Abstract:
Apparatus and method for use in the sterile sampling of liquid from a container, the apparatus having a normally vertical tubular sight chamber coupled by its lower end to a sample port assembly. The upper end of the chamber is fitted with an inlet tube through which sample liquid can be received and a filtered vent to allow air to flow to and from the sight chamber while preventing the ingress of bacteria in to the chamber. The sample port assembly has a tubular body encasing a sheathed needle assembly so that evacuated phials can be inserted into the body and pressed onto the needle assembly to withdraw samples of liquid collected in the sight chamber, the sight chamber preferably having transparent walls that are marked with graduations so that each phial can be withdrawn from the needle assembly after the desired amount of liquid has been collected.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims priority from Australian provisional patent application serial number 2003906364, filed Nov. 19, 2003. 
   FIELD OF THE INVENTION 
   This invention relates to methods and apparatus for the sterile sampling of liquids in containers in ways that minimize the danger of contaminating the liquid in the container by the sampling process. It may be applied to the sampling of platelets and other blood products from collection pouches. 
   For convenience and without meaning to exclude other forms of containers, the liquid containers to be sampled will herein be called pouches. As it will be normal for the pouch being sampled to be arranged above the sampling apparatus to take advantage of the hydrostatic head thus provided, it will be convenient to refer to parts of the apparatus as being above or below, or as being upper or lower, with respect to other parts. However, the pouch and sampling apparatus could be arranged so liquid flow does not flow under gravity, in which case some parts are likely to be more distal or proximal relative to other parts (with respect to the user). Accordingly, the terms ‘upper and ‘lower’, ‘above’ and ‘below’ should be understood as being equivalent to ‘distal’ and ‘proximal’ (respectively) as used herein. 
   BACKGROUND OF THE INVENTION 
   There are occasions in medical practice where it is desirable to check the sterility or other properties of a liquid stored in a pouch before that liquid is administered to a patient or otherwise used. Examples are blood and blood components such as serum and platelets. The US blood industry association, the American Association of Blood Banks (AABB), an association that is globally recognized, recently updated the technical requirements for blood collection, storage and testing and has included a new pre-transfusion QC requirement that will go into effect in March 2004. The new QC test requirement involves testing stored platelets for evidence of bacteria. If bacteria are detected in a unit (ie, a pouch) of platelets, that unit will not be eligible for transfusion. In order to perform the necessary tests, multiple samples of platelets are usually extracted from the platelet container into respective sample phials. In some cases samples from multiple pouches are mixed and then tested. However, there is serious danger that the sampling procedure itself can introduce bacteria into the pouch liquid. 
   The pouches usually have attached plastic filling tubes that have been heat-sealed. To take a sample, a sharp hollow steel needle attached to a syringe can be inserted into the filling tube and some of the liquid withdrawn before the needle pulled out of the tube. Desirably, the filling tube can be heat-sealed again between the pouch and the puncture point. Some pouches are provided with ‘needleless ports’, which have septums that can be penetrated by blunt cannulae attached to syringes. In either case, bacteria can be introduced into the pouch during the sampling process and/or by subsequent entry through the puncture site. The use of a blunt cannular with a needleless port not risks introducing bacterial into the pouch but it normally does not allow for subsequent heat-sealing to isolate the port. Of course, collecting samples by using a needle to puncture the thin wall of the pouch itself offers the worst alternative because of the likelihood that, after withdrawal of the needle, the thin wall of the pouch will not seal sufficiently to prevent the ingress of bacteria through the puncture site. 
   SUMMARY OF THE INVENTION 
   The present invention provides methods that allow multiple samples of a liquid in a primary container (here called a ‘pouch’) to be taken with minimal danger of contaminating the liquid in the container during the sampling process. The method involves connecting a closed sterile sight chamber with the pouch in a sterile manner to allow fluid to flow into the chamber while at the same time allowing air within the chamber to be displaced through a bacterial filter to atmosphere. The connection between the sight chamber and the pouch is then terminated (severed or closed), isolating the pouch from the sampling apparatus. Only then are samples of liquid withdrawn from the sight chamber, while allowing air to flow into the chamber through the bacterial filter. Though there may still be risk of contamination of liquid in the sight chamber as samples are withdrawn, such contamination cannot carry through to the liquid in the pouch. 
   Where the pouch is provided with a sealed flexible thermoplastic outlet tube, a similar inlet tube is connected to the chamber and a connection between the outlet tube and the inlet tube is preferably effected by ‘sterile-docking’ the outlet tube and the inlet tube to establish sterile connection therebetween. [Sterile-docking is a known technique and is disclosed, for example, in U.S. Pat. No. 4,369,779 to DuPont.] However, the method of the invention preferably includes the steps of closing (eg, by clamping) the inlet tube below the point where the sterile-docking is to take place, releasing the clamp after the sterile-docking has been effected to allow a quantity of liquid to flow from the pouch to the chamber, re-closing the inlet tube to stop liquid flow and then heat sealing both the pouch outlet tube and the chamber inlet tube (allowing the docked portion of these tubes to be discarded). Alternatively, where the pouch is only provided with a septum port, the chamber inlet tube can be fitted with a blunt-tipped cannular adapted to enter that port to establish the connection between the pouch and the chamber in a substantially sterile manner. While the clamping and unclamping procedure just indicated can also be followed with advantage, the connection between the pouch and the sight chamber should be terminated by withdrawing the cannular before samples are drawn-off from the sight chamber. 
   The method may also include entering evacuated sample phials into a cup-like sample port (which has a sheathed needle that is connected to the chamber) to effect the withdrawal of portions of the liquid in the chamber as separate samples. Since the needle is sheathed, the outlet of the sight chamber is sealed until the first sample is taken so there is minimal danger of contamination of the pouch liquid via the chamber. Since all samples are drawn-off while the chamber is disconnected from the pouch, there is no danger that the sample gathering procedure will contaminate the liquid in the pouch and there is only a very slight danger that the sampling procedure will contaminate liquid within the chamber or the samples. The sample port can be rigidly attached to the sample chamber so that the chamber can be held vertical and in view by gripping the sample port in one hand while inserting successive files into the port with the other hand. 
   The sight chamber can be conveniently formed from the transparent barrel of a medical syringe having volume graduations so that the amount of liquid withdrawn in each sample can be judged and controlled. Though the use of a flexible-walled bag-like chamber is also envisaged, it is not preferred. 
   As liquid may flow into the chamber too quickly when the pouch is connected, or be may be withdrawn too quickly from the chamber when a phial is inserted into the sample port, the method may include the step of at least partially closing the chamber vent to regulate the rate of egress or ingress of air from and to the chamber. A hinged cap may be provided for closure of the chamber vent and can be used for the function indicated. Of course, the rate of inflow of liquid from the pouch to the chamber can also be regulated by the use of a clamp valve fitted to the inlet tube. 
   From another aspect, the invention comprises apparatus for use in dispensing samples of liquid drawn from a pouch in a sterile manner, the apparatus including a sight chamber with inlet means, such as the aforementioned thermoplastic inlet tube, for conveying liquid from the pouch to the chamber under sterile conditions. The chamber also has outlet means adapted to permit flow of liquid from the chamber in one or more samples. A filtered vent is provided in the chamber to permit displaced air to flow from the chamber when liquid flows therein and to permit air to flow into the chamber when liquid flows therefrom, the filtered vent serving to block passage of airborne particles including bacteria into the chamber. Valve means (such as a tube clamp) can be provided in association with the inlet means to control flow of liquid into the chamber and also to isolate the chamber from the pouch. 
   The sample dispensing means is preferably the aforementioned sample port, which is preferably rigidly connected to the lower end of the sight chamber. The sheathed needle of the sample port preferably has a threaded hub by which it is screwed into the closed end of the sample port from the outside, the needle hub preferably being inhibited from unscrewing by ratchet means operable between the hub and the closed end of the port. The sample port may have a hinged cap for closing the open end against accidental intrusion of the finger of a user into contact with the needle point. 
   The cap preferably includes locking means whereby it can be held closed after use of the sample port and, if necessary, reopened for the insertion of another phial or bottle. The locking means can comprise a tab or catch on the cap that engages with a hole or abutment on the body of the port, or it may comprise flanges on the cap and body that engage with one another in the manner of the catch of a purse. 
   The apparatus may include a tubular spacer that slidlingly fits into the open end of the sample port for the purpose of guiding phials that are of much smaller diameter than the port. The spacer may include radially extending tabs by which it may be gripped between a thumb and finger of a user so that these digits cannot enter the sample port when the spacer is inserted. The spacer is adapted to clip to or snap onto or into the sample port, preferably in such a way that it can be removed from the port (if desired) by again holding the tabs between thumb and finger. 
   Apparatus of this type may be incorporated in products by manufacturers of blood collection packs, apheresis kits, urinary catheter kits, plural and abdominal cavity aspiration kits and the like. In such applications the inlet tubes would be attached by the manufacturer to the kits and it would not be necessary for the user to make the initial connection. However, it may be preferred to employ a frangible connector in the inlet tube to effect the initial connection between the source of the sample liquid and the sterile sampling apparatus of the present invention. In one particular application, the inlet tube, chamber and sample port may be attached to the platelet pouch of an aphaeresis kit by the kit manufacturer without the need for separate sterile packaging. The port would then be immediately ready for use in drawing samples from the pouch without the need for separate sterile docking procedure. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a conventional blood or platelet pouch. 
       FIG. 2  is a perspective view of the sampling apparatus of the preferred embodiment. 
       FIG. 2A  is an enlarged perspective sectional view of the sample port of the apparatus of  FIG. 2  taken on section plane II-II of  FIG. 2 . 
       FIG. 3  is a side elevation of the apparatus of  FIG. 2  with the principal components shown separated from one another, the sample port also being shown in section, the section plane being indicated at II-II in  FIG. 2 . 
       FIG. 4  is a perspective view of the apparatus of  FIGS. 1-3  modified in a first way that allows the use of a blunt cannular to access a septum-port in the pouch to be sampled. 
       FIG. 4A  is an enlarged view of the blunt cannular used in the modified apparatus of  FIG. 4 . 
       FIG. 5  is a perspective view of the apparatus of  FIGS. 1-3  modified to allow samples from multiple pouches to be obtained and mixed before being dispensed to sample phials. 
       FIG. 6  is a perspective view of the sample port of the apparatus illustrated in the previous Figures and a spacer element for use therewith. 
       FIG. 7  is a perspective view of the sample port of  FIG. 6  with the spacer element inserted into the sample port. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  shows a liquid container comprising a conventional sealed plastic pouch  10  containing a unit of platelets liquid, generally indicated at  12 . Pouch  10  may have blanked-off tube connections  14  that may have been used during collection of the platelets but it will generally have at least one attached outlet or pouch tube  16  that is heat-sealed at its free end  17 . Pouch  10  may also be provided with a split-septum needless port  18  through which a hollow blunt cannular can be inserted to extract samples of liquid  12 . Samples of liquid may also be drawn from tube  16  by the use of a syringe and sharp medical needle. As already noted, both these methods of withdrawing samples involve contamination risk, both to the extracted sample and to the liquid in the pouch. 
   Turing now to  FIGS. 2 ,  2 A and  3 , the apparatus  50  of the preferred embodiment will now be described. Apparatus  50  is preferably supplied as a sterile unit. It has a plastic inlet or sample tube  52  that is that is heat-sealed at its free upper (or distal) end  54  and is fitted with a pinch clamp  55 , which is shown in the open position in which tube  52  is not pinched or blocked. Apparatus  50  also includes a tubular transparent and semi-rigid sight chamber  56  that has an open upper or distal end  57  closed by a closure  58  that has a first tubular spigot  60  connected to the lower or proximal end  62  of sample tube  52  and a second tubular spigot  64  that forms or is connected by a short tube  65  to a filter  66  though which chamber  56  can be vented to atmosphere. Filter  66  is fitted with bacterial filter media (not shown) that allows air to pass but blocks the passage of bacteria, such filter media being known in the art and being commercially available. Preferably, a hinged cap  67  is attached to filter  66  so that the open end of filter  66  can be sealed, if desired. 
   Sight chamber  56  is conveniently formed from the transparent barrel of a conventional medical syringe that has appropriate volume graduations  68  and a tapered lower or proximal end  70  that terminates in an external spigot-like female Luer socket  72 . 
   A sample port assembly  80  is rigidly connected to Luer socket  72 , port assembly  80  comprising (i) a cup-like hollow cylindrical body  82  having a closed upper or distal end  84  and an open lower or proximal end  86  and (ii) a sampling needle assembly  88  ( FIG. 2A ) screwed into upper end  84  of body  82  so as to extend coaxially therein. Body  82  is preferably molded from plastic with an integrally hinged cap  90  attached to its lower or proximal end  86 . Hinged cap  90  is provided with a locking tab  92  that engages with a slot  94  in the side of body  82  so that the cap  90  is held in the closed position to prevent inadvertent contact between the fingers of a user and needle assembly  88  in body  82 . Lower end  86  of body  82  and the periphery of cap  90  are provided with outwardly extending flanges  96  and  98  respectively by which the cap can readily pried open again, if desired, between the user&#39;s finger and thumb. 
   Referring particularly to the enlarged drawing of  FIG. 2A , sampling needle assembly  88  comprises a pointed hollow steel needle  100  that is surrounded by a rubber-like sheath  102  and is supported by a molded externally threaded hub  104  having an upper or distal end  106  formed with a distal male Luer spigot  108  (see  FIG. 3 ). Male Luer spigot  108  engages with female Luer socket  72  to form a rigid connection between sample port assembly  80  and sight chamber  56 . Hub  104  is screwed into a hollow boss  110  formed in distal or upper end  84  of body  82 . 
   The assembled sampling apparatus  50  is normally shipped as a unit in a sterile pack with vent cap  67  and port cap  90  closed. This minimizes the danger that the edges of the caps will penetrate the packaging during handling. The supply of apparatus  10  with vent cap  67  closed allows sight chamber  56  to remain sealed to atmosphere until sample tube  52  has been docked with pouch tube  16 . Similarly, the supply of apparatus  50  with port cap  90  closed ensures that a finger of a user cannot enter port  56  while apparatus  50  is being handled or coupled to pouch  10 . Such contact would be likely to cause the point of needle  100  to puncture sheath  102  thus breaking the seal to the chamber via its outlet. Pinch clamp  55  is normally fitted in the open position so that the risk of permanently kinking inlet tube  52  is minimized. 
   To ready the assembly  50  for use after removal from its pack (not shown), caps  67  and  90  are opened and clamp  55  is closed. Inlet or sample tube  52  is then placed along side pouch tube  16  in a sterile docking jig, the preferred area for sterile docking being indicated by spaced markings  112  on sample tube  52 . The sterile docking procedure is then performed in the normal manner, simultaneously cutting off the sealed ends of tubes  16  and  52  and connecting the severed ends of these tubes together for fluid communication (as described above). Clamp  55  and vent cap  67  are then opened to allow the desired amount of liquid to flow from pouch  10  into sample chamber  56 , after which clamp  55  is closed to stop further flow. Flow of liquid  12  from pouch  10  will normally occur under gravity and/or with slight pressure on pouch  10 , the flow being assisted by the open vent  66  that allows the air within sight chamber  56  to be displaced. Hence, apparatus  50  will normally be arranged substantially vertically and below pouch  10 , with sample tube  52  uppermost and sample port  80  lowermost. This allows the amount of sample liquid in sight chamber  56  to be accurately determined by reference to graduations  68  before clamp  55  is operated to close sample tube  52 . Preferably, at this stage, pouch tube  16  is heat-sealed and severed above the docking point and sample tube  52  is heat sealed and severed below the docking point, the docked connection then being discarded. This keeps sampling apparatus  50  sealed and sterile during collection of the sample liquid in sight chamber  56 , except for the egress of displaced air though bacterial filter  66 . Sample port cap  90  is then prized open by using flanges  96  and  98  to ready apparatus  50  for dispensing of individual sample portions of the sample liquid held in sight chamber  56 . 
   With assembly  50  held generally vertically, preferably by gripping sample port  80  in one hand, vacuum bottles or phials (not shown) are entered upwards into body  82  from open lower end  86  and pushed onto sheathed needle assembly  88  so that needle  100  pierces the sheath  102  and passes through the soft bung of the bottle or phial to suck portion of the liquid in chamber  56 . As soon as the desired amount of liquid has been removed, the bottle or phial is pulled from needle assembly  88  and sample port  80 , leaving sheath  102  to re-cover needle  100 . Successive samples can be quickly and conveniently taken in this way using successive phials or bottles. If desired, port cap  90  can be moved to the closed position between each sample. 
   Where a liquid with lower viscosity than platelets, or where a large gauge sampling needle  100 , is employed, the flow of liquid from sight chamber  56  to the sample phial or bottle may be too fast to accurately judge the portion required for each phial. The flow rate can be reduced by at least partially closing the opening of vent  66  with a finger or thumb or with cap  67 . When sufficient samples have been extracted, or when chamber  56  has been emptied, assembly  50  can be discarded using an appropriate disposal container. Before doing so, however, port cap  90  should be snapped closed to mitigate possible contact between a finger of the user and needle  100  and vent cap  67  should be closed to prevent seepage of liquid from the vent. 
   Turning now to  FIGS. 4 and 4A  that illustrate a modified sampling apparatus  200  that is very similar to as apparatus  50  described above except for some particular modifications. Accordingly, those parts of apparatus  200  that are essentially the same as those of apparatus  50  have been assigned the same reference numerals. The first important modification is a blunt cannular  202  fitted to the upper or distal end of sample tube  52  instead of heat-sealed end  54 . The cannular tip  204  is of conventional design (and is shown greatly enlarged in  FIG. 4A ) having side inlet apertures  206  and a non-coring nose  207 . The second important modification is in the way that port cap  90  is locked closed. In this case locking tab  92  is omitted together with cooperating slot  94  and the lateral flanges  96   a  and  98   a  on open end  86  of port body  82  and on cap  90  (respectively) are modified so that they can snap together in the closed position like the closure commonly used in ladies purses. The omission of tab  92  simplifies the molding procedure and the omission of slot  94  reduces the possibility of liquid dripping from port body  82 . 
   A third modification comprises the use of a ratchet-like engagement between the radial face of Luer needle hub  92  and the radial face of a boss  110  on the closed upper end  84  of port  80  in such a way as to inhibit unscrewing of needle assembly  88 . In this case, ratchet teeth  210  are formed on the radial face of boss  110 . 
   Another optional modification to apparatus  50  and/or  200  described above is embodied in apparatus  220  of  FIG. 5 , which apparatus has many components common to the foregoing apparatus, such components again being assigned the same reference numerals. The first modification embodied in apparatus  220  is the replacement of former inlet or sample tube  52  by four sample tubes  52   a ,  52   b ,  52   c  and  52   d , each having a heat sealed distal end ( 54   a ,  54   b ,  54   c  and  54   d , respectively) and each having its own clamp ( 55   a ,  55   b ,  55   c  and  55   d , respectively). The lower or proximal ends of tubes  52   a ,  52   b ,  52   c  and  52   d  are coupled by a four-way connector  222  to inlet spigot  60 . Multiple inlet or sample tubes  52   a - 52   d  are provided so that liquid can be extracted from respective multiple pouches into common sight chamber  56  and mixed therein before being dispensed to one or more sample phials (not shown) without any possible danger of cross contamination between pouches. 
   Thus, the advised procedure for generating a mixed sample from multiple pouches is to close all clamps  55   a - 55   d , sterile dock a first pouch to, say sample tube  52   a , release clamp  55   a  to allow a first quantity of liquid to flow from the first pouch to sample chamber  56 , close clamp  55   a , heat-seal and sever the outlet tube of the first pouch, heat-seal and sever inlet tube  52   a  above clamp  55   a , and then repeat these steps for each pouch and each sample tube ( 52   b - 52   d ) in turn. Thus, at no tinge would more than one pouch be connected to the apparatus and no outlet tube of a pouch would be docked to a used inlet tube of the apparatus, so cross-contamination between the pouches would be excluded. A possible but less desirable procedure would be to connect more than one pouch to sight chamber  56  via respective inlet tubes  52   a - 52   d  and to operate respective clamps  55   a - 55   d , ensuring that only one clamp was open at one time. 
   The second modification embodied in apparatus  220  illustrated in  FIG. 5  is the use of a large diameter filter housing  66   a  connected to spigot  64  via an elbow connector  224 . The larger housing  66   a  allows the use of a filter element (not shown) of larger area to provide less restricted air flow and, consequently, to permit more rapid in-flow of liquid into chamber  56  and more rapid draw-off of samples using vacuum phials. The third modification embodied in apparatus  220  relates to sample port  80   a  and will be described with reference to  FIGS. 6 and 7 . 
     FIGS. 6 and 7  show modified sample port  80   a  adapted for use with a skeletal molded plastic spacer element  250  of generally tubular form that can be pushed upward (as indicated by arrow  252 ) into body  82  of a modified sample port  80   a  to allow narrow diameter phials to be reliably aligned with needle assembly  88 , larger diameter bottles or phials being aligned by the walls of the port body itself. Spacer element  250  is provided with two radial outwardly-extending tabs  254  on its lower or proximal end  256  and open end  86  of port body  82  is provided with a radial outwardly-extending flange  258  having a pair of opposed notches  260  therein, each notch  260  being proportioned to accommodate respective ones of tabs  254  in a snap fit. The use of outwardly extending tabs that engage the rim portion of open end  86  of port  80   a  allows spacer element  250  to be inserted by holding it between thumb and finger in such a way that contact between either digit and needle assembly  88  (or the interior of body  82 ) is strongly inhibited. It will be noted from  FIGS. 6 and 7  that sample port cap  90  employs the purse-type snap closure described with respect to  FIG. 4 , which has inter-engaging radial tabs  96   a  and  98   a  on open end  86  of port body  82  and on cap  90  (respectively). 
   Normally, the user of sampling apparatus having modified sample port  80   a  and associated spacer  250  will use either large or small diameter phials and, if small diameter phials have been selected, will insert spacer element  250  before the apparatus is connected to pouch tube  16 . However, there are occasions where the user is required to collect samples in both small and large diameter phials. This may be necessitated by the destined use of the sample phials or by the type of machines to which they will be coupled. In that event, the user will transfer sample(s) to the large phial or phials before fitting spacer element  250  and, after fitting spacer element  250 , then transfer sample(s) to the smaller phial or phials. In the event that a mistake is made and spacer element  250  is inserted before all large diameter phials have been filled, the user can remove spacer element  250  by gripping the edges of tabs  254  and squeezing them together to unlatch them from their respective notches  260 . Again, it will be noted that this action is effected without the need for the user to put a finger into spacer  250  or body  82  of port assembly  80 . 
   While a preferred embodiment of the invention has been described and illustrated together with some variants, it will be appreciated by those skilled in the art that many other changes can be made without departing from the scope of the present invention as defined by the following claims.