CA1327555C - Centrifugal separation of blood - Google Patents

Abstract

Abstract of the Disclosure Returning red blood cells to a patient after a centrifuge separation procedure by connecting an inflow line of a separation channel to an outflow line to provide a closed loop and recirculating liquid through it to remove blood cells. Also disclosed is pulling more liquid out of a flexible separation channel than permitted into it in order to reduce the volume of liquid to be used in returning cells to the patient.

Description

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CENTRIFUGAL SEPARATION OF ~LOOD

Field of the Invention The invention relates to centrifugal separation of blood.

Backqround of the Invention Centrifugal separators used in continuously ~ separating blood components can employ a disposable `; plastic channel that is fitted within a centrifuge bowl ;' that is rotatably driven by a motor. The channels c 10 typically have an inlet for whole blood and two or more outlets at different radial locations to remove separated ractions of blood components in the channels, plasma being at the most radially inward loca~ion and red blood cells being at the most radially outward `; ~ 15 location. In various com~onent collection or exchange procedures the red blood cells are usually returned to the patient/donor along with some other components during the continuous separation procedure.
At the end of a separation procedure, it is 0 desirable to remove the red blood cells remaining in the channel ànd to return them to tha patient/donor. In one prior art centrifuge system involving a plastic separation channel of the general type disclosed in Kellogg et al. U.S. Patent No. 4,094,461, at the end of - 25 a run saline is connected to the input line. A pinch valve blocks the input line while a pump pulls on an output line to causa the channel to collapso, and the pinch valve then unblocks tha input line, causing saline to quickly enter the channsl and to 1ush red blood cells out.

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:,, `. Summary of the Invention . In one aspect the lnvention features centrl:Euge appar-. ., atus lncluding a separation channel for separating blood compon-ents, an lnflow line to and outflow llnes from the channel, means for connecting tha inflow llne to the outflow line to provide a closed loop, and means for recirculating llquid through the chan-nel to free and suspend blood cells ln the channel, whereby the blood cells can be returned to a patlent/donor.
The lnventlon also provides centrifuge apparatus com-prising a flexible separatlon channel for separating blood compon-ents, an inflow llne to and out10w lines from the channel, an out~low pump mounted to control flow on an outflow llne, means ~or pulllng more liquld out of the channel with the outflow pump than ls permitted lnto the channel in order to reduce the volume of ll~uid, and means for returning cells in the channel to the patient/donor, whereby the volume of liquld to be returned to the patient/donor is reduced.
In a further aspect, the invention provides a method of returning blood cells to a patient/donor after a centrifuge separ-atlon procedure comprlsing providln~ centrlfuge apparatus lnclud-ing a separation channel for separatlng blood componen~s and an inflow line to and outflow lines from sald channel, endlng a cen-trlfuge separation procedure by stopplng rotatlon of said separ-atlon channel, connectlng sald lnflow llne to a sald outflow llne to provide a closed loop, and reclrculatlng liquid through said channel to free and suspend blood cells ln said channel while sald channel ls not rotating.

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; 2a 74424-18 An addltional aspect of the inventlon provldes the method of returnlng blood cells to a patlent/donor after a centri-fuge separatlon procedure comprlslng provldlng centrlfuge apparatus lncluding a flexlble - separatlon channel for separating blood components and an lnflow .~:
llne to and outflow llnes from sald channel, and pulllng more llquld out of sald channel wlth an outflow ~, pump than ls permitted lnto sald channel ln order to substantlally collapse salcl channel to reduce the volume of liquld to be used ln returnlng cells to sald patlent/donor, and ~; rlnslng liqui~ through sald channel while malntaining sald channel collapsed to flush blood cells from said channel , while using a decreased volume of liquid owing to the decreased volume of sald channel.
Other features and advantages of the inventlon will be apparent from the following descrlE~tion of a preferred embodiment thereof and from the claims.
; DescrlPtlon of the Preferred Em~odlment The preferred embodiment wlll now be described.

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Drawinqs ; ~ Fig. 1 is a hydraulic schematic of a centrifugal blood separating sys~em according to the invention.
Fig. 2 is a chart describing an automatic method of returning red blood cells to a patient/donor at the end of a separation procedure usiny the Fig. 1 system. ~.
~`: Structure Refarring to Fig. 1, there is shown blood centrifugal separating system 10, used to continuously separate components in blood removed from a patient via inflow line 12. Separation is in disposable plastic separation channel 14, which is mounted in a bowl (not shown) and rotated.
Blood inflow line 12 and disposable channel~14 f are par~ af a disposable tubing 5et including waste "~
collect bag 16, plasma collect bag 18, platelet collect baqs ~0, 22, inflow and return air chambers 24, 26, and seal-less multichannel rotation connection assembly 28 Se.g., as shown in U.S. Patent No. 4,146,172). The disposable tubing set is mounted on the ront surface of ~ a machine having peristaltic pump rollers to provide, - with the tubing, anticoagulant pump 30, inlet pump 32, plasma pump 34, and collect pump 3~, and pinch valve assemblies to provide, with the tubing, two-position return line valve 38, three-position plasma valve 40, three-position collect valve 42, two-position red blood cell line valve 44, and wa6te~divert valve assembly 39, including two-position waste valve 41, and three-position divert valve 43. The tubing set also includes filter/connector 46, for connecting separately supplied bag of saline 4~, filter/connector 50, for connecting separately supplied bag of anticoagulant Sl, ~, ~ ' -and connector 49, for connecting return saline bag 53.
The tubing set also includes manually-activated pinch clamps, namely saline supply clamp 52, collect clamps 54, plasma collect clamp 56, saline return clamp s5~ and S patient access supply and return clamps 57, 59. (Some of the manually-activated pinch clam~s have structures that do not emp~oy the decreasing wid~h slots shown for all clamps in Fig. 1.) Inflow line 12 joins saline supply line 58 and anticoagulant supply line 60 from pump 30 at four-way junction 29. From junction 29 inflow line 12 passes through inlet pump 32 and into inflow air chamber 2~.
From there inflow line 12 continues to seal-less :. connectiorl assembly 28.
Disposable plastic channel 1~ is a two-staqe channel of the type d~scribed in more d~tail in U.S.
Patent n N~. ~9~5~,995 Oth~r disposable plastic channels, for example, the type shown in the Kellogg patent mentioned above, can also bQ used.
Th~ outflow lines from chann01 14 inclu~e red blood cell return line 66, plasma line 68, and platelet collec~ line 70. Red blood cel]. line 66 is directly conn~cted to return drip chamber 26. Plasma lin~ 68 and platelet collect linP 70 pass through their respective :~ 25 pU3TlpS 3~, 36 and branch into two lines each, which pass ~hrough thr~-position valves 40, 42. Th~ee-position plasma valve ~0 can bQ operated to permit ~low to plasma collecs bag 18 ~collect position~, to return line 72 ~return position), or to both (variable position).
Three-position collec~ valve 42 can similarly permit low to bags 20, 2~ (collect position), to re~urn line :. 72 (re~urn posi~ion), or ~o bo~h (variable position~.
Three-position divert valve 43 can similarly permit flow -~ , ~.,: - ' - ,, A in ei~her or both of its lines, and two-position valve 41 can permit or block flow through it to waste bag 16.
Return saline bag 53 is connected to re~urn line 74 at three-way junction 63.
Operation In operation, the tubing set shown in Fig. 1 is installed on the machine and connec~ed to saline bag 4~, anticoagulant bag 51, and return saline bag 53. Saline solution is pumped into the tubing set to prime it. The 10 venipuncture needles connected to inf low lina 12 and return line ~4 are inserted in the patient/donor, and supply pinch clamp 57 is opened, permitting removal of blood rom the patient/donor, whil~ return pinch clamp 59 initially remains closed. The collection procedure 15 begins, the pumps operating to supply whole blood to channel 14 via inflow line 12 and to remove the separated red blood cells in line S6, plasma in line fi~, and platelets in line 70. ~uring the initial operation, the saline in the tubing set is di.splaced by the 20 incoming blood and separated bloocl components and is diverted at return air chamber 26 for collection in waste bag 16. Valve 41 is used to permit removal of saline to waste bag 16 at the begi.nninq of a donor/patient procedure, an~ to remove air from chambers 2S 24, 26, when needed. When the separated red blood cells and plasma reach junction 63, wasteJdivert valve a6sembly 39 is closed, and return valve 38 is opened.
The red blood cells and plasma are returned to the patient via lina 74, and platelets are collected in bags 30 20~ 22. During the collection procedure three-position collect valve 42 blocks flow to return line 72 and permits flow to collect bags 20, 22, and plasma return valve 40 permits flow to return line 72 and blocks flow to plasma collect bag 18. The flow through the tubing , . ' ~ " ' ~ '' :
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' - 6 - 1 3 2 7 5 5 5 d set during the collection procedure is as indicated by solid arrow~ in Fig. 1.
At the end of a collection procedure, the method described in Fig. 2 is employed to return red blood cells to the patient. First, prior to Step 1, the operator closes supply clamp 57, disconnects the venipuncture needle connected to the inflow line 12, and opens pinch valve 52 to provid~ access to supply saline in bag 48. The operator then returns the system to the automatic mode by ac~ivating a CONTINUE control.
Anticoagulant pump 30 is stopped, as indicated in the listinq for Step 1, and the other pumps operate (at desired flowrates) and the valves maintain their conditions, permitting continued collection of platelets for a few minutes while 60 ml saline flows through inflow tube 12, and drip chamber 24 (approximately 10-15 ml volume) and into channel 14 (approximately 160 ml volume). At this point the operator clamps and disconneots collectio~ bags 20, 22 and returns to the automatic mode by activating tha CLEAR control.
In Step 2, the centrifuge is stopped, causing an immediate breakdown in the layers in channel 14; this results in some of the red blood cells mixing with the separated plasma and saline in channel 14 and some remaining compacted at the outer wall of channel 14, primarily 1~ the first stage region between the inlet and the red blood cell outlet. Inlet pump 32 is operated while plasma and collect pumps 3~, 36 are : stoppe~, causing all flow from channel 14 to be through rsd blood cell line 66. This causes the red blood cells in line 66 along with approximately 90 ml of the volume ;~ of channel 14 to be flushed through lino 66 (which has very little volume) and return air chamber 26 into return line 74, about 10-15 ml remaining in return air "

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~ 7 - l 327 555 , chamber 26. Al~hough line 66 has little volume, during operation it is packed with a very high density of red blood cell~. During Step 3 the flow in channel 14 is substantially short circuited along the short flow path from the inlet to the red cell outlet, the region between these two including the majority of the red blood cells. At the end of Step 2, the liquid in line 66 has a much lower concentration of red blood cells.
The 40 ml volume is chosen to substantially remova all free red blood cells from channel 14.
In Step 3, red blood cell line valve 44 and return line valve 38 are closed; plasma and collect valves 40, 42 are in the return position (so that all liquid through them goes to return line 72), and waste 15 valve 39 is placed in the recirculate posi~ion with ..
two-position valve 41 closed and three-position 43 open, causing the liquid to take the r~circulating flow path shown by dashed arrows on Fig. 1. Thus liquid flows from inlet air chamber 24 throu~h line 12 into and through channel 14, and from channel 14 the liguid goes through lines 68, 70, pumps 34, 36, and return line 72 to return air chamber 26. From there the liquid goes through three-position divert valve 43 and returns to drip chamber 24. If red blood cell lin~ valve 44 were not closed, thQre would bQ short circuitin~ of ~he liquid through lt. There i5 no flow to or from the patient/donor during this step. During Step 3, the red ~- blood cells are flushed off the channel wall by recirculating liguid through channel 14 at a high ~; 30 flowrate of 200 ml per minute for 90 seconds. There is approximately 225 ml in the closed circuit, causing the liquid to be recirculated through the path approximately 1.33 times. Of the 225 ml closed loop volume, approximately 100 ml or more is saline solution.

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~ 1 327555 69204-159 In Step 4, waste valve 39 is moved to the closed position, and return valve 3~ is opened, permitting return of plasma, freed red blood cells, and mixed saline to the patient/donor. ~ecause inlet pump 32 is stopped, and plasma pump 34 is operated, channel 14 is collapsed, reduc~ng its 160 ml volume by about 125 ml to about 35 ml.
In Step 5, inlet pump 32 is opera~ed at 50 ml per minute, and plasma pump 34 is oparated at 50 ml per minu~e, matching ~he inflow bu~ maintaining the collapsed state of channel 14. More freed red blood cells are returned to the patient, with plasma and mixed saline.
A volum~ of 58 ml is r~turned in this step, becausa after this amount has been re~urned the liquid is predominantly saline.
The o~erator disconnects the return line ~o the patientJdonor. In Step 6, return valve 38 is automatically closed.

Other Embod:lments O~her embodiments of the invention are wi~hin th~ scope o~ the following claims. For example, the collecting step need (Step 1) not be used, ~he 60 ml ~: volume being added to ~he 90 ml volume of ~hQ S~ep 2.
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Claims (12)

1. A method of returning blood cells to a patient/donor after a centrifuge separation procedure comprising providing centrifuge apparatus including a separation channel for separating blood components and an inflow line to and outflow lines from said channel, ending a centrifuge separation procedure by stopping rotation of said separation channel, connecting said inflow line to a said outflow line to provide a closed loop, and recirculating liquid through said channel to free and suspend blood cells in said channel while said channel is not rotating.

2. The method of claim 1 wherein an outflow line is a red blood cell line for removing red blood cells, and further compris-ing, prior to said connecting, flushing said red blood cell line to remove red blood cells therein, and thereafter blocking said red blood cell line, and wherein during said recirculating said red blood cell line is maintained blocked.

3. The method of claim 2, further comprising, prior to said flushing, disconnecting said inflow line from said patient/donor and connecting a supply saline solution to said inflow line, and wherein, after said connecting and prior to said flushing, compo-nents separated in said channel are collected.

4. The method of returning blood cells to a patient/donor after a centrifuge separation procedure comprising providing centrifuge apparatus including a flexible sep-aration channel for separating blood components and an inflow line to and outflow lines from said channel, and pulling more liquid out of said channel with an outflow pump than is permitted into said channel in order to substantially collapse said channel to reduce the volume of liquid to be used in returning cells to said patient/donor, and rinsing liquid through said channel while maintaining said channel collapsed to flush blood cells from said channel while using a decreased volume of liquid owing to the decreased volume of said channel.

5. The method of claim 4 wherein inflow to said channel is blocked during said pulling to substantially collapse said chan-nel.

6. The method of claim 5 wherein an outflow line is a red blood cell line for removing red blood cells, and further compri-sing, prior to said pulling, flushing said red blood cell line to remove red blood cells therein, and thereafter blocking said red blood cell line, and wherein during said pulling said red blood cell line is maintained blocked.

7. The method of claim 5, further comprising, prior to said flushing, disconnecting said inflow line from said patient/donor and connecting a supply saline solution to said inflow line, and wherein, after said connecting and prior to said flushing, compo-nents separated in said channel are collected.

8. The method of claim 1 wherein said channel is flexible, and further comprising, after said recirculating, pulling more liquid out of said channel with an outflow pump than is permitted into said channel in order to reduce the volume of liquid to be used in returning cells to said patient/donor.

9. The method of claim 8 wherein inflow to said channel is blocked during said pulling to substantially collapse said chan-nel, and further comprising thereafter rinsing liquid through said channel while maintaining said channel collapsed to flush blood cells from said channel while using a decreased volume of liquid owing to the decreased volume of said channel.

10. The method of claim 1 wherein said apparatus includes an inflow line drip chamber and a return line drip chamber that both have waste lines joined at a waste function, and wherein said con-necting includes operating said valve to cause liquid to be able to flow from said return line drip chamber to said inflow line drip chamber via said waste lines.

11. The method of claim 1 wherein said outflow lines include a plasma outlet line and a platelet collect outlet line,

12 said plasma outlet line and said platelet collect outlet line each branching into two lines, one each connected to a collection bag and one each joined at a return junction connected to a return line to said patient/donor, and wherein said apparatus includes valves controlling flow through said two lines, and wherein said connecting includes operating said valves to cause liquid to be able to flow through said return junction.