Fluid sample collection device

An evacuated blood sample collection tube is provided with a stopper carrying a one-way valve for preventing blood drawn into the tube from flowing back to the patient, and for preventing blood trapped in the valve after a sample has been taken, from flowing to the sample during centrifugal blood phase separation. The valve includes an elastomeric valve member and a ring member which moves in response to centrifugal forces to a position in which it applies pressure on the valve member to maintain the valve closed during centrifugation.

BACKGROUND OF THE INVENTION 
This invention relates to blood sampling devices and more particularly to 
blood collection devices having anti-backflow valve means. 
Evacuated containers or tubes having needle-pierceable stoppers are used 
extensively in drawing blood samples for clinical testing. A conventional 
method of obtaining a sample is to employ a blood collection tube, and a 
tube and needle holder having a double-ended needle cannula. After the 
distal end of the cannula is placed in the vein of a patient, the tube is 
moved in the holder until the proximal end of the needle passes through 
the stopper. The negative pressure in the tube facilitates the drawing of 
the blood from the vein of the patient. The filled collection tube is 
subsequently centrifuged to centrifugally separate the blood into its 
relatively light phase, serum or plasma, and its relatively heavy cellular 
phase. After phase separation, the light phase is removed for testing. 
Where serum is to be separated, a blood clot is allowed to form before 
centrifugation. 
When employing conventional collection tubes, faulty techniques in drawing 
blood can cause drawn blood to be returned to the patient. For example, if 
the content of the tube is allowed to contact the proximal end of the 
needle and a tourniquet is not removed soon after blood begins to flow or 
if the arm of a patient is raised, a drop in venous pressure may cause the 
backflow of blood from the tube to the patient. Also, if a force is 
applied to the tube in a manner to compress the stopper against the tube 
holder while the tube contains blood, a pumping effect may be produced 
causing withdrawn blood to flow back to the patient. It is, of course, 
important to prevent the flow of blood drawn back into the patient 
especially where non-sterile collection tubes are used or where reagents 
or chemicals are used in the tube for specific test purposes. 
Valves have been provided in the needle assembly associated with the tube 
holder for preventing the backflow of drawn blood to the patient. U.S. 
Pat. No. 3,874,367, for example, shows a valve disposed in a needle 
assembly. This construction, however, is relatively expensive since it 
requires two needles, two hubs, and the steps of securing each needle to 
its hub. 
It is also known to employ a valve in the tube and connected to the tube 
stopper for preventing the backflow of blood from the tube to the patient. 
For example, devices having such anti-backflow valves are shown in U.S. 
Pat. Nos. 4,112,924 and 4,134,512. Such valves generally have a valve 
chamber into which blood flows from the needle, and a pressure responsive 
valve member which opens the valve when the pressure in the valve chamber 
is greater than the pressure in the evacuated tube to thereby allow the 
blood sample to flow into the tube. Should the fluid pressure in the tube 
become greater than that in the vein under certain conditions, the valve 
will prevent backflow of blood from the tube to the patient. 
One disadvantage of using such anti-backflow valves of the type shown in 
the above patents is that some blood remains in the valve chamber after 
the tube is filled and it is possible or even likely that the valve will 
open and allow the flow of such blood into the sample sometime during 
phase separation due to centrifugal forces acting on such blood and the 
valve. Such blood (or blood clot) could then contaminate the light phase 
of the blood sample resulting in inaccurate or unreliable blood test 
results. 
In copending application Ser. No. 810,257, filed June 27, 1977, and 
assigned to the same assignee as this application, a blood collection 
device is disclosed having a valve constructed such that a blood clot 
trapped in the valve chamber after the device is filled with a blood 
sample will tend to be trapped in a narrow passage of the valve so as to 
reduce the chance of it contaminating serum. However, it is possible under 
certain conditions that some sample contamination may occur with that 
device. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide a blood 
collection device which substantially avoids the above-mentioned 
undesirable features. A more specific object of the present invention is 
to provide a blood collection device including a container having a valve 
therein which prevents blood flow from the container to the source of 
blood and prevents any trapped blood in the valve from flowing into the 
blood sample during centrifugation. 
In accordance with one form of the present invention, a blood collection 
device is provided that includes a container having a needle-pierceable 
stopper closing one end, a collection chamber, and a one-way valve 
disposed in the container which allows fluid to flow from a blood source 
and through the needle and valve to the container but prevents fluid flow 
from the container to the source of fluid, and means responsive to 
centrifugal forces for maintaining the valve closed during centrifugation 
of the container. 
These, as well as other objects and advantages of the present invention 
will become apparent from the following detailed description and 
accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings, and particularly to FIG. 1, a fluid 
collection device 10 is shown disposed in a conventional tube and needle 
holder 12. The holder 12 includes a cylindrical portion 14 having an open 
end 16 for receiving the collection device 10 and a closed end 18 carrying 
a needle assembly 20 having a double-ended needle cannula or hypodermic 
needle 22. Needle 22 is fixed to a threaded hub 24 that is threadedly 
connected to the holder 12. The needle 22, which is pointed at each end, 
extends longitudinally along the axis of the holder and has a distal end 
portion 26 exterior to the holder and a proximal portion 28 extending 
proximally within the cylindrical portion 14. 
Collection device 10 is shown including an evacuated blood collection 
container or tube 30 having an integrally closed bottom or proximal end 32 
and an upper or distal open end 34 in which is disposed a 
needle-pierceable closure stopper 36. Preferably, stopper 36 is formed of 
a suitable elastomeric or rubber material, such as a butyl compound, 
conventionally used in blood collection devices, and such that the stopper 
will maintain a negative pressure within the tube 30 and be self-sealing 
upon removal of a needle that has pierced the stopper. Tube 30 provides a 
blood collection chamber 38 within the tube below or proximally of stopper 
36. The stopper has a lower cylindrical portion 40 which extends into the 
tube 26 and which is provided with a bottom central cylindrical recess 42 
which is directly below or proximal the central portion of the stopper. 
Disposed within the collection tube 30 and extending proximally of the 
stopper 36 is a one-way, anti-backflow, fluid pressure responsive valve 
indicated generally at 44. The valve 44 includes a hollow body member 46 
which is received in the stopper recess 42, a resilient valve member 48 on 
the body member 46, and a valve locking member 50. 
The body member 46 has an annular ridge 52 at the distal end which extends 
radially outwardly and has an outer annular sharp edge which frictionally 
engages the inner cylindrical wall of the recess 42 of the stopper to fix 
the valve 44 in place in the bottom of the stopper. The distal end of the 
valve body 46 is shown engaging the bottom of the stopper recess 42. 
The hollow body member 46, as also seen in FIG. 2, has a distal cylindrical 
portion 54 integrally connected to a generally conical or radially 
outwardly flaring proximal portion 56 having its maximum diameter at the 
proximal end. The portions 54 and 56 form a valve chamber indicated at 58. 
Portion 56 is shown having a closed bottom or proximal end wall 59 and 
four openings 60, 61, 62 and 63 circumferentially spaced 90.degree. apart 
and extending through the sidewall of the body portion 56 and connected 
with valve chamber 58. 
The resilient valve member 48 is shown as an elastomeric or rubber-like 
sleeve normally covering and closing body sidewall openings 60-63. Valve 
member 48 is formed to have an unstressed shape substantially 
complementary to the outer sidewall surface of the valve body 46 as seen 
in FIG. 3. Sleeve 48 may be made of any suitable elastomeric material, for 
example, polyurethane. The valve sleeve 48 has a cylindrical portion 64 
and a conical portion 66 which closely surrounds the body member portions 
54 and 56, respectively, as seen in FIG. 1. When on the valve body 46, the 
sleeve 48 provides a close fit which closes the four sidewall openings 
60-63 in the valve body 46, but with only slight pressures applied to the 
body at the sidewall openings. That is, the sleeve is only slightly 
stretched over the conical body portion 56 so that while the sidewall 
openings are closed in the absence of any pressure differential across the 
sleeve at the openings, even a slight pressure on the interior side of the 
sleeve, that is, on the valve chamber 58 side of the sleeve 48, relative 
to that on the outer or exterior side of the sleeve, or that within the 
collection chamber 38, will cause the sleeve to move away from one or more 
of the sidewall openings 60-63 and open the valve 44. On the other hand, 
any pressure differentials which are of reverse nature, that is, where a 
greater pressure exists on the exterior side of the sleeve 48 than on the 
interior side of the sleeve, increase the pressure tending to close the 
valve openings 60-63. 
The valve locking member 50 is shown in the form of a ring having its 
minimum inner diameter slightly greater than the outer diameter of the 
cylindrical valve sleeve portion 64 when the sleeve 48 is initially 
disposed on the valve body 46 as seen in FIG. 1. With this relationship, 
the ring is loosely disposed in surrounding relation with the body member 
46 and sleeve 48. Ring 50 has a distal cylindrical inner wall 70 
connecting with a proximal generally conical wall portion 72 having its 
maximum inner diameter at the proximal end. The wall portion 72 is shown 
having an incline similar to that of the outer surface of the sleeve 
portion 66. 
In FIG. 1, the valve locking ring 50 is loosely disposed on the valve and 
does not interfere with the operation of the valve, that is, it does not 
prevent the valve from opening when a blood sample is taken or prevent the 
valve from functioning to prevent the backflow of blood from the tube 30 
to the patient should the pressure in collection chamber 38 exceed that in 
the vein of the patient. 
The valve locking ring 50 is movable from its loose or inactive condition 
or position on the valve sleeve 48 (FIG. 1), to a valve locking position 
shown in FIG. 4. In FIG. 4, the valve 44 is secured in its closed position 
by the ring such that no blood can flow in either direction through any of 
the sidewall openings 60-63 or between the valve and collection chambers 
38 and 58. The ring 50 is movable between its inactive and locking 
positions in response to centrifugal forces generated during 
centrifugation of the blood filled collection tube 30, as will be 
discussed hereafter. In the valve locking position, the inclined inner 
wall 72 of ring 50 clamps the proximal end portion of the valve sleeve 
portion 66 against the outer peripheral surface of the proximal end 
portion of the valve body or end wall 59 to seal the valve chamber 58 from 
the collection chamber 38. The sleeve portion 64 extends distally a 
distance sufficient to prevent blood from flowing between body portion 54 
and sleeve portion 64 under any operating conditions. 
The ring 50 may be made of a metal, such as brass, or other material such 
as a suitable plastic material. For example, the ring 50 may be molded of 
a suitable relatively hard plastic such as an acrylic containing a filler, 
such as silica, or other material which will cause the ring to have an 
adequate density. The density of the ring 50 should be great enough to 
cause the ring to move from its initial loose condition (FIG. 1) to its 
valve closing or locking position (FIG. 4) and provide a sufficient 
pressure on the sleeve 48 to maintain the valve closed during 
centrifugation of the filled tube. 
In use, the pointed end of the distal portion 26 of needle 22 is inserted 
into a source of fluid, such as in the vein of a patient, indicated in 
phantom at 68 in FIG. 1, and the blood collection tube 30 is moved 
distally along the cylinder 14 until the stopper engages the distal end 
wall 18 of the holder. During this movement, the inner portion 28 of 
needle 22 pierces stopper 36 and enters the valve chamber 58. Because of 
the difference in fluid pressures in the vein and collection chamber 38, 
blood flows from the vein 68 into valve chamber 58, through one or more 
openings 60-63 in valve body member 46, and into chamber 38. Because of 
the pressure differentials across the valve sleeve 48, the sleeve moves 
radially outwardly away from the body member at one or more of the 
openings allowing blood to flow between the proximal end portions of the 
sleeve 48 and the valve body 46. Since valve locking member 50 is in its 
inactive position spaced generally distally of the sidewall openings 60-63 
during the taking of a blood sample, it does not, in any way, interfere 
with the flow of blood from the vein and needle 22 into the valve chamber 
58, through the valve sidewall openings and into the collection chamber 
38. Any tendency for blood to flow during the sample taking step from the 
collection chamber 38 back into the valve chamber 58 and into the needle 
to the patient, is prevented by the closing of the elastic sleeve member 
48 against the body member 46 about the openings 60-63. 
When the tube 30 has been filled with the blood sample, the tube 30 is 
removed from holder 12 and generally allowed to stand, for example, for a 
half-hour to an hour, to permit a blood clot to form where serum is to be 
separated from the whole blood. After a blood clot has formed, the 
collection tube 30 is placed in a centrifuge and centrifuged for a time 
sufficient to separate the relatively light phase or serum from the 
heavier cellular phase. When desired, known automatic phase separating 
devices or gel-like sealant materials may be employed to automatically 
provide a barrier at the interface of the separated serum and cellular 
phases after separation. 
When the blood filled tube 30 is placed in the centrifuge and the 
centrifuge is turned on, the locking ring 50 is moved by centrifugal 
forces to its valve locking position (FIG. 4). Because of the 
complementary conical surfaces 56, 66 and 72 of the body member 46, sleeve 
48, and ring 50, respectively, the ring seats firmly over the sleeve 
maintaining the valve closed during the continued centrifugation of the 
tube. Thus, no blood that is trapped in the valve chamber 58 can escape to 
the sample in chamber 38 during centrifugation. After complete phase 
separation, the tube may be removed from the centrifuge and the light 
phase removed from the tube for clinical testing purposes. 
In the modified embodiment shown in FIGS. 5-8, an anti-backflow valve 80 is 
shown frictionally secured in a recess 82 of a stopper 84 of an evacuated 
collection tube 86 by a sharp annular ridge 87 on the valve. The valve 80 
includes a valve body 88 including a main generally cylindrical body 
member 90 and an end cap or base member 92 connected by a central screw 94 
to the proximal end of the body 90. Valve 80 also includes annular 
resilient valve member or seal 96, and a slidable, centrifugally actuated 
valve locking member or ring 98. 
The valve body 90 is hollow and provides a valve chamber 100, and has an 
end wall 102 at the proximal end which has a plurality of 
circumferentially spaced axial openings 103 and a central threaded hole 
104 for receiving screw 94, as best seen in FIG. 6. The valve body 90 is 
open at both ends and has a proximal end portion 105 with a reduced outer 
diameter. The cap 92, seen also in FIG. 7, is generally cup-shaped and is 
connected by means of screw 94 passing through a threaded central opening 
101 in the cap in telescoping relation with the valve body 90. The inner 
diameter of the cap 92 at its distal end is greater than the outer 
diameter of the proximal end portion 105 of the valve body 90 providing an 
annular blood flow passage 106 between the body and cap members 90 and 92. 
The resilient valve member 96 is shown in the form of an annular sealing 
ring sealingly engaging and surrounding the proximal end portion 105 of 
valve body 90 and engaging the distal end of cap 92 to normally close 
passage 106 against the flow of fluid between the valve chamber 100 and 
the blood collection tube chamber indicated at 108. The proximal end of 
the sealing ring 96 is notched to provide an annular end wall L-shaped in 
cross-section which receives the distal end wall of the cup-shaped cap 92. 
The inner diameter of the sealing ring at the distal end is substantially 
less than its inner diameter at its proximal end, the distal end providing 
a sealing lip 109. The sealing ring 96 also has an outer conical or 
tapered surface 110 that tapers from its distal end radially outwardly to 
its proximal end. 
The valve locking ring 98, seen also in FIG. 8, has an inner cylindrical 
wall surface 112 connected to a proximal conical or tapered wall surface 
114 which is complementary in shape to outer tapered wall surface 110 of 
the sealing ring 96. The ring 96 may be made, for example, of a suitable 
elastomeric material such as a suitable butyl rubber or other rubber-like 
material. The locking ring 98 may be made of the same material as that of 
the locking ring 50 of FIG. 1. 
When a blood sampling needle, indicated at 116 in FIG. 5, is inserted 
through stopper 84 and into valve chamber 100, the fluid pressure 
differential across the valve or between chambers 100 and 108 causes the 
L-shaped portion 107 of the sealing ring 96 to move away from the annular 
distal end of cap 92 and allow blood to flow in passage 106. Blood flow 
from the needle and valve chamber 100 to the blood collection chamber 108. 
The sealing ring portion 107 will close the valve or passage 106 in the 
event of a pressure reversal that would tend to allow blood to flow back 
to the patient. 
After the collection tube 86 is filled, it is subsequently placed in a 
centrifuge to centrifugally separate the blood phases. After the 
centrifuge is started, the centrifugal forces acting on the locking ring 
98 move it proximally into the position shown in FIG. 8 wherein the 
locking ring applies a clamping force on the inclined surface 110 of the 
sealing ring 96. The ring 98 then holds the sealing portion 107 against 
the valve body and cap to prevent any blood or blood clot remaining in the 
valve body chamber 100 or cap 92 from moving through the passage 106 past 
portion 107 to the collection chamber 108. Thus, during centrifugation, 
any blood that was trapped in the valve during the filling of the 
collection tube cannot enter the blood sample portion of the tube 
regardless of the centrifugal forces encountered during centrifugation. 
It will be apparent that in both embodiments described herein, that any 
blood or blood clot formed and trapped in the valve is positively 
prevented from moving into the blood collection portion of the tube during 
centrifugation by the described centrifugally actuated valve securing or 
locking means. Thus, such trapped blood cannot contaminate the sample. 
After phase separation, the separated light phase, serum or plasma, will 
be prevented by the elastomeric sealing sleeve or ring from contacting the 
blood trapped in the valve. Also, if the tube is opened to remove the 
serum after centrifugation, any blood trapped in the valve is maintained 
within the sealed valve chamber and is removed when the stopper is removed 
from the tube. 
The relatively movable valve members, that is, the valve body and 
elastomeric sealing ring, of each embodiment, are constructed, as 
described, so that each is a one-way valve allowing fluid flow only from 
the needle to the collection chamber so as to avoid blood reflux or 
blackflow from the device to the patient. Preferably, the valves are 
normally closed as shown. The resilience of the elastomeric sealing 
members 48 and 96 provide the slight biasing force maintaining the valves 
normally closed. Also, in both of the illustrated embodiments, the 
elastomeric sealing ring has a pressure applied by the valve securing or 
locking member, or is clamped thereby, in a valve closing direction 
against the valve body upon centrifugation of the blood containing tube. 
In this way, during continued centrifugation, no blood can flow from the 
valve to the collection chamber since the valve is ensured against opening 
by the securing member. The locking members or rings 50 and 98 have an 
inner diameter relative to the outer diameter of the valve body, or are 
sized, such that the ring can move from its normally loose inactive 
position (FIGS. 1, 5) about the valve body to its valve closing or locking 
position (FIGS. 4, 8). The complementary inclined surfaces of the 
elastomeric valve member and the securing ring provide good transfer of 
pressure to the sealing areas of the valve member during centrifugation of 
the device. 
As various changes could be made in the above construction without 
departing from the scope of the invention, it is intended that all matter 
contained in the above description or shown in the accompanying drawings 
shall be interpreted as illustrative and not in a limiting sense.