Abstract:
A resealable conduit is used to remove or add fluid to a closed system without coring or contamination of the fluid. The conduit can include funnel-shaped guide means, duck bill valve means and beveled tip puncturing means. A conduit resting angle of less than about five degrees can be achieved. A tip bevel angle between about ten and twenty degrees is preferred. The beveled tip can have a rotated or twisted blade surface extension. A blade surface extension formed with a ninety degree rotation of the blade surface is preferred. Alternately, the puncturing means can include a needle point or a flat cutting surface.

Description:
BACKGROUND 
     The present invention is directed to a resealable conduit and method for removing or adding fluid to a closed system. The fluid can be of any type. 
     Physiological fluid samples in containers need to be easily accessible without compromising the integrity of the sample. Closed systems such as stoppered physiological fluid sample tubes are accessed to remove one or more aliquots of the fluid. Alternately, fluid can be added to the sample tube, such as when a dilution is desired. Various diagnostic and therapeutic tests can be performed upon the aliquots. Physiological fluids such as, for example, blood or urine are frequently collected and stored in sample tubes closed by a rubber or elastomeric material stopper. 
     Typically, fluid samples are removed from a stoppered tube by removing the stopper, inserting a pipette stem into the fluid, aspirating fluid into the pipette and replacing the stopper. This access method can create aerosols and exposes sample fluid to the local environment. Aseptic conditions can thereby be violated Biohazard can arise when this prior art fluid access method is used if the sample tube contains virulent or infectious organisms. These problems are compounded when the sample tube is reaccessed to remove further fluid samples. 
     A further problem is coring, which can occur when a hollow conduit is inserted through a rubber or like-material stopper. Coring is the removal of stopper material from the wall of the stopper as a hollow conduit is forced through the stopper. The cored material can enter the bore of the conduit thereby blocking it. Additionally, cored material can fall into the sample fluid when insertion of the conduit is complete, thereby contaminating the sample and rendering it unsuitable for analysis. 
     Needle tip conduits for piercing rubber septums or stoppers are known. These devices suffer from the disadvantages of coring, lack of a closure valve to prevent fluid backflow when tipped or inverted, high cost and inability to maintain essentially aseptic conditions. 
     Accordingly, there is a need for a low cost stored in closed sample tubes without coring and with maintenance of a high level of fluid asepsis. The device and method should permit repeatable access to such body fluids with minimal risk of creating aerosols, biohazard or contamination of either sample fluid or the sampling environment. 
     SUMMARY 
     The present invention is directed to a low cost resealable conduit device and method which meets these needs. The resealable conduit can be inserted with little or no coring, through a rubber or like-material stopper of a fluid-containing sample tube. An elongated tubular member such as the stem of a pipette is inserted through the conduit to aspirate fluid. Alternately, fluid can be added by the pipette. The resealable conduit has closure means to prevent fluid backflow during normal handling, has re-entrant capability, is disposable, and minimizes risk of aerosol creation or contamination of a sample or the sampling environment. 
     A resealable conduit according to the present invention has guide means, puncturing means, and valve means. The guide means receives and guides the leading end of an elongated tubular member, such as a pipette stem, into the bore of the conduit. The guide means has a mouth into which the tubular member can be removably inserted. The puncturing means is used for puncturing a rubber or like-material stopper so that the conduit can be inserted through the stopper. The normally closed valve means is disposed in the conduit bore. 
     The mouth of the guide means can have a cross-sectional shape that is, for example, square, rectangular, circular, or elliptical. Preferably, the mouth of the guide means is circular or elliptical and the guide means is funnel-shaped. 
     The puncturing means preferably has a beveled tip to assist passage of the conduit through a stopper. The wall adjacent the leading edge of the bevel tip can be thickened for support. The leading edge can have a needle point or a flat puncturing surface. Alternately, the flat puncturing surface can be in the form of a blade surface extension. 
     Preferably, the valve means is a &#34;duck bill&#34; valve because such valves are easy to make, inexpensive and effectively provide the desired one way mechanical access while preventing fluid backflow. 
     The guide and puncturing means can be formed as parts of an integral conduit body or they can be formed separately and assembled. To provide structural support, a reinforcing rib can run vertically along the exterior of the conduit. 
     A preferred method for removing fluid from a closed system includes the steps of: inserting the beveled tip of a resealable conduit through a closure member of the system; inserting an elongated tubular member through the conduit; aspirating fluid into the tubular member; and withdrawing the tubular member from the conduit. The conduit can then close under valve action. This method can also include the additional step of scoring the top of the closure member before inserting the beveled tip through closure member to help prevent coring. A preferred method for adding fluid to a closed system is the same as that just recited, except that instead of aspirating fluid, fluid is dispensed through the tubular member. 
     An apparatus within the scope of the present invention for removing fluid from or adding fluid to a closed system can include a resealable conduit, an elongated tubular member, such as a pipette, a closure member, such as a rubber stopper, and any combinations thereof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features, aspects, and advantages of the invention are illustrated by the following drawings. 
     FIG. 1 is an exploded perspective view of a pipette, resealable conduit and stoppered sample tube. 
     FIG. 2 is a vertical, cross-sectional view of the resealable conduit taken along line 2--2 of FIG. 1. 
     FIG. 3 is a top plan view taken along line 3--3 of FIG. 2. 
     FIG. 4 is an enlarged bottom view taken along line 4--4 of FIG. 2. 
     FIG. 5 is a fragmentary, vertical, side cross-sectional view taken along line 5--5 of FIG. 2. 
     FIG. 6 is a fragmentary, vertical, cross-sectional view illustrating initial piercing contact by the resealable conduit. 
     FIG. 7 is a vertical, cross-sectional view of the resealable conduit in use. 
     FIG. 8 is a side elevational view of the resealable conduit illustrating bevel angle. 
     FIG. 9 is a side elevational view of the resealable conduit illustrating resting angle. 
     FIG. 10 is a fragmentary, vertical, cross-sectional view of an alternate form of the bevel tip. 
     FIG. 11 is a top plan view of an alternate form of the guide means. 
     FIG. 12 is a fragmentary, vertical, cross-sectional view taken along line 12--12 of FIG. 11. 
     FIG. 13 is a vertical, cross-sectional view taken along line 13--13 of FIG. 12. 
     FIG. 14 is a fragmentary, side elevational, cross-sectional view of a further alternate form of the bevel tip. 
     FIG. 15 is a bottom view taken along line 15--15 of FIG. 14. 
     FIG. 16 is a fragmentary, side elevational, cross-sectional view of a further embodiment of the bevel tip. 
    
    
     DESCRIPTION 
     FIG. 1 shows a resealable conduit 10, and a pipette 11 with elongated tubular member or stem 12 for insertion into, at a first end of the conduit, a mouth 13 of guide means 14. Pipette 11 can be a component of anautomated fluid removal or addition apparatus. Alternately, pipette 11 can be operated manually. Conduit 10 has a bore 15 running the length of conduit 10. Bore 15 is wide enough for easy insertion and withdrawal of pipette stem 12. Bore 15 is wide at mouth 13 and narrower in cylindrical tube 16 of conduit 10. Tube 16 terminates at an end remote from guide means 14 in a second end. 
     The second end can have a beveled tip 17 to help reduce or prevent coring. Coring is believed to be a function of, at least, bevel angle (BA), stopper thickness and stopper material. The mouth 13 of guide means 14 canin horizontal cross-section be suitably square, rectangular, circular, elliptical or funnel-shaped, with tapered walls, as shown in FIG. 1, so that a pipette stem that is not directly centered over the long axis of the bore axis will upon contact with a wall of the guide means 14 be guided into the more narrow part of bore 15. This guiding feature is advantageous whether the resealable conduit is used in a manual operation or as part of an automated apparatus, such as a serum splitting instrument. Conduit 10 can have a reinforcing rib 18 running vertically along the exterior tube 16. Rib 18 functions to strengthen the tube to prevent cracking or buckling of conduit 10 when it is inserted through a closure means such as stopper 19 of sample test tube 20. 
     FIG. 2 shows that guide means 14 has valve means 21. Valve means 21 is a one-way closure device and prevents the backflow of fluid from sample tube20. Valve means 21 is capable of opening and closing. Typically, the valve means can open, as shown by phantom lines 22 and 23 in FIG. 2, when pressure is applied to the outer face of the valve. The valve can close when the pressure is withdrawn and/or due to construction of the valve means from a self-sealing material, such as an elastomeric material. Any type of resealable closure means can be a suitable valve means. Valve means 21 can have at least two leaflets 24, 25 made of a resilient material that will reseal when pressure, as from the urging of pipette stem 12, is withdrawn. Thus, the leaflets normally rest against each otherto close the valve. As shown in FIG. 3, leaflets 24 and 25 can taper towards one another. Periphery 26 of the leaflets can be fixed or sealed to guide means 14. 
     Valve 21 can be a &#34;duck bill&#34; valve (available from Vernay Europa B.V., P.0. Box 310, 875 Yellow Spring, Dayton, Ohio 45387). A duck bill valve isinexpensive, can be mechanically and/or chemically sealed to conduit 10 at valve periphery 26, and provides a one-way mechanical and/or fluid flow through conduit 10. Thus, entry into the resealable conduit is permitted in one direction, while not allowing fluid flow in the opposite direction.The duck bill valve can be made of a silicone rubber material to facilitateopening and closing of the leaflets. 
     Beveled tip 17 has a leading edge 27 and a trailing edge 28. Tip 17 can be integral with the rest of conduit 10 or can be constructed from a needle coated with a substance such as teflon and inserted into cylindrical tube 16. In one embodiment, the leading edge defines a flat cutting or puncturing surface 29. Cutting surface 29 is the first area of conduit 10 that comes into contact with the stopper 19. 
     FIG. 4 illustrates twist angle (TA). Twist angle is the angle of rotation of the cutting edge. Twist angle can be described as the angle formed between a cutting surface 29 and a tangent 30. Tangent 30 is drawn from the exterior of conduit 10 adjacent cutting surface 29. Thus, twist angle is the angle from tangent 30 through which cutting surface 29 is twisted or rotated during formation of the puncture means. Twist angle is between about 0° and about 180° to help prevent coring of the stopper, reduce the required puncture force, and help prevent excess tearing of the stopper during puncturing. Preferably, twist angle is about90° so as to help minimize the amount of coring, puncture force and stopper tearing. 
     FIG. 5 shows another view of the guide means 14 and upper part of the tube 16 of the conduit illustrated in FIG. 2. FIG. 6 shows the initial piercingcontact of cutting edge 29 into the rubber or rubber-like material 31 of stopper 19. FIG. 7 shows conduit 10 in use with a pipette stem 12 insertedtherethrough. 
     FIG. 8 illustrates bevel angle (BA). Bevel angle is the angle between a tangent from the leading edge and the trailing edge of a beveled tip. Coring of a rubber or elastomeric closure means is reduced when bevel angle is greater than about 0° and less than about 75°, withminimal or no coring occurring when the bevel angle is between about 10° and about 20°. Preferably, therefore, the conduit has a bevel with a bevel angle between about 10° to about 20°. 
     The bevel angle influences the resting angle (RA). FIG. 9 illustrates resting angle. It was found that simple bevels, wherein the leading and trailing edges are joined by a straight line, gave little or no coring anda low resting angle. Preferably, the bevel is a simple bevel. Resealable conduits with bevel angles of between 10° to about 20° were found by Applicants to have the lowest resting angles. Resting angle is the angle insertion of conduit 10 through a stopper. Upon insertion through a stopper, the conduit should assume as nearly a vertical positionas possible, that is, have a low resting angle, so that when a pipette stemis inserted through the conduit, the stem will not impact the wall of the sample tube. Preferably, therefore, the resting angle is less than about 20°, such as 10°, 5° or even about 0°. Low resting angle can assist low friction access of a pipette stem to fluid within a sample tube. 
     FIG. 16 shows another embodiment of the invention. Tip 17 can have a leading edge 27 with a cutting surface 29 terminating in a needle point 33. A puncturing, needle tip is easy to construct and gives little or no coring. Optionally, conduit wall 34 adjacent puncturing needle 33 can be thickened to provide support. 
     In yet another embodiment, as shown in FIGS. 14 and 15, cutting edge 29 canbe a blade surface extension 35. Blade surface extension 35 can have a twist angle of between about 0° and less than about 180°. Preferably, the twist angle of blade surface extension 35 is about 90°, for the reasons given previously. Extension 35 can blend into the structure of the cylindrical tube 16; that is, extension 35 tapers to nothing along the longitudinal axis of the conduit. 
     FIGS. 11, 12 and 13 show additional embodiments of the guide means 14 and valve means 21. A circular lip 36 of valve means 21 is joined to a mating circular flange 37 formed from the wall of guide means 14. Flange 37 can be adjacent the mouth of the guide means. 
     Conduit 10 can be of any suitable size depending upon parameters such as stopper material, stopper diameter, pipette stem length and diameter, etc.Conveniently, conduit 10 can be approximately 1/4 to 3/8 inch in inside diameter at mouth 13, and decrease uniformly in diameter to approximately 1/8 inch in inside diameter at tube 16. Tube 16 can be about one inch in length with a wall thickness of about 1/16 inch. 
     Conduit 10 can be thermoformed from an acetyl or other thermoplastic which will permit molding of sharp , edges at the beveled tip, which will remainsharp over time. The conduit can be made from a styrene such as ABS (acrylongitrile butadiene styrene). 
     Conduit 10 is inserted through a stopper 19 by puncturing stopper 19 with the beveled tip 17 of conduit 10. Pipette stem 12 is then inserted throughthe duck bill valve of conduit 10 and fluid 32 is aspirated from tube 20 into the pipette. Alternately, fluid can be dispensed into the sample tubefrom the pipette. Finally, pipette stem 12 is withdrawn from conduit 10. Duck bill valve 21 provides reentrant capability. 
     To help prevent coring of the cap, the cap can be scored before puncture bythe conduit. Scoring involves the marking or &#34;scoring&#34; of the stopper with a sharp object. The cut or shallow slit thereby made in the cap stopper can assist initial puncturing by the conduit and also assist passage of the conduit through a cap stopper without coring. 
     In use, resealable conduit 10 is positioned over the top of a conventional physiological fluid collection tube 20. Tube 20 can contain any of a variety of physiological or nonphysiological fluids. As tube 20 is either brought to the conduit 10 or conduit 10 is brought to tube 20, tip 17 contacts the top of stopper 19. 
     The present invention also includes within its scope an apparatus comprising a conduit 10, pipette 11 and a sample tube stopper 19 or any combination of these components, with or without insertion of the conduit 10 through the stopper 19. 
     Any septum-type closures that can be pierced to gain access to a closed system on a repeatable and resealable basis are suitable for the present conduit 10. The resealable conduit renders unnecessary removal of the stopper of a sample tube to access fluid contained by the stoppered tube. The conduit allows essentially aseptic removal of fluid on a repeatable basis. The present invention is inserted through a stopper and remains, inpart, exterior to the stopper. 
     The disclosed resealable conduit can be used manually or as part of an automated procedure. In a manual operation, the user presses the puncture means through the septum of a closed system, followed by insertion of a tubular member into the conduit. Fluid can be added to or removed from theclosed system through the tubular member, typically a pipette stem. 
     Alternately, or in conjunction with one or more manually effected steps, the puncture means of the conduit can be inserted through the septum or stopper in a machine-assisted step. When used in an automated procedure, the tubular member can be a pipette or a probe component of a stand-alone or workstation instrumentation. For example, the resealable conduit can beused in conjunction with the Beckman Synchron Clinical Analyzers, such as the Beckman CX-5. 
     Significant advantages of the invention include: 
     1. Non-coring penetration of a rubber or like-material stopper by the conduit; 
     2. A conduit that is resealable, with one-way mechanical access and that prevents fluid backflow; 
     3. Re-entrant conduit capability; 
     4. Low-friction access to sample by a pipette or other tubular member; 
     5. Disposable, resealable conduit; 
     6. Essentially biohazard-free operator interaction; and 
     7. Essentially biohazard-free serum (or other physiological or nonphysiological fluid) transfer. 
     The resealable conduit provides a solution to the problem of aseptically violating the cap of a sample tube in order to repeatably remove fluid, such as a physiological fluid from the tube without the creation of aerosols, biohazards or exposing the blood products to the exterior environment without containment. The conduit is constructed inexpensively so as to be a disposable device. 
     Although several embodiments of the invention have been disclosed, it should be understood that the present invention is in no way limited thereby and that its scope is to be determined by the appended claims.