Surgical cassette

Abstract: A cassette (500) is provided for use in combination with a surgical handpiece (10) and a control console (501) for controlling irrigation and/or aspiration fluid flows in the handpiece (10) having a housing (502) with an external surface and an interface (504) adapted to be held in operative association with the control console (501), an inlet coupling (506), a pump tube (518) having an inlet (512) and a discharge line (522) in fluid communication with a waste container (118) and a fluid flow passage (514) in fluid communication with the inlet coupling (506) and the pump inlet (512) consisting of an open channel formed in the external surface and a gasket (136) adhered to the external surface to seal the channel fluid-tight. The cassette is suitable for use with microsurgical instruments, such as a hand held ultrasonic microsurgical cutter as used for example in eye surgery.

Description: Microsurgical instruments typically are used by surgeons for removal of tissue from delicate and restricted spaces in the human body, particularly in surgery on the eye, and more particularly in procedures for removal of the crystallin lens or the vitreous body. Such instruments include a control console and a surgical handpiece with which the surgeon dissects and removes the tissue. The handpiece has a surgical tool such as an ultrasonic microsurgical cutter for cutting or fragmenting the tissue and is connected to the control console by a long power cable and by long conduits or flexible tubes for supplying an irrigation fluid to the surgical site and for withdrawing or aspirating fluid and fragmented tissue from the site. The cutting, irrigation and aspiration functions of the handpiece are controlled by the remote control console that not only provides power for the surgical cutter (e.g., an ultrasonically vibrated needle), but also controls the flow of irrigation fluid and provides a source of reduced pressure (relative to atmosphere) for the aspiration of fluid and fragmented tissue. The functions of the console are controlled manually by the surgeon, usually by means of a foot-operated switch. The multiple connections that are required between the handpiece and the console for the power cable and the suction and irrigation lines have made the preparation and interconnection of the equipment prior to the surgical procedure extremely complex, with the resultant concerns over maintaining the sterility of the equipment and assuring error free connection. Accordingly, in the typical microsurgical instruments, the fluid handling connections have come to be centralized in a "cassette" that contains in one unit all of the connections for the aspiration and irrigation lines, internal conduits for directing the flow of fluids, valves for controlling the flow of fluids into and out of the handpiece, a receptacle for aspirated fluid and tissue and may contain the tube portion of a peristaltic pump. The cassette typically is supplied in a sterile package with color-coded connecting tubing already attached. Thus, setting up the equipment requires only connecting the cassette tubing to the surgical handpiece and irrigation fluid source and inserting the cassette into a receptacle in the console. The receptacle may contain the roller head portion of a peristaltic pump (or some other access to reduced pressure), an aspiration line pressure sensor and devices for operating the valves in the cassette and for controlling the flow of irrigation or aspiration fluids through the fluid conduits within the cassette. For convenience and to maintain sterility, the cassette may be discarded after a single use or sterilized and reused. Such a cassette is disclosed, for example in US-A-4,713,051 (Steppe, et al.) which describes a cassette intended to cooperate with a control console that has the roller head element of a peristaltic pump as well as protruding occluder bars that can pinch or block the internal flexible tube conduits that carry fluids through the cassette. The cassette also has an irrigation transfer tube that vents irrigation fluid into the aspiration conduit to relieve quickly the reduced pressure created within the aspiration conduit of the cassette when the aspiration function is discontinued by the surgeon. When the cassette is installed in the console, an arcuate cutout on the top of the cassette containing the compressible tube portion of the peristaltic pump engages the roller head to supply a source of reduced pressure for the handpiece. The output of the peristaltic pump is collected in a flexible bag suspended from the cassette. While the cassette described in US-A-4,713,051 has proved useful, the use of flexible tubes as internal fluid conduits requires accurate assembly of the tubes within the two-part housing of the cassette for proper operation, a complex, multi-step manufacturing process. Furthermore, the method of occluding fluid flow by pinching the flexible tubes relies entirely on the resilient properties and the quality of the tubes, variables that are not easily controlled during manufacture to assure consistent, predictable performance. Another microsurgical cassette is disclosed in US-A-4,758,238 (Sundblom, et al.), which uses channels molded into the body of the cassette and sealed by a stretchable covering gasket held taut against the molded body by a cover plate as internal fluid conduits. At certain points along the conduits, enlarged round chambers are formed in the conduits that allow enough room for the conduit to be blocked by valve stems stretching the gasket tightly against the conduit inlet to seal the conduit. This cassette requires not only the use of mechanical valves stems, but also that the gasket perform the dual function of serving as one wall of an extensive system of fluid conduits within the cassette and as a stretchable diaphragm to block the fluid flow at the selected locations. This dual function requires expensive gasket materials (i.e. silicone rubber), a multi-piece cassette and demanding assembly procedures. US-A-4,798,580 (DeMeo, et al.) discloses a microsurgical cassette having a peristaltic pump tube within the cassette that cooperates with a roller drive on the console to provide a source of reduced pressure for the aspiration function of the microsurgical handpiece. A vent is provided for venting the suction conduit to the atmosphere when the peristaltic pump is stopped. This vent consists of a flexible tube that is compressed and thereby pinched shut by an occluder bar in the console. The occluder bar pinches the tube, thereby closing the vent, whenever the peristaltic pump is operating and the bar is pulled away from the tube, thereby opening the vent, when the peristaltic pump is stopped to vent atmospheric air into the suction line. An irrigation fluid conduit is provided consisting of an inlet port for connection to a source of irrigation fluid, an outlet port for connection to the tubing supplying irrigation fluid to the microsurgical handpiece and a flexible tube within the cassette connecting the inlet port and the outlet port. A portion of the tube can be alternatively pinched shut or opened to prevent or permit the flow of irrigation fluid by pressure from an occluder bar similar tothe vent line occluder bar. Thus, by using compressible tubing as the control valves for the vent and irrigation fluid conduits and a two-part housing, this cassette has the same limitations as the cassette discussed above in US-A-4,713,051. US-E-33250 (Cook) describes a cassette assembly for a microsurgical system, including a body portion, a collection vessel and an occludable conduit for suction or aspiration, and may also include an occludable conduit for infusion or irrigation, from/to a surgical site. Whilst the conduit inlets may be integrally moulded in the body portion, the internal conduits within the hollow section of the body of the cassette are formed from lengths of flexible tubing which have to be connected using plug-in connectors to the respective conduit inlets, which increase the number of components. Accordingly, a need has continued to exist for a surgical cassette that is capable of simple and easy assembly while allowing the selection of reliable, predictable materials and structures for each function performed by the cassette at the lowest possible cost. An objective of the present invention is to provide a surgical cassette having an internal capacitance chamber in the irrigation conduit, in order to smooth out fluid pressure fluctuations within the irrigation line, for example to help prevent irrigation fluid from being sucked back from the surgical site if pressure were to drop suddenly. According to the present invention, there is provided a cassette for use in combination with a surgical handpiece and a control console for controlling irrigation and/or aspiration fluid flows in the handpiece, in accordance with claim 1. Preferably, the capacitance chamber is defined by an open channel in an external surface of the housing and a gasket adhered to the external surface for a fluid-tight seal. The partial vacuum generating means is preferably a peristaltic pump tube, most preferably self-winding, and the motive force is a peristaltic pump roller head, most preferably having a pump tube winding slot. The present invention is intended to improve upon prior art surgical cassettes by providing a cassette having a one-piece housing adapted to be held in operative association with a control console. Integrally formed channels on the external surface of the housing form three sides of various fluid flow passages within the cassette. A plastic gasket may be adhered to the cassette to seal the channels and to form the fourth side of the fluid flow passages. Advantageously, the pump may be self-contained within the cassette and adapted to cooperate with a source of motive power contained in the console. The invention will now be described with reference to the accompanying drawings, in which; FIG. 1 is an exploded perspective view of a surgical cassette according to the present invention, FIG. 2 is a diagrammatic perspective view of the fluid conduits of the cassette illustrated in FIG. 1, FIG. 3 is a partial fragmentary view of an interface slot on a surgical console suitable for use with the cassette illustrated in FIG. 1, FIG. 4 is a hydraulic/pneumatic schematic view of the cassette illustrated in FIG. 1, FIG. 5 is an exploded cross-sectional view of the cassette of the present invention viewed on section line 32-32 in FIG. 4. As illustrated in FIGS 1-5, a surgical cassette according to the invention comprises a cassette 700, which contains external peristaltic pump tube 702, housing 704, molding 706, front gasket 708, rear gasket 710, collection container 712 and hydrophobic filter 714 that prevents liquid from entering vent 754 or air vent line 744. Housing 704 contains aspiration fluid inlet coupling 746, irrigation fluid inlet coupling 748, irrigation fluid outlet coupling 750 and peristaltic pump tube inlet 716 and peristaltic pump tube outlet 718 that are offset from each other relative to front 720 and rear 722 of cassette 700. As can best be seen in FIG. 3, this offset or diagonal orientation of pump tube 702 forces pump tube 702 into winding slot 726 in roller head 724 when cassette 700 is placed within interface slot 728 in the console (not shown). When roller head is initially rotated, winding slot 726 winds or stretches pump tube 702 over roller head 724, eliminating the need for pump tube 702 to be manually wound over roller head 724. As roller head 724 completes one full revolution, pump tube 702 slides out of winding slot 726 and becomes fully stretched over and frictionally engaged with roller head 724. The housing 704 also contains a capacitance chamber 730, an essential feature of the invention, that is closed to front 720 of cassette 700 and open to rear 722 of cassette 700, and a plurality of irrigation and aspiration fluid flow passage-forming channels 732 that are open to rear 722 of cassette 700. Chamber 730 and channels 732 are sealed fluid tight by rear gasket 710. Channels 732 are arranged so that irrigation fluid entering cassette 700 through irrigation fluid inlet coupling 748 can be directed into pump tube 702 to quickly increase the pressure within pump tube 702 if required by the surgeon. However, the pressure within pump tube 702 can be much lower than the pressure within irrigation line 734, and when irrigation valve 752 is opened to allow irrigation fluid to enter pump tube 702, the reduced pressure within pump tube 702 can cause irrigation line 734 to act as a suction line and draw fluid from the eye. To help prevent such an occurrence, chamber 730 acts as a pressure capacitor to smooth out pressure fluctuations within irrigation line 734. As can be seen in FIG. 5, when irrigation line 734 is pressurized with irrigation fluid, gasket 710 expands slightly to increase the volume of irrigation fluid in chamber 730. If the pressure level within irrigation line 734 drops suddenly, the elastic nature of rear gasket 710 causes it to contract, thereby helping to maintain a positive pressure within chamber 730 and smooth out any pressure fluctuations. In addition, as illustrated in FIG. 5, chamber inlet 738 and chamber outlet 733 may contain barbs 742 that permit irrigation fluid flow through inlet 738 into chamber 730 and out of chamber 730 through outlet 733 but restrict irrigation fluid flow backwards through outlet 733 into chamber 730 and out of chamber 730 through outlet 740, thereby helping to prevent irrigation fluid from leaving the eye.

Claims: A cassette (700) for use in combination with a surgical handpiece and a control console for controlling irrigation and/or aspiration fluid flows to the handpiece, the cassette comprising a housing (704) having an interface (706) adapted to be held in operative association with the control console, a means for generating a partial vacuum through interaction with a motive force provided by the console, valve means (752) to control fluid flows through the cassette to the handpiece operable by a valve actuator in the console, at least one fluid coupling (746,748,750)) integrally formed in the housing, at least one fluid flow passage (732) comprising open channel(s) formed integrally in the housing and in fluid communication with a respective fluid coupling and a gasket (710) located over the channel(s) to seal the channel(s) fluid-tight characterized by an irrigation fluid capacitance chamber (730), wherein an irrigation fluid inlet flow passage is in communication with an irrigation fluid inlet coupling (748) and the capacitance chamber, an irrigation fluid outlet flow passage is in communication with the capacitance chamber and an irrigation fluid outlet coupling (750) to form a continuous irrigation fluid flow passage (732) between the irrigation fluid inlet coupling and the irrigation fluid outlet coupling. A cassette according to claim 1, wherein the capacitance chamber (730) is defined by an open channel in an external surface (722) of the housing, and a gasket (710) adhered to the external surface (722) for a fluid-tight seal. A cassette according to claim 1 or claim 2, in which the partial vacuum generating means includes a self-winding peristaltic pump tube (702) and the motive force is a peristaltic pump roller head (724) having a pump tube winding slot (726). A cassette according to any of claims 1 to 3, wherein the continuous irrigation fluid flow passage (732) contains barbs (742) that restrict flow in one direction only.

Inventors: BERKMAN JOHN W, BEUCHAT CHARLES E, ETHERINGTON ROGER, WALBRINK HAROLD J, BERKMAN, JOHN W., BEUCHAT, CHARLES E., ETHERINGTON, ROGER, WALBRINK, HAROLD J.
Applicants: ALCON LAB INC, NESTLE SA, ALCON LABORATORIES, INC., NESTLE S.A.
Application year: 1993
Main classification: A61M1
IPC codes: A61F9, A61M39, A61M1