Abstract:
Methods and apparatus are disclosed whereby the initial flow of blood during blood collection is diverted to a sample pouch to trap the skin plug and to allow samples to be taken during subsequent blood collection to a normal blood bag. This is effected by connecting the needle line ( 106 ), the sample line ( 118 ) to the sample pouch ( 116 ) and the bag line ( 114 ) to the blood bag to a multi-port valve ( 110 ) that includes an actuator ( 120 ). During the procedure, the valve ( 110 ) may be attached to the arm ( 100 ) of the donor by means of a wrist-strap ( 112 ).

Description:
TECHNICAL FIELD 
     This invention relates to blood collection methods, and to apparatus for use therewith, in which venous blood is collected from blood donors and in which one or more blood samples are collected for analysis. 
     BACKGROUND OF THE INVENTION 
     It is imperative that the taking of samples during donation is done in such a way that contamination of the collected blood cannot occur through the process of sample collection. This rules out the use of tubular sampling ports and their associated vacuum phials, the use of pierceable or pre-slit septum ports, and the use of hypodermic needles to draw off samples from the blood line during donation, it being thereby possible for bacteria to be introduced into the blood flowing to the collection bag. Accordingly, it is standard practice to take samples after the desired amount of blood has been collected and after the line to the collection bags has been sealed. Samples can then be taken, using sampling ports, piercing the blood-line with a sampling needle or by dripping blood into open collection phials at any point between the IV needle (that is still in the donor&#39;s vein) and the point at which the line has been sealed. 
     Examples of known blood sampling methods in blood collection procedures are provided in the disclosure of U.S. Pat. No. 4,786,286 by Baxter International Inc. This publication, and that of WO 94/12093 also by Baxter, further disclose the use of in-line containers of various designs for blood sample collection after blood collection has been completed. In WO 90/12606, Baxter discloses the use of pre-slit septum ports for blood sampling during infusion techniques (but not during blood donation procedures). Other in-line sampling ports are disclosed by Spacelabs Inc in European patent publication No. 0 376 168. 
     Despite careful precautions to avoid contamination in blood collection procedures, a small percentage of blood packs become contaminated with bacteria. It is becoming recognised that, despite the use of topical disinfectants prior to puncture, contamination can occur by the inclusion of bacteria from the skin of the donor at the puncture site. The literature suggests that, in rare cases, a hollow vena-puncture needle can cut a ‘plug’ of skin from the donor&#39;s arm and that this plug may be carried into the collection bag along with the blood. It is postulated that the thickness of the plug is sufficient to protect bacteria within or just below the epidermis from the effects of the topical bactericide so that contamination of a blood pack can occur. 
     Besides not being wholly effective in preventing blood-pack contamination, the sampling procedures indicated above extend the duration of the collection procedure and the period during which the IV needle is in place in the patient&#39;s arm. This is because sample collection must be effected after the full unit of blood has been collected and the blood line has been sealed. 
     U.S. Pat. No. 3,654,924 to Wilson et al. teaches the use of a flow-through sample pouch formed around a portion of the blood line that includes a frangible connection so that, if a sample is required, the connection can be broken and blood allowed to flow into the sample pouch. U.S. Pat. No. 5,167,656 to Lynn also teaches the use of a flow-through sample-pouch but omits the use of the frangible connection in the blood line. Lynn&#39;s pouch fills with blood as blood flows to the bag-set and, after a unit of blood has been collected in the set, the line up-stream and down-stream from the pouch is sealed and the IV needle is withdrawn. Samples of blood may then be taken from the pouch. The use of such flow through pouches has the advantage that the procedure is shorter for the donor because samples can be taken from the pouch after the needle is removed from the donor&#39;s arm. However, the procedure is not significantly shortened from the standpoint of the phlebotomist who must still wait until collection is finished and the blood line has been sealed before taking samples. More importantly, it is highly likely that any skin plug in the initial flow of blood will be carried through the sample pouch and into the collection bag. 
     U.S. Pat. No. 4,056,101 to Geissler discloses the use of an in-line trap which is set to collect the first few millilitres (ml) of blood drawn from a donor. It is manually operable by pulling on the blood line to cause the remainder of blood flowing from the donor to pass to the bag-set. Its stated purpose is to capture tissue thromboplastin generated by the trauma of vein penetration. However, the device is not fool-proof. If the phlebotomist pulls on the blood line too early, the tissue thromboplastin will flow to the collection bag; if the blood line is not pulled sufficiently firmly to close the trap, the blood in the trap will mix with blood flowing to the collection bag. Moreover, since operation of this device depends upon a sliding joint between the blood-line in the body of the trap, it is not a closed system. It is possible that bacteria could find their way into the trap, and for blood to be transferred out of the trap, through the sliding joint. 
     Though Geissler makes no comment regarding the potential danger of contamination via a skin-plug, the trap of U.S. Pat. No. 4,506,101 will not offer a certain safeguard against this danger. First, as noted above, it is not fool-proof in that blood in the trap can mix with blood flowing to the bag-set if the trap is not operated correctly. Second, even if the trap is operated correctly, it is quite possible that a skin plug contained in the first few milliliters of blood will flow straight into the open end of the blood line which is directly opposite the inlet to the trap. Moreover, Geissler&#39;s trap is of no value in providing blood samples because there is no way of accessing the blood collected by the trap, nor was that intended as the volume of the trap is far too small to provide the samples normally required from each donor (30 to 40 ml). 
     In Japanese patent application No. 09028265 (Publication No. 10211274), Terumo Corp teaches the use of a first in-line frangible seal in the blood line between the IV needle and the blood bag and a second in a branch sample line connected to the blood line upstream of the first connector. Each seal blocks its respective line until it is broken by external manipulation of the line. After the IV needle is inserted in the donor, the second seal is broken to allow blood to flow into the sample line for removal via a sample port connected to the sample line. The first seal is then broken to permit flow of blood to the collection bags. While this procedure is intended to ensure that the initial blood flow is directed to the sample tube, portion of that flow (perhaps containing the skin plug) will fill the blood line upstream of its seal and then be conveyed to the blood pack after the first seal is broken. If samples are taken during blood collection, the system will be opened; if samples are taken after collection has been completed and the blood line sealed, the procedure will be prolonged (as with the conventional procedure). 
     Finally, it will be appreciated that, whilst the present invention is concerned with blood sampling in association with the collection of blood from donors, systems are known for collecting samples of arterial blood during medical procedures that employ indwelling catheters for infusing saline solutions or medication and that attempt to minimise blood spillage or waste during sample collection. For example, U.S. Pat. No. 5,772,608 to Dhas discloses a system for infusing medication into the artery of a patient that uses manually operable valves to employ the patient&#39;s arterial blood pressure to flush the medication from the line into a waste bag before blood samples are taken from the line via a normal sampling port. The issue of contamination of collected blood by skin plugs and is the like are clearly not relevant in such procedures. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention involves the use of a multi-port/multi-position valve in the blood line from the needle to the collection bag that can be operated to first connect the needle line to a branch line at the start of the blood collection procedure and then connect the needle line to the bag line for blood collection. The arrangement is preferably such as to ensure that any skin plug is diverted with the initial blood flow to the branch line. Preferably, the branch line itself comprises—or is connected to—a sealed container or pouch for holding sample blood. The branch line may therefore be referred to below as the ‘sample line’. 
     The multi-port valve preferably seals-off the bag-line while the sample blood is collected and seals off the sample line while main blood collection takes place. This ensures that any skin plug and thromboplastin is captured by the sample container and allows samples for analysis to be drawn from the sample container (using conventional techniques) while blood collection takes place. Thus, the likelihood of pack contamination is reduced and the time taken for the procedure is shortened. 
     As between 30 and 60 mIs of blood is normally required for a normal set of samples during blood collection from a single donor, it will be seen that there is plenty of initial blood flow to carry any skin plug into the sample container and that, furthermore, there is no possibility that the skin plug can find its way from the sample line into the blood line to the bag-set. 
     The valve may be fitted with safety means to ensure that (i) the initial blood flow cannot be inadvertently transferred to the bag line, (ii) the bag-line and the sample line can never be interconnected and/or (iii) neither the bag line nor the sample line can be reconnected to the needle line after blood flow to the bag set has been terminated by use of the valve. 
     More than one sample container may be employed and clamps or similar devices may be used to direct sample blood flow to each in turn until sufficient sample blood has been collected. This allows the initial blood flow (containing any skin plug) to wash any anticoagulant or saline fill in the needle and sample lines into the first sample container so that blood directed to subsequent sample containers will be free of such diluents. 
     If the sample container(s) is rigid or semi-rigid, some means of allowing air therein to escape as it fills will be required. Filtered vents with automatic shut-offs for this purpose are well known in the art. Preferably, however, the sample container is a small flexible lay-flat pouch substantially free of air, (not unlike the bags of the collection set) which can expand as blood flows into it. Such a sample pouch can be divided into a plurality of interconnected sub-pouches that are collectively or individually capable of being removed from the sample line for later access. Preferably, the volume of blood taken for samples in this way should be controllable by the phlebotomist in a simple manner; for example, by folding over and dipping the pouch or closing off one or more of the sub-pouches or containers. Most preferably, the volume of blood collected for samples may be controlled by the use of the valve operated manually by the phlebotomist, though the use of such a valve may be in addition to control of the volume of the sample collection container(s). 
     For convenience, the sample container will be referred to below as a ‘pouch’ though it will be appreciated from the above that such a container is not the only one envisaged. 
     The valve means may be a rotary or linear valve, or a combined rotary and linear valve. It is preferably such that it can only be operated in one direction so that (i) the sample pouch cannot be re-connected to the blood line after flow to the collection bag has been closed off, and (ii) the bag set cannot be reconnected to the blood line after the valve has been placed in the ‘off position’ at the end of blood collection. However, it is also desirable (but not essential) for the valve to be arranged to allow anticoagulant to be fed to the bag set during manufacture so that the valve can be fitted to the blood lines before filling and, of course, prior to sterilisation. 
     The valve means may incorporate a sample port for the connection of a conventional sampling syringe, vacuum phial or other sampling device, thereby saving the need for a Y-connector in the line to the sample pouch. For example, the port may comprise a pre-slit septum device of the type disclosed in WO 90/12606 by Baxter International Inc. The valve actuator means and the sample port may be fixed together so that the sample port may be used to manipulate the valve. 
     The valve may be anchored to the arm of the donor by a suitable strap or the like. Conveniently, this may be a wrist strap and the valve can be attached to the strap by Velcro or the like. The immobilisation of the blood line in this way is an added advantage for the comfort of the donor and may avoid the need for the use of a conventional adhesive strip for this purpose. The strap also ensures that the movement of the sample pouch necessary for operation of the sample port and vacuum phials cannot affect the needle line or the blood collection line. 
     As already indicated, the valve may provide a connector for the sample port or a tube could be led from the valve for connection to the sample port. Alternatively, a tube having a sample port (or a connector for such a port) on one end may be connected by its other end to the bottom of the sample pouch. In that case, it is preferable to attach the sample port itself to the top of the sample pouch so that it does not hang down and is located at a convenient angle for use. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     Having broadly portrayed the nature of the present invention, exemplary embodiments will now be described with reference to the accompanying drawings, in which: 
     FIG. 1 illustrates a blood collection set formed in accordance with the first example of the present invention wherein a rotary multi-port valve on a wrist-strap is employed. 
     FIG. 2 is a series of three diagrams, (a), (b) and (c) showing the valve of FIG. 1 in horizontal section in respective operational positions. 
     FIG. 3 is a plan view of the valve of FIG. 1 taken on section plane III—III of FIG.  4 . 
     FIG. 4 is a sectional elevation of the valve of FIG. 1 taken on section line IV—IV of FIG. 3 assuming that the actuator knob of the valve is in place. 
     FIGS. 5A to  5 D are sectional elevations of the multi-port valve of the second example, each Figure showing a different operational position of the valve. 
     FIG. 6 is a perspective view of the third example of a multi-port valve formed in accordance with the present invention. 
     FIG. 7 is a series of diagrams, identified as (i) to (v) showing the operation of the valve of FIG. 6 in respective operational positions. 
     FIG. 8 is a perspective view of the fourth example of a multi-port valve formed in accordance with the present invention. 
     FIG. 9 is a sectional plan view of the body of the valve of FIG.  8 . 
     FIG. 10 is a perspective view of the fifth example of a multi-port valve formed in accordance with the invention. 
     FIG. 11 is a plan view of the bottom half the valve of FIG. 10 taken on plane XI—XI of FIG.  10 . 
     FIG. 12 is an enlarged cross section of the valve of FIGS. 10 and 11 taken on plane XII—XII of those FIGS. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring particularly to FIG. 1, the first embodiment of the invention is shown in position on a donor&#39;s arm  100  with the needle  102  in place in a vein and blood being collected, needle  102  being partially located within a needle guard  104  into which it is withdrawn when it is pulled from the donor&#39;s vein by the needle tube or line  106 . Needle guard  104  is affixed to arm  100  by an adhesive tape  108 . 
     This embodiment employs a multi-port rotary valve  110  that is fixed to a wrists trap  112  and is arranged to switch blood flowing from needle tube or line  106  to either the bag tube or line  114  that is connected to the bag set (not shown) or to a sample pouch  116  via a sample tube or line  118 . Valve  110  is manually operated by turning the arrow-shaped actuator knob  120 , the body  122  of the valve being temporarily attached to the donor&#39;s arm  100  by wrist strap  112 . A tube  124  extends upwardly from the bottom of sample pouch  116  and is attached by a clip or hook  125  to sample line  118 , the upper end of tube  124  being connected to the sheathed needle (not shown) of a conventional sample port  126 . [In this and succeeding examples, the needle line, bag line and sample line are additionally indicated by the letters N, B and S respectively]. 
     At the start of blood collection (ie, when needle is being inserted into arm  100 ), valve  110  is set (as shown) so that blood from needle line  106  is directed into sample line  118  and no blood flows into bag line  114 . After sufficient sample blood has been collected in pouch  116 , valve actuator  120  is turned to direct blood flow from needle line  106  to blood line  114  for collection in the bag set (not Shown). In that position, there is no connection between needle line  106  and sample line  118 . Accordingly, while collection is taking place, samples can be taken from pouch  116  by the use of sample port  126  and vacuum phials (not shown) in the normal manner. 
     The operation of multi-port rotary valve  110  is illustrated in the three positions—(a), (b) and (c)—of the valve shown in FIG.  2 . The body  122  of valve  110  comprises a stator ring  130  that has an inlet  106   a  for connection to needle line  106 , a first outlet  118   a  for connection to sample line  118  and a second outlet  114   a  for connection to bag line  114 . The inlet and outlets open to or from a central chamber in ring  130  within which an cylindrical actuator  132  is located for rotary (or, more precisely, arcuate) movement therein. Actuator has a curved channel  134  and a straight channel  136  extending from one side thereof to the other, the channels separate and not connected. In position (a), blood from needle line inlet  106   a  is directed to sample line outlet  118   a  via curved channel  134  while bag line outlet  11   4 a is sealed off. In position (b), blood from needle line inlet  106   a  is directed to bag line outlet  114   a  via straight channel  136  and sample line outlet  118   a  is sealed off. In position (c), inlet  106   a  and both outlets  114   a  and  118   a  are sealed off or closed preparatory to disposal of the unit. It will also be seen that there is an intermediate position between positions (a) and (b) in which the inlet and both outlets are closed. 
     Valve  110  allows for an optional sampling port  138  in the top of rotor/actuator  132 . This may be a self-sealing port that will accept the tapered spigot of a standard syringe or sampling port. If the sampling port includes a raised spigot, it can be used to rotate the rotor  132  of valve  110 . It will be seen that port  138  is only connected to sample line outlet  118   a  (and, thus, to sample pouch  116 ) when actuator  132  is in position (b), but this allows the samples to be drawn off with complete safety while blood is flowing to the bag set. Normally, it will be more convenient to sample via sample pouch line  124  and sample port  126  as described with reference to FIG.  1 . In that case, since there is no need for port  138  in valve  110 , port  138  can be omitted and channel  134  can be straight like channel  136 , if desired. 
     During manufacture of the blood collection assembly, it may be convenient to attach valve  110  to the various connecting lines and the sample pouch before anticoagulant is introduced into the bag set and the assembly is sterilised. In that case, valve  110  is set so that its rotor is as shown in (b) so that anticoagulant can be introduced into the bag set via the needle line  114  and bag line  114 . Normally, anticoagulant is not required in the sample pouch  116 . For foolproof operation of valve  110 , it is desirable that (i) rotor  132  can only turn dockwise and (ii) it cannot be turned beyond position (c) of FIG.  2 . One way of achieving this will be described with reference to FIGS. 3 and 4. 
     As depicted in FIGS. 3 and 4, valve  110  is shown in position (b) of FIG. 2 where sample port  138  is in communication with sample-line outlet  118   a . In this example, sampling port  138  comprises a short hollow spigot  140  that stands up from the upper surface of rotor  132 , has a bore  142  that connects with outlet  118   a  and has its upper end sealed by a pre-split septum  146  of a type known in the art. Rotor/actuator  132  has a central integral upstanding shaft  148  of trapezoidal section that takes knob  120  (FIG.  4 ), shaft  148  having external detents  150  so that knob  120  is a snap-fit thereon. As previously noted, body comprises a ring-like moulding  130  that includes inlet  106   a  and outlets  114   a  and  118   a  and that encompasses rotor  132 , which is retained between a disc-like bottom plate  154  and a ring-like top catch-plate  156 . Rotor  132  is provided with a pair of peripheral ring seals  157  and  159  in a manner known in the art. 
     The inner periphery  158  of catch-plate  156  is formed with a pair of opposed inwardly projecting stops  160  and  162  that limit the rotary movement of rotor  132  by engaging spigot  140  of port  138 . When rotor/actuator  132  is in position (a) of FIG. 2, the base of spigot  140  (indicated by dotted-line circle a in FIG. 3) abuts stop  160 , and, when rotor/actuator  132  is in position (c) of FIG. 2, spigot  140  abuts stop  162  (as indicated by circle c). As already noted, rotor  132  is shown in FIGS. 3 and 4 in position (b) of FIG. 2, this being indicated by the letter b applied to spigot  140  in FIG.  3 . 
     The inner periphery of catch-plate  156  is also formed with a pair of inwardly projecting ratchet teeth  164  and  166 , tooth  164  being diametrically opposite spigot  140  when in position (b) of FIG.  2  and tooth  164  being diametrically opposite spigot  140  when in position (c) of FIG.  2 . The teeth are engaged by a resiliently mounted pawl  168  formed integrally with knob  120 . In FIG. 3, with rotor  132  in position (b), pawl  168  is shown engaging tooth  164 , preventing return of the rotor to position (a). When rotor  132  is in position (c), pawl  168  engages tooth  166 , preventing return of rotor  132  to position (b). In fact, rotor  132  will be locked in position (c) since it cannot be advanced clockwise any further because of abutment of spigot  140  with stop  162 . 
     This arrangement allows valve  110  to be assembled at manufacture with knob  120  fitted to shaft  148  but not pressed down to engage detents  150 . In this position of knob  120 , pawl  164  is located above the level of catch-plate  156  so that it cannot engage either of teeth  164  or  166 , allowing rotor  132  to be turned clockwise or anticlockwise between positions (a), (b) and (c). Thus, after tubes  106 ,  114 , and  118  have been fitted, valve  110  can be set in position (b) and anticoagulant fed to the bag set via needle line  106 , passage  136  and bag line  114  and the entire assembly can be sterilized. After sterilization, rotor  132  can be turned anticlockwise to position (a). Actuator knob  120  can then be pressed firmly downwards to engage indents  150  and bring pawl  168  into the same plane as catch plate  156 . Thereafter, the assembly can be used as described with reference to FIGS. 1 and 2. 
     The second example of a multi-port valve suitable for use in the system of the invention is illustrated in longitudinal section in FIGS. 5A to  5 D. This valve  200  has a T-shape body  202  having axially aligned spigots  204  and  206  onto which needle line  106  and bag line  114  are respectively attached. An actuator  208  is mounted for sliding and rotational movement within body  202  and is fitted with a knob  210  on its upper end, its lower end being formed as a spigot  212  to take sample line  118 . Actuator  208  has an upper cross-bore  214  and a lower axial bore  216  that communicates with a side opening  218 . Optionally, body  202  can have a rear port  220  (shown in broken lines) that is fitted with a septum or is otherwise adapted for connection to a syringe or sampling port. Actuator  208  has four inset-moulded ring seals (shown shaded but not assigned reference numerals for the sake of clarity), seals being located above and below cross-port  214  and seals being located above and below side port  218 . 
     In the position shown in FIG. 5A, valve actuator  208  is set to channel blood from needle line  106  direct to the sample tube  118  via outlet spigot  212  and to close-off outlet spigot  206  to bag line  114 . After sufficient blood for samples has been taken, valve member  208  is pressed down to bring cross-bore  214  to the same level as spigots  204  and  206 , closing off port  218  and stopping the flow of blood from needle line  106  while keeping bag line  114  closed. This position is shown in FIG.  5 B. Actuator  208  is then turned through 90 degrees using knob  210  to align cross bore  214  with inlet spigot  204  and outlet spigot  206  so that blood can flow from needle line  106  to bag line  114 , as shown in FIG.  5 C. In this position of actuator  208 , side port  218  is aligned with rear sample port  220  of body  202  so that samples can be drawn off via that port while blood collection is under way without ‘opening’ the blood line (ie, needle line  106  and bag line  114  of FIG. 1) to contamination via sample line  118  or rear sample port  220  in body  202 . Finally, after sufficient blood has been collected, valve member  208  is turned through a further 90 degrees to dose off the flow of blood to the bag set and so as to close off sample port  220 . This final position is shown in FIG.  5 D. 
     The top of valve body  202  is fitted with slots  222  that are engaged by L-shape members  224  depending from the underside of knob  210 . This prevents actuator  208  from being rotated until it has been pushed down. A ratchet mechanism (not shown) then constrains actuator  208  to only turn clockwise. Stop means (also not shown) prevent member  208  from being turned beyond the position of FIG.  5 D. 
     The third example of a multi-port/multi-position valve suited for use in the system of the invention is shown in FIGS. 6 and 7. This valve is a linear slide-valve  300  into which needle line  106  is led and from which bag line  114  and sample line  118  emerge, needle line  106  having a Y-junction  302  from which lines  114  and  118  emerge and are led over opposite edges of a central mandrel or anvil  304  (see FIG. 7) located in the casing  306  of valve  300 . In this valve, needle line  106  can be regarded as the inlet, the point of exit of sample line  118  can be regarded as the first outlet and the point of exit of the bag line  114  can be regarded as the second outlet. The valve is operated by an actuator knob  308  arranged for sliding movement guided by a longitudinal slot  310 . Knob  308  is connected to a sliding actuator  312  (FIG. 7) that is located within casing  306  and that comprises a bar  314  with a roller  316  mounted at each end. The arrangement is such that bar  314  is moved longitudinally by knob  308  so that rollers  316  ride on tubes  114  and  118  to compress them against mandrel  304 , according to the shape of the mandrel. 
     FIG. 7 diagrammatically indicates the function of valve  300  in five stages (i) to (iv). In stage (i), actuator  312  is to the far left and all lines are open so that they can be sterilised. Before the needle is inserted into the donor&#39;s vein, actuator  312  is moved to the position shown in stage (ii), where the bag line  114  is pinched closed by the lower roller against mandrel  304  but the sample line  118  remains open. The needle is then inserted and blood from needle line  106  flows through sample line  118  to sample pouch  116 . After sufficient sample blood has been collected, actuator  312  is moved to the position shown in stage (iii) in which both bag line  114  and sample line  118  are blocked. Moving actuator  312  further to the right to position (iv) results in the release of bag line  114  (because of the shape of mandrel  304 ) so that blood flows through bag line  114  to the collection bags. While collection is proceeding, samples can be drawn off pouch  116  using sample port  126  (FIG.  1 ). After sufficient blood has been collected, actuator  312  is moved to the extreme right as shown in stage (v) so that both bag line  114  and sample line  118  are again closed. The needle is withdrawn, the bag line crimped and severed and the needle, tube and valve assembly are disposed of in a suitable manner. 
     To prevent actuator  312  being moved in the reverse direction (ie, from right to left in FIGS. 6 and 7) the top of valve casing  306  is provided with three pairs of protrusions  320 ,  322  and  324  along its sides that are engaged by knob  308  in a ratchet-like manner. The protrusions are located on the casing so that: when knob  308  is moved right to engage protrusions  320 , actuator  312  is located in position (ii) [FIG.  7 ] and blood is directed to the sample line  118  and pouch  116  [FIG.  1 ]; when knob  308  is moved right to engage protrusions  322 , actuator  312  is located in position (iv) and blood flows to bag line  114 ; when knob  308  is moved to the extreme right and engages protrusions  324 , actuator  312  is in position (v) and both lines  114  and  118  are sealed. 
     The fourth example of a multi-port or multi-position valve suited to use in the system of the invention is shown in FIGS. 8 and 9. The valve  400  has an external casing  402  into which is led needle line  106  and from which bag line  114  and sample line  118  emerge. [Casing  402  is not shown in FIG.  9 .] A rotating actuator knob  404  operates valve  400 , turning about an axis that lies transverse to the blood lines. A bifurcated valve body  406  (FIG. 9) is located in casing  402  and has an inlet  408  into which needle line  106  is secured, a first outlet  410  into which sample line  118  is secured and a second port  412  into which bag line  114  is secured. A barrel-like actuator  414  fits within a cylindrical recess in body  406  between the inlet and outlets and is formed integrally with or attached to actuator knob  404  for rotation thereby. Actuator  414  has a first cross bore  416  that can be aligned with first outlet  410  upon rotation of the actuator casing  402  and a second cross bore  418  that can be similarly aligned with second outlet  412 , bores  416  and  418  being spaced apart and oriented at right angles to one another. A first pair of ring seals  420  and  422  are arranged one on each side of bore  416  and a second pair of ring seals  424  and  426  are arranged one on either side of bore  418  to ensure that blood cannot leak between the bores around actuator barrel  414 . 
     Depending upon the orientation of actuator  414 , bore  416  can be aligned with first outlet  410 , bore  418  can be aligned with second outlet  412 , and between those positions, both ends of both bores can be closed by body  406 . Thus, at the start of bleeding, actuator  414  is turned by knob  404  to bring bore  416  into line with outlet  410  to connect the needle line  106  with the sample line  118 . Then, by further turning actuator  414 , bore  416  is turned so that this connection is broken and flow to sample line  118  is stopped. Further rotation of actuator  414  then brings bore  418  into line with second outlet  412  to connect needle line  106  with bag line  114 , while still cutting off flow to sample line  118 . This allows blood collection to proceed while samples are taken from sample pouch  116  as previously described. Finally, further rotation of actuator  414  results in blood flow to bag line  114  being cut off while still stopping all flow to the sample line  118 . The needle may then be withdrawn, the bag lines severed and the valve assembly disposed of. 
     The fifth example of a multi-port or multi-position valve suited for use in the system of the invention is shown at  500  in FIGS. 10 and 11 and, as in the previous example. Includes a casing  502  into which needle line  106  enters and divides in to sample line  118  and bag line  114  that emerge from the casing. As with the third example, it is appropriate to regard the needle line near the junction of the sample and bag lines as the inlet to the valve, to regard the point at which the sample line emerges from the casing as the first outlet and to regard the point at which the bag line emerges from the casing as the second outlet of the valve. An actuator knob  504  emerges from the centre of the upper half  506  of casing  502 . It can be turned to effect the functions of the valve. The bottom half  508  of casing  502  is shown in FIG. 11 with the top half  506  removed. Tube  118  is fitted between a pair of arcuate channel walls  510  and  512  formed around one side on the upper surface of bottom half  508 , while tube  114  is fitted between similar channel walls  514  and  516  on the other side of bottom  508 . A circular ridge  510  forms the inner sides of the channels while part circular peripheral ridges  512  and  514  form the outsides of the respective channels. Portions of these walls (identified by the suffix a) rise higher than the rest from bottom half  508 . 
     In this example, the actuator comprises a radially extending axle  518  pivoted at its centre to a shaft  519  on which knob  504  is fixed and by which it can be turned about the axis of shaft  519 . Axle  518  carries an idling roller  520  on each end that can run on tube  118  and/or  114  and pinch them closed in their respective channels. While it is able to move up and down to a limited degree in shaft  519  because its pivot pin  522  is located in a slot  524 , axle  518  is biased toward base  508  by a leaf spring  526 . The force of spring  526  is taken by a flange  528  on the bottom of shaft  519  that engages a recess in the base of bottom half  508 . and carrying a roller  520  at each end When halves  506  and  508 of valve casing  502  are assembled, the axle and rollers are fully contained with the casing and are spring-loaded onto the bottom half  508  of the casing. 
     In an alternative arrangement, the rollers may be mounted directly to the upper half  506  of casing  500 , which can rotate relative to the lower half  508 , and the two halves of the casing may be spring-loaded together so as to bias the rollers onto the tubes  114  and  118 . In that case, the rollers and the upper part of the casing would form the actuator means, allowing knob  504  to be omitted. Both versions of the valve  500  operate in the manner explained below. 
     The operation of valve  500  is conveniently explained by reference to the pairs of letters A to D of FIG. 11 that indicate a sequence of positions of the axle and/or rollers (not shown). The valve is shipped with the actuator rollers in position A—A supported on the bottom casing half  508  and not on tubes  114  and  118 . In this position, anticoagulant can be fed to the bag-set and the whole assembly can be sterilised. When the valve is ready to use, the actuator rollers are moved to position B—B in which bag line  114  is pinched dosed by one roller but in which sample line  118  remains open because its roller is held up by the raised portions  510   a  and  512   a  of the channel walls between which tube  118  is confined. Note that this position of the valve is that shown in FIG.  12 . After sufficient blood has been collected in the sample pouch  116 , the rollers are moved through position C—C (in which both tubes are blocked) to position D—D in which the sample line  118  is blocked and bag line  114  remains open because its roller is held off the tube by ramps  514   a  and  516   a . [As in the previous examples, samples can be drawn from sample pouch  116  while blood flows to the collection bag via line  114 .] Finally at the end of the blood collection procedure, the rollers are moved to position E—E in which both tubes are again blocked. As in the other examples, it is preferable that some ratchet mechanism be employed to ensure that (i) the rollers cannot be moved in the anticlockwise direction (in FIG. 11) and (ii) they cannot be moved clockwise beyond position E—E. 
     While a number of examples have been described, it will be appreciated that many variations and alterations can be made thereto without departing from the scope of the invention as defined by the following claims. 
     It will also be appreciated that the first two examples are to be preferred over the others because they preclude the possibility that the skin plug might lodge in the bag line just after the Y-joint with the sample line, even though the bag-set tube is closed off further down stream. Nevertheless, all examples offer substantial advantages over the conventional collection procedures by reducing procedure time by allowing samples to be drawn during blood collection.