; 
         FIG. 5D  is a schematic illustrating a cassette under another exemplary embodiment; 
         FIG. 6A  is an isometric view illustrating a portion of a pump head and a cassette under another exemplary embodiment; 
         FIG. 6B  is a front view illustrating a portion of a cassette under an exemplary embodiment; 
         FIG. 7A  is an illustration of a portion of a pump head and a cassette under another exemplary embodiment; 
         FIG. 7B  is an illustration of a portion of a cassette under another exemplary embodiment; and 
         FIG. 8  is a schematic illustration of a cassette and pump for use with an eye treatment system under one embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for the purpose of clarity, many other elements found in typical surgical, and particularly optical surgical, apparatuses, systems, and methods. Those of ordinary skill in the art may recognize that other elements and/or steps are desirable and/or required in implementing the present invention. However, because such elements and steps are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements and steps is not provided herein. The disclosure herein is directed to all such variations and modifications to the disclosed elements and methods known to those skilled in the art. 
     The figures and descriptions provided herein may have been simplified to illustrate aspects that are relevant for a clear understanding of the herein described apparatuses, systems, and methods, while eliminating, for the purpose of clarity, other aspects that may be found in typical similar devices, systems, and methods. Those of ordinary skill may thus recognize that other elements and/or operations may be desirable and/or necessary to implement the devices, systems, and methods described herein. But because such elements and operations are known in the art, and because they do not facilitate a better understanding of the present disclosure, for the sake of brevity a discussion of such elements and operations may not be provided herein. However, the present disclosure is deemed to nevertheless include all such elements, variations, and modifications to the described aspects that would be known to those of ordinary skill in the art. 
     Embodiments are provided throughout so that this disclosure is sufficiently thorough and fully conveys the scope of the disclosed embodiments to those who are skilled in the art. Numerous specific details are set forth, such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. Nevertheless, it will be apparent to those skilled in the art that certain specific disclosed details need not be employed, and that exemplary embodiments may be embodied in different forms. As such, the exemplary embodiments should not be construed to limit the scope of the disclosure. As referenced above, in some exemplary embodiments, well-known processes, well-known device structures, and well-known technologies may not be described in detail. 
     A surgical cassette, also referred to as a medical pack, a fluidic cassette, or simply, a cassette, is used to facilitate irrigation and aspiration during surgical procedures, such as phacoemulsification surgery. The surgical cassette may be inserted and mounted to a surgical console and become part of an overall phacoemulsification surgery system. The surgical cassette may perform a myriad of functions, such as effluent material collection, tube pressure sensing, and control the flow of fluid through tubing encased within the cassette and between a surgical handpiece and a surgical console. 
     A surgical cassette typically comprises a front plate and a back plate, and may also include a gasket at least partially there between. The front plate and back plate may also be welded together to avoid the use of a gasket or other intermediate portion. Molded within either/or the front plate and the back plate may be pathways for tubing to be inserted thereby creating desired pathways for the tubing around the gasket. In an embodiment where there is a gasket, the gasket may comprise one or more valves and one or more sensors to promote fluid flow through the tubing along the desired pathways. In an embodiment where there is no gasket, any valves known in the art may be used, e.g. rotary valve. 
     Surgical cassettes may utilize different types of sensors to monitor vacuum, flow, and/or pressure of certain fluid lines or channels during the surgical process. Other single use cassettes may use a low cost pressure diaphragm on the cassette with a console mounted Linear Variable Differential Transformer (LVDT) to measure the deflection of the pressure diaphragm with either a low rate spring pushing the LVDT against the surface of the pressure diaphragm or a magnet coupling the LVDT to the surface of the diaphragm, or a combination of both a spring and magnet. The spring force and/or friction force associated with movement of the LVDT sensing element reduces the accuracy and repeatability of this type system. Other systems may use laser triangulation displacement sensors to measure the deflection of a pressure diaphragm. In addition, other systems may use a ferromagnetic element in the cassette which couples to a magnetic element in the console, which may be coupled with a strain gauge. 
     Referring now to  FIG. 1A , a system  10  for treating an eye E of a patient P generally includes an eye treatment probe handpiece  110  coupled with a console  115  by a cassette  250 . Handpiece  110  generally includes a handle for manually manipulating and supporting an insertable probe tip. The probe tip has a distal end which is insertable into the eye, with one or more lumens in the probe tip allowing irrigation fluid to flow from console  115  and/or cassette  250  into the eye. Aspiration fluid may also be withdrawn through a lumen of the probe tip, with console  115  and cassette  250  generally including a vacuum aspiration source, a positive displacement aspiration pump, or both to help withdraw and control a flow of surgical fluids into and out of eye E. As the surgical fluids may include biological materials that should not be transferred between patients, cassette  250  will often comprise a sterilizable (or alternatively, disposable) structure, with the surgical fluids being transmitted through flexible and/or rigid conduits  120  of cassette  250  that avoid direct contact in between those fluids and the components of console  115 . 
     When a distal end of the probe tip of handpiece  110  is inserted into an eye E, for example, for removal of a lens of a patient P with cataracts, an electrical conductor and/or pneumatic line (not shown) may supply energy from console  115  to an ultrasound transmitter of handpiece  110 , a cutter mechanism, or the like. Alternatively, handpiece  110  may be configured as an irrigation/aspiration (I/A) and/or vitrectomy handpiece. Also, the ultrasonic transmitter may be replaced by other means for emulsifying a lens, such as a high energy laser beam. The ultrasound energy from handpiece  110  helps to fragment the tissue of the lens, which can then be drawn into a port of the tip by aspiration flow. So as to balance the volume of material removed by the aspiration flow, an irrigation flow through handpiece  110  (or a separate probe structure) may also be provided, with both the aspiration and irrigation flows being controlled by console  115 . 
     To avoid cross-contamination between patients without incurring excessive expenditures for each procedure, cassette  250  and its flexible conduits  120  may be disposable. However, the flexible conduit or tubing may be disposable, with the cassette body and/or other structures of the cassette being sterilizable. Cassette  250  may be configured to interface with reusable components of console  115 , including, but not limited to, peristaltic pump rollers, a Venturi or other vacuum source, a controller  125 , and/or the like. 
     Console  115  may include controller  125 , which may include an embedded microcontroller and/or many of the components common to a personal computer, such as a processor, data bus, a memory, input and/or output devices (including a user interface  130  (e.g. touch screen, graphical user interface (GUI), etc.), and the like. Controller  125  will often include both hardware and software, with the software typically comprising machine readable code or programming instructions for implementing one, some, or all of the methods described herein. The code may be embodied by a tangible media such as a memory, a magnetic recording media, an optical recording media, or the like. Controller  125  may have (or be coupled with) a recording media reader, or the code may be transmitted to controller  125  by a network connection such as an internet, an intranet, an ethernet, a wireless network, or the like. Along with programming code, controller  125  may include stored data for implementing the methods described herein; and may generate and/or store data that records parameters corresponding to the treatment of one or more patients. 
     Referring now to  FIG. 1B , a simplified surgical console is illustrated, where a fluid path may be demonstrated under an exemplary embodiment. In this example, an irrigation source  151  may be configured as a bottle or bag hanging from an IV pole hanger  150 . It is understood by those skilled in the art that, while an integrated IV pole is illustrated, other configurations, utilizing standalone/static IV poles, pressurized infusion sources, and/or other suitable configurations, are contemplated by the present disclosure. 
     An exemplary irrigation path for fluid may be realized via tubing cassette  154  having cassette tubing interface  153 , which receives fluid from irrigation source  151  via drip chamber  152 . Irrigation line  156 A and aspiration line  157  are coupled to handpiece  158 . Irrigation fluid may flow from drip chamber  152  through the irrigation tubing into tubing cassette  154 . Irrigation fluid may then flow from the tubing cassette through handpiece irrigation line  156 A which may be coupled to an irrigation port on handpiece  158 . Aspirated fluid may flow from the eye through the handpiece aspiration line  157  back to tubing cassette  154  and into a waste collection bag  155 . A touch screen display  159  may be provided to display system operation conditions and parameters, and may include a user interface (e.g., touch screen, keyboard, track ball, mouse, etc.—see controller  125  of  FIG. 1A ) for entering data and/or instructions to the system of  FIG. 1B . 
     Referring to  FIG. 2 , an exemplary cassette system showing some of the components and interfaces that may be employed in a phaco system, such as ones illustrated in  FIGS. 1A-B . Handpiece  110  may be connected to (or coupled with) the input side of sensor  221 , typically by fluid pathways such as fluid pathway  220 . Sensor  221  may be a pressure, flow, or a vacuum sensor that measures pressure, flow or vacuum, respectively. In a preferred embodiment, sensor  221  is a pressure sensor. The output side of sensor  221  is connected to valve  202  and also connected to pump  205  within cassette  250  via fluid pathway  222 . Valve  202  maybe any known valve in the art, e.g. flow selector valve, rotary valve, etc. Valve  202  may also be coupled with pump  205 . The exemplary embodiment may configure valve  202  to interface between handpiece  110 , vacuum tank  204 , pump  205 , which may be a peristaltic pump but may be another type of pump, and collection  206 . In this configuration, the system may operate valve  202  to connect handpiece  110  with vacuum tank  204  or with pump  205  based on signals received from console  115  resulting from the surgeon&#39;s input to user interface  130  or touch screen display  159 . In an embodiment of the present invention, handpiece  110  is connected to pump  205  and valve  202  provides fluidic connection and disconnection between handpiece  110  and tank  204 . As discussed herein in greater detail, an aspiration level sensor  210  may be communicatively coupled to vacuum tank  204 . 
     The valve  202  illustrated in  FIG. 2  may provide a connection between vacuum tank  204  and fluid pathway  222 . The exemplary embodiment is not limited to one valve and may be realized using two valves each having at least two output ports, possibly connected together to provide the functionality described herein. For example, a pair of two valves may be configured in a daisy chain arrangement, where the output port of a first valve is directly connected to the input port of a second valve. Console  115  may operate both valves together to provide three different flow configurations. For example, using two valves, valve one and valve two, valve one may use output port one, which is the supply for valve two. Valve two may connect to one of two ports providing two separate paths. When valve one connects its input port to its second output port rather than the output port that directs flow to the second valve, a third path is provided. It is also envisioned that valve  202  may be or comprise one or more pinch valves. The one or more pinch valves may be located along fluid pathway  220 ,  222  and/or  223 , or any other fluid pathway as discussed herein. 
     Console  115  may also comprise vacuum pressure center  260  which may provide a vacuum through fluid pathway  224  to vacuum tank  204 . The vacuum provided through fluid pathway  224  may be regulated by control module  261  based on signals received from aspiration control module  263  which may result from the surgeon&#39;s input to user interface  130  and/or based on other signals received from sensor  221 . Aspiration control module  263  may also control pump control  264  and allow for operation of pump  205  for the movement of fluid from both the handpiece  110  and the vacuum tank  204  to collector  206  via pathway  225 . 
     In the configuration shown, vacuum pressure center  260  includes a vacuum source  262 , such as a venturi pump and an optional control module  261  (and valve (not shown)), but other configurations are possible. In this arrangement, vacuum pressure center  260  may operate to remove air from the top of vacuum tank  204  and deliver the air to atmosphere (not shown). Removal of air from vacuum tank  204  in this manner may reduce the pressure within the tank, which may reduce the pressure in the attached fluid pathway  220 , to a level less than the pressure within eye  114 . A lower reservoir pressure connected through valve  202  may cause fluid to move from the eye, thereby providing aspiration. 
     Thus, while a single valve  202  is illustrated in  FIG. 2  associated with aspiration, it is to be understood that this illustration represents a valve arrangement, including one or more valves (e.g. flow selector valve, rotary valve, or the like) performing the functionality described herein, and is not limited to a single device or a single valve. In the exemplary sensor  221 , a strain gauge or other suitable component may communicate or signal information to console  115  to provide an amount of vacuum sensed in the handpiece fluid pathway  220 . Console  115  may determine the actual amount of vacuum present based on the communicated information. 
     In an embodiment, sensor  221  monitors fluid pressure in the line, and can be used to determine when fluid flow should be reversed, such as encountering a certain pressure level (e.g. in the presence of an occlusion), and based on values obtained from the sensor  221 , the system may control valve  202  and the pumps illustrated. It is to be understood that while components presented in  FIG. 2  and other drawings of the present application are not shown connected to other system components, such as console  115 , they are in fact connected for the purpose of monitoring and control of the components illustrated. 
     With respect to sensor  221 , emergency conditions such as a dramatic drop or rise in pressure may result in a type of fail-safe operation. The exemplary embodiment employs sensor  221  to monitor the flow conditions and provide signals representing flow conditions to the system such as via console  115  for the purpose of controlling components shown including but not limited to valve  202  and the pumps shown. The fluid pathways or flow segments of surgical cassette system  200  may include the fluid connections, for example flexible tubing, between each component represented with solid lines in  FIG. 2 . In an embodiment, the fluid connections may include molded fluid channels. 
     Handpiece  110  may be connected to (or coupled with) the output side of irrigation pressure sensor  231 , typically by fluid pathways such as fluid pathway  230 . Sensor  231  may be a pressure, flow, or a vacuum sensor that measures pressure, flow or vacuum, respectively. In a preferred embodiment, sensor  231  is a pressure sensor. The input side of irrigation pressure sensor  231  is connected to valve  203  within cassette  250  via fluid pathway  232 . Valve  203  may be any known valve in the art, e.g. flow selector valve, rotary valve, etc. The exemplary embodiment may configure valve  203  to interface between handpiece  110 , irrigation tank  242 , pump  240 , which may be a peristaltic pump but may be another type of pump, and irrigation fluid source  112 . In this configuration, the system may operate valve  203  to connect handpiece  110  with gravity feed or pressurized irrigation based on signals received from console  115  resulting from the surgeon&#39;s input to user interface  130 . 
     The valve  203  illustrated in  FIG. 2  may provide a connection between irrigation tank  242 , irrigation fluid source  112 , and fluid pathway  232 . The exemplary embodiment is not limited to one valve and may be realized using two valves each having at least two output ports, possibly connected together to provide the functionality described herein. For example, a pair of two valves may be configured in a daisy chain arrangement, where the output port of a first valve is directly connected to the input port of a second valve. Console  115  may operate both valves together to provide three different flow configurations. For example, using two valves, valve one and valve two, valve one may use output port one, which is the supply for valve two. Valve two may connect to one of two ports providing two separate paths. When valve one connects its input port to its second output port rather than the output port that directs flow to the second valve, a third path is provided. It is also envisioned that valve  203  may be or comprise one or more pinch valves. The one or more pinch valves may be located along fluid pathway  230 ,  232 ,  233 ,  234  and/or  235 , or any other fluid pathway as discussed herein. 
     Console  115  may also comprise irrigation pressure center  270  which may provide a positive pressure through fluid pathway  237  to irrigation tank  242  using an applied pressure from pressure source  272 . The pressure provided through fluid pathway  237  may be regulated by control module  271  based on signals received from irrigation control module  273  which may result from the surgeon&#39;s input to user interface  130  and/or based on other signals received from sensor  231 . Irrigation control module  273  may also control pump control  274  and allow for operation of pump  240  for the movement of fluid from irrigation fluid source  112  to collector irrigation tank  242  via pathway  236 . As discussed herein in greater detail, an irrigation level sensor  211  may be communicatively coupled to irrigation tank  242 . 
     While a single valve  203  is illustrated in  FIG. 2  associated with irrigation, it is to be understood that this illustration represents a valve arrangement, including one or more valves performing the functionality described herein, and is not limited to a single device or a single valve. In the exemplary irrigation pressure sensor  231 , a strain gauge or other suitable component may communicate or signal information to console  115  to provide an amount of pressure sensed in the handpiece fluid pathway  230 . In another embodiment, depending upon the sensor used, an amount of vacuum or flow may be sensed in the handpiece fluid pathway  230  and communicated to console  115 . Console  115  may determine the actual amount of pressure present based on the communicated information. 
       FIG. 3  illustrates an exemplary cassette system showing some of the features which may be employed in a phaco system. The illustrated cassette body  300  of cassette  250  is shown from the back side (or second side). Cassette body (or cassette fluidics portion)  300  may include a series of detents, also referred to as notches or catch surfaces, along its outer edge for receiving at least a portion of a retention device which may be associated with a surgical console to facilitate the retaining of the cassette to console and to at least partially assist in properly seating the cassette in the portion of the console meant to receive the cassette. As illustrated in  FIG. 3 , a cassette may include at least three sets of detents capable of accepting an attachment means provide by the console, such as, for example, upper detents  310 , center detents  311 , and lower detents  312 . As will be described in greater detail below, the detents may be operated on in tandem or in a piecemeal fashion by a retention device of the surgical console. 
     An exemplary cassette may also include at least one pressurized fluid inlet  321  which may be in fluid communication with at least one filter within filter cavity  320 . The pressurized fluid, for example, air, may be supplied to the cassette through fluid inlet  321  and introduced into pressurized irrigation tank  340  and may be in further communication with pressure sensor  360 . There may similarly be at least one vacuum inlet  323  which may be in fluid communication with at least one filter within filter cavity  322 . The vacuum applied through vacuum inlet  323  may be in communication with vacuum tank  342  and may be in further communication with aspiration channel  330  and aspiration channel  370 . Each of the pressurized irrigation tank  340  and vacuum tank  342  may include a level sensing device  344  and  346 , respectively. 
     Irrigation fluid may enter the cassette through inlet  382  and may enter irrigation channel  332 . Irrigation valve  350  controls the flow of irrigation fluid and may allow for gravity fed irrigation fluid to be supplied to irrigation outlet  380  from irrigation channel  332  or pressurized irrigation fluid from pressurized irrigation tank  340 . In either instance, and even when irrigation valve  350  is in the “off” position relative to both irrigation fluid sources, the amount of pressure associated with the delivery of the irrigation fluid may be measured by irrigation sensor  360 . Similarly, aspiration pressure may be measured by the aspiration sensor  362  in close proximity to aspiration inlet  384 . Aspiration fluid which may enter though aspiration inlet  384  may enter aspiration channel  330  under pressure produced by at least one peristaltic pump, for example, and may also enter vacuum tank  342  under the influence of at least a partial vacuum through valve  352 . 
     As discussed above, cassette  250  may also include at least two rotary valves which may enable the cassette to change modes for aspiration and irrigation. The aspiration valve switches between flow mode aspiration and vacuum mode aspiration, with an off position between the two mode positions. The irrigation valve switches between gravity mode irrigation and pressurized irrigation, with an off position in between the two modes. In gravity irrigation mode, the bottle height may control the irrigation pressure. The irrigation valve may be turned such that the flow from the bottle flows through the irrigation valve to the pressure sensor and out to the surgical site through the handpiece. Note that the fluidic channel to the irrigation pump may be sealed off by means of the pump rollers sealing off the peristaltic pump bladder. If the irrigation pump is not running, there will be no flow through the pump. 
     The present invention may include a cassette having an internal flow interface as at least partially illustrated in  FIG. 4 .  FIG. 4  illustrates the back side (or second side) of a cassette  250 . Such a cassette flow interface may receive fluids, as described in greater detail herein, which may be driven by bladders joined to cassette  250  to move fluids through the cassette. Cassette fluidics portion (or cassette body)  400  may include a plurality of channels, each with at least one inlet and one outlet. Each channel formed in the cassette fluidics portion  400 . For example, channel  410  may have outlet  402  and outlet  404 . Each of outlet  402  and  404  may include a plurality of openings in which fluids may enter and exit the channel  410 . Similarly, channel  420  may have at least one inlet  424  and inlet  422 . When used for transmitting aspiration liquids during cassette engagement, fluids may travel through channel  410 , pass through outlets  402  and  404  and then enter drain channel  420  through inlet  424  and inlet  422 . In an embodiment of the present invention, the outlets from channel  410  may be in fluid communication with specific inlets in channel  420 . Each inlet and outlet described herein may be shaped to control flow and turbulence of the fluid to be moved through the cassette and may be circular, oval, and/or any shape which may impact fluid flow. As would be appreciated by those skilled in the art, the flow may be reversed and may be used for both irrigation and aspiration functions as desired by the user. 
     The cassette fluidics portion  400  may include channels that allow for simultaneous flow through a variety of inlets and outlets within the same channel network to provide desired flow characteristics, such as control of flow and turbulence. For example, irrigation fluid may enter the cassette  250  through channel  440  with fluid exiting through outlets  442 ,  446 , and  444 . The fluid may enter channel  430  through inlets  434 ,  432 , and  436 . In an embodiment of the present invention, the outlets from channel  440  may be in fluid communication with specific inlets in channel  430 . Each inlet and outlet described herein may be shaped to control flow and turbulence of the fluid to be moved through the cassette and may be circular, oval, and/or any shape which may impact fluid flow. As would be appreciated by those skilled in the art, the flow may be reversed and may be used for both irrigation and aspiration functions as desired by the user. 
     In some embodiments, as illustrated in  FIG. 4 , channel  410  may have an inlet from an aspiration tube connection to a cassette, such as connection  384  and pressure sensor area  362  of  FIG. 3 . The ports  402  and  404  of  FIG. 4  may be channel  410  outlets. In some embodiments, channel  410  outlets may also be bladder inlets (i.e., inlet is larger, bypass is smaller). Ports  402  may be inlet ports to aspiration bladder section  506 . In some embodiments, port  404  may be a bypass port to  505 . Port  424  may be a bladder outlet port from  506  and port  422  may be the outlet for  505 . In some embodiments, channel  420  may be an aspiration drain channel with the drain connected to a drain hole  370 . In  FIG. 4 , the aspiration bladder rollers may be configured to rotate counter-clockwise. 
     In some embodiments of the present invention, an irrigation pump, which may have clockwise rotating rollers in  FIG. 4 , may supply fluid from  382  into channel  332 . Ports  442  of bladder section  512 , port  446  of bladder section  511 , and port  444  of bladder section  510  may be irrigation bladder inlet ports. The irrigation outlet ports may include: port  434  (bladder section  512 ), port  432  (bladder section  511 ) and port  436  (bladder section  510 ), and direct flow from the bladder to the irrigation tank  340 , through channel  430 . 
     In an embodiment of the present invention, and as illustrated in  FIG. 5A , the front side (or a first side) of a cassette  250  is shown. The cassette  250  may include an assembly of bladders including at least one aspiration bladder. For example, aspiration bladder may include two sections, such as section  505  and section  506 . Further, the assembly of bladders may include an irrigation bladder. The irrigation bladder may include three sections, such as section  510 , section  511 , and section  512 . 
     An assembly of compressible bladders as illustrated in  FIG. 5A  on assembly  515  may be communicatively coupled to the back of cassette fluidics portion  400  and may form a part of cassette  250  may comprise a plurality of bladders which may form at least the top portion of a fluid channel which may interoperate with the fluid channels illustrated in cassette fluidics portion  400 . For example, bladder  505  may communicatively connect outlet  404  and inlet  422 . Similarly, bladder  506  may communicatively connect outlet  402  and inlet  424 . Bladder  510  may communicatively connect outlet  444  and inlet  436 , bladder  511  may communicatively connect outlet  446  and inlet  432 , and bladder  512  may communicatively connect outlet  442  and inlet  434 . As illustrated in  FIG. 5B , each of the bladders of assembly  515  may form a channel when placed against a planar surface, which channels may be linearly uniform and/or have a variable volume over their respective lengths. In some embodiments, an aspiration bladder may be mounted to a flat surface and an irrigation bladder may be mounted to and make a channel with a conical surface. 
     In an embodiment of the present invention, as illustrated in  FIG. 5C , each bladder may have at least a minimum uniform channel volume throughout the channel as measured by a measured height formed between the bladder  560  and a planar surface represented by line  550 . The minimum uniform height may be greater than about 0.5 mm and may be less than about 3.5 mm (although each channel may be non-uniform in height and/or radius and may be designed to hold a specific volume of fluid). The minimum uniform radius of a channel may be greater than about 1.5 mm and may be less than about 3.5 mm. In an embodiment of the present invention, the minimum radius at position  522  may be 2.25 mm. In an embodiment of the present invention, at least one second radius may be found within the bladder, such as a height of 3.5 mm at position  524 . The at least one second length portion  530  may be bordered on each side by first length portion  520  and third length portion  525 . The change in height between first length portion  520  and second length portion  530  may occur gradually over the length of first length portion  520 , for example, or may occur over a small distance between the two portions sufficient to accommodate an angular rise. For example, such an angular rise may be equivalent to about 118 degrees from the top-most portion of first height portion. 
     In an embodiment of the present invention, and as further illustrated in  FIG. 5C , bladder  560  may have at least two foot portions  540  located in either end of the bladder which may be at least partially in communication with planar surface  550 . The top of bladder  560  may not follow the same geometry as the inner channel forming portion and may include additional angular elements. For example, first portion  520  may include a sloped portion on its proximate end while second portion  530  may include at least two sloped portions to accommodate any underlying channel height rise as between first portion  520  and third portion  525 . In an embodiment of the present invention, the thickness of the bladder may be substantially uniform over most of its length and may be generally concave over the channel forming portion of the bladder. 
     As further illustrated in  FIG. 5D , in an embodiment of the present invention, cassette  250  may comprise cassette body  300  which may include on the front face assembly  515  and panel  560 . Valves  352  and  350  may be at least partially housed within cassette body  300  and in an embodiment, may be at least partially retained in cassette body  300  by panel  560 . Similarly, pressure sensors  360  and  362  may be placed in communication with cassette body  300  and in an embodiment, may be sealed and/or retained by panel  560 . As would be appreciated by those skilled in the art, assembly  515  and panel  560  may be combined into a single article and may be mechanically and/or chemically fastened to cassette body  300 . Tubing assembly  585  may include fluid pathways for both irrigation and aspiration, for example, to fluidly couple with a surgical handpiece. Tubing assembly  585  may be preferably connected to the bottom of cassette body  300  for ease of use but may be joined at any position to cassette body  300  as may be considered useful by those skilled in the art. 
     The back side of cassette body  300  may include filters  565  and may be sealed by plate  570 . As would be appreciated by those skilled in the art, plate  570  may be mechanically and/or chemically fastened to cassette body  300 , for example. Drain bag  580  may be fastened to the exterior of plate  570  and may be in fluid communication with one or more fluid conduits within cassette body  300 . Fluid from within the cassette body  300  may be expelled into fluid bag  580 , which may be replaceable and/or itself drained to allow for the expelling of more fluid than could be held in the volume of a single fluid bag  580 . Panel  570  may also have attached thereto handle  575  which may provide for easier handling of cassette  250 , for example during insertion and removal from a surgical console. Handle  575  may be attached at one or more points on panel  570  and may take any number of forms, such as, for example, a ring, square, or other geometric shape. 
     The bladder assembly of the present invention may have portions offset from one another and may have portions in multiple planes, for example. One or more of the bladders may include conic portions, cylindrical portions, and wavy portions, for example. In an embodiment of the present invention, a first bladder assembly may be in a first plane and a second bladder assembly may be in a second plane. For example, as illustrated in  FIG. 6A  in an isometric view, the console engagement side of cassette  250  may include assembly  515  which may be shaped to compliantly accept a roller head assembly  600  (which is shown in repose from a surgical console). The roller head assembly  600  may comprise at least two pump heads, each of which may operate independently from each other. The outermost pump head, pump head  605 , for example, may comprise a vertically disposed surface (relative to cassette  250 ) which may include a plurality of roller assemblies, such as roller assembly  620 . An inner pump head, pump head  610 , may have a non-linear shape and may, for example, be shaped as a conical frustum, for example. Each pump head may also be spring loaded and or otherwise moveable such that each pump head may have the ability to adjust to the orientation of a mating cassette. In an embodiment of the present invention, each roller assembly may contain rollers having geometry to minimize slip between a portion of the roller assembly surface and a bladder. For example, a roller may have a conical geometry which allows the roller axis to pass approximately through the center of roller rotation. 
       FIG. 6B  shows an illustration of the console interface or cassette receptacle for mating a single use cassette with the console. The irrigation and aspiration valves on the single use cassette will center on each of irrigation valve lever  650  and aspiration lever valve  652 , respectively, once the cassette has been mounted to the console interface  800 . As discussed herein, each one of the valve levers may operate responsive to at least one received signal indicative of at least one parameter. Such parameters may include, for example, fluid pressure and fluid volume associated with fluid in the system, whether or not the fluid is in communication with either valve. Similarly, a parameter associated with at least one of a vacuum, a positive pressure and gravity, may also be used with the present invention. 
     In an embodiment of the present invention each of the irrigation valve and aspiration valve may be in fluid communication with each other. The valves of the present invention may also be fluidly connected to a line under vacuum and/or to atmosphere. Similarly, the valves of the present invention may receive one of either pressurized fluid or gravity-fed fluid and may provide a vent for at least one fluidly connected line. In an embodiment of the present invention, either one of the valves may be partially open to at least one line communicatively connected thereto. 
     In an embodiment of the present invention, when cassette  250  is seated against roller head assembly  600 , the roller assemblies of the pump heads may communicatively engage the bladders of assembly  515 . For example, as shown in a cut-out view as illustrated in  FIG. 7A  and as discussed above, pump head  605  may comprise a roller assembly which may further comprise a roller  712 , roller body  711  and a spring means  710 . Roller  712  may be movably affixed to roller body  711  and may be under a downward force provided by spring means  710 , which itself may be affixed to both the pump head  605  and roller body  711 . Each roller  712  may engage a portion of a bladder  720  which may be removably affixed to a portion of assembly  515  and may engage a bladder with sufficient force as to deform the bladder and cause fluid flow within the channel formed between the bladder  720  and the assembly  515 . In an embodiment of the present invention, a roller may deform the bladder is a manner sufficient to stop all fluid flow 
     Further, as illustrated in  FIGS. 7A and 7B , a portion of assembly  515  may include ports, such as ports  730  and  732 , which may correspond to inlets and outlets of fluid channels located on the opposite side of assembly  515  as discussed above. Shown without the pump head, the portion of assembly  515  may comprise multiple bladders, each creating a flow channel  734  between the bladder and assembly  515 . Although the illustration shows two ports into channel  734 , as contemplated by the present invention, any number of ports may be provided. 
     As illustrated in the simplified block diagram of  FIG. 8 , a control module associated with a surgical console may control at least one motor which may control the at least two pump heads. As discussed above, each individual pump head may be independently rotated and controlled from a dedicated motor and/or a single motor and may further be responsive to at least one spring mechanism to allow for adjustments in orientation of the pump heads relative to an engaged cassette. In an embodiment of the present invention, each pump head may be controlled by a dedicated motor placed in line along a shaft which may itself have at least two independent drive shafts. The pump heads may provide peristaltic flow within the engaged cassette and provide rotation in either a forward or reverse direction. As would be known to those skilled in the art, the control module may receive signals from the pump motor(s) and associated pump encoder(s) responsive to signals received from the surgical console and/or attached devices, such as, for example, a foot pedal and a surgical instrument. 
     The encoder may comprise an index line output on the motor shaft. There may be two hard stops within the cassette at the following positions: for irrigation at: pressurized irrigation connected and gravity irrigation connected; and for aspiration at: vacuum tank connected and vacuum tank disconnected. There may be a third position on the irrigation valve of irrigation off (no irrigation flow out of the cassette). It is possible to use the index line of the encoder or an absolute position encoder to know the physical orientation of the valve driver head. This may require alignment of the index position to the pump driver head position during manufacturing. A spring in the valve driver head may be used to mate with the rotary valve in the cassette without knowing the orientation of the valve driver head. This would rely on the spring loading to be reliable over wear and would allow the heads to be resistant to any misalignment with a part of the pump head and the cassette. 
     Similarly, during startup of the console, the motor may spin until the index line is activated, which may be used to place the valve driver head in a specific orientation and zero the encoder counts and motor driver step position. On cassette insertion, the valve stepper motor may spin so that the spring-loaded valve driver head may mate with the cassette. The motor may continue spinning until it hits a hard stop in the cassette. There may be a timeout or certain number of rotations to allow before setting an error that the valve head has not mated. The motor position at the hard stop (reported from either/both the motor driver step position and/or the encoder position) may be saved for returning to that position later during operation. The motor may rotate in the opposite direction to hit the second hard stop. When the motor contacts the hard stop (detect from the encoder and from step loss detection in the motor driver), the encoder and/or step position may be saved for returning to that position later during operation. The angular travel range between hard stops can be checked for an error condition (if there is foreign material or stiction stalling the motor before a hard stop), and the middle irrigation position of off can be set as the middle of the irrigation hard stop range. 
     Safe state for the system may be when gravity irrigation is connected and aspiration is stopped. The irrigation valve may need to return to the gravity position in a safe state error condition. In an embodiment, for example, the system may require either having the system battery backup always being present and sufficient for the 10 seconds of operation or providing enough capacitive hold on the 24V line and an indication that power is going down to move the valve to the intended position if the battery backup is insufficient. 
     In an embodiment of the present invention, a peristaltic pump may consist of elements that pinch and articulate along the closed flexible fluid conduit created, in part, by an aspiration bladder, to force fluid through the conduit. At least two pinchers, such as rollers, wipers, cams, or shoes, may sequentially engage and pinch the conduit against a rigid structure and articulate along the conduit length to cause fluid flow. Before the lead pincher disengages the conduit, a subsequent pincher may engage the conduit and articulate along it to ensure continued fluid flow. During disengagement, a momentary disruption of downstream flow may occur as fluid fills the void as the conduit regains its pre-deformed shape. Similarly, upstream flow may be disrupted as the subsequent pincher engages the conduit and fluid is displaced. These disruptions may result in flow and/or pressure pulses both upstream and downstream flow. The present invention may eliminate such pulses upstream of the pump rather than merely mitigating such pulsation. 
     As may be known to those skilled in the art, one typical method to mitigate such pulsation may involve shaping a rigid structure to control the manner in which the pinchers engage and disengage the conduit to lessen the severity of pulsation by increasing pulse duration. Similarly, larger sections of bladder tubing may be used, as well as varying pump speed to cancel out known pulsations. Pulsation may also be diminished by employing a void in a rigid structure portion such that as three pinchers are simultaneously engaging the flexible conduit, the middle pincher momentarily encounters the rigid structure void thus reducing or eliminating its pinch before fully re-engaging the conduit. The manner in which the pincher encounters the void may mitigate pulsation upstream or downstream of the pump. Further still, other methods may employ a length of semicircular flexible open conduit with capped ends mounted and sealed to a rigid structure, with inlet and outlet flow are provided by ports in the rigid structure under the flexible conduit. In such embodiments, the ends of the fluid volume of these conduits may be tapered to control the manner in which the pinchers engage and disengage the conduit. In embodiments using a semi-circular open conduit, grooves in the rigid structure near the ends of the conduit may provide fluid bypass under the pinched conduit which lessens the severity of and increases the duration of pulses. 
     In an embodiment of the present invention, a pulseless peristaltic pump may eliminate pulses upstream (inlet side) by providing a flexible conduit of varying volume or displacement in the section of conduit that is engaged by the pinchers. The pulse caused by the subsequent roller engaging the flexible conduit may be absorbed inside of this length of flexible conduit which may result in pulseless flow into the pump. The pulse is essentially cancelled at its source. The present invention is easy to manufacture and does not require additional pump parts. In an embodiment of the present invention, roller tracks may be employed to promote constant pump speed and pulseless flow and decreases the cost and complexity of the pump motivating drive. 
     In an embodiment of the present invention, at least two separate flexible conduits, created in part by bladders, are arranged in a circular pattern, plumbed together in parallel, and engaged by a pump roller head, as illustrated by  FIG. 6 . Each conduit may consist of a short length of semicircular or similarly shaped flexible open conduit (such as a bladder) that may be mounted and sealed to a cassette so that the cassette and bladder together form a fluid flow path, such as flow channel  734  as illustrated in  FIG. 7B . Inlet and outlet flows are provided by ports in the cassette under each end of the bladders. 
     The bladder sections may be plumbed in parallel inside the cassette while a motor-driven rotating pump head with eight pump roller heads, for example, engages the cassette and bladders. The rollers may be arranged in a circular pattern with the rotational axis of each roller intersecting the pump head rotational axis. The rollers may rotate along a flat and annular path on the front face of the cassette while simultaneously manipulating the bladders. In an aspiration bladder, for example, upstream or inlet pulseless flow may be achieved by shaping the bladder so that the fluid volume of the conduit behind the first roller increases incrementally and exactly to absorb the fluid displaced as the second roller proceeds to pinch the bladders, as illustrated in  FIG. 7A , for example. Thus, the pulse caused by the second roller may be absorbed inside of the bladder and may result in pulseless flow into the pump, which may be embodied by a bulge in the bladder. 
     In an embodiment of the present invention, bypass ports in the cassette may be placed slightly downstream of the location where the rollers initially seal a bladder against the cassette. These ports may promote pulseless performance by precisely defining pumping handoff from the first roller to the second. In an embodiment of the present invention, pump speed may be held constant through each pump rotation pump to avoid flow and pressure variation. Two features of the pump of the present invention promotes constant speed by reducing torque pulses caused by interaction between rollers and cassette. Rollers are primarily supported by the front face of the cassette. This mitigates torque variation by providing a smooth, flat, and rigid roller track surface. The bladder wall thickness is tapered at each end of the bladders which effectively provide ramps instead of bumps where the rollers engage and disengage the bladders, as illustrated in  FIG. 5C , for example. 
     In an embodiment of the present invention, a conical flexible open conduit with at least one fluid path of semi-circular or similar cross-section mounted and sealed to the inside or outside of a conical structure and manipulated by rollers in a rotary pump head may be used. Similarly, in an embodiment of the present invention, a cylindrical flexible open conduit with at least one fluid path of semi-circular or similar cross-section mounted and sealed to the inside or outside of a cylindrical structure and manipulated by rollers in a rotary pump head. In an embodiment of the present invention, a linear flexible open conduit with at least one fluid path of semi-circular or similar cross-section mounted and sealed to a flat or curved structure and manipulated by a linear pump head such as rollers that are linked together in a chain driven by pulleys or sprockets. Similarly, in an embodiment of the present invention, a flexible conduit such as a round tube pinched against a flat or curved structure and manipulated by a linear pump head such as rollers that are linked together in a chain driven by pulleys or sprockets. 
     Those of skill in the art will appreciate that the herein described apparatuses, engines, devices, systems and methods are susceptible to various modifications and alternative constructions. There is no intention to limit the scope of the invention to the specific constructions described herein. Rather, the herein described systems and methods are intended to cover all modifications, alternative constructions, and equivalents falling within the scope and spirit of the disclosure, any appended claims and any equivalents thereto. 
     In the foregoing detailed description, it may be that various features are grouped together in individual embodiments for the purpose of brevity in the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that any subsequently claimed embodiments require more features than are expressly recited. 
     Further, the descriptions of the disclosure are provided to enable any person skilled in the art to make or use the disclosed embodiments. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein, but rather is to be accorded the widest scope consistent with the principles and novel features disclosed herein.