U.S. patent number 3,897,343 [Application Number 05/446,383] was granted by the patent office on 1975-07-29 for plasma separator-hydrostatic pressure type.
This patent grant is currently assigned to Becton, Dickinson and Company. Invention is credited to Waldemar A. Ayres.
United States Patent |
3,897,343 |
Ayres |
July 29, 1975 |
Plasma separator-hydrostatic pressure type
Abstract
A blood collection and separator assembly of the type suitable
for centrifuging to separate the plasma from the cellular phase of
blood is disclosed. The assembly includes a collection container
and a piston disposed therein for sealing off the plasma phase from
the cellular phase after centrifuging is terminated. The piston has
a specific gravity greater than the plasma but less than the
cellular phase. Automatic compressible means is associated with the
piston and is responsive to increased hydrostatic pressure caused
by centrifugation so that the hydrostatic pressure reduces the
diameter of the piston to provide a by-pass passage between the
walls of the container and the piston so that the cellular phase
can pass downwardly around the piston while the plasma phase passes
upwardly therearound while the piston comes to rest at the
plasma-cellular interface, and when the hydrostatic force is
terminated the compressible means expands to form a liquid tight
seal to prevent subsequent mixing of the separated phases.
Inventors: |
Ayres; Waldemar A. (Rutherford,
NJ) |
Assignee: |
Becton, Dickinson and Company
(East Rutherford, NJ)
|
Family
ID: |
23772384 |
Appl.
No.: |
05/446,383 |
Filed: |
February 27, 1974 |
Current U.S.
Class: |
210/516; 422/918;
210/789 |
Current CPC
Class: |
B01L
3/50215 (20130101) |
Current International
Class: |
B01L
3/14 (20060101); B01d 021/26 () |
Field of
Search: |
;23/23B,258.5,259,292
;128/2F,214R,218M,272 ;210/83,84,131,359,514-518,DIG.23,DIG.24
;233/1A,1R,26 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Hart; Charles N.
Assistant Examiner: Mukai; Robert G.
Attorney, Agent or Firm: Kane, Dalsimer, Kane, Sullivan and
Kurucz
Claims
What is claimed is:
1. A piston adapted for use for separating the light phase of blood
from the cellular or heavy phase of anti-coagulant treated blood
disposed in a separator assembly including a blood collection
container comprising:
a piston having an average specific gravity heavier than the light
phase of blood but lighter than the heavy phase so that when the
blood is separated into its component phases the piston will
migrate to the light phase-heavy phase interface; said piston
comprising;
a body portion which is generally cylindrical and has a diameter
less than the internal diameter of the blood collection container;
a substantially non-porous, flexible sleeve member mounted around
said body portion and sealed around the top and bottom ends
thereof, thereby forming an annular space therebetween, said space
having a gas therein, said gas having a pressure greater than
atmospheric pressure and selected so as to expand the flexible
barrier means to form a liquid-tight seal when mounted within the
container and said gas being compressible when subjected to
increased hydrostatic force so that the flexible barrier means will
move away from the inner walls of the container to break the seal
and permit the piston to move toward the cellular-plasma interface
when centrifuged.
2. The piston of claim 1 wherein the piston is formed of
polystyrene having a specific gravity of substantially 1.06.
3. A blood separator assembly capable of separating anti-coagulant
treated blood into its component parts of light phase and heavy
phase comprising:
a container having at least one open end which is adapted to
receive blood for subsequent separation into a light phase and a
heavy phase;
a closure sealing the open end of the container, the closure being
formed of a self-sealing, elastomeric material which is penetrable
by a cannula through which blood to be separated is conducted into
the container;
a piston having an average specific gravity lighter than the heavy
phase but heavier than the light phase;
said piston having a body portion which is generally cylindrical
and has a diameter less than the internal diameter of the blood
collection container;
a compressible sleeve mounted on the interior walls of the
container, so as to form a seal with said piston when said piston
is positioned within said sleeve and said sleeve is uncompressed,
the sleeve being made of closed cell elastomeric material having a
smooth surface and said sleeve is responsive to hydrostatic forces
whereby when said sleeve is compressed by subjugation to
hydrostatic forces, said piston no longer forms a seal with said
sleeve, thereby providing a passage for the light phase and heavy
phase of the blood to move past the piston.
4. The assembly of claim 3 wherein the piston is formed of
polystyrene having a specific gravity of substantially 1.06.
5. The assembly of claim 3 wherein said compressible sleeve is made
of closed-cell elastomeric sponge material having a smooth surface.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to plasma separator assemblies and
particularly to a plasma separator having a piston and a
compressible means associated therewith which automatically
compresses when subjected to increased hydrostatic pressure caused
by centrifugal force to provide a passageway between the piston and
the interior of the collection container so that the cellular phase
can pass downwardly around the piston in the container while the
liquid or plasma phase passes upwardly therearound.
DESCRIPTION OF THE PRIOR ART
It is known to separate blood into its component parts by
centrifugation, for example, the assembly disclosed in U.S. Pat.
No. 2,460,641. However, this particular assembly does not employ a
means for sealing the separated plasma or serum phase from the
cellular phase.
It is also known to provide assemblies for manually separating the
plasma or serum phase from the cellular phase, for example, as
disclosed in U.S. Pat. Nos. 3,586,064; 3,661,265; 3,355,098;
3,481,477; 3,512,940 and 3,693,804. In all of these devices serum
is collected in a blood collection container and means are provided
for separating the plasma phase from the cellular phase employing
filters, valves, transfer tubes or the like.
It is also known to provide assemblies for the sealed separation of
blood in which a piston is actuated by centrifugal force such as
disclosed in U.S. Pat. Nos. 3,508,653 and 3,779,383. These devices
use either a distortable piston made of a resilient material or
valve means associated with the piston to affect a sealed
separation after centrifugation.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a plasma
separator assembly having a piston and a compressible means which
automatically seals off the plasma phase from the cellular phase
after centrifuging is terminated. It is another object of the
invention to provide a piston having means associated therewith
which is compressible to provide a path around the piston to permit
the passage of the plasma phase to pass upwardly therearound while
permitting the cellular phase to pass downwardly therearound and
which will automatically seal the piston in the container when
centrifuging is terminated.
It is an object of the invention to provide a plasma separator
assembly which is economical to manufacture and can be used in
conjunction with standard blood collecting equipment.
My invention generally contemplates the provision of a blood
collection container for receiving blood and having at least one
open end which is adapted to receive a closure for sealing the end
of the container. A piston is disposed within the container and has
automatic compressible means associated therewith for sealing off
the light liquid plasma phase from the cellular phase of the blood.
The compressible means is responsive to increased hydrostatic
pressure produced by centrifugal force acting on the blood. The
piston has a specific gravity greater than the plasma phase but
less than the cellular phase so that the piston will move to the
plasma interface and establish a liquid tight seal in the container
after centrifuging is terminated.
DESCRIPTION OF THE DRAWINGS
For a better understanding of the invention, reference is had to
the drawings which illustrate the preferred embodiments of the
invention herein.
FIG. 1 is a sectional elevational view of the plasma separator
assembly illustrating a pointed cannula penetrating the stoppered
end of the container through which blood is introduced into the
container prior to separation.
FIG. 2 is a sectional elevational view after the cannula has been
removed and the blood sample has been collected and separated into
its phases during centrifugation and the centrifugal force has
increased the hydrostatic pressure of the blood and has compressed
the automatic compressible means associated with the piston thereby
opening a passageway connecting the chamber regions above and below
the piston.
FIG. 3 is a view similar to FIG. 2 after the assembly has been
centrifuged and the centrifugation has been stopped, the automatic
compressible means having been released so as to be in sealing
engagement with the container walls.
FIG. 4 is a sectional elevational view of another form of the
invention illustrating automatic compressible means mounted on the
container wall and in a compressed condition, which provides for
the passage of plasma upwardly in the container while the cellular
or heavy phase passes downwardly to form an interface between the
phases in the container during centrifuging of the assembly.
FIG. 5 is a view similar to FIG. 3 after centrifuging has ceased
which illustrates the automatic compressible means in sealing
engagement with the piston to form a liquid tight seal which
separates the plasma phase from the cellular phase in the
assembly.
FIG. 6 is a sectional elevational view of the piston after
centrifuging has ceased illustrating another form of the automatic
compressible means which can be used in conjunction with the
embodiment of FIG. 1.
FIG. 7 is an elevational sectional view of the piston of FIG. 6
when subjected to increased hydrostatic pressure generated by
centrifuging the blood filled separator assembly.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
For a better understanding of the invention here is a description
and the drawings of illustrative embodiments, particularly as shown
in FIGS. 1-3.
In FIG. 1 the separator assembly 10 comprises a tubular container
12 which is sealed at its open end by closure 14. Closure 14 is
preferably made of rubber which is capable of being penetrated by
cannula 15 so that blood can be transferred from a blood source
into container 12 under aseptic conditions. The closure is made of
elastomeric material and should be self-sealing so that when the
cannula is removed there will be no loss of blood passing through
the penetration portion of closure 14 as illustrated in FIG. 1.
Disposed in container 12 is piston 16 which is preferably made of
one or more materials having an average specific gravity of
approximately 1.06; for example, polystyrene may be used. Also,
piston 16 should be made of a material which is inert to blood and
to the resilient O-ring which is mounted in the annular groove 19
of piston 16. The parts forming the assembly may contain an
anti-coagulant material. Piston 16 has mounted thereon compressible
means such as O-ring 18 which automatically compresses when the
assembly is subjected to increased hydrostatic pressure generated
by centrifugal force. Compressible means is in the form of an
O-ring 18 made of closed cell sponge rubber with a smooth outside
surface (or equivalent) normally having an interference fit sealing
the piston 16 relative to the container 12. However, when increased
hydrostatic pressure is generated by centrifugation, O-ring 18 is
compressed unsealing the piston and thereby providing a passageway
through which plasma and red cells may flow to form an interface.
The piston has a specific gravity of approximately 1.06, which is
less than the specific gravity of the cellular phase of blood but
is heavier than the plasma phase of the blood. When blood is
collected in container 12, as illustrated in FIG. 1, and the
container is centrifuged, as illustrated in FIG. 2, the cellular
phase will pass downwardly into the bottom portion of container 12
while piston 16 moves upwardly to finally come to rest at the
plasma-cellular interface. When centrifuging is terminated the
hydrostatic pressure drops and the O-ring 18 expands to form a
liquid tight seal, as illustrated in FIG. 3.
FIG. 2 shows conditions during centrifuging. O-ring 18 is
illustrated in a compressed condition with piston 16 positioned at
the plasma-cellular interface. Compression of O-ring 18 has created
passageway 20 between the piston and the inside wall of the
container so that the plasma can move upwardly through passage 20
and around piston 16 and red cells can move downwardly through
passage 20. When centrifuging ceases, O-ring 18 will expand and
re-establish the seal as illustrated in FIG. 3.
Thus, the invention embodiment shown in FIGS. 1-3 includes sealing
means responsive to or activated by changes in hydrostatic
pressure.
FIGS. 4 and 5 illustrate another form of compressible sealing means
responsive to hydrostatic pressure which will automatically form a
liquid tight seal to separate the plasma phase from the cellular
phase when centrifuging of the assembly is terminated.
FIG. 4 is similar to the embodiment illustrated in FIG. 2 in that
assembly 10' is in the process of being centrifuged and
compressible means 17' is in a compressed condition to provide
passage 20' around piston 16' to permit piston 16' to move upwardly
within the container along with the plasma phase while the cellular
phase moves downwardly toward the bottom of the container.
Container 12' is fitted with a closure 14' of the type described in
the embodiment of FIG. 1. Piston 16' is made of material preferably
having an average specific gravity of about 1.06 (for example,
polystyrene) which is lighter than the cellular phase of blood but
heavier than the plasma phase. Compressible means 17' automatically
compresses in response to increased hydrostatic pressure generated
by centrifugal force, and automatically expands when the
centrifugal force is terminated. The compressible means is mounted
in the form of a sleeve 17' on the interior surface of the
container 12' at a point between the plasma-cellular interface so
that when piston 16' is permitted to move upwardly in the container
piston 16' will come to rest at the plasma cellular interface.
Then, when centrifuging is stopped, the piston 16' will be in
sealing liquid-tight engagement with the compressible means as
illustrated in FIG. 5. Compressible sleeve 17' is preferably made
of closed cell sponge rubber with a smooth outer skin (or
equivalent) and is mounted on the inside surface of container
12'.
FIGS. 6 and 7 illustrate another form of compressible sealing means
responsive to and actuated by changes in hydrostatic pressure.
Piston 16" is formed of a suitable material having an average
specific gravity greater than blood plasma but less than that of
the cellular phase of blood.
Compressible means 17" is in the form of a substantially non-porous
elastomeric sleeve 18" expanded by slightly compressed air (or
other suitable gas) and is secured on piston 16" around the upper
and lower edges 22, 24 of sleeve 18". Piston 16" is formed having a
body portion 25. A plurality of spaced annular grooves 26 are
formed in body portion 25. Upper and lower flanges 29 and 27 of
body portion 25 form shoulders 29 for mounting sleeve 18" thereon
illustrated in FIG. 6. In FIG. 7 compressible means 17" is
illustrated in a compressed condition with much of the air
compressed into annular grooves 26 due to the increased hydrostatic
generated by the centrifugal force so that resilient, compressible
element 18" is in a compressed position to form passage 20" to
permit the piston to move toward the plasma-cellular interface in a
manner comparable to that illustrated in FIG. 2.
In the embodiment of FIGS. 4 and 5 the compressible element 17' is
preferably made of a closed cell sponge rubber with a smooth outer
skin and is cemented or otherwise fixed to the inside wall of
container 12' as illustrated in FIGS. 4 and 5. It should be
understood that the piston in the embodiments illustrated herein
can be inserted into the assembly prior to use as described or it
can be inserted after the blood has been collected by simply
removing closure 14 and manually inserting the appropriate piston
in the corresponding type container and then centrifuging the
assembly to permit the piston to move downwardly in the container
to the plasma cellular phase interface rather than upwardly as
described. Also, if the pistons are not put into the containers
until after the blood has been centrifuged into the light phase and
the heavy phase, then these devices can be used for serum, as
distinguished from plasma. Then the containers would be centrifuged
a second time to move the pistons to the serum red cell
interface.
It is also apparent that tube 12 can be formed having openings at
each end with the piston positioned at one end so that with blood
being collected through the closure member at the opposite end the
piston will move downwardly in the container rather than
upwardly.
When operating the separator assembly as set forth in the preferred
embodiments the blood collection tube 12 which is fitted with
closure 14 is preferably evacuated so that when cannula 15
penetrates the closure 14 blood will fill container 12
automatically. It is also contemplated that the separator assembly
of the invention herein may be constructed so as to be suitable for
use with blood collecting assemblies described in U.S. Pat. Nos.
3,460,641; 3,469,572 and 3,494,352. It should be understood that
when the blood is being collected where the piston 16, 16' or 16"
is in the bottom of the container then the blood being collected
will be anti-coagulated so that a clot will not form which might
cause a malfunction of the piston.
After the blood has been collected in container 12, assembly 10 is
ready for centrifuging. The compressible means, such as the O-ring
18 or the compressible sleeve 17' or the inflated annular ring 18"
will be compressed when subjected to increased hydrostatic pressure
resulting from centrifugal force. Centrifugation will also cause
the serum to pass upwardly in the container around the piston 16
through passage 20 and at the same time for the cellular phase to
move toward the bottom of the container while the piston moves
towards the cellular-plasma interface. When the blood has been
separated the piston will lie at the plasma-cellular interface and
when centrifuging ceases the compressible means 18 will re-expand
to form a liquid tight seal as shown in FIG. 3. Thus, an assembly
is provided in which blood can be controlled, centrifuged,
separated into its plasma and cellular phases and shipped through
the mails for further analytical determinations without the plasma
mixing with the cellular phase even though the assembly is inverted
and handled roughly.
While variations of the invention herein may be had, the objectives
of the invention have been illustrated and described, it is
contemplated that changes in design can be made without departing
from the spirit of the invention described herein.
* * * * *