Abstract:
An ophthalmic irrigation/aspiration venting system that vents a portion of an aspiration circuit by drawing sterile air from a bag. The bag is provided with an air reservoir member to ensure that an adequate air volume is available.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to air venting in an ophthalmic irrigation/aspiration system via a closed bag system and to a structure for a closed bag used in an ophthalmic irrigation/aspiration system. 
     2. Related Art 
     The Storz Millennium Microsurgical System uses a venturi pump for irrigation and aspiration. When venting is in progress for the irrigation/aspiration aspects of the microsurgical system, air is drawn through the pump, through the bag and into the aspiration circuit. The air that is drawn is ambient air. 
     The Phacotron Gold microsurgical system also employs air venting. In this system, a T is provided into an aspiration circuit. The T provides direct access to the ambient air and is controlled by a pinch valve. During venting, the controlling pinch valve is opened which permits ambient air to flow directly into the aspiration circuit and relieve residual pressure. 
     There is no known venting system which provides a sterile volume of venting air. In addition, there is no known system which divides an aspiration circuit and air vents one of these divided sections. 
     There is a need in the art to provide a system that draws sterile air from, not through, the bag to accomplish venting. 
     There is a further need in the art to provide a bag with an air reservoir member for guaranteeing a supply volume of sterile air. 
     SUMMARY OF THE INVENTION 
     It is in view of the above problems that the present invention was developed. The invention is a venting system that vents a portion of an aspiration circuit by drawing sterile air from a bag. The bag is provided with an air reservoir member to ensure that an adequate air volume is available. 
    
    
     Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with reference to the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and form a part of the specification, illustrate the embodiments of the present invention and together with the description, serve to explain the principles of the invention. In the drawings: 
     FIG. 1 illustrates an ophthalmic irrigation/aspiration system in accordance with the present invention; and 
     FIG. 2 illustrates a cross-section view of a bag in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the accompanying drawings in which like reference numbers indicate like elements, FIG. 1 illustrates an ophthalmic irrigation/aspiration system shown generally at  10 . Ophthalmic irrigation/aspiration system  10  includes bottle  12 , pump  14 , bag  16 , and irrigation/aspiration circuit  18 . 
     Located variously throughout irrigation/aspiration circuit  18  for controlling fluid communication are irrigation pinch valve  22 , bridge pinch valve  24 , aspiration pinch valve  26 , and calibration pinch valve  28 . Irrigation circuit shown generally at  36  comprises first section  38  and second section  40 . One end of second section  40  is adapted to contact eye  32 . Aspiration circuit shown generally at  48  comprises lower section  49 , third section  50 , fourth section  52 , and fifth section  54 . Lower section  49  is adapted at one end to contact eye  32 . 
     The workings of this ophthalmic irrigation/aspiration system  10  are clearly set forth in a co-pending patent application Ser. No. 09/173,451, filed Oct. 15, 1998, and titled Ophthalmic Aspiration System with Selectable Vent Method filed by inventors James Perkins, William Neubert, and Jeffery Knight and is hereby incorporated by reference in its entirety. Still further information is provided in a co-pending patent application Ser. No. 09/173,452, filed Oct.15, 1998, and titled Fluid Venting in Ophthalmic Irrigation/Aspiration System filed by inventors James Perkins and Jeffery Knight and hereby is incorporated in its entirety. 
     During fluid venting, pump  14  is stopped. Accordingly, no fluid enters in the pump inlet  55  through third section  50  nor exits pump outlet  56  to discharge directly into first opening  15  of bag  16 . Aspiration pinch valve  26  closes and calibration pinch valve  28  is opened. Thus third section  50 , fourth section  52 , and fifth section  54  of aspiration circuit  48  are isolated from lower section  49  of aspiration circuit  48 . The residual vacuum pressure existing in third section  50 , fourth section  52 , and fifth section  54  pulls air from second opening  17  of bag  16 . 
     Thus, a portion of irrigation/aspiration circuit  18  is air vented. 
     In another example, pump  14  is stopped, aspiration pinch valve  26  closes, calibration pinch valve  28  opens, bridge pinch valve  24  is closed, and irrigation pinch valve  22  is open. As a result, air is drawn from second opening  17  of bag  16  to vent aspiration circuit  48 . This results in a slight pressure differential between one end of second section  40  of irrigation circuit  36  and lower section  49  of aspiration circuit  48 . A practical result of this slight pressure differential is that material is guided from the irrigation side to stay at the aspiration side of an irrigation/aspiration handpiece (not shown). This characteristic emulates air venting in irrigation/aspiration systems which do not utilize a positive displacement pump as is utilized and shown at  14  of ophthalmic irrigation/aspiration system  10 . 
     As shown in FIG. 2, bag  16  is formed from first wall  58  and second wall  60  joined together at weld  62 . Disposed within bag  16  is a first air reservoir member  64  made from a cellular material, a sponge. Also, a second air reservoir member  66  may be disposed within bag  16  which is a spacing element that ensures a predetermined distanced separation between first wall  58  and second wall  60 . While two reservoir members are shown in FIG. 2, it is preferred that only one air reservoir member be present within bag  16 . In the preferred embodiment, first and second air reservoir members  64  and  66  provide sterile air in a volume sufficient to provide relief to the vacuum pressure demands in aspiration circuit  48 . 
     In view of the foregoing, it will be seen that the several advantages of the invention are achieved and attained. 
     The embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. 
     As various modifications could be made in the constructions and methods herein described and illustrated without departing from the scope of the invention, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalents.