Abstract:
An aspirator cassette includes a housing having first and second ends sealed off by first and second end caps, respectively. A partition mechanism is enclosed within the housing for dividing its internal volume into first and second regions. First and second fluid flow ports are mounted on the first and second end caps, respectively, to provide fluid flow paths into and from the first and second regions, respectively. When the first region is filled with liquid, its associated first port is connected to a vacuum source for sucking the liquid out of the region, whereby as the liquid is removed, the partition mechanism responds by decreasing the volume of the first region, and increasing the volume of the second region causing its second port to draw a vacuum for sucking fluid from an aspiration device connected to the second port.

Description:
FIELD OF THE INVENTION 
   The present invention is related broadly to aspirating systems, and more particularly to such systems including disposable cassettes for receiving aspirated fluid from a site being irrigated, such as but not limited to a surgical site. 
   BACKGROUND OF THE INVENTION 
   Many surgical systems require instruments and devices that provide for the use of fluids to irrigate surgical sites, and further provide for the aspiration of the fluids from the surgical sites, typically on a continuous or selectively intermittent process during the surgery. In many such prior systems, surgical cassettes are used to collect fluid aspirated from the surgical sites, whereby after use, due to contamination from the fluids, the now contaminated cassettes are typically disposed of. Many of the known cassettes are very expensive, and represent increased surgical costs for hospitals, and other health providers that must use such cassettes. There has been a long felt need in the art to provide devices or mechanisms for preventing the contamination of expensive surgical cassettes, thereby permitting continuous use of the primary cassette during multiple surgeries, to offer substantial cost savings to the health providers. 
   A vitrectomy is an example common surgical procedure performed for retinal eye disorders that typically requires use of the aforesaid surgical systems. More specifically, a vitrectomy is performed to remove vitreous humor (jelly-like liquid) from the posterior segment or back of eye. To maintain the integrity of the eye while vitreous is being aspirated, balance salt solution is continually infused. 
   To perform a vitrectomy, the retinal surgeon uses one type of the aforesaid surgical systems known as a vitrectomy “unit.” The vitrectomy unit serves as a “source pump” or “vacuum pump”. Disposable components and instruments such as a Vitreous Cutter (cutter), Tubing Sets (tubing) and Cassette Reservoir (cassette) are attached to the vitrectomy unit. Together, the vitrectomy unit and disposable components make up a vitrectomy “system.” 
   The vitrectomy unit itself is usually a large stand alone device that is not sterile, and is activated by the surgeon using a foot pedal. The disposable vitreous cutter is physically held by the surgeon and placed into the eye. When the vitrectomy unit is activated, vitreous is aspirated through the cutter and tubing. 
   The cassette is not handled by the surgeon during the operation. Rather, a circulating nurse secures the cassette to the vitrectomy unit. The cassette has three primary functions. First, relative to one example in the prior art, because of its special proprietary design, it allows the vitrectomy unit to activate. 
   Once the vitrectomy unit is activated by inserting the proprietary cassette, the surgeon is then permitted to control vacuum and/or aspiration flow rate via use of a foot pedal. Fluids may now be vacuumed and or/aspirated out of the eye via the cutter and carried away through the tubing for deposit into the cassette. 
   In most vitrectomy units, a cassette is required for activation. The cassette is generally produced as a disposable component. Prior to the start of each vitrectomy, a new cassette is opened and installed in the vitrectomy unit. A new cassette is used because in each case the cassette is contaminated from eye fluids. After the vitrectomy, the cassette is then thrown away per hospital protocol regarding bio-contamination. 
   In addition to being a reservoir for eye fluids, the cassette has another purpose. The cassette is specially designed with proprietary features to ONLY activate a proprietary vitrectomy unit for which it was designed. Therefore, use of a certain vitrectomy unit is dependent upon using the same company&#39;s proprietary cassette. This is how companies generate residual sales after selling a one time purchase of the vitrectomy unit. 
   An example of one such prior surgical cassette of a vitrectomy system is disclosed in Jung et al. U.S. Pat. No. 6,059,544, entitled “Identification System For A Surgical Cassette,” issued on May 9, 2000. As shown in  FIGS. 1 and 2  hereof, the cassette  10  includes a single piece plastic housing  12  that has a handle  44  for installing and removing the cassette  10  from a vitrectomy unit (not shown). The cassette  10  is a relatively complicated device, as described in the aforesaid patent. Certain, but not all of the features of cassette  10  will now be described. With further reference to  FIGS. 1 and 2 , cassette  10  further includes aspiration lines  18  and  20 , a peristaltic pump tube  16  having one end connected to an output port  30 . A drain bag  14  is provided, and includes holes  32  to allow it to hang from hooks  26  provided on the cassette  10 . A port  28  of the drain bag  14  is secured to an output port  30  associated with peristaltic pump tube  16 . The drain bag  14  further includes a one-way valve  22  for preventing the backup of fluid into the cassette  10 , and a sampling port  24  for permitting a sample of fluid to be drawn from the bag for testing, or other purposes. The cassette  10  further includes a first vacuum input port  13 , and a second vacuum port  15 , as shown. Note both the cassette  10 , and its associated drain bag  14 , are provided by Alcon Laboratories, Inc., of Fort Worth, Tex. Due to the obvious complexity of the cassette  10 , it represents a relatively high cost component for users, that must be disposed of after a first use, along with the associated drain bag or bags  13 . Note that chamber  64  provides for receiving materials or aspirated liquid (contaminated eye fluid) drawn into chamber  64  through aspiration lines  18  and  20 . 
   The present inventors recognized that if a method and device is developed for permitting users of the aforesaid cassette  10 , and similar such cassettes, to continually use the cassettes, considerable cost savings will be provided. Accordingly, as described in detail below, the present inventors developed a disposable surgical cassette that is substantially inexpensive relative to the cost of surgical cassettes such as cassette  10 , whereby the present inventive surgical cassette is disposable, while permitting extended continuous use of the cassette  10  when used in association therewith. However, the present invention is not limited to permitting continual use of the aforesaid Alcon cassette  10 , and can be used in other aspirating systems. For example, it is expected that the present inventive cassette will also have use in surgical aspirating systems in both posterior and anterior surgical fields. In addition, it is expected that the present inventive cassette will have use in industrial systems. 
   SUMMARY OF THE INVENTION 
   The inventors have developed a unique secondary cassette having one application for vitrectomy surgeries that can adapt to any vitrectomy unit. This cassette is used in addition to a “proprietary primary cassette” already installed on the vitrectomy unit. During a vitrectomy, the new secondary cassette protects the primary cassette from contamination, and therefore the latter can be continually used in successive surgical procedures. Additionally, the integrity of the primary cassette is maintained and not compromised because it does not have to be removed after each surgery from the vitrectomy unit it was designed for. 
   The present secondary cassette has several functions. First, it acts as a reservoir for eye fluids so as not to allow contamination of known primary cassettes. Second, it works in tandem with existing primary cassettes to maintain a vacuum system for removing of vitreous and fluids. Third, it provides sterile or non-contaminated water to the primary cassette to keep it operational. Fourth, it serves as a barrier between contaminated fluids and sterile or non-contaminated water sent to the primary cassette. 
   In one embodiment of the invention, the present secondary cassette is set up and operates in the following manner. Specially designed tubing is attached to two separate luer ports located on opposing ends of the secondary cassette. Tubing from one luer port is attached to a vitreous cutter hand piece and extrusion instrument. Tubing from the other port is attached to the primary cassette. Inside the secondary cassette and sealed to the inside luer port (that goes to the vitreous cutter) is a pouch or bladder type receptacle. This pouch is for collection of fluids aspirated from the eye. The pouch can be provided by a thin walled collapsible bag consisting of a suitable material such as plastic or latex. 
   During set up, sterile water is poured into the present secondary cassette through a separate large opening (third port). This third port is designed to include a screw-on cap for sealing the port. The entire device is filled with sterile or non-contaminated water. During use, this water is suctioned out of the device through the non-pouch luer port and into the primary cassette. The water is necessary to circulate through the primary cassette during activation. 
   Using a foot pedal, a surgeon activates the vitrectomy unit to generate suction as needed. Suction is created when the vitrectomy unit aspirates sterile or non-contaminated water from the secondary cassette. When this occurs and water is suctioned out of the secondary cassette, the pouch inside the device expands and creates a reciprocating suction effect. When this occurs, intraocular fluids are aspirated into the cutter tip, up through tubing and into the pouch of the secondary cassette. Hence, fluids are suctioned out of the eye. When the procedure is completed, the contaminated secondary cassette, associated tubing and cutter are disposed. The primary cassette can be drained of the sterile water and left installed for the next procedure. 
   In another embodiment of the invention, the secondary cassette includes a sealed container of any desirable cross section, in which a collapsible bag is filled with sterile or non-contaminated fluid. The container is sealed in a manner making the container air tight. The open end of the collapsible bag is sealed around the inside portion of an output port located at one side of the cassette. The other chamber of the cassette is provided with an input port. In use, the output port is connected to a vacuum source for aspirating the sterile fluid out of the collapsible bag, whereby as the fluid is removed from the bag, the bag collapses and produces a vacuum in the interior portion of the cassette surrounding the bag. The input portal is connected to an operating device, such as but not limited to a surgical instrument, whereby the vacuum created in the interior space of the cassette surrounding the collapsible bag causes the irrigation fluid to be drawn from the aspirating device into the cassette for collection. 
   In yet another embodiment of the invention, for surgical applications, the input and output ports of either of the immediately above-described two embodiments each include mechanical fastening mechanisms for permitting attachment thereto. 
   In each of the above-described embodiments of the invention, for another and preferred embodiment, the secondary cassette includes a housing consisting of transparent material. Also the collapsible bag preferably consists of translucent or transparent material. As a result, a user can observe the extent of sterile or non-contaminating fluid left in the cassette at any time, and aspirating fluid drawn into the cassette or bag at any given time, dependent upon the method of use of the cassette. Note that in certain applications, the housing and/or bag can consist of opaque material. In yet another embodiment, the bag can be replaced by a piston. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various embodiments of the present invention will now be described with reference to the drawings, in which like items are identified by the same reference designation, wherein: 
       FIG. 1  is a front elevational view of a cassette in the prior art. 
       FIG. 2  is an exploded perspective or pictorial of the cassette of  FIG. 1  in association with a drain bag. 
       FIG. 3A  is a front elevational view of a first embodiment of the invention. 
       FIG. 3B  is a cross-sectional view for one embodiment of the invention of  FIG. 3A  taken along  3 B- 3 B thereof. 
       FIG. 3C  is a cross-sectional diagram taken along  3 C- 3 C for another embodiment of the invention relative to  FIG. 3A . 
       FIG. 4  is an exploded longitudinal cross-sectional and cutaway view of an exploded assembly diagram for another embodiment of the invention. 
       FIG. 5  is a pictorial view of yet another embodiment of the invention. 
       FIG. 6  is a front elevational view of a cassette for another embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In  FIG. 3A , first and second embodiments of the present invention are shown. More specifically, in a first embodiment an aspirator cassette  300  includes in this example a cylindrical or tubular housing  302  enclosing a thin-walled flexible bag  304 . One end of the housing  302  is sealed off by a first end cap  306  that includes a centrally located port  308  providing a fluid flow path therethrough into the interior of the bag  304 . The other end of the housing  302  is sealed off by a second cap  310  that includes therethrough a second port  312  providing a fluid flow path into the interior space of volume  314  of housing  302  surrounding the bag  304 . In this example, the cross section of the housing  302  is circular, but is not meant to be limiting in that the cross section can be made in any desirable shape, such as oval, elliptical, rectangular, and so forth. As will be described in greater detail below, a plug  316  is configured for in one embodiment of the invention (as shown in  FIG. 3B ) to provide access to the interior of the bag  304 , and in another embodiment of invention (as shown in  FIG. 3C ) to provide access to the interior volume or space  314  of housing  302  surrounding the bag  304 . Note that the plug  316  can be configured in many ways, such as being threaded for screw-in use, or for a frictional fit, or any other suitable configuration. 
   With further reference to  FIG. 3B , a circular threaded collar  318  is provided with a circular flange  319  for sealing around the hole provided in the side of the bag  304 . The flange  319  can be sealed to bag  304  through use of any suitable adhesive, such as silicone seal, for example. The collar  318  further includes an interior threaded short tubular member  320  having portions of its free end secured in an airtight connection to a hole  322  to the side of the housing  302 , as shown. Again, the securement can be made through use of a suitable adhesive, or electronic welding, for example, to provide an airtight seal. In the embodiment of the invention of  FIG. 3B , the plug  316  is removed from the housing  302  and bag  304  to permit access to the interior of the bag  304 . 
   In the embodiment of the invention of  FIG. 3C , a threaded collar  324  includes a short interior threaded tubular portion  326  secured in an airtight manner within a hole  328  in a side portion of the housing  302 . To further insure a good mechanical and airtight connection, the collar  324  also includes a circular flange portion  330  that is secured around the interior wall portions of the housing  302 , via use of any suitable adhesive, such as silicone seal, for example. In this embodiment, the plug  316  is unscrewed and removed from the collar  324  for permitting access to the interior volume  314  of the housing  302 . 
   A third embodiment of the invention is shown in  FIG. 4 . In this embodiment, the housing  302  includes an interior threaded end portion  332  at one end, and a similar interior threaded portion  334  at its other end. A threaded end cap  336  is provided for screwing into and providing an airtight seal at the threaded end  332  of housing  302 . Cap  336  includes a first port  308  providing a fluid path through the cap into the interior section of a thin-walled collapsible bag  304 . The open end of the bag  304  is sealed in an appropriate airtight manner to the outer circumferential interior portion of the cap  336 , as shown. A screw-in plug  339  is provided for securement into a threaded hole  340  through the cap  336 , for permitting easy access to the interior of the bag  304 . Alternatively, rather than using the removable plug  339 , a sealable port  342  can be provided for providing access into the interior bag  304  through a circular sidewall opening  322  of housing  302 , as shown in the embodiment of  FIG. 3B . The threaded cap  338  is provided at the other end of the housing  302  for screwing into an interior end-threaded portion  334  thereof for providing an airtight seal. A second port  312  is provided through the cap  338 , as shown. 
   In a fourth embodiment of the invention, as shown in  FIG. 5 , a disposable cassette  400  is provided by housing  402  having a rectangular cross section. However, the shape of the housing  402  is not meant to be limiting as shown, and can be configured to have any desirable cross section, such as circular, oval, elliptical, and so forth. A cap  404  is provided at one end of the housing for providing an airtight seal at that end. Similarly, at the other end of the housing, a cap  406  is provided for insuring an airtight seal at that end. The housing  402  encloses a collapsible bag  304 , as in other embodiments of the invention. A plug  316  is provided on one side of a housing  402  for either providing in one embodiment access to the interior of the bag  304  in a manner substantially similar to that shown in the embodiment of the invention of  FIG. 3B , or for providing access to the interior portion of the housing  402  surrounding the bag  304  substantially as shown in the embodiment of the invention of  FIG. 3C . First and second ports  406  and  408  are provided at the end cap  404  for access into the interior of bag  304 , whereby the open end  305  of the bag  304  is sealed to the inside surface of the cap  404  in a manner surrounding the ports  406  and  408 . A second pair of ports  410  and  412  are provided in the end cap  405  for access into the interior volume of the housing  402  surrounding the bag  304 , as shown. 
   The materials used for the various embodiments of the invention will now be described for purposes of example only, and are not meant to be limiting, and that any other suitable material can be used. The housing  302  of  FIG. 3A ,  303  of  FIG. 4 ,  402  of  FIG. 5 , and  502  of  FIG. 6  (see below), preferably consist of any suitable transparent material such as Plexiglas, for example. The end caps  306  and  310  of  FIG. 3A ,  336  and  338  of  FIG. 4 ,  404  and  405  of  FIG. 5 , and  510  and  508  of  FIG. 6 , can consist of any suitable material, such as Delrin®. The ports  308  and  312  of  FIG. 3A , and of  FIG. 4 , and the ports  406 ,  408 ,  410 ,  412  of  FIG. 5 , can be provided by Luer-Lok®s for surgical applications, and otherwise can be provided by flow ports, or other mechanical fastening mechanisms, depending upon the application. The plug  316  of  FIGS. 3A ,  3 B,  3 C and  FIG. 5 , and the plug  339  of  FIG. 4 , can each consist of Delrin®, or any other suitable material. As previously mentioned, the thin-wall collapsible pouch or bag  304  can be provided by any suitable material, such as polyurethane, latex, and so forth. 
   Operation of the various embodiments of the invention will now be described. In a first embodiment of the invention as shown in  FIGS. 3A and 3B , the plug  316  is removed from the housing  302 , to permit liquid to be put into and substantially fill the bag  304 . In surgical applications, the liquid can be saline, or any other suitable non-contaminating fluid, for example. In certain applications, the liquid may be required to be sterile. After filling the bag  304  with liquid, the plug  316  is reinstalled in order to seal off the bag  304 . Thereafter, the port  308  is connected to a vacuum source for drawing liquid from the bag  304  at a desired flow rate, and the port  312  is connected to a device for aspirating fluid from a surgical site, for example, or some other site that is being irrigated. As fluid or liquid is sucked out of the bag  304 , it collapses creating a vacuum within the interior space  314  of the housing  302 , this vacuum being provided at port  312  for drawing fluid from the aspirating device to the interior space  314  of housing  302 . A further example of use of the present invention, as with this first embodiment and the other four embodiments of the invention, the first port of output port  308  can be a Luer-Lok®, connected by appropriate tubing to one of the vacuum input ports  13  or  15  of the Alcon cassette  10 . Upon a vacuum being provided at the input port  13  or  15 , via operation of the peristaltic pump creating a vacuum in tube  16 , fluid from the bag  304  of the present cassette  300  is drawn through the input port  13  or  15  of the Alcon cassette  10 , and ultimately from the Alcon cassette  10  into the drain bag  14 . In this example, upon completion of the surgical procedure, the cassette  300  is removed from the Alcon cassette  10 , and disposed of. The Alcon cassette  10  is drained of the saline fluid or other fluid collected, and the associated drain bag emptied, permitting reuse in multiple procedures of both the Alcon cassette  10 , and the drain bag  14 . The substantially less expensive cassette  300  is disposed of. 
   In a second embodiment of the invention as shown,  FIGS. 3A and 3C , the ultimate operation of the invention is substantially similar to that of the first embodiment, except that the port  312  is connected to the vacuum source, such as input port  13  or  15  of the Alcon cassette  10 , and the port  308  of the cassette  300  is connected to the aspirating device. Initially, the plug  316 , as shown in  FIG. 3C , is for permitting saline solution or sterile liquid to be put into the space  314  of the cassette  300  surrounding the bag  304 . After the liquid is so installed, the plug  316  is screwed back into the threaded collar  304  for providing an airtight and fluid tight seal. When the vacuum source is applied to the port  312 , the vacuum source begins to draw fluid or liquid from the interior space of volume  314  of cassette  300 , causing the collapsible bag to expand, in turn creating a vacuum at the port  308  for drawing fluid from an aspirating device connected thereto into the bag  304 . As bag  304  expands, it increases its interior volume, and causes a decrease in the volume within cassette  300  surrounding bag  304 . When the surgical or industrial process is completed, as with the first embodiment of the invention, the cassette  300  is removed and disposed of. In certain applications, it may be required that when the bag  304  becomes filled with aspirating fluid, in the second embodiment of the invention, or when the interior volume  314 , of the cassette  300  becomes filled with aspirated fluid, as with the first embodiment of the invention described above, that the particular surgical or industrial operation is temporarily stopped, in order to permit replacement of the a new cassette  300  for the spent cassette  300 . 
   Operation of the third embodiment of the invention is shown in  FIG. 4  is substantially similar to that of the aforesaid first two embodiments of the invention. More particularly, in one use of the third embodiment of the invention, the caps  336  and  338  are installed as shown with the bag  304  secured to the cap  336  as previously described. Next, the plug  339  is removed from the cap  336  to permit the bag  304  to be filled with saline solution or a sterile solution such as sterile water, dependant upon the application. The ports  308  and  312  are connected as previously described for the embodiment of the invention of  FIG. 3B , and operation of the third embodiment is then the same as that of the first embodiment of the invention. The alternative cassette  301  is then disposed of after use. Contrariwise, the third embodiment of the invention can be operated as previously described for the second embodiment of the invention of  FIGS. 3A and 3C . Specifically, the cap  336  along with the bag  304  secured thereto is screwed into the threaded end  332  of the housing  303 . The cap  338  is removed, and saline solution or a sterilized liquid such as sterilized water is fed into the volume of the housing  303  surrounding the bag  304 . Thereafter, the cap  338  is secured to the threaded end portion  334  of the housing  303 . The port  312  is then connected to a vacuum source for drawing fluid from the interior volume of housing  303 , thereby causing the bag  304  to again expand, for creating a vacuum at the port  308 , the latter being connected to an aspirating device drawing fluid into the bag  304 , as described for the second embodiment of the invention. 
   Operation of the fourth embodiment of the invention as shown in  FIG. 5  will now be described. In one mode of operation, the plug  316  is removed for filling the bag  304  with saline solution or an appropriate sterilized liquid, for example, the plug  316  will then be reinstalled into the housing  402  and bag  304 . Next, the ports  406  and/or  408  are connected to a vacuum source for drawing liquid from the bag  304 , and the ports  410  and/or  412  are connected to an aspirating device, for drawing fluid or liquid therefrom into the interior volume  403  of the housing  402  surrounding the bag  304 , in a manner similar to that described for embodiments of the invention described above. Alternatively, in the alternative configuration described for the embodiment of the invention of  FIG. 3C , the plug  316  is removed for providing access to the interior volume  403  of the housing  402  surrounding the bag  304 , and the interior volume  403  is filled with an appropriate saline solution, or sterilized fluid, or other appropriate liquid, as required, and the plug  316  is then reinstalled. Thereafter, either one or both of the ports  410 ,  412  are connected to a vacuum source for drawing fluid from the interior space of the housing  402 , causing the bag  304  to expand, in turn creating a vacuum in ports  406  and  408 . The ports  406  and/or  408  are connected to aspirating devices for drawing liquid therefrom into the bag  304 , in a manner similar to that described above for previous embodiments of the invention. 
   With reference to  FIG. 6 , a fifth embodiment of the invention is shown. In this embodiment, a cassette  500  includes a housing  502 , having female threads  505  provided at each of a first end  504 , and female threads  507  provided at a second end  506 . A male threaded end cap  508  is screwed into the end  506  for sealing off that end, as is a male threaded second end cap  510  screwed into the other end  504  for sealing off that end. A fluid port  512  is mounted on the end cap  508  for providing a fluid flow path into a first volume region  514  of housing  502 . Similarly, another fluid flow port  516  is mounted on the end cap  510  for providing a fluid flow path into a second volume region  518  of the housing  502 . A piston  520  is slideably mounted within the housing  502 , and depending upon its position therein, determines the volume of the first region  514 , and the volume of the second region  518 . In this example, the piston  520  is provided with two O-rings  522  secured within grooves (not shown) around the circumference of the piston  520 . Note that in one application, the ports  512  and  516  can be provided by Luer-Lok®s, respectively. As an example of the operation of this embodiment of the invention, assume that port  516  is configured for connection to a vacuum source, whereas port  512  is configured for connection to the output port of an aspirator device. Assume further that the piston  520  is located proximate the end cap  508 , maximizing the volume of the second region  518 , which is initially filled with a liquid, such as saline, for example, but not limited thereto. When the vacuum source is connected to port  516 , it begins to suck or draw liquid out of region  518 , in turn causing the piston  520  to move toward the opposite end at  510 . As piston  520  begins to move towards end cap  510 , a vacuum is created in the region  514  of housing  502 , whereby the vacuum is applied via port  512  to the aspirator device, causing fluid to be sucked therefrom into the volume of the region  514 . This process continues until the piston  520  is proximate to the end cap  510 , as a result of the liquid in region in  518  having been completely drawn away therefrom by the vacuum source. At this point, it is expected that the cassette  500  will be removed from the aspirator system, discarded, and replaced by a new cassette  500 , if the aspirating operation or procedure is to be continued. 
   Although various embodiments of the invention are shown and described, they are not meant to be limiting. Those of skill in the art may recognize certain modifications to these embodiments, which modifications are meant to be covered by the spirit and scope of the appended claims. For example, the housing  302 ,  303 ,  402 , and/or  502  can consist of metal, glass, a suitable plastic, or any other suitable material.