GB2095588A

GB2095588A - Fluid container for use in a centrifuge

Info

Publication number: GB2095588A
Application number: GB8209830A
Authority: GB
Original assignee: International Business Machines Corp
Current assignee: International Business Machines Corp
Priority date: 1978-07-21
Filing date: 1979-07-12
Publication date: 1982-10-06
Also published as: GB2095588B; GB2025797A; CA1159803A; JPS5515688A; DE2925010A1; ES482170A1; SE7906179L; JPS575585B2; IT7923938A0; IT1165127B; FR2460718A1; FR2460718B1; NL7905622A; GB2025797B

Abstract

A fluid container 13 for use in a centrifuge is removably disposed in a channel 5 in a filler piece 3 in a centrifuge bowl 1. The container 13 is a polyvinyl chloride tube which receives whole blood to be centrifuged through a connection 17, so as to collect red cells, platelets and plasma. The whole blood enters at the inner wall of a first portion of the container which is curved inwardly to meet a second portion from the end of which platelets and plasma are collected. The first portion is wider than the second portion and a counterflow is set up in the first portion whereby red cells collect on the outer wall thereof for collection from blood entry end. <IMAGE>

Description

1

GB2 095 588A

1

SPECIFICATION

Fluid container for use in a centrifuge

5 The present invention relates to containers for use in a centrifuge. 5

According to the present invention, there is provided a fluid container for use in a centrifuge and intended for removable disposition in a channel in a centrifuge rotor; the channel passing around the rotational axis of the rotor, said container having first and second ends connected by first and second interconnected portions, the first portion starting at a further radial distance 10 from the rotational axis of the rotor than the second portion and being curved inwardly to meet 10 the second portion, and the second portion having a progressively larger radius of curvature along its length, fluid connections to the first end of the container for introducing fluid near the inner wall and for withdrawing part of the fluid near the outer wall, and fluid connection means for withdrawing the remaining part of the fluid from the second end of the container, whereby, 15 in use, part of the fluid introduced at the first end counterflows back to the first end for 15

withdrawal therefrom, whilst the remaining part of the fluid flows to the second end for withdrawal therefrom.

The scope of the invention is defined by the appended claims; and how it can be carried into effect is hereinafter particularly described with reference to the accompanying drawings in 20 which:— 20

Figure 1 shows an exploded perspective view of a centrifuge with a container according to the present invention;

Figures 2 and 3 are a plan and elevational section respectively of a filler piece included in the centrifuge of Fig. 1; and

25 Figures 4A and 4B are an exploded plan and elevation respectively of a cavity with plug 25

included in the container of Fig. 1.

A centrifuge bowl 1 (Fig. 1) is arranged to be spun around an axis of rotation by suitable means, not shown. The bowl may be formed of any suitable material such as metal or plastics or a combination of materials. Seated within the bowl 1 is a filler or centre piece 3 which can be 30 formed of any suitable material, by moulding and/or machining. The filler piece 3 is 30

dimensioned so that when in place in bowl 1, the filler will be concentric with the bowl. It can be retained in place on a central hub, or on the outer rim or a plurality of distributed bosses or pins. A channel 5, described later in detail, is machined, moulded or otherwise formed in the top surface of filler piece 3. The filler piece 3 has a central hole or opening 7 which 35 accomodates the fluid connections to a fluid container, to be subseuently described, and a 35

rotating seal 9. Also the opening may be dimensioned to fit over a central hub in the bowl, to accurately locate and retain the filler piece. The seal 9 may be of the type shown in U.S. Patent 3,489,145, for example. Filler piece 3 also has a plurality of radial slots 11 in the upper portion of the piece, which receive fluid connections or tubes to the container.

40 The fluid container 1 3 comprises a length of semi-rigid tubing, preferably of medical grade 40 polyvinyl chloride and having a substantially rectangular cross section. Different cross-sectional areas are provided, as later described. The tubing is formed in a spiral-like configuration as shown, with each end sealed in a cavity 16. The container is generally shaped to fit the channel 5. Fluid connections to the container are provided by a plurality of tubing connections 17, 18, 45 19 and 20, to the cavity 16, one of which (1 7) serves as an input connection for whole blood. 45 The cavity 16 is divided into two separate chambers, one of which serves a dual function as an input chamber and red blood cell chamber and the other of which serves as a collection chamber for platelet concentrate and plasma. Connection 18 is for extraction of the red cells, connection 19 serves as an output connection for plasma, and connection 20 serves as a 50 platelet concentrate outlet. When the container 1 3 is placed in channel 5, the tubes 1 7 through 50 20 are placed in appropriate slots 11 in filler piece 3.

Fig. 2 is a plan view of the filler piece shown in Fig. 1, and further shows the relationship between the various elements, particularly the geometric relationship for the various portions of the channel, and hence for the container.

55 It should first be noted that the channel, and hence the container, has two basic geometric 55 patterns. The first portion, extending for substantially 1 30 degrees, is circular about a centre slightly offset from the true centre of rotation of the centrifuge, so as to spiral inwards by a first predetermined amount for the first part thereof (ARC1) and is spiralled inwards by a second predetermined amount for approximately the last 25 degrees of arc (ARC2). The second portion 60 comprises four arcuate segments (ARC3, ARC4, ARC5, ARC6), each having a different radius of 60 different increasing magnitudes respectively, and extending from different centres, which are located at variously displaced distances from the true centre. These segments extend through arcs ARCS, ARC4, ARC5 and ARC6, respectively, and total to substantially 180 degrees. The spiral is defined by the equation:

2

GB2095588A 2

r = 138.9e~ 230-in millimetres,

where 9 is the angle from the maximum end of the spiral, in radians, and is approximated by the four circular arcs having four different radii and turned from four different centres. The radii, 5 centre location and angular extremes of the four arcs are defined in the following table: 5

CENTRE LOCATION ANGULAR EXTREMES SEGMENT CENTRE RADIUS FROM X-X FROM Y-Y FROM ARC CENTRE

10

15

ARC1

C1

83.1

1.0

0

20°14'

150°21'

ARC2

C2

51.9

26.1

15.4

150°21'

175°35'

ARC3

C3

77.4

8.2

15.7

175°35'

215°35'

ARC4

C4

91.0

19.3

7.8

215°35'

255°35'

ARC5

C5

106.9

23.2

7.6

255°35'

295°35'

ARC6

C6

125.5

15.2

24.4

295°35'

335°35'

10

15

The linear measurements are in millimetres.

20 These segments taken together form a spiral portion for platelet concentrate collection as 20

subsequently described.

A short transition portion TP couples the first and second portions together. As shown, the transition section leads radially inward from the outlet end of the first portion to the inlet end of the second portion. The inlet connection 17 for the whole blood is connected to the inlet

25 chamber of the cavity joining the ends of the tubing. Also, the fluid connection 18 to the inlet 25 chamber is provided for removing the red blood cells which are centrifuged against the outer wall of the first portion. The end of connection 18 extends outwardly almost to the outer wall of the inlet chamber, so that the packed red cells can be removed without removing any of the incoming whole blood.

30 The curve of the first portion is such that the red blood cells which move to the outer wall 30 flow against the direction of flow of the incoming whole blood, and reach the bottom of the inlet chamber, from whence they are removed by the connection 18. The input connection 17 is terminated at the top or inward end of the inlet chamber, so that the whole blood and the packed red cells are adequately separated.

35 Separation of platelets occurs in both the first and second portions. Some of the platelets 35

which separate in the first portion settle on the interface between the red cell and plasma in the transition portion. These platelets tend to be the largest and therefore, most desirable platelets to collect. Consequently, the first portion of the channel is designed such that these separated platelets can esily be spilled over into the second portion without spilling many red cells.

40 The first portion of the channel has the following features:— 40

1 The inner wall of the first portion is smooth, continuous and gently changing so that the interface can be drawn to the innermost radial point of the channel without any substantial turbulence in the flow which would cause an excessive mixing of the red cell-platelet-plasma interface.

45 2 The majority of the first portion of the channel has a gradual inward curve to assist in 45

pumping the separated red cells back to the red blood cell port.

3 At the downstream extreme, the inward curve of the first portion of the channel sharpens.

This provides a comfortable operating point for the interface at which the plasma layer in the majority of the channel is very thin and the risk of accidentally spilling red cells to the second

50 channel is minimal. Keeping the plasma layer thin is essential to high yields because the thin 50 layer yields a high plasma velocity which assists in keeping the platelets moving toward the second stage.

4 The first portion of the channel tapers so as to narrow just prior to the entrance to the second portion. This narrowing is used to concentrate the platelets which are intentionally

55 spilled to the second portion after collecting on the interface of the first portion. The narrowing 55 makes it easier to detect when the majority of the platelet concentrate has been spilled.

Using conventional stroboscopic techniques, the operator of the centrifuge can observe the interface at the transition portion, and adjust the flow rates so that the interface approaches very closely the inner wall of the container at the exit bend from the first portion. Such platelets as

60 have already been separated will then move at high velocity through the transition portion and 60 into the second narrower portion of the container. It has been found that high flow velocity of the concentrate is very necessary if the platelets are not to aggregate into clumps, which would then require a resuspension operation. For this reason, the inner width of the container for the second portion is reduced to substantially one quarter the inner width of the first portion, for

65 example, one sixteenth inch and one quarter inch respectively. Reduction in the cross section 65

GB2 095 588A

results in high flow velocity in the narrower portion.

The terminal or outlet end of the second portion of the container enters a collecting chamber 23 in the cavity 1 6 at one side thereof, slightly above the outward wall or bottom of the cavity. The platelet concentrate outlet connection 20 extends from the inward or top end of the cavity 5 down to, but not touching the bottom. As noted previously, it is necessary to keep the cross- 5

sectional area relatively small in order to achieve high flow rates. Thus the platelet concentrate connection 20 is on the order of one thirty-second of an inch inner diameter as compared with three-sixteenths inch inner diameter for the other connections. The plasma outlet connection 19 enters the chamber 23 at the top or inward end of the cavity.

10 Fig. 3 is a cross-sectional elevation view taken along the section line Ill-Ill in Fig.2., and shows 10 the radial positions of parts of the first and second portions.

It will be readily apparent to those skilled in the art that the embodiment described above provides an assembly in which a plurality of filler pieces could be interchangeably utilized in the same centrifuge bowl, including the one described above. If such interchangeability is 15 undesirable or unnecessary, a one-piece rotor may be used, forming, with the container, another 15 preferred embodiment of the invention.

Referring to Figs. 4A and 4B, the cavity 16 comprises a bottom 25 and a top or plug 27,

each preferably moulded from suitable plastic, and then cemented together. A boss or projection 29 on the top 27 contacts a portion 31 of bottom 25 and is cemented thereto to effectively 20 divide the cavity into two chambers, an inlet chamber 33 and an outlet chamber 23. A side 20 opening 37 receives the inlet end of the first portion of the fluid container, and side opening 39 receives the outlet end of the second portion of the container. The whole blood input connection 17 is received in the portion of plug 27 at the top of the inlet chamber 33. The red blood cell connection 18 has an extension 41 which extends to the bottom of inlet chamber 33, where the 25 red blood cells collect after retroflow in the first spiral portion of the container. The plasma 25

outlet connection 19 is terminated in the portion of plug 27 at the top of the outlet chamber 23. The platelet output connection 20 is received in a groove 43 extending along the cavity and having its outer end cemented in a passage 45 which opens into the outermost end of the outlet chamber 23.

30 From the foregoing, it will be apparent that a low cost simple disposable fluid container is 30 provided which is economical to fabricate and can be discarded after a single use, thereby removing the expensive duties of cleaning and sterilizing required with reusable centrifuge containers.

Claims

35 CLAIMS 35

1. A fluid container for use in a centrifuge and intended for removable disposition in a channel in a centrifuge rotor, the channel passing around the rotational axis of the rotor, said container having first and second ends connected by first and second interconnected portions, the first portion starting at a further radial distance from the rotational axis of the rotor than the

40 second portion and being curved inwardly to meet the second portion, and the second portion 40 having a progressively larger radius of curvature along its length, fluid connections to the first end of the container for introducing fluid near the inner wall and for withdrawing part of the fluid near the outer wall, and fluid connection means for withdrawing the remaining part of the fluid from the second end of the container, whereby, in use, part of the fluid introduced at the

45 first end counterflows back to the first end for withdrawal therefrom whilst the remaining part of 45 the fluid flows to the second end for withdrawal therefrom.

2. A container according to claim 1, in which the first and second portions are formed in a length of semi-rigid tubing having a substantially rectangular cross-section.

3. A container according to claim 1 or 2, in which the first portion is wider than the second

50 portion and tapers down to the width of the second portion. 50

4. A container according to claim 3, in which the first portion comprises a first part annular segment of a first radius of curvature connected to a second part annular segment of a second smaller radius of curvature which leads into a tapering segment leading into the second portion.

5. A container according to claim 3 or 4, in which the second portion comprises a

55 connected series of part annular segments of progressively larger radius of curvature. 55

6. A container according to any preceding claim, in which the first portion is connected at the first end to an inlet chamber and the second portion is connected at the second end to an outlet chamber.

Printed for Her Majesty's Stationery Office by Burgess & Son (Abingdon) Ltd.—1982.

Published at The Patent Office, 25 Southampton Buildings, London. WC2A 1AY. from which copies may be obtained.

6. A container according to any preceding claim, in which the first portion is connection at the first end to an inlet chamber and the second portion is connected at the second end to an outlet chamber.

7. A container according to claim 6, in which the inlet and outlet chambers are formed in a

60 common member. 60

8. A fluid container substantially as hereinbefore described with reference to Figs. 1, 2, 4A and 4B of the accompanying drawings.

CLAIMS (28 May 1 982)

65 1. A fluid container for use in a centrifuge and intended for removable disposition in a 65

4

GB2 095 588A

4

channel in a centrifuge rotor, the channel passing around the rotational axis of the rotor, said container having first and second ends connected by first and second interconnected portions, the first portion starting at a further radial distance from a point which, when the container is in the channel in the rotor, lies on the rotational axis of the rotor than the second portion and 5 being curved inwardly to meet the second portion, and the second portion having a progres- 5

sively larger radius of curvature along its length, fluid connections to the first end of the container for introducing fluid near the inner wall of the container and for withdrawing part of the fluid near the outer wall of the container, and fluid connection means for withdrawing the remaining part of the fluid from the second end of the container, whereby, in use, part of the 10 fluid introduced at the first end counterflows back to the first end for withdrawal therefrom 10

whilst the remaining part of the fluid flows to the second end for withdrawal therefrom.