Abstract:
A surgical system having a cassette with an aspirant vent line that permits a fluidic connection between the inlet to a aspirant pump and the outlet of the aspirant pump through a vent valve. When the aspiration vent valve is open, fluid flows from the pump outlet into the pump inlet, thereby releasing any pressure within the pump inlet. Such a system does not require a second source of irrigation fluid, minimizes pressure surges into the irrigation fluid line and does not affect the fluidic performance of the aspiration system.

Description:
[0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 10/430,974, filed May 7, 2003, currently co-pending which is a continuation-in-part of U.S. patent application Ser. No. 10/407,388, filed Apr. 4, 2003, which is a continuation-in-part application of U.S. patent application Ser. No. 09/846,724, filed May 1, 2001, now U.S. Pat. No. 6,572,349 B2, which is a continuation of U.S. patent application Ser. No. 09/437,392, filed Nov. 10, 1999, now U.S. Pat. No. 6,293,926 B1, and a continuation-in-part of U.S. patent application Ser. No. 10/153,371, filed May 28, 2002, and is a continuation-in-part application of U.S. patent application Ser. No. 09/925,989, filed Aug. 9, 2001, now U.S. Pat. No. 6,740,074 B1, which is a continuation-in-part of U.S. patent application Ser. No. 09/771,945, filed Jan. 29, 2001, now U.S. Pat. No. 6,632,214 B1, which is a divisional of U.S. patent application No. 09/387,357, filed Aug. 31, 1999, now U.S. Pat. No. 6,261,283 B1. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    This invention relates generally to the field of cataract surgery and more particularly to an aspiration system for a handpiece for practicing the phacoemulsification technique of cataract removal.  
           [0003]    The human eye in its simplest terms functions to provide vision by transmitting light through a clear outer portion called the cornea, and focusing the image by way of the lens onto the retina. The quality of the focused image depends on many factors including the size and shape of the eye, and the transparency of the cornea and lens.  
           [0004]    When age or disease causes the lens to become less transparent, vision deteriorates because of the diminished light which can be transmitted to the retina. This deficiency in the lens of the eye is medically known as a cataract. An accepted treatment for this condition is surgical removal of the lens and replacement of the lens function by an artificial intraocular lens (IOL).  
           [0005]    In the United States, the majority of cataractous lenses are removed by a surgical technique called phacoemulsification. During this procedure, a thin phacoemulsification cutting tip is inserted into the diseased lens and vibrated ultrasonically. The vibrating cutting tip liquifies or emulsifies the lens so that the lens may be aspirated out of the eye. The diseased lens, once removed, is replaced by an artificial lens.  
           [0006]    A typical ultrasonic surgical device suitable for ophthalmic procedures consists of an ultrasonically driven handpiece, an attached cutting tip, and irrigating sleeve and an electronic control console. The handpiece assembly is attached to the control console by an electric cable and flexible tubings. Through the electric cable, the console varies the power level transmitted by the handpiece to the attached cutting tip and the flexible tubings supply irrigation fluid to and draw aspiration fluid from the eye through the handpiece assembly.  
           [0007]    The operative part of the handpiece is a centrally located, hollow resonating bar or horn directly attached to a set of piezoelectric crystals. The crystals supply the required ultrasonic vibration needed to drive both the horn and the attached cutting tip during phacoemulsification and are controlled by the console. The crystal/horn assembly is suspended within the hollow body or shell of the handpiece by flexible mountings. The handpiece body terminates in a reduced diameter portion or nosecone at the body&#39;s distal end. The nosecone is externally threaded to accept the irrigation sleeve. Likewise, the horn bore is internally threaded at its distal end to receive the external threads of the cutting tip. The irrigation sleeve also has an internally threaded bore that is screwed onto the external threads of the nosecone. The cutting tip is adjusted so that the tip projects only a predetermined amount past the open end of the irrigating sleeve. Ultrasonic handpieces and cutting tips are more fully described in U.S. Pat. Nos. 3,589,363; 4,223,676; 4,246,902; 4,493,694; 4,515,583; 4,589,415; 4,609,368; 4,869,715; 4,922,902; 4,989,583; 5,154,694 and 5,359,996, the entire contents of which are incorporated herein by reference.  
           [0008]    In use, the ends of the cutting tip and irrigating sleeve are inserted into a small incision of predetermined width in the cornea, sclera, or other location. The cutting tip is ultrasonically vibrated along its longitudinal axis within the irrigating sleeve by the crystal-driven ultrasonic horn, thereby emulsifying the selected tissue in situ. The hollow bore of the cutting tip communicates with the bore in the horn that in turn communicates with the aspiration line from the handpiece to the console. A reduced pressure or vacuum source in the console draws or aspirates the emulsified tissue from the eye through the open end of the cutting tip, the cutting tip and horn bores and the aspiration line and into a collection device. The aspiration of emulsified tissue is aided by a saline flushing solution or irrigant that is injected into the surgical site through the small annular gap between the inside surface of the irrigating sleeve and the cutting tip.  
           [0009]    During surgery, the hollow, resonating tip can become occluded. During occlusion, vacuum can build in the aspiration line downstream of the occlusion. When the occlusion eventually breaks apart, this pent up vacuum is released into the eye which can, depending upon the amount of vacuum, draw a significant amount of fluid from the eye, thereby increasing the risk of anterior chamber collapse. To address this concern, modem surgical console can detect increases in aspiration line vacuum beyond normal operating parameters and therefore predict occlusions. These consoles can then either stop or slow the aspiration pump, or sound an alarm so that the surgeon can take appropriate precautions.  
           [0010]    The cassettes used in modem consoles also allow the aspiration line to be vented, either to atmosphere or to a liquid so as to reduce or eliminate vacuum surge upon occlusion break. Prior art air vented cassettes allow ambient air to enter the aspiration line, however, venting air into the aspiration line changes the fluidic performance of the aspiration system. Liquid venting systems allow irrigation fluid to bleed into the aspiration line, thereby reducing any impact on the fluidic performance of the aspiration system. Liquid venting cassettes are more fully described in U.S. Pat. Nos. 4,832,685 and 4,935,005 (Haines) and U.S. Pat. No. 4,713,051 (Steppe, et al.), the entire contents of which being incorporated herein by reference. When higher aspiration vacuums are used, cassettes that vent the aspiration line to the irrigation line can cause high pressure surges in the irrigation line. Other systems provide a separate source of irrigation fluid to vent the aspiration line, requiring the use of two irrigation fluid sources and increasing the cost and complexity of the system.  
           [0011]    Therefore, a need continues to exist for a simple surgical system that allows rapid venting of excess aspiration vacuum without introducing pressure variations in the irrigation line or the downstream aspiration line.  
         BRIEF SUMMARY OF THE INVENTION  
         [0012]    The present invention improves upon the prior art by providing a surgical system having a cassette with an aspirant vent line that permits a fluidic connection between the inlet to a aspirant pump and the outlet of the aspirant pump through a vent valve. When the aspiration vent valve is open, fluid flows from the pump outlet into the pump inlet, thereby releasing any pressure within the pump inlet. Such a system does not require a second source of irrigation fluid, minimizes pressure surges into the irrigation fluid line and does not affect the fluidic performance of the aspiration system.  
           [0013]    Accordingly, one objective of the present invention is to provide a surgical system having a aspiration line vent.  
           [0014]    Another objective of the present invention is to provide a surgical system having a cassette that allows the aspiration line to be vented of excess vacuum.  
           [0015]    Another objective of the present invention is to provide a surgical system having a cassette that vents the aspiration line to an aspirant collection chamber.  
           [0016]    Another objective of the present invention is to provide a surgical system that vents the aspiration line without introducing pressure surges in the irrigation line.  
           [0017]    Another objective of the present invention is to provide a surgical system that vents the aspiration line without affecting the fluidic performance of the aspiration system.  
           [0018]    These and other advantages and objectives of the present invention will become apparent from the detailed description and claims that follow. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0019]    [0019]FIG. 1 is a schematic illustration of a first embodiment of the system and cassette of the present invention.  
         [0020]    [0020]FIG. 2 is a schematic illustration of a second embodiment of the system and cassette of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]    As best seen in FIG. 1, first embodiment of system  10  of the present invention generally includes surgical console  12  and cassette  14 . Console  12  may be any suitably modified commercially available surgical console, such as the SERIES TWENTY THOUSAND® LEGACY®V, INFINITI® or ACCURUS® surgical systems available from Alcon Laboratories, Fort Worth, Tex. Cassette  14  may be any suitably modified commercially available surgical cassettes, such as those described in U.S. Pat. Nos. 5,267,956, 5,364,342 and 5,499,969 (Beuchat, et al.) and U.S. Pat. No. 5,899,674 (Jung, et al.), the entire contents of which being incorporated herein by reference. Cassette  14  is held in operative association with console  12  by means well-known in art.  
         [0022]    As seen in the FIG. 1, console  12  generally contains aspiration pump mechanism  16 , which may be any suitable flow or vacuum based pump, such pumps being widely known in the art. For example, pump mechanism  16  may be a peristaltic pump roller head that interacts with a peristaltic pump tube formed by aspiration line  20  and aspiration exhaust line  34 . Aspiration line  20  is connected to surgical handpiece  22  on one end and end  18  of aspiration line  20  opposite handpiece  22  interacts with pump mechanism  16  so as to draw fluid through handpiece  22 . Aspiration line  20  is intersected between handpiece  22  and  18  by aspiration vent line  24 . In fluid communication with aspiration vent line  24  is pressure sensor  26 , which may be one of a variety of invasive or non-invasive pressure sensors well-known in the art.  
         [0023]    Cassette  14  generally contains fluid reservoir  28 . Extending from reservoir  28  at or near bottom  29  is aspiration vent line  32 , which fluidly connects to aspiration vent line  24  through vent valve  30 . Aspirant or exhaust from pump mechanism  16  is directed into reservoir  28  through aspiration exhaust line  34 . Reservoir  28  may also vent to ambient through fluid line  41 , waste bag  40  and vent line  36 , which may contain antimicrobial filter  38 .  
         [0024]    As discussed above, while it is preferred that pump mechanism  16  be a peristaltic roller head and aspiration line  20  and aspiration exhaust line  34  be formed in one continuous length so as to form a peristaltic pump tube that interacts with pump mechanism  16 , one skilled in the art will recognize that aspiration line  20  and aspiration exhaust line may be formed as a separate piece or pieces or may be formed integrally with cassette  14  and that pump mechanisms  16  other that peristaltic pump roller heads may be used, such as linear peristaltic pumps.  
         [0025]    In addition, pressure sensor  26  is depicted as being contained within console  12 . One skilled in the art will recognize that portions of pressure sensor  26 , such as a pressure diaphragm (not shown) may be contained in or on cassette  14  and interact with a force transducer or other means (not shown) contained within console  12 .  
         [0026]    In use, cassette  14  is installed on or within console  12  and held in operative association with console  12  by means well-known in the art. System  10  is primed initially with clean surgical fluid so that a small amount of fluid fills reservoir  28 . During surgery, pump mechanism  16  draws aspirant through handpiece  22  and into reservoir  28 . If the vacuum within aspiration line  20  is too high and needs to be vented, vent valve  30  is opened allowing aspirant to be drawn off of bottom  29  of reservoir  28  (reservoir  28  being at or near ambient) and into aspiration line  20  (which contains a vacuum) through aspiration vent line  24 . One skilled in the art will recognize that by varying the vertical position of reservoir  28  relative to aspiration line  20 , various vent head pressures may be achieved. Reservoir  28  may be relatively small, and not capable of holding all of the aspirant collected during surgery. Waste bag  40  may be used to drain and hold excess fluid from reservoir  28 , through fluid line  41  above bottom  29  of reservoir  28 . Waste bag  40  may be integrally formed within cassette  14  or may be formed as a separate collapsible bag attached to cassette  14 , as is well-known in the art.  
         [0027]    As best seen in FIG. 2, second embodiment of system  100  of the present invention generally includes surgical console  112  and cassette  114 . Console  112  may be any suitably modified commercially available surgical console, such as the SERIES TWENTY THOUSAND® LEGACY® or ACCURUS® surgical systems available from Alcon Laboratories, Fort Worth, Tex. Cassette  114  may be any suitably modified commercially available surgical cassettes, such as those described in U.S. Pat. Nos. 5,267,956, 5,364,342 and 5,499,969 (Beuchat, et al.) and U.S. Pat. No. 5,899,674 (Jung, et al.), the entire contents of which being incorporated herein by reference. Cassette  114  is held in operative association with console  112  by means well-known in art.  
         [0028]    As seen in FIG. 2, console  112  generally contains aspiration pump mechanism  116 , which may be any suitable flow or vacuum based pump, such pumps being widely known in the art. For example, pump mechanism  116  may be a peristaltic pump roller head that interacts with a peristaltic pump tube formed by aspiration line  120  and aspiration exhaust line  134 . Aspiration line  120  is connected to surgical handpiece  122  on one end and end  118  of aspiration line  120  opposite handpiece  122  interacts with pump mechanism  116  so as to draw fluid through handpiece  122 . Aspiration line  120  is intersected between handpiece  122  and  118  by aspiration vent line  124 . In fluid communication with aspiration vent line  124  is pressure sensor  126 , which may be one of a variety of invasive or non-invasive pressure sensors well-known in the art.  
         [0029]    Extending from vent line  134  is aspiration vent line  132 , which fluidly connects to aspiration vent line  124  through vent valve  130 . Aspirant or exhaust from pump mechanism  116  is directed into vent line  132  through aspiration exhaust line  134  but is prevented from entering line  124  by valve  130 . Exhaust line  134  empties into waste bag  40 , which may vent waste bag  140  to atmosphere through vent line  136 , which may contain antimicrobial filter  38 .  
         [0030]    As discussed above, while it is preferred that pump mechanism  116  be a peristaltic roller head and aspiration line  120  and aspiration exhaust line  134  be formed in one continuous length so as to form a peristaltic pump tube that interacts with pump mechanism  116 , one skilled in the art will recognize that aspiration line  120  and aspiration exhaust line  134  may be formed as a separate piece or pieces or may be formed integrally with cassette  114  and that pump mechanisms  116  other that peristaltic pump roller heads may be used, such as linear peristaltic pumps.  
         [0031]    In addition, pressure sensor  126  is depicted as being contained within console  112 . One skilled in the art will recognize that portions of pressure sensor  126 , such as a pressure diaphragm (not shown) may be contained in or on cassette  114  and interact with a force transducer or other means (not shown) contained within console  112 .  
         [0032]    In use, cassette  114  is installed on or within console  112  and held in operative association with console  112  by means well-known in the art. System  100  is primed initially with clean surgical fluid so that a small amount of fluid fills exhaust line  134  and waste bag  140 . During surgery, pump mechanism  116  draws aspirant through handpiece  122  and into exhaust line  134 . If the vacuum within aspiration line  120  is too high and needs to be vented, vent valve  130  is opened allowing aspirant to be drawn out of exhaust line  134  and into aspiration line  120  (which contains a vacuum) through aspiration vent line  124 , effectively shunting positively pressurized fluid from exhaust line  134  into negatively pressurized aspiration line  120 .  
         [0033]    This description is given for purposes of illustration and explanation. It will be apparent to those skilled in the relevant art that changes and modifications may be made to the invention described above without departing from its scope or spirit. For example, one skilled in the art will recognize that by varying the vertical position of the distal end of exhaust line  134  relative to aspiration line  120 , various vent head pressures can be achieved.