Abstract:
A known disposable per use surgical primary cassette is modified to avoid contamination thereof during use by aspirated fluid from a vitreous cutter connected thereto by bypassing the aspirated fluid into a receiving chamber of a relatively less expensive disposable secondary cassette, whereby during use a vacuum produced in a chamber of the primary cassette connected to the receiving chamber of the secondary cassette in turn produces a vacuum in the receiving chamber of the latter for drawing aspirated fluid from the vitreous cutter directly into the receiving chamber.

Description:
RELATED PATENT 
     The present invention is related to U.S. Pat. No. 7,540,855, entitled “Disposal Aspirator Cassette,” dated Jun. 2, 2009, the teachings of which are incorporated herein to the extent they do not conflict herewith. 
     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 of a 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, balanced salt solution is continually infused into the surgical site. 
     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” and/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 and other bodily fluids are aspirated through the cutter and tubing, and ultimately are collected within the cassette. 
     The cassette is usually not handled by the surgeon during the operation. Rather, a circulating nurse preoperatively 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. 
     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 previously used cassette is contaminated from eye fluids. After the vitrectomy, the cassette is then thrown away per hospital protocol regarding bio-contamination. 
     Second, 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. Typical cassette designs include features that maintain a constant fluidic resistance, to assist the physician in maintaining control of the aspiration flow rates through the cutter. 
     Third, in addition to the first and second functions, 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. A cassette identification system  34  consists of a plurality of tabs  36  for identifying the cassette when it is plugged into an associated vitrectomy unit. 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 port  13 , and a second vacuum port  15 , as shown. Aspirator line  18  is connected between port  13  and a vacuum port  66 . Aspirator line  20  is connected between port  15  and another vacuum port  68 . 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  14 . Note that chamber  64  provides for receiving materials or aspirated liquid (contaminated eye fluid) drawn into chamber  64  through aspiration lines  18  and  20  by a vacuum produced in chamber  64  via vacuum input port  21  being connected to a vacuum source of the associated vitrectomy unit. 
     Alcon Laboratories, Inc. provides the cassette  10  in what they identify as a Total Plus Pack. The latter includes the cassette  10  along with a number of other disposable components. 
     The present inventors recognized that if a system is developed for permitting users of the aforesaid cassette  10 , modified for use in the present system, to continually use the cassette, considerable cost savings will be provided. Accordingly, as described in detail below, the present inventors developed a system including a disposable surgical cassette that is substantially inexpensive relative to the cost of surgical cassettes such as the modified cassette  10 , whereby the present inventive surgical cassette is disposable, while permitting extended continuous use of the modified cassette  10  when used in association therewith. However, the present invention is not limited to permitting continual use of the aforesaid modified 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 system including a unique secondary cassette having one application for vitrectomy surgeries that can adapt to a wide range of vitrectomy units. This cassette is used in addition to a modified primary cassette already installed on the vitrectomy unit. During a vitrectomy, the new secondary cassette protects the modified primary cassette from contamination, and therefore the latter can be continually used in successive surgical procedures. 
     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 removal of vitreous and fluids. Third, the secondary cassette can be configured to collect a greater volume of aspiration fluids (greater capacity) than afforded by the primary cassette alone. 
     In one embodiment of the invention, the present system and secondary cassette is set up and operates in the following manner. Plastic tubing is attached to two separate ports located on one end of the secondary cassette. Tubing from one modified port of the primary cassette is attached to a vitreous cutter hand piece and extrusion instrument. Tubing from one port of the secondary cassette is attached to a new vacuum port of the modified primary cassette. Tubing from the other port of the secondary cassette is attached to a new aspirator port of the modified primary cassette, the latter being connected by tubing to the modified port of the primary cassette attached to the vitreous cutter. 
     Using a foot pedal, a surgeon activates the vitrectomy unit to generate suction as needed. Suction is created by the vitrectomy unit at the new vacuum port of the modified primary cassette. When this occurs a vacuum is formed in the secondary cassette, for causing intraocular fluids to be aspirated into the cutter tip, therefrom through the tubing attached to the one modified new aspirator port of the primary cassette, and therefrom through aforesaid tubing and the other port of the secondary cassette, into an aspirated fluid receiving chamber of the secondary cassette. Hence, fluids are suctioned out of the eye into the secondary cassette. When the procedure is completed, the contaminated secondary cassette, associated tubing and cutter are discarded. 
     Note that the secondary cassette includes a pair of spaced apart eyelets protruding away from a top cap portion to permit the secondary cassette to be hung from mating hanging hooks or prongs of the primary cassette. Also, the secondary cassette can be formed to provide a sealed container of any desirable cross section, such as circular or square, for example. The top cap portion of the secondary cassette, in one embodiment is provided with a secondary aspirator port, and a secondary vacuum port. A bottom cap of the secondary cassette can be provided with a drain or sampling third port in another embodiment of the invention. 
     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. As a result, a user can observe the amount of aspirating fluid drawn into the secondary cassette at any given time. Note that in certain applications, the secondary cassette can consist of opaque material. 
    
    
     
       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. 3  is a front elevational view of a first embodiment of the invention showing a modified primary cassette, connected by tubing to a secondary cassette. 
         FIG. 4  is back elevational view of the front embodiment of the invention of  FIG. 3 . 
         FIG. 5  is a pictorial view of the embodiment of the invention relative to  FIG. 3  looking at an angle toward the front of the modified primary cassette with the secondary cassette spaced therefrom. 
         FIG. 6  is a back elevational view of the secondary cassette for the first embodiment of the invention. 
         FIG. 7  is a cross-sectional view taken along  7 - 7  of the secondary cassette of  FIG. 6 . 
         FIG. 8  is a pictorial view of a secondary cassette for another embodiment of the invention. 
         FIGS. 9 ,  10 , and  11  show top plan, right side elevational, and bottom plan views, respectively, of a luer port device for another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In  FIG. 3 , a first embodiment of the invention is shown that includes a disposable aspirator cassette  100  attached to a modified Alcon cassette  102  via flexible plastic tubing  104  and  106 , (to be described in greater detail below). Through experimentation, the present inventors discovered that the primary cassette  10  shown in  FIGS. 1 and 2 , required modification to permit use of the disposable aspirator cassette  100  therewith. More specifically, the Alcon cassette  10  of  FIGS. 1 and 2  was modified by installing a vacuum port  108  in a front portion of chamber  64 . Also, vacuum port  66  has been sealed off and cut down. A keyhole  110  is cut into the side of housing  12  in the area where vacuum port  66  was formerly located, for retaining a portion of tubing  106 , as shown. Aspiration line  18  of the prior cassette  10  has been eliminated, and a modified vacuum and/or aspirator port  112  with an end of tubing  106  attached thereto is removably installed in the position where the former first vacuum input port  13  was located. To accomplish the latter modification, a U-shaped slotway  114  has been cut into the top edge portion of housing  12  where port  13  was formerly located. The port  112  is provided by a specially designed snap-in Luer Lock as shown in  FIGS. 9 through 11 . As shown in the latter figures, the port  112  includes a front portion  116  for connection to an end of aspirator tubing  118  associated with a vitreous cutter handpiece (not shown). A circular central portion  120  of port  112  includes an opposing pair of centrally located grooves  122 , as shown. The back portion of port  112  is circular for receiving an end of tubing  106  (see  FIGS. 3 and 4 ). A throughhole  126  (see  FIGS. 9-11 ) is provided in the port  112 , as shown. The grooves  122  of port  112  provide a friction tight fit within the U-shaped slotway  114 , as shown, for retaining port  112 . The modified Alcon cassette  102  has been modified in a manner to permit it to operate substantially identically with its associated vitrectomy unit (not shown) as an unmodified Alcon cassette  10 . 
     In an alternative embodiment, the modification of cassette  10  can be accomplished by leaving port  66 , input port  13 , and tubing  18  in place. Tubing  20  would then be removed, port  68  sealed off and cut down, a keyhole  110  located where port  68  was positioned, vacuum port  15  eliminated, and the U-shaped slotway  114  cut into the former location of vacuum port  15 . As in the previous embodiment, the modified vacuum and or aspirator port  112  will now be located in slotway  114  in the former location of vacuum port  15 . Otherwise, the alternative embodiment is utilized as described below for the former embodiment. 
     With further reference to  FIG. 3 , and to  FIGS. 4 ,  5 , and  6 , the modified Alcon cassette  102  represents a primary cassette, whereas the disposable cassette  100  represents a secondary aspirator cassette. As shown, the disposable cassette, in one embodiment of the invention, includes a cylindrical or tubular housing  128 . One end of the housing  128  is sealed off by a top cap  130  that includes a centrally located secondary vacuum port  132  for connection via tubing  104  to the vacuum port  108  of the modified primary cassette  102 . Also included in the top cap  130  is a secondary aspirator port  134  spaced away from port  132 , the former being connected via tubing  106  to the aspirator port  112  of the modified Alcon primary cassette  102  as shown. A pair of spaced apart eyelets  136  are provided on the top cap  130  nears its circumferential edge for permitting the temporary or disposal aspirator cassette  100  to be hung from the hooks  26  of the primary cassette  102  during use. The other end of the secondary cassette  100  is sealed off by a bottom cap  138 . In this example, the bottom cap  138  is provided with a centrally located drain or sample port  140 . As shown in  FIGS. 3 through 7 , O-ring seals  142  are incorporated in the top end cap  130  and bottom end cap  138  for providing a vacuum tight seal for secondary cassette  100 , and for securing the associated end caps thereto. Note that the illustration of O-ring seals  142  is not meant to be limiting, whereby any other suitable sealing means can be used. Note also that the use of eyelets  136  for hanging cassette  100  is not meant to be limiting, in that many other mechanisms can be used to support cassette  100 , even laying it on a table. 
     With reference to  FIGS. 1 and 3 , as previously indicated, the primary cassette  10  of  FIG. 1  is modified, as shown in  FIG. 3  as modified cassette  102 , by removing the original aspiration line  18 , cutting off and plugging the vacuum port  66 , cutting the keyhole  110  into the housing  12 , and cutting the U-shaped slotway  114  into the top portion of the housing  12  where the first vacuum input port  13  was previously located, and is now eliminated. With the primary aspirator port  112  installed in the U-shape slotway  114 , as previously described, the taut top half portion of the tubing  106  between the aspirator port  112  and the keyhole  110  is identically located as the previously described aspiration line  18 . As a result, when the modified primary cassette  102  is plugged into the associated vitrectomy unit, the latter unit is then operative to control pinch valves (not shown) to pinch off a top section of the tubing  106  for preventing further suction of aspirated fluid from the vitreous cutter handpiece, when such action is required by the ophthalmic surgeon. 
       FIG. 8  shows an alternative embodiment for the invention that includes a rectangular or square shaped disposable secondary or aspirator cassette  144 . The housing  146  is shown to have a rectangular or square shape, but alternatively can have any desired shape. In this alternative embodiment, the ends of the housing are sealed off by a non-removal top cap  148 , and non-removal bottom cap  150 . Otherwise, this alternative embodiment includes eyelets  136 , centrally located secondary vacuum port  132 , a secondary aspirator port  134 , and a drain or sample port  140 , each being employed for use as previously described for the first embodiment of the invention described above. 
     The materials used for the various embodiments of the invention will now be described for purposes of example, and are not meant to be limiting, that any other suitable materials can be used. The housing  128  for the first embodiment of the invention, housing  146  for the second embodiment of the invention, and the top cap and bottom cap  148 ,  150 , respectively, for the second embodiment of the invention typically consist of any suitable transparent material such as Plexiglas, for example. The end caps  130  and  138  for the first embodiment of the invention associated with the secondary cassette  100  can consist of any suitable material, such as Delrin®. The flexible plastic tubings  104 , and  106  are preferably provided by any suitable relatively transparent plastic tubing, but can otherwise be opaque if preferred. 
     With further reference to  FIGS. 3 through 6 , a three-way stopcock  119  is installed in one embodiment of the invention in aspirator tubing  118 . The ports  121  and  123  can be used to selectively connect a vitreous cutter handpiece (not shown) and/or an extrusion needle (not shown) to aspirator tubing  118 . Note that other ophthalmic surgical devices can be connected to aspirator tubing  118 , in that the invention is not meant to be limited to use with vitreous cutters and/or extrusion needles. Also, in another embodiment of the invention, a hydrophobic and/or pathogen filter  105  is connected in the fluid path of tubing  104  to both filter air sucked into chamber  64  of cassette  102 , and to block the flow of liquid and/or biological contaminants from aspirator cassette  100  into chamber  64 . 
     Operation of the present invention will now be described. In the preferred embodiment of the invention, before connections from the secondary cassette  100  are made to the modified primary cassette  102 , keyhole  110  and slotway  114  of the latter are open or free of any attachments or components. The secondary cassette  100  is provided as a subassembly with an end of tubing  104  attached to secondary vacuum port  132 , and an end of tubing  106  attached to aspirator port  134  (see  FIGS. 3 ,  4 , and  5 ). Filter  105  is installed in tubing  104  as shown, and the other end of tubing  104  is free. The other end of tubing  106  is connected to the primary aspirator port  112 , via mating luer connections (not shown). Aspirator tubing  118  has one end connected to aspirator port  112 , and its other end connected to the three-way stopcock  119 . The free end of tubing  104  is connected to a male or female luer connector for later connection to a mating luer connection (not shown) of vacuum port  108  of primary cassette  102 . The provision of this subassembly facilitates the rapid attachment or connection of the secondary cassette  100  by hospital personnel to the primary cassette  102 . More specifically, the interconnection therebetween is made by installing aspirator port  112  in slotway  114  of primary cassette  102 , pulling tubing  106  taut between port  112  and keyhole  110 , and pushing apportion of tubing  106  into keyhole  110  of primary cassette  102  for secure retention therein, thereby retaining tubing  106  taut. The luer connector on the free end of tubing  104  is connected to the mating luer connector of vacuum port  108  of primary cassette  102 . Following this, the disposable secondary cassette  100  or  144  is then installed via its&#39; eyelets  136  onto the hooks  26  protruding from the modified primary cassette  102  (see  FIGS. 3-5 ). Also, before installing the disposable secondary cassette  100  or  144 , one must be sure that the drain or sample port  140  is closed. The modified primary cassette  102  is installed onto its associated vitrectomy unit. Next, a vitreous cutter handpiece (not shown), and/or an extrusion needle (not shown) are connected via associated tubing (not shown) to ports  121  and  123  of three-way stopcock  119 . 
     Once the associated vitrectomy unit (not shown) is turned on, it will rotate a cam wheel against peristaltic pump tube  16  of primary cassette  102 . The vitrectomy unit connects a vacuum source to vacuum input port  21 , thereby creating a vacuum in chamber  64 , and in the interior receiving chamber  152  of the associated secondary cassette  100  or  144 . The vacuum created within the chamber  152  of the associated secondary cassette  100  or  144  will in turn cause aspirated fluid from the vitreous cutter (not shown) and/or the extrusion needle (not shown) to be drawn from tubing  118 , through tubing  106 , and port  134  into the aspirated fluid receiving chamber  152  of the associated secondary cassette  100  or  144 . When the operation is completed, the vitrectomy unit is turned off, the vitreous cutter handpiece and/or the extrusion needle, along with the subassembly including associated aspirator tubing  118 , aspirator port  112 , and tubing  106  and  104  are removed from the primary cassette  102 , and discarded along with the secondary aspirator cassette  100  or  144 . In preparation for the next operation, a new disposable secondary cassette  100  or  144 , in this example, provided as a subassembly as described above, is installed as previously described for initiating the next operation. In other words, all of the components contaminated by aspirated fluid are discarded. In this manner, the primary cassette  102  can be reused indefinitely until such time that it may develop a defect. 
     Note that the secondary cassettes  100 ,  144  of  FIG. 3 , respectively, are shown with tubing  104  and  106  attached, each connected at one end to ports  132  and  134 , respectively. As described for the preferred embodiment of the invention, various connection tubings are luer connections. However, in alternative embodiments, the connections can be via any suitable connections or attachments. For example, it is expected that for production versions of secondary cassettes  100 ,  144 , that non-removable tubing barbs will be used, thereon. 
     Note further that typically disposable vitreous cutters and/or extrusion needles are expected to be used. However, if any such devices used are reusable, after a given operation, they will be removed, sterilized, and provided for later reuse. 
     Although various embodiments of the invention have been 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, although various materials have been indicated for purposes of example for use in the present invention, any other suitable materials can be utilized.