United States Patent [19]
`Heath et al.
`
`[11] Patent Number:
`[45] Date of Patent:
`
`4,666,598
`May 19, 1987
`
`[54] APPARATUS FOR USE WITH FLUID FLOW
`TRANSFER DEVICE
`
`[75] Inventors: Gary B. Heath, Aurora; William G.
`Palsulich, Boulder; Keith J. Manica,
`Littleton; Jack C. Swan, Jr., Boulder,
`all of Colo.
`
`[73] Assignee:
`
`Cobe Laboratories, Inc., Lakewood,
`C010.
`[21] App]. NO.: 740,545
`[22] Filed:
`Jun. 25, 1985
`
`[51] 1111.014 ............................................ .. B01D 13/00
`[52] us. c1. .................................. .. 210/239;210/137;
`210/321.3; 210/416.1
`[52] Field Of Search ............ .. 210/90, 137, 206, 321.2,
`210/3213, 321.4, 433.2, 645, 646, 927, 741, 239,
`232, 416.1
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`3,774,762 11/1973 Lichtenstein .............. .. 210/3213 X
`4,077,882 3/ 1978 Gangemi ..................... .. 210/90
`4,263,808 4/1981 Bellotti et a1.
`.......... .. 73/714
`4,370,983 2/1983 Lichtenstein .............. .. 210/3212 X
`
`FOREIGN PATENT DQCUMENTS
`
`0134-436 3/1985 European Pat. Off, .
`
`Primary Examiner-Richard V. Fisher
`Assistant Examiner-W. Gary Jones
`[57]
`ABSTRACT
`A ?uid ?ow chamber cassette that can be mounted with
`either its front wall or rear wall against a supporting
`machine and has a ?exible tube that extends from a
`sidewall and forms a loop that is symmetrical about a
`loop axis that is transverse to the side wall so that the
`loop will be acted upon by a pump roller on the ma
`chine both when the front wall is against the machine
`and when the rear wall is against the machine. Also
`disclosed is automatically ?xing the initial liquid levels
`and amounts of air in venous and arterial chambers of
`?uid ?ow transfer device apparatus by having the arte
`rial chamber inlet enter the arterial chamber at a posi
`tion higher than the arterial chamber outlet, having the
`venous chamber inlet enter the venous chamber at a
`position higher than the venous chamber outlet, and
`priming the apparatus by causing reverse ?ow, so that
`the liquid rises in the venous and arterial chambers to
`the level of the entrances of the inlets. Also disclosed is
`sensing pressure of ?uid in a ?uid ?ow chamber by
`placing an impermeable ?exible diaphragm over a hole
`in a rigid wall of the fluid ?ow chamber, providing a
`second chamber on the other side of the diaphragm, and
`sensing the pressure in the second chamber.
`
`15 Claims, 9 Drawing Figures
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`'U. S. Patent May19,1987
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`Sheet1of2
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`4,666,598
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`FIG 1
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`US. Patent Mayl9, 1987
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`Sheet2of2
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`FIG 4
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`FIG 5
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`APPARATUS FOR USE WITH FLUID FLOW
`TRANSFER DEVICE
`
`FIELD OF THE INVENTION
`The invention relates to apparatus used with ?uid
`?ow transfer devices such as dialyzers and methods of
`using the apparatus.
`
`BACKGROUND OF THE INVENTION
`Fluid ?ow transfer devices such as dialyzers are used
`to continuously remove impurities from a patient’s
`blood. The blood is typically pumped through tubes and
`arterial and venous bubble traps of disposable tubing
`sets connecting the patient to a dialyzer mounted on a
`dialysate preparation and supply machine.
`Bellotti et al. US. Pat. No. 4,263,808 discloses, as a
`tubing set replacement, a one-piece hydraulic circuit
`that includes arterial and venous bubble trap chambers
`in which blood enters at entrances above the bottoms of
`the chambers and leaves near the bottoms of the cham
`bers. Pressure in the chambers can be determined by
`transducers placed against impermeable latex mem
`branes covering holes communicating with upper por
`tions of the chambers.
`
`25
`
`30
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`35
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`45
`
`SUMMARY OF THE INVENTION
`In one aspect the invention features a ?uid ?ow
`chamber cassette that can be mounted with either its
`front wall or rear wall against a supporting machine and
`has a ?exible tube that extends from a sidewall and
`forms a loop that is symmetrical about a loop axis that is
`transverse to the side wall so that the loop will be acted
`upon by a pump roller on the machine both when the
`front wall is against the machine and when the rear wall
`is against the machine. The orientation of the cassette
`and the direction of ?uid ?ow through the cassette can
`thus be changed by simply changing whether the front
`or the rear wall is mounted against the machine.
`In preferred embodiments the ?exible tube is con
`40
`nected at one end to a chamber outlet at the bottom of
`the chamber and at the other end to the inlet of a ?ow
`passage in the cassette, which inlet is located at the same
`distance from the loop axis as the chamber outlet; the
`cassette has two chambers (arterial and venous cham
`bers) and additional ?exible tubes for connecting a dia
`lyzer between the ?ow passage and the venous cham
`ber; the outlet of the venous chamber is at the bottom of
`the venous chamber; and the inlets to the arterial and
`venous chambers enter the arterial and venous cham
`bers at locations above the outlets of the chambers. In
`use with a dialyzer, blood from a patient ?ows through
`the arterial chamber, the symmetrical pump loop, and
`the ?ow passage to the dialyzer, and from there through
`the venous chamber and back to the patient. After dial
`ysis has been completed, the cassette and dialyzer are
`inverted and remounted on the machine in an upside
`down position, and disinfecting solution is pumped
`through them in the reverse direction, ?lling all regions
`of the cassette, dialyzer and tubing.
`In another aspect the invention features automatically
`?xing the initial liquid levels and amounts of air in ve
`nous and arterial chambers of ?uid ?ow transfer device
`apparatus by having the arterial chamber inlet enter the
`arterial chamber at a position higher than the arterial
`chamber outlet, having the venous chamber inlet enter
`the venous chamber at a position higher than the venous
`chamber outlet, and priming the apparatus by causing
`
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`4,666,598
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`2
`reverse ?ow, so that the liquid rises in the venous and
`arterial chambers to the levels of the entrances of the
`inlets, and the amount of air in the chambers remains
`fixed, even after ?ow is reversed during normal opera
`tion with blood.
`In another aspect the invention features sensing pres
`sure of ?uid in a ?uid ?ow chamber by placing an im
`permeable ?exible diaphragm over a hole in a rigid wall
`of the ?uid ?ow chamber, providing a second chamber
`on the other side of the diaphragm, and sensing the
`pressure in the second chamber.
`‘In preferred embodiments the diaphragm is circular
`and includes a corrugated portion formed symmetri
`cally about the center, so that the diaphragm moves
`with little stretching, and the diaphragm is suf?ciently
`elastomeric so that it returns to its original shape when
`not restrained from movement; the corrugated portion
`is semicircular in cross-section; and the ?uid ?ow cham
`ber is provided by a cassette that is removably mounted
`on a machine carrying a pressure transducer, and the
`second chamber is defined by a portion of the machine
`surrounding the transducer and a rigid retainer that
`covers the diaphragm, is carried by the cassette and has
`an opening adapted to sealably engage the portion sur
`rounding the transducer on the machine.
`Other features and advantages of the invention will
`be apparent from the following detailed description of a
`preferred embodiment of the invention and from the
`claims.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`The drawings will be brie?y described ?rst.
`
`DRAWINGS
`FIG. 1 is a diagrammatic elevation, partially in sec
`tion, of a cassette for use with a ?uid ?ow transfer
`device according to the invention.
`FIG. 2 is a diagrammatic, partially exploded, rear
`perspective view of the FIG. 1 cassette.
`FIG. 3 is a front perspective view of the FIG. 1 cas
`sette.
`FIG. 4 is a vertical sectional view, taken at 4—4 of
`FIG. 1, of the FIG. 1 cassette.
`FIG. 5 is a partial vertical sectional view, taken at
`5—5 of FIG. 1, of the FIG. 1 cassette.
`FIG. 6 is a partial vertical sectional view, taken at
`6—6 of FIG. 1, showing a pressure sensing portion of
`the FIG. 1 cassette connected to a pressure sensor of a
`machine on which the FIG. 1 cassette is mounted.
`FIG. 7 is a partial sectional view, taken at 7—7 of
`FIG. 1, showing another pressure sensing portion of the
`FIG. 1 cassette.
`FIG. 8 is an exploded partial sectional view of the
`FIG. 6 pressure sensing portion.
`FIG. 9 is an elevation, partially in section, of another
`embodiment of a cassette according to the invention.
`
`STRUCTURE
`Referring to FIGS. 1-5, there is shown ?uid ?ow
`chamber cassette 10, including tubing for connection to
`access needles for a patient, a blood pump roller, a
`dialyzer, and sources of saline and heparin solutions.
`Cassette 10 is made of clear PVC plastic and includes
`two major ?uid ?ow chambers, arterial chamber 14 and
`venous chamber 16, through which blood ?ows prior to
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`and after passing through a dialyzer connected to dia
`lyzer in?ow tube 18 and dialyzer out?ow tube 20.
`Arterial tube 22 is connected to arterial inlet 24, lead
`ing to narrow vertical in?ow passage 26 that enters
`arterial chamber 14 about two-thirds of the way up
`chamber 14 at opening 28. At the bottom of arterial
`chamber 14 is arterial outlet 30 connected to ?exible
`tube 32, that forms a loop that is symmetrical about axis
`33 and is squeezed by the rollers of a peristaltic pump on
`a dialysate preparation machine (not shown) on which
`cassette 10 is mounted in use.
`The other end of tube 32 is connected to inlet 34 to
`channel 36, which extends along the upper portion of
`cassette 10 and ends at outlet 38, connected to dialyzer
`in?ow tube 18. Heparin port 40 at the top of cassette 10
`is connected to heparin tube 42 and leads to channel 36.
`Saline in?ow port 44 is connected to saline tube 46 and
`leads to the upper part of arterial chamber 14 (FIG. 4).
`Dialyzer tube 20 is connected to inlet 48 leading to
`narrow vertical in?ow passage 49 that enters venous
`chamber 16 about slightly more than one-half of the
`way up chamber 16 at opening 47. Outlet 50 of venous
`chamber 16 is connected to venous tube 52. Positioned
`above and blocking the entrance to outlet 50 is plastic
`blood ?lter 54. On the front walls of arterial chamber 14
`and venous chamber 16 are access ports 56, 58, which
`have rubber plugs 59 sealing them shut (FIG. 5). Needle
`guards 61 prevent needles inserted into plugs 59 from
`going too far into chambers 14, 16.
`Referring to FIGS. 2 and 6-8, is seen that back plate
`98 has holes 60, 62 to arterial chamber 14 and venous
`chamber 16 covered by diaphragms 64, 66, which are
`identical, except that their orientations are reversed.
`Diaphragm 64, subject to negative pressure in arterial
`chamber 14, has its semicircular corrugated portion 80
`extending away from chamber 14, and diaphragm 66,
`subjected to positive pressure in chamber 16, has its
`semicircular corrugated portion extending into cham
`ber 16. Behind diaphragms 64, 66 are diaphragm retain
`ers 68, 70, having cylindrical passages 71 therethrough
`for receiving cylindrical extensions 82 of pressure sen
`sors 83 mounted on the face of the machine that cassette
`10 is connected to in use (FIG. 6). At the peripheries of
`diaphragms 64, 66 are beads 72 that are squeezed be—
`tween annular surfaces 74, 76 of retainers 68, 70 and
`opposing annular surfaces 78 surrounding holes 60, 62.
`Edge portions 96 of diaphragms 64, 66, are squeezed
`between lips 63 of retainers 68, 70 and opposing lips 65
`surrounding holes 60, 62, thereby forming seals between
`the diaphragms and the retainers and between the dia
`phragms and the back plate.
`Referring to FIG. 6, it is seen that extension 82 carries
`O-ring 84, which forms a seal with the inner surface of
`cylindrical passage 71. Pressure transducer element 85
`is exposed to chamber 87, which includes the volume
`within walls 86, passage 88 (in extension 82) and the
`region between the inner surface of retainer 68 and
`diaphragm 64. An identical pressure sensor mates with
`the inner surface of cylindrical passage 71 of retainer 70.
`semicircular corrugated portion 80 extends around
`diaphragm 64, is 0.125” in radius at its outer surface and
`extends 180° about its center. The opposing surface of
`retainer 68 has the same radius, but does not extend a
`full 180° near the center but ends at surface 89, located
`0.065" above center portion 90 of diaphragm 64. On the
`opposite surface of diaphragms 64, 66 are four radial
`projections 92, useful on diaphragm 66 in the venous
`chamber to prevent blocking of passage 88. Diaphragm
`
`4,666,598
`4
`64 is 0.010" thick at semicircular portion 80, and is
`0.020" thick at center portion 90 and edge portion 96
`near bead 72. Diaphragm 64 is made of silicone rubber
`(available under the trade designation MDX4‘45l5
`from Dow Corning) and is nontoxic. Corrugated por
`tion 80 can roll in either direction without stretch or
`friction, and is sufficiently elastomeric to return to its
`original shape when not restrained from movement by
`?uid conditions in the chambers.
`As is perhaps best seen in FIG. 4, cassette 10 is pri
`marily made of two molded PVC pieces, ?at back plate
`98, and front piece 100, in which are formed the ports
`and walls for the various chambers and passages. Back
`plate 98 is joined to front piece 100 by solvent bonding.
`Retainers 68, 70 are similarly solvent bonded to back
`plate 98.
`
`OPERATION
`In use, cassette 10 is snapped onto the dialysate prepa
`ration machine (not shown) by clothespin-like clips on
`the machine that engage projection 45 and the tubular
`extensions providing arterial outlet 30 and ?ow passage
`inlet 34. After back plate 98 of cassette 10 has been
`brought against the machine and locked into position,
`extensions 82 of the pressure sensors on the machine are
`automatically inserted into cylindrical passages 71 of
`retainers 68, 70, sealing with them at O-rings 84.
`Looped tube 32 fits around the rollers of a peristaltic
`pump (not shown) also carried on the front of the ma
`chine; the axis of the blood pump intersects loop axis 33.
`Referring to FIG. 1, the direction of ?ow during
`dialysis is shown by the solid arrowheads, and the direc
`tion of ?ow during priming is shown by the open ar
`rowheads. Prior to use with a patient, cassette 10, its
`various tubes and the hollow ?ber dialyzer connected
`to them are primed with saline solution by connecting
`the end of venous tube 52 to a saline bag and operating
`the pump acting on tube 32 in the direction indicated by
`the open arrowhead (clockwise direction). This causes
`the saline solution to be pulled into venous chamber 16.
`The amount of liquid in chamber 16 is automatically
`determined by the height of opening 47 at the end of
`inlet passage 49 from inlet 48. Once the saline solution
`reaches the level of opening 47, the ?uid volume and
`the amount of air in chamber 16 does not change, except
`that the pump is operated at a slightly higher than nor
`mal speed when initially filling the venous chamber to
`provide a level slightly higher than opening 47 so that
`bubbles do not continue to be carried to the dialyzer
`during priming. Saline solution then travels through
`tube 20, the dialyzer connected to it, tube 18, passage 36
`and tube 32 into the outlet to arterial chamber 14. The
`fluid level in arterial chamber 14 is automatically set by
`the height of opening 28. The saline solution then trav
`els through arterial line 22. Once all the air has been
`removed from the dialyzer, the arterial line is connected
`to a needle which had been inserted into the patient and
`clamped shut. The dialyzer need not be inverted after
`priming, as was common in the prior practice. Also,
`because of the self-leveling of liquid in chambers 14, 16,
`the priming of the apparatus is much quicker than, re
`quires less operator effort than, and is more reliable than
`the timing-consuming priming of prior blood tubing
`sets, which priming included manual liquid level adjust
`ments.
`A heparine source is connected to line 42, and a saline
`source is connected to line 46. Heparin is automatically
`fed into passage 36, to prevent blood clotting in the
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`dialyzer. Because passage 36 is at positive pressure, the
`heparin will not be drawn into the apparatus at a faster
`than desired rate. Saline line 46 is maintained in a
`clamped position and is provided as an emergency sup
`ply of additional liquid to be quickly administered to the
`patient in case of shock.
`The blood pump is then operated in the forward
`(counter-clockwise) direction, drawing blood from the
`patient into tube 22 and through the passages of cassette
`10 and the associated tubes, replacing the saline solution
`in it by forcing the saline solution out of the end of tube
`52. Once cassette 10, the dialyzer, and associated tubes
`have ?lled with blood the blood pump is stopped. The
`end of venous line 52 is connected to a needle into the
`patient, and dialysis can then begin with the pump going
`in the counterclockwise direction, the blood ?owing as
`indicated by the solid arrowheads.
`During dialysis the amounts of air within chambers
`14, 16 remain constant. Pressure is monitored by pres
`sure sensors 83, which are isolated from the blood ?ow
`20
`path by nontoxic diaphragms 64, 66. Chamber 14 is
`generally at a negative pressure (about — 150 mm Hg),
`and chamber 16 is generally at a positive pressure (about
`+150 mm Hg). The air spaces in chambers 14, 16 pro
`vide compliant volumes to accommodate pressure per
`turbations caused by the operation of the peristaltic
`pump. The level in arterial chamber 14 is slightly lower
`than it was during priming, and the level in venous
`chamber 16 is slightly higher than during priming,
`owing to the switching between positive and negative
`pressure conditions with the change in pump direction.
`Diaphragm 64 moves without stretch or friction (owing
`to corrugated portion 80) into chamber 14, causing the
`pressure in chamber 87 to be equal to that in chamber
`14. Diaphragm 66 similarly moves toward retainer 70,
`rolling at corrugated portion 80 without stretch or fric
`tion, causing the pressure chamber associated with its
`transducer to equal that in chamber 16.
`After dialysis, line 22 is disconnected from the patient
`and connected to a source of saline solution, allowing
`the blood in the hydraulic circuit to be returned to the
`patient. Heparine line 42 and saline line 46 are discon
`nected from the respective sources and reconnected
`together. Cassette 10 and the associated dialyzer are
`then inverted, with the front of cassette 10 being against
`the machine, and outlet 30 being at the top and inlet 34
`being at the bottom. Disinfecting solution is then drawn
`into tube 22 and through the system by running the
`pump in a clockwise direction, causing the solution to
`occupy all regions in the circuit. Arterial line 22 and
`venous line 52 are connected together, and the cassette
`and dialyzer can then be stored with the solution, which
`will be ?ushed out prior to reuse on the same patient.
`
`45
`
`OTHER EMBODIMENTS
`Other embodiments of the invention are within the
`scope of the following claims.
`For example, FIG. 9 shows cassette 110 for use in
`single needle dialysis. Inlets 149, 128 to venous and
`arterial chambers 116, 114 are at lower positions (inlet
`149 being about one-fourth of the way up from the
`bottom and inlet 128 being about one-half of the way up
`from the bottom), to provide larger air volumes, to
`permit the liquid volumes to vary during the arterial
`and venous phases with smaller pressure changes.
`What is claimed is:
`1. A ?uid ?ow chamber cassette assembly for mount
`ing on a machine including a peristaltic pump roller
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`moving about a pump axis and means for supporting a
`?uid ?ow transfer device, said cassette assembly com
`prising
`a rigid plastic casing having front and rear walls
`spaced from each other and a side wall between
`said front and rear walls at one side to partially
`de?ne a ?rst ?uid ?ow chamber, said casing also
`having a ?rst chamber inlet to said chamber, and a
`?rst chamber outlet from said ?rst chamber formed
`in said side wall,
`a ?rst ?exible tube for directing liquid from said ?rst
`chamber to said transfer device, said ?rst tube
`forming a portion of a loop adapted to be acted
`upon by said roller of said peristaltic pump, one end
`of said ?rst tube being connected to said ?rst cham
`ber outlet and another portion of said loop being
`secured to said casing so that said loop is symmetri
`cal about a loop axis transverse to said sidewall,
`said loop axis passing through said pump axis when
`mounted on said machine, and
`mounting means for mounting said casing on said
`machine in two positions, the ?rst position being
`said rear wall against said machine, the second
`position being said front wall against said machine,
`portions of said loop being on opposite sides of said
`loop axis when changed from said ?rst to said sec
`ond position.
`2. The cassette of claim 1 wherein said loop axis is in
`a horizontal position when said cassette is mounted on
`said machine, said ?rst chamber outlet is at the bottom
`of said chamber when said rear wall is mounted against
`said machine, and said ?rst chamber outlet is at the top
`of said ?rst chamber when said front wall is mounted
`against said machine.
`3. The cassette of claim 1 wherein said cassette also
`has a ?ow passage, a ?ow passage inlet located on said
`side wall at the same distance from said loop axis as said
`?rst chamber inlet, and a ?ow passage outlet connected
`to a second ?exible tube for connecting to a ?uid ?ow
`transfer device, and wherein said ?rst tube is connected
`to said ?ow passage inlet.
`4. The cassette of claim 3 wherein said cassette has a
`second chamber having a second inlet and a second
`outlet, said second inlet being connected to a third ?exi
`ble tube for connecting to said ?uid ?ow transfer de
`vice.
`5. The cassette of claim 4 wherein said loop axis is in
`a horizontal position when said cassette is mounted on
`said machine, said ?rst chamber outlet is at the bottom
`of said chamber when said rear wall is mounted against
`said machine, and said ?rst chamber outlet is at the top
`of said ?rst chamber when said front wall is mounted
`against said machine, and wherein said second outlet is
`at the bottom of said second chamber when said rear
`wall is mounted against said machine, and said second
`outlet is at the top of said second chamber when said
`front wall is mounted against said machine.
`6. The cassette of claim 5 wherein the entrance of said
`?rst inlet to said ?rst chamber is located above said ?rst
`outlet when said rear wall is against said machine.
`7. The cassette of claim 6 wherein the entrance of said
`second inlet to said second chamber is located above
`said second outlet when said rear wall is against said
`machine.
`8. The cassette of claim 7 wherein said entrance of
`said second inlet to said second chamber is about one
`half of the way up said chamber when said rear wall is
`against said machine.
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`9. The cassette of claim 7 wherein said entrance of
`said second chamber is about onesfourth of the way up
`said chamber when said rear wall is against said ma
`chine.
`10. The cassette of claim 6 wherein said entrance of
`said ?rst inlet to said ?rst chamber is located about
`one-half of the way up said chamber when said rear
`wall is against said machine.
`11. The cassette of claim 6 wherein said entrance of
`said ?rst inlet to said ?rst chamber is located about
`two-thirds of the way up said chamber when said rear
`wall is against said machine.
`12. The combination of the cassette of claim 4 and a
`?uid ?ow transfer device connected to said second
`?exible tube and said third ?exible tube and a machine
`including a peristaltic pump roller, means for engaging
`said mounting means, and means for supporting said
`
`4,666,598
`8
`?uid ?ow transfer device in two positions, one position
`being with said ?ow passage inlet being on top and said
`?rst outlet being on the bottom, a second position being
`with said ?ow passage inlet being on the bottom and
`said ?rst outlet being on top.
`13. The cassette of claim 3 wherein said cassette has a
`?rst access port to said ?rst chamber, and a second
`access port to said ?ow passage.
`14. The cassette of claim 3 wherein said mounting
`means comprises tubular projections that extend from
`said side wall about axes parallel to said loop axis and
`provide said ?rst outlet and said ?ow passage inlet.
`15. The cassette of claim 14 wherein said mounting
`means further comprises a projection extending from
`said cassette on the opposite side from said side wall.
`1!
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