US3887465A

US3887465A - Serum/plasma separator {13 {0 cannula fluid by-pass type

Info

Publication number: US3887465A
Application number: US446384A
Authority: US
Inventors: Waldemar A Ayres
Original assignee: Becton Dickinson and Co
Current assignee: Becton Dickinson and Co
Priority date: 1974-02-27
Filing date: 1974-02-27
Publication date: 1975-06-03
Anticipated expiration: 1992-06-03

Abstract

A self-contained fluid separator assembly capable of separating blood into its component parts of plasma or serum, the light phase, and cellular portion, the heavy phase, is disclosed. The assembly comprises a container having a first open end for receiving blood for subsequent separation and a second open end for removing separated light phase; and closures sealing the open ends of the container, the closures being formed of a selfsealing elastomeric material which is penetrable by a cannula. A piston responsive to centrifugal force is slidably disposed within the container, having its lateral surfaces in sealing contact with the inner surfaces of the container. The piston divides the chamber defined by the container into upper and lower compartments. In its initial position within the container, the piston is in cooperation with a conduit means sealed by a seal means responsive to centrifugal force. The assembly is operated by first filling the lower chamber with blood to be separated. Separation is carried out at relatively low centrifugal speeds. Following separation, the centrifugal speed is increased, removing the conduit seal to establish communication between upper and lower compartments. Pressure of the descending piston forces the light phase blood component through the conduit and into the upper chamber where it is isolated. When the piston reaches a predetermined position, continued cooperation between piston and conduit terminates, closing the communication between upper and lower chambers. With communication terminated, the incompressibility of the contents of the lower chamber prevent further descent of the piston. Centrifugal force may then be terminated, leaving the blood specimen separated into light and heavy phases which are permanently isolated from each other by the now impermeable piston.

Description

June 3, 1975 SERUM/PLASMA SEPARATOR CANNULA FLUID BY-PASS TYPE [75] Inventor: Waldemar A. Ayres, Rutherford,

NJ. [73] Assignee: Becton, Dickinson and Company,

East Rutherford, NJ.

[22] Filed: Feb. 27, 1974 [21] Appl. No.: 446,384

[52] US. Cl. 210/130; 210/516; 2l0/DIG. 23; 2l0/DIG. 24 [51] Int. Cl B0ld 21/26 [58] Field of Search 23/230 B, 258.5, 259, 292; 128/2 F, 214 R, 218 M, 272; 210/83, 84, 131, 359, 514-518, DIG. 23, DIG. 24, 130; 233/1 A, l R, 26

[56] References Cited UNITED STATES PATENTS 2,305,278 12/1942 Smith 128/218 M 2,313,483 3/1943 Smith 128/218 M 2,869,543 l/1959 Ratcliff et al. 128/218 M 3,706,305 12/1972 Berger et al. 210/DlG. 24

Primary ExaminerCharles N. Hart Assistant Examiner--Robert G. Mukai Attorney, Agent, or Firml(ane, Dalsimer, Kane, Sullivan and Kurucz [5 7 ABSTRACT A self-contained fluid separator assembly capable of separating blood into its component parts of plasma or serum, the light phase, and cellular portion, the heavy phase, is disclosed. The assembly comprises a container having a first open end for receiving blood for subsequent separation and a second open end for removing separated light phase; and closures sealing the open ends of the container, the closures being formed of a self-sealing elastomeric material which is penetrable by a cannula. A piston responsive to centrifugal force is slidably disposed within the container, having its lateral surfaces in sealing contact with the inner surfaces of the container. The piston divides the chamber defined by the container into upper and lower compartments. In its initial position within the container, the piston is in cooperation with a conduit means sealed by a seal means responsive to centrifugal force.

The assembly is operated by first filling the lower chamber with blood to be'separated. Separation is carried out at relatively low centrifugal speeds. Following separation, the centrifugal speed is increased, removing the conduit seal to establish communication between upper and lower compartments. Pressure of the descending piston forces the light phase blood component through the conduit and into the upper chamber where it is isolated. When the piston reaches a predetermined position, continued cooperation between piston and conduit terminates, closing the communication between upper and lower chambers. With communication terminated, the incompressibility of the contents of the lower chamber prevent further descent of the piston. Centrifugal force may then be terminated, leaving the blood specimen separated into light and heavy phases which are permanently isolated from each other by the now impermeable piston.

3 Claims, 2-Drawing Figures SERUM/PLASMA SEPARATOR CANNULA FLUID BY-PASS TYPE BACKGROUND OF THE INVENTION 1. Field of the Invention i The invention concerns an assembly for the separation and isolation of blood plasma and blood serum from blood.

2. Brief Description of-the Prior Art It is known to separate blood into its component parts by centrifugation, particularly employing a sealed container suchas I is disclosed in US. Pat. No. 2,460,641. This patent discloses a container having a closure at its open end which is capable of being penetrated by a cannula through which blood passes into the container. Clinical laboratories have heretofore used this device to collect a blood sample for subsequenttioned initially adjacent the stopper for closing the container. After the blood to be separated is in the container the assembly is centrifuged. After the blood is separated, increased centrifugal force is applied to the container, the seal between the inner surface of the container and piston is broken and the piston is deformed, moving down through the light phase with the light phase passing solely around thelateral surfaces of the piston and the inner surfaces of the container. When the piston reaches the interface between the light phase and the heavy phase, the piston movement is stopped, the force is terminated, and the seal is reestablished between the inner surface of the container and the resilient piston to present a barrier between the two phases.

Disclosed in my US. Pat. No. 3,779,383 is a serum/- plasma separator as'compared with which the present apparatus of my invention utilizes certain different principles and construction elements. 7

Other devices known to the artare generally the filtration devices which separate blood into its compo nent phases such as those disclosed-in US. Pat. Nos. 3,481,477 and 3,512,940.

SUMMARYOF THE INVENTION The invention comprises: a self-contained fluid separator assembly capable of separating blood into its component parts of plasma or serum and cellular part comprising (a) a container having a first open end which is adapted to receive blood for subsequent separation into a light phase and a heavy phase and a second open end'for removing the separated light phase; (b) closures sealing the open ends of the container, the closures being formed of a self-sealing elastomeric ma terial which is penetrable by a cannula; (c) a piston slidably mounted in said container, having a specific gravity greater than the cellular portion-of the blood to be separated and having means on' an outer surface in sealing engagement with an inner surface of the container; said piston being disposed in said container so as to separate said chamber into upper and lower compartments; said piston being initially mounted in said container at a position adjacent to said second end and being movable by centrifugal force to a second position within saidcontainer, whereby said upper chamber is expanded in volume and said lower chamber is reduced in volume; a tube having one end fixed to the closure for said second end and one end free, terminating within the chamber defined by said container, said tube having an opening into said chamber at the terminal free end and an opening into said chamber at the fixed end; seal means closing said opening at the terminal, free end of said tube, said means being removable by centrifugal force; said piston in its initial position cooperating with said tube, whereby said tube forms a conduit through said piston, communicating with said upper and lower compartments, said piston in its second position being removed from cooperation with said tube, whereby said conduit is terminated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional side elevation of a separator assembly of the invention illustrating a cannula penetrating one of the closures through which blood is introduced into the container prior to separation.

FIG. 2 is a'view similiar to FIG. 1 illustrating the separation of the blood into the light phase and heavy phase with the piston separating the two phases.

DETAILED DESCRIPTION OF THE INVENTION For a better understanding of the invention, a description of the drawings of the illustrative embodiments is had, particularly with respect to the embodiments shown in FIGS. 1 and 2.

Referring to FIG. 1, it is seen that the separator assembly 10 comprises a tubular member or container 12 having mounted in each open end 11, 15

closures

14 and 16.

Closures

14 and 16 are made of a self-sealing elastomeric material such as rubber which are capable of receiving cannula 18 penetrated therethrough as illustrated in FIG. 1, for conducting blood 5 into the container. When the cannular is removed the closure is resealed with no loss of blood 5 passing through the penetration portion 31 as illustrated in FIG. 2.

Closure 14 is formed having a depending cylindrical bodyportion 20 and a flanged head portion 22 integrally formed therewith. Body portion 20 has a diameter slightly greater than the internal diameter of the container 12 so that closure 14 when mounted into end 11 provides a pressure fit to seal the end. Head portion 22 is preferably shaped in the form of a hexagon and is slightly greater in diameter than body portion 20 which permits the assembly to be positioned on its side without danger of rolling. An upper axial recess 24 is provided for easy access through stopper 16 which reduces the force required to penetrate with cannula 18. A lower annular recess 21 is provided in the bottom surface 19 of closure 14 for receiving an initial flow of separated blood plasma or serum as hereinafter described in greater detail. The recess 21 is in open communication with upper compartment 45 which is defined 'by the container walls 13, closure 14 and the upper surface 41 of piston 40.

Stopper 16 is formed preferably of the same material as'stopper'14. Stopper 16 has a cylindrical body portion 28 and an integrally formed head portion 30 having an outer axial recess 24. Body portion 28 has an inner annular recess 29 to provide a self-sealing penetrable zone 31 to facilitate insertion of cannula 18 with minimum force while maintaining a sealed closure. As noted above, stopper or closure 14 as well as 16 is inserted into ends 11 and 15 respectively in compression to maintain ends 11 and 15 of container 12 in sealed engagement.

Container 12 is formed preferably of glass but a suitable plastic material may be employed. Intermediate ends 11 and 15 of container 12 is piston 40 which moves from the initial starting position illustrated in FIG. 1 under centrifugal force to the terminal position after the separation of the light phase from the heavy phase, as shown in FIG. 2. The piston comes to rest slightly above the interface 4 between the separated lighter phase 5a and heavier phase 5b of the separated blood 5 as will be hereinafter described. It is necessary to have a piston 40 possessing a specific gravity exceeding the specific gravity of blood. Further, the piston 40 component of the invention herein does not deform; that is, the seal of the piston 40 with respect to the inner surface 13 of the container 12 is constantly maintained throughout its travel from its initial position of FIG. 1 to its terminal position of FIG. 2.

Piston 40 includes a tubular metal insert 52 which is mounted in annular recess 54 of piston 40. Metal insert 52 is preferably made of stainless steel or other rigid, chemically inert material having a specific gravity greater than blood. Piston 40 is formed of elastomeric material and is provided with annular recess 54 which is dimensioned to receive tubular member 52 in an interference fit so that no air space remains in annular recess 54.

The elastomeric portion of piston 40 comprises an outer wall 48 and spaced therefrom is inner wall 46 which defines annular recess 54. Formed integrally with wall 48 are a plurality of axially spaced sealing rings 50 which contact the inner wall surface 13 of container 12 in sealing engagement. Piston 40 when mounted in container 12 will maintain sealing contact with inner wall 13 of container 12 throughout its path of travel within container 12. During the centrifuging operation hereinafter described, piston 40 is subjected to centrifugal forces which start the descent of the piston and this action establishes a pressure differential on the top and bottom surfaces of diaphragm 44. Diaphragm 44 has a relatively small thickness and lies adjacent stopper 14 in its initial position as seen in FIG. 1, with a small space 45 separating piston 40 from closure Piercing diaphragm 44 of piston 40 and thereby traversing the body of piston 40 from lower end 86 to upper end 41 is tube 80 having

openings

82, 84. Tube 80 is rigidly fixed in position to closure 14 at a point adjacent to opening 84. Upper opening 84 comunicates with recess 21 and opening 82 at the lower end of tube 80 would communicate with chamber 3 of container 12 if it were not sealed with centrifugal seal 90 as shown in FIG. 1.

To operate the separator asesmbly of the invention, it is preferred that the assembly be first evacuated of air so that when cannula 18 penetrates closure 16 blood will fill the lower chamber 3 of container 12 without requiring the use of an air vent.

After cannula 18 is withdrawn and chamber 3 of container 12 is filled with blood 5 the assembly 10 is placed in a centrifuge and the blood is separated employing relatively low centrifugal forces which do not cause the seal or 40 to move from their initial positions. At this low speed centrifugation, the light phase is separated from the heavier phase of the blood 5. Thereafter the rotational speed of the centrifuge is increased. Then, centrifugal seal 90, having an interference fit with the end of tube 80 is spun off by the centrifugal force, and falls to the bottom of container 12, as shown in FIG. 2, leaving opening 82 of cannula 80 open. The opening of cannula 80 provides an outlet for the light phase 5a to travel upward and exit from opening 84 of tube 80 into recess 21. This removal of liquid permits piston 40 to descend further in light phase 50 forcing additional light phase 5a to travel through tube 80 and into recess 21 which communicates with the expanding chamber 45. When piston 40 approaches the end of tube 80 and slides off the lower end of tube 80, the selfsealing nature of the highly resilient elastomeric diaphragm 44 closes the opening formed when tube 80 pierced diaphragm 44. Withpiston 40 now disassociated from tube 80 as illustrated in FIG. 2, the conduit between upper chamber 45 and lower chamber 3 is closed. The blood phases being incompressible, piston 40 cannot descend farther and thereby stops slightly above the interface between the separated blood phases as shown in FIG. 2. In this location piston 40 forms an impervious barrier between the now separate and isolated blood phases. During its descent, piston 40 maintained sealing engagement with inner wall 13 of container 12. Thus, there is a complete seal and isolation of the component phases of the blood, which will not remix.

One skilled in the art will readily observe that by predetermining the length of tube 80 one can predetermine the location where piston 40 will come to rest.

In an optional embodiment of the invention as shown in FIGS. 1 and 2 a filter element may fill the recess 21 within closure 14, as shown in FIG. 2. Thus, by insertion of a filter element in the flow path of light phase 5a it is possible to simultaneously filter the light phase while it is being isolated from the heavy phase of the blood.

What is claimed is:

1. A self-contained fluid separator assembly capable of separating blood into its component parts of light phase plasma or serum, and heavy phase cellular material, comprising:

a container having a first open end which is adapted to receive blood for subsequent separation into a light phase and a heavy phase and a second open end for removing the separated light phase;

closures sealing the open ends of the container, the closures being formed of a self-sealing elastomeric material which is penetrable by a cannula;

a piston slidably mounted in said container having a specific gravity greater than the specific gravity of the blood and having means on an outer surface in sealing engagement with an inner surface of the container, said piston having a diaphragm portion forming partial upper and lower surfaces of said piston, said diaphragm portion being of a selfsealing elastomeric material penetrable by a cannula; said piston being disposed in said container so as to separate the chamber defined by said container with said closures, into upper and lower compartments;

said piston being initially mounted in said container at a position adjacent to said second end and being constructed and arranged ,to move at a predetermined centrifugal force to a second position within said container, whereby said upper compartment is expanded in volume and said lower compartment is reduced in volume;

a tube of pre-determined length having one end fixed to the closure for said second end and one end free, terminating within said chamber, said tube having an opening into said chamber at the terminal free end and an opening into said upper compartment at the fixed end;

seal means closing said opening at the terminal, free end of said tube, said seal means being constructed and arranged to disengage from said tube at said predetermined centrifugal force;

said piston in its initial position cooperating with said tube, so that said tube pierces the diaphragm portion of said piston, whereby said tube together with said seal means forms a closed conduit through said piston, and whereby upon disengaging of said seal means by centrifugal force, communication between said upper and lower compartments is established, said piston in its second position being removed from cooperation with said tube, whereby said conduit is terminated and the diaphragm portion of said piston previously pierced by said tube is self-sealed.

2. The self-contained fluid separator of claim I wherein the piston includes a rigid tubular sleeve mounted in a generally tubular outer body portion formed of rubber and having at least one sealing ring on its outer portion for sealing engagement with the inner wall of the container.

3. The piston of claim 1 wherein a tubular metal sleeve is mounted in sealing engagement in a complementary annular recess formed in a rubber body portion having an interference fit so that substantially no air space is provided between the walls defining the annular recess and the inner and outer walls of the rigid tubular member.

Claims

1. A self-contained fluid separator assembly capable of separating blood into its component parts of light phase plasma or serum, and heavy phase cellular material, comprising: a container having a first open end which is adapted to receive blood for subsequent separation into a light phase and a heavy phase and a second open end for removing the separated light phase; closures sealing the open ends of the container, the closures being formed of a self-sealing elastomeric material which is penetrable by a cannula; a piston slidably mounted in said container having a specific gravity greater than the specific gravity of the blood and having means on an outer surface in sealing engagement with an inner surface of the container, said piston having a diaphragm portion forming partial upper and lower surfaces of said piston, said diaphragm portion being of a self-sealing elastomeric material penetrable by a cannula; said piston being disposed in said container so as to separate the chamber defined by said container with said closures, into upper and lower comparTments; said piston being initially mounted in said container at a position adjacent to said second end and being constructed and arranged to move at a predetermined centrifugal force to a second position within said container, whereby said upper compartment is expanded in volume and said lower compartment is reduced in volume; a tube of pre-determined length having one end fixed to the closure for said second end and one end free, terminating within said chamber, said tube having an opening into said chamber at the terminal free end and an opening into said upper compartment at the fixed end; seal means closing said opening at the terminal, free end of said tube, said seal means being constructed and arranged to disengage from said tube at said predetermined centrifugal force; said piston in its initial position cooperating with said tube, so that said tube pierces the diaphragm portion of said piston, whereby said tube together with said seal means forms a closed conduit through said piston, and whereby upon disengaging of said seal means by centrifugal force, communication between said upper and lower compartments is established, said piston in its second position being removed from cooperation with said tube, whereby said conduit is terminated and the diaphragm portion of said piston previously pierced by said tube is self-sealed.

1. A self-contained fluid separator assembly capable of separating blood into its component parts of light phase plasma or serum, and heavy phase cellular material, comprising: a container having a first open end which is adapted to receive blood for subsequent separation into a light phase and a heavy phase and a second open end for removing the separated light phase; closures sealing the open ends of the container, the closures being formed of a self-sealing elastomeric material which is penetrable by a cannula; a piston slidably mounted in said container having a specific gravity greater than the specific gravity of the blood and having means on an outer surface in sealing engagement with an inner surface of the container, said piston having a diaphragm portion forming partial upper and lower surfaces of said piston, said diaphragm portion being of a self-sealing elastomeric material penetrable by a cannula; said piston being disposed in said container so as to separate the chamber defined by said container with said closures, into upper and lower comparTments; said piston being initially mounted in said container at a position adjacent to said second end and being constructed and arranged to move at a predetermined centrifugal force to a second position within said container, whereby said upper compartment is expanded in volume and said lower compartment is reduced in volume; a tube of pre-determined length having one end fixed to the closure for said second end and one end free, terminating within said chamber, said tube having an opening into said chamber at the terminal free end and an opening into said upper compartment at the fixed end; seal means closing said opening at the terminal, free end of said tube, said seal means being constructed and arranged to disengage from said tube at said predetermined centrifugal force; said piston in its initial position cooperating with said tube, so that said tube pierces the diaphragm portion of said piston, whereby said tube together with said seal means forms a closed conduit through said piston, and whereby upon disengaging of said seal means by centrifugal force, communication between said upper and lower compartments is established, said piston in its second position being removed from cooperation with said tube, whereby said conduit is terminated and the diaphragm portion of said piston previously pierced by said tube is selfsealed.

2. The self-contained fluid separator of claim 1 wherein the piston includes a rigid tubular sleeve mounted in a generally tubular outer body portion formed of rubber and having at least one sealing ring on its outer portion for sealing engagement with the inner wall of the container.