United States Patent [19J
`Kell
`
`[11]
`
`(45)
`
`4,412,916
`Nov. 1, 1983
`
`[54] AIRLESS ARTIF ICIAL KIDNEY ASSE MBLY
`Inventor: Michael J . Kell, Decatur, Ga.
`[75]
`[73] Assignee: Cordis Dow Corp., Miami, Fla.
`
`[21) Appl. No.: 276,751
`(22) Filed:
`J un. 24, 1981
`
`Int . CJ.l .............................................. BOID 31/ 00
`[51]
`[52) U.S. Cl. ...................................... 210/ 90; 210/188;
`210/262; 210/296; 210/300; 210/309;
`210/321.3; 210/335; 210/436; 210/456;
`210/472; 55/159; 55/421
`(58) Field of Search ..................... 210/87, 90, 94, 120,
`210/188, 259, 260, 262, 295, 296, 300, 305- 310,
`321, 323, 335, 433, 436, 455, 456, 472, 927;
`128/675, 748, DIG. 3, 214; 73/38, 714, 706,
`715; 55/59, 318, 42 1
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`3,447,570 6/1969 Collins .................................. 222/88
`3,523,408 8/1970 Rosenberg ............................ 55/159
`3,554,035 1/1971 Buisson et al. ........................ 73/726
`3,713,341 1/1973 Madsen et al. ........................ 73/7 15
`3,778,971 12/1973 Granger et al. ...................... 551159
`3,854,907 12/1974 Rising ............................. 210/436 X
`
`3,993,062 11/1976 Jess ........................................ 55/159
`4,004.587 1/1977 Jess ...................................... 210/314
`4,077,882 3/1978 Gangemi ............................... 210/90
`4.184,489 1/1980 Burd ............................... 128/214 R
`4,231,87 1 11/l 980 Lipps et al. ........................... 210/87
`
`Primary Examiner- David R. Sadowski
`Attorney, Agent, or Firm-Neal A. Waldrop; Jay C.
`Taylor
`
`ABSTRACT
`(57)
`The invention provides an artificial kidney extracorpo(cid:173)
`real circuit assembly including an artificial kidney hav(cid:173)
`ing detachably attached multifunctional subassembly
`means for automatically venting gas bubbles from liquid
`flowing therethrough, · for continuously sensing the
`liquid pressure of and for fil tering said liquid, together
`with blood tubes for connecting a patient's artery to the
`kidney and the subassembly outlet port to a patient's
`vein.
`T he subassembly includes means associated with a hy(cid:173)
`drophobic gas bubble vent w hich prevent clogging,
`minimize blood clotting and insure against ambient gas
`entry through the vent.
`
`14 Claims, 9 Drawing Figures
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`AIRLESS ARTIFI CIAL KIDNEY ASSEMBLY
`
`This invention is an improvement on the artificial
`kidney of U.S. Pat. No. 4,231,871 and more particularly 5
`on the kidney shown in FIG. 10 thereof.
`
`BACKGROUND OF THE INVE NTION
`In hemodialysis treatments using an artificial kidney
`it is necessary, in the interest of patient safety, to moni- 10
`tor the positive pressure of the blood being returned to
`a patient"s vein and to insure that the returning purified
`blood is free of particulate matter and gas bubbles.
`Heretofore, it has been conventional to perform the
`blood pressure measuring step by incorporating a ve- 15
`nous drip chamber in the blood tube that is connected to
`the patient's vein.
`T ypically the venous drip chamber is secured to a
`stand or support adjacent the patient such that it re(cid:173)
`mains upright during the treatment to insure the rise of 20
`gas bubbles to the top portion of the chamber. The
`bubble chamber serves the dual function of bubble re(cid:173)
`moval and of providing a site for measuring the pressure
`of the blood in the return tube path to the patient's vein.
`The drip chamber is a closed receptacle and as pressure 25
`changes or separated bubbles add to the air space at the
`top of the chamber it is necessary, periodically, to inject
`a needle into the air space and suck out some of the gas
`to maintain a preset level in the chamber to avoid the
`possibility of air bubbles reaching the patient and caus- 30
`ing a fatal embolism.
`There are a number of undesirable aspects to the use
`of such venous drip chambers. First, repetitive needle
`penetrations increase the potential of creating a non(cid:173)
`sterile circuit. Second, relatively constant observation 35
`of the blood level by the clinic attendant is required and
`personal withdrawal of excess gas requires time and
`effort during the normal four to six hour hemodialysis
`treatment. T hird, there is a continuously existing blood-
`air interface within the drip chamber and the exposure 40
`of a patient's blood to air during the extended four or
`more hours during the hemodialysis treatment tends to
`degrade, contaminate, denature, or even clot the blood
`in the chamber. For this reason, a need for an airless
`artificial kidney system has been recognized since at 45
`least the early 1970's as hollow fiber artificial kidney use
`increased. FIG. 10 of U.S. Pat. No. 4,231,871 suggests
`the use of a microporous vent and blood pressure mea(cid:173)
`suring means located in the venous line without show(cid:173)
`ing a specific construction of either unit.
`It was found that microporous vents having the form
`of a disc mounted at the top of a tubular shaped filter
`device, as shown in FIG. 10 of U.S. Pat. No. 4,231,871,
`had two operational problems. First, when using a hy(cid:173)
`drnphobic'miiterial such as polytetrafluoethylene, bav- 55
`ing micro-sized c>penings in the range of about I to
`abouf 30 microns in the vent disc, clogging of the small
`openings with blood platelets occurred as the time of
`use extended and on occasion there was some foaming
`and some clotting of the blood adjacent the lower sur- 60
`face of the hydrophobic vent. Second, it was found that
`opera.ting conditions which placed a negative pressure
`on the lower surface of the vent disc caused air to be
`drawn through the vent and into the blood chamber.
`The im'proved microporous vent containing subassem- 65
`bly of this invention· overcomes both of these problems ·
`and provides an improved air.less operating system, as
`will be explained in detail hereinafter.
`
`1
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`4,412,916
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`Microporous vents per se and certain constructions
`using microporous vents to remove air, or entrained
`gases, from blood or other liquids prior to, or during,
`intravenous injection into a patient were known prior to
`this invention. Hydrophobic microporous membranes
`are shown in U.S. Pat. Nos. 3, 778,971 and 3,993,062 and
`a combination of a hydrophilic and a hydrophobic sepa(cid:173)
`rator is shown in U.S. Pat. Nos. 3,854,907, 4,004,587 and
`3,523,408. These constructions employ tubular separa(cid:173)
`tor configurations, pouch-shaped devices as well as
`combinations of cylindrical separators with disc shaped
`separating membranes. The problem of ambient air
`entering into a gas separating filter is recognized in U.S.
`Pat. No. 4, 190,426 and a variety of mechanical check
`valve constructions have been developed to overcome
`that problem and are discussed in a number of U.S.
`patents described in columns I and 2 of U.S. Pat. No.
`4,190,426, w hich discussion is hereby incorporated
`herein.
`The microporous vent construction of this invention
`employs a special housing conliguration that includes
`only a hydrophobic separator and a novel, non(cid:173)
`mechanical means to prevent the entry of ambient air
`into the filtering chamber.
`In the past, measurement of blood pressure in the
`venous blood tube was accomplished by connecting a
`pressure transducer to the air space above the blood in
`the venous drip chamber since the pressure on the air in
`that space is the same as the blood pressure in the same
`chamber. As above stated, elimination of the blood-air
`interface is desirable and this invention employs pres-
`sure measuring means which does not require air, or gas
`of any composition, to interface with blood in the blood
`return path to the patient. Rather, blood pressure mea(cid:173)
`suring means and the microporous vent are combined in
`a single tubular housing together with a blood filter that
`during hemodialysis operates completely filled with
`blood and free of air or other gas. The blood pressure
`measuring means employs a compressible diaphragm in
`a spherical or cylindrical receptacle mounted into the
`wall of the housing such that the diaphragm contacts
`the blood flowing through the housing as it returns to
`the patient. The blood pressure measuring receptacle
`contains air isolated from the blood in the housing by
`the compressible diaphragm. Movement of the dia(cid:173)
`phragm responsive to the pressure on the blood in
`contact with it in the housing expels air from the recep(cid:173)
`tacle which is connected to a remotely located pressure
`indicator precalibrated to refler.t blood pressure. Pres-
`50 sure detecting and measuring devices which include a
`deformable element having the shape of bellows, trun(cid:173)
`cated cones, hemispheres or a diabolo are shown in U.S.
`Pat. No. 3,554,035. A frusto-conical, thin membrane
`disposed in a housing which transmits blood pressure
`variations through a pressure transmitting medium to a
`pressure transducer is shown in U.S. Pat. No. 4,077,882.
`Pressure transducers which employ flexible diaphragms
`have been used as gauges for gasoline or oil in U.S. Pat.
`No. 2,385,382, for sterile fluid measurements as shown
`in U.S. Pat. No. 3,818,765, and for blood as shown in
`U.S. Pat. No. 3, 713,341. Pressure transmitting means
`responsive to pressure activated diaphragm elements
`include various fluids such as air, mercury, gasoline,
`etc., as shown in U.S. Pat. Nos. 2,369,707 and 3,349,623,
`or mechanical means as shown in U.S. Pat. No.
`2,272,950. The above identilied prior art represents the
`most pertinent art known to applicant relating Lo the
`separate microporous vent and diaphragm actuated
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`The multifunctional subassembly operates air-free
`and provides a microporous vent element in a modified
`configuration combining the filter and blood pressure
`measuring means, which minimizes blood denaturation
`5 and clotting and improves deaeration efficiency auto(cid:173)
`matical!y during a hemodialysis treatment by means
`adopted to prevent clogging, or closing, of the micro(cid:173)
`sized openings in a disc-shaped hydrophobic vent. The
`microporous vent configuration includes simple, non·
`10 mechanical means which prevent ambient gas ingress
`into the device through the vent in the event negative
`pressure develops on the lower surface of the vent disc
`during priming of the circuit prior to blood flow, or
`during the hemodialysis treatment.
`
`BRIEF DESCRIPTION OF THE ORA WINGS
`F IG. 1 is a perspective view of the artificial kidney
`assembly of this invention having a multifunctional
`subassembly attached to the upper end of the kidney.
`FIG. 2 is an enlarged cross-sectional view of the
`multifunctional subassembly of FIG. 1 taken along the
`longitudinal center line thereof.
`FIG. 3 is a top plan view ofa broken away portion of
`the artificial kidney showing the attached subassembly
`of FIG. 2.
`FIG. 4 is a cross-sectional view of the subassembly of
`FIG. 2 taken along the line 4-4 thereof.
`F IG. 5 is a cross-sectional view of a modification of
`the subassembly of FIG. 1.
`FIG. 6 is an exploded view of the parts of the modi(cid:173)
`fied subassembly of F IG. S.
`FIG. 7 is a view of the replaceable diverter element
`taken along line 7-7 of FIG. 6.
`FIG. 8 is a view of the lower end portion of the
`housing of the subassembly of FIG. 5 taken along the
`line 8-8 of FIG. 6.
`FIG. 9 is a side view of the replaceable diverter of the
`modified subassembly of FIG. S.
`
`3
`pressure measuring elements which arc satisfactory for
`use, in modified form, in the subassembly of this inven(cid:173)
`tion.
`In addition to the automatic dcacrating, blood pres(cid:173)
`sure measuring, filtering subassembly of this invention,
`the overall airless artificial kidney assembly includes an
`artificial kidney and a blood tube for supplying blood
`from a patient's artery to the kidney and a blood tube
`for returning blood from the blood pressure measuring,
`air venting, filtering subassembly to the patient's vein.
`By virtue of combining the functions of automatic bub·
`ble separation and blood pressure measuring into a com·
`bination means that eliminates the need for a blood-air
`interface to enable pressure determination, it becomes
`possible to eliminate the conventional venous drip 15
`chamber as a part of the blood tubing set. Convention(cid:173)
`ally, blood tube sets have also included injection sites
`for heparin administration and blood sampling sites,
`which permit needle insertion through the blood tube
`wall. Constructions of such sites that assure safety to the 20
`nurse or technician using same are shown in shown U.S.
`Patents as Nos. 4,184,489, and 3,447,570. The direct,
`rigid attachment of the subassembly of this invention to
`the artificial kidney permits elimination of such separate
`blood tube site constructions by the incorporation of
`one or more of such sites into selected, accessible wall
`surface locations of the subassembly housing. The sub(cid:173)
`assembly of this invention does include at least one such
`site. The elimination of the venous drip chamber and 30
`access sites from the blood tube set makes it feasible to
`flush and clean the blood tubes as well as the artificial
`kidney after a hemodialysis treatment to a degree of
`cleanliness that enables safe reuse of the blood tubes and
`the artificial kidney, whereas prior practice required 35
`discarding the entire blood tubing set. It remains desir(cid:173)
`able to discard the subassembly, or portions thereof,
`after a single use and to replace it, or the portions, with
`a substitute.
`To the best knowledge of applicant, the assembly of 40
`this invention is the first artificial kidney assembly
`which has enabled the cleansing of a patient's blood in
`an extracorporeal circuit that is airless and free of a
`blood-air interface at any location in the extracorporeal
`circuit. It is also the first such assembly that has pro- 45
`vided the option of safe reuse of the blood tubing as well
`as the artificial kidney.
`
`25
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENT
`As shown in the drawings, the assembly of the inven·
`tion, generally designated 10, comprises an artificial
`kidney 12, a multifunctional subassembly genera.Hy des(cid:173)
`ignated 14 and attached to the kidney outlet port 15
`adjacent its upper end, a blood tube 16 attached to the
`inlet port 18 of kidney 12, and a blood tube 20 attached
`to the outlet port 22 of subassembly 14. Each of the
`opposite ends of blood tubes 16, 20 is provided with
`50 conventional attachment means 24, 26, respectively, for
`connection of the tubes to fistula means of conventional
`type.
`Subassembly 14, as shown, comprises a generally
`cylindrical, elongated housing generally designated 28
`55 which contains three integral, interconnected means
`which provide necessary functions to insure safe opera(cid:173)
`tion of assembly 10 in an extracorporeal circuit during
`hemodialysis treatment. The first means, generally des·
`ignated 30, serves
`to automatically deaerate, or
`60 degasify, blood flowing into and from housing 28 by
`venting such bubbles to atmosphere. The second means
`is a filter 32. The third means, generally designated 34,
`is a blood pressure sensing device.
`In normal use of assembly 10, blood from the patient's
`65 artery is fed through tube 16 into inlet port 18 of kidney
`12, which as shown is a hollow fiber kidney of the type
`shown in U.S. Pat. No. 4,231,871. The blood then flows
`downwardly through integral blood channel 19 into the
`
`SUMMARY OF THE INVENTION
`The invention provides an improved extracorporeal
`hemodialysis treatment circuit which detoxifies blood in
`an airless artificial kidney assembly.
`The assembly comprises an artificial kidney, a detach(cid:173)
`ably attached multifunctional air venting, blood pres·
`sure measuring and filtering subassembly and blood
`tubes to connect the patient's artery to the kidney and
`the outlet port of the subassembly to a patient's vein. In
`the preferred embodiment the multifunctional subas(cid:173)
`sembly combines and interconnects the vent, blood
`pressure measuring means and filter in a small, compact,
`common housing that may be easily disconnected from
`the kidney and blood tube and discarded after a single
`use to thereby enable safe reuse of the kidney and blood
`tubes by replacement of the discarded subassembly
`device. Alternately, the vent, blood diverter and the
`filter may be removed from the subassembly housing
`and replaced with substitute elements or cleaned and
`replaced prior to sterilization for reuse.
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`lower end header portion 36, then moves upwardly
`through the interiors of the thousands of semipermeable
`hollow fibers (not shown), then outwardly through
`upper header 38 into subassembly 14, and downwardly
`in the direction of the arrow shown in FIG. 2 for return 5
`to the patient's vein through blood tube 20.
`Automatic deareation means 30 comprises a hydro(cid:173)
`phobic disc-shaped membrane 40 mounted so as to en(cid:173)
`close the upper end of housing 28 at a location spaced
`upwardly from the point of entry of inlet tube 52 into 10
`housing 28, a cover 42 spaced a small distance above the
`upper surface of membrane 40 and secured to, or into,
`the waJJ of housing 28 so as to form a liquid-tight cham(cid:173)
`ber 44 between the upper surface of membrane 40 and
`the lower surface of cover 42. An overlying gas-venting 15
`closure member 46 having a centrally located vent
`opening 48 is sealed into the upper end of housing 28.
`The lower surface of closure 46 is spaced slightly up(cid:173)
`wardly from the top surface of support 42. Chamber 44,
`when filled with water, or the like, through vent 48 and 20
`the plurality of apertures 50 in support 42, forms a thin
`layer of liquid, which overlies the upper surface of
`membrane 40 and sealingly separates the upper surface
`of membrane 40 from the ambient atmosphere. The thin
`layer of water permits gas bubbles migrating upwardly 25
`through the micro-sized pores in membrane 40 to pass
`through the water layer to atmosphere while concur(cid:173)
`rently preventing atmospheric gases from moving
`downwardly and through membrane 40 into the interior
`of housing 28. This simple inexpensive arrangement of 30
`parts to provide a liquid chamber 44 contiguous to the
`upper surface of membrane 40 insures against retro(cid:173)
`grade in-Oow of atmospheric gases into housing 28 at
`any time the pressure on the lower surfac.e of venting
`membrane 40 may become lower than atmospheric. 35
`Such conditions, although abnormal, may exist, for
`example during priming of the circuit prior to hemodial(cid:173)
`ysis use as sterile saline is pumped through the arterial
`blood line and through the kidney, or such lowered
`pressure may occur during hemodialysis in the event of 40
`stopping, or malfunction, of the blood pump which
`normally maintains the desired blood pressure during
`hemodialysis treatment, i.e., a pressure in the range of
`about 35-250 mm. of mercury above normal atmo-
`spheric pressure.
`·
`Microporous vent 40 may be satisfactorily made from
`any hydrophobic membrane material having a structure
`that permits permeation of air, or gas, through the thin
`layer of the material and concurrently prevents the
`migration of blood or other aqueous liquid through the 50
`layer under the positive pressures that may be encoun(cid:173)
`tered during normal or abnormal conditions of use, that
`is, at pressures between about 10 and about 400 mm. of
`mercury above normal atmospheric pressure. Hydro(cid:173)
`phobic material such as the polytetrafluoroethylenes, 55
`polyfluoro-chloroethylenes, polyethylenes, polypropyl(cid:173)
`enes and the like are satisfactory. Polytetrafluoroethyl(cid:173)
`ene is preferred and is commercially available with
`micro-pore sizes varying from 0.02 to 30 microns under
`the trademarks TEFLON or GORE-TEX from Du- 60
`Pont, Wilmington, Del., or W. L. Gore & Associates,
`Elkton, Md., U.S.A., respectively.
`It was found that a polytetrafluoroethylene mem(cid:173)
`brane having an average pore size of 0.2 micron pos(cid:173)
`sessed the best bubble venting to atmosphere character- 65
`istics but the pores of the membrane had an unaccept(cid:173)
`able tendency to clog with blood components, probably
`platelets or micro-clots, when blood entered the cham-
`
`6
`ber of housing 28 closely adjacent the lower surface of
`vent 40 and continuously flowed past, or bathed, that
`lower surface. It was found, however, that such pore
`clogging could be eliminated or minimized by creating
`a stagnant layer of blood immediately adjacent the
`lower surface of vent 40. Deaeration means 30 provides
`a preferred construction which insures maintenance of
`the required thin, stagnant blood layers in contact with
`the lower surface of vent 40. Blood entering kidney
`outlet port 15 passes into housing 28 through blood flow
`directing, or baffiing, means 52 which is a tube sealingly
`fitted into kidney port 15 and which directs incoming
`blood laterally into housing 28 to its axial center line
`and then bends downwardly in a 90° bend, as shown,
`into a tube portion 54A which extends along the longi(cid:173)
`tudinal axis of housing 28 and directs blood flow into
`filter 32 in the direction of the arrow, FIG. 2. The 90°
`angle of deflection of tube 52 has been found to maxi(cid:173)
`mize the depth of the stagnant blood layer adjacent vent
`40 and the lack of pore clogging with blood during
`hemodialysis usage, but it is to be understood that other
`angles less than 90• that direct blood now from parallel
`to the lower surface of vent 40 and downwardly into
`housing 28 are suitable for use. Moreover, the blood
`tube 52 may be satisfactorily replaced with any baffling
`member, or other means, which projects into the incom-
`ing blood path and deflects blood flow away from vent
`40 such that the required stagnant blood layer immedi(cid:173)
`ately adjacent the lower surface of vent 40 is preserved.
`Filter 32 is sealed to the inner wall 29 of housing 28
`by any suitable means, such as heat sealing, ultrasonic
`welding, press fit, or the like, to insure th;i.t all of the
`blood which enters housing 28 will pass through the
`filter before it reaches outlet port 22. Filter 32 may be
`fabricated from any blood compatible filtering material
`having a pore size which permits easy passage of blood
`therethrough and separates any debris or solids that
`may have entered the blood in the prior traverse
`through the inlet blood line 24 or kidney 12. A number
`of commercially available and heretofore used filters
`that are well known to those skilled in this art may be
`satisfactorily employed. As shown, the preferred filter
`32 tapers gradually inwardly from its upper end toward
`its sealed lower end, but this shape is only desirable
`45 rather than necessary.
`Blood pressure sensing, or measuring, device 34 is a
`gas tight receptacle formed of a generally hemispheri(cid:173)
`cal-shaped compressible, or flexible, diaphragm, or
`dome, member 54, which pwjects from the wall of
`housing 28 inwardly, and a rigid, generally hemispheri(cid:173)
`cal-shaped dome 56, which projects outwardly from
`housing 28, and is provided with an integrally attached
`gas outlet port 58. As shown, rigid dome 56 is attached
`to an opening 60 in the waJJ 29 of housing 28 defined by
`outwardly projecting bosses 62, 64 by heat sealing or
`ultrasonic welding of the opposed peripheral ledge 66
`which locks the peripheral edge 68 of diaphragm 54
`between bosses 62, 64 and ledge 66 and thus forms a gas
`tight cavity 70 in device 34. Outlet port 58 is adapted for
`connection to means for transmitting gas to a remotely
`located pressure gauge or pressure measuring means of
`conventional type such as a pressure transducer or the
`like, not shown. Pressure sensing means 34 functions to
`reflect small changes in pressure of the blood flowing in
`housing 28 and the consequent deflection of the flexible
`convex dome 54 into cavity 70 as pressure increases,
`and vice versa. The gas that is thus displaced is transmit(cid:173)
`ted to a previously calibrated pressure transducer, not
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`shown, to provide a continuous pressure indication on a
`conventionaJ indicator, or the transmitted gas may be
`used to activate an alarm or pressure control means to
`maintain the preset safe pressure level of normal opera(cid:173)
`tion.
`Diaphragm 54 may be made from any blood compati(cid:173)
`ble flexible material such as silicone rubber. T he pre(cid:173)
`ferred shape for positive pres!.ure measurement is the
`convex hemispherical shape as shown. It is to be under(cid:173)
`stood that a blood pressure sensing device similar to
`device 34 may be used in the arteriaJ feed line between
`the patient's arterial fistula and a blood pump, if desired.
`In that event. blood sensing device 34 would be modi(cid:173)
`fied to operate at negative pressures, that is pressures
`less than normal patient blood pressure of 50-75 mm. of
`mercury. T he only modification required is to employ a
`generally similar diaphragm of concave configuration
`instead of the inwardly projecting portion 54. The con(cid:173)
`cave diaphragm will function similarly by contact with
`the blood in housing 28. In either the concave or convex
`configuration, diaphragm 54 is preferably tapered from
`its peripheral edge toward its crown to counteract hys(cid:173)
`teresis losses in its flexures and attain the highest degree
`of response to extremely small changes in pressure. For
`example, for a two centimeter diameter diaphragm 54,
`diaphragm thickness at the periphery of 0.02 inch is
`gradually thinned to the apex, or hemispherical central
`portion, to a thickness in the range of about 0.005 to
`0.008 inch.
`Housing 28 is provided w ith injection site 72 and
`sample site 74. Each is provided with a penetrable resil(cid:173)
`ient seal, or closure, member 76, 78, respectively, for
`permitting conventional needle entry to the blood in
`housing 28 for such typical purposes as injecting medi(cid:173)
`cants into the blood through site 72 and sampling the
`blood through site 74 or vice versa. As shown, sites 72,
`74 are located on the exposed upper surface of housing
`28 when it is attached to kidney 12 to insure easy, con(cid:173)
`venient access as desired during ordinary hemodialysis
`treatment usage.
`In the modified form of the subassembly 14 which is
`shown in F IGS. 5- 9, a design is provided w hich enables
`replacement of only a portion of the subassembly after
`each use. T he subassembly is altered majorly in the
`upper end portion such that the blood diverter and
`microporous vent can be removed by disassembly and
`replaced; the filter may also be removed and replaced, if
`desired. The modified subassembly also makes possible
`the removal of the blood diverter, the vent and the filter
`element for cleaning outside the housing. The cleaned
`clements prior to sterilization for reuse.
`Referring particularly to FIGS. 5 and 6, the modified
`subassembly 114 includes an upper wall portion 129 of
`the housing 128 that is provided on its lower end with a
`double ledge portion 131 for attachment or joining to a
`mating ledge portion 133 of wall 129 by any suitable
`means such as adhesives. ultrasonic welding or the like.
`Wall portion 129 includes a blood inlet port 111 having
`stepped ledges 113 for attachment to mating stepped
`surfaces in the kidney port, not shown, and terminates
`at its upper end in an externally threaded connecting
`portion 115.
`The replaceable blood divertcr generally designated
`141 is a one-piece, cylindrically shaped member havi11g
`a blood inlet tubular portion 152 and a downwardly
`extending, axially located diverter portion 154. Blood
`divcrtcr 141 has an outside diameter portion 143
`adapted to snugly interfit \Vith the inside diarnetral sur-
`
`5
`
`8
`faces of wall 129 and an undercut smaller oiameter
`portion 145 (FIG. 9) which is adapted to abut and be
`surrounded by the upper end portion 147 of fil ter 132.
`Diverter 141 has an upwardly extending, generally
`triangular shaped locator arm member 149 which tapers
`from the upper surface 153 of inlet tube 152 o utwardly
`and upwardly to a reversely tapered upper end ledge
`155. The peripheral portion 157 of arm 149 has the same
`outside diameter as the lower portion 143 and is pro-
`10 vided adjacent its upper end with a longitudinally ex(cid:173)
`tending locator key 159 having a lower end tapered
`surface 161 which is adapted to interfit w ith slot 163 in
`the upper end of wall 129 as an assist during assembly.
`A removable cap generally designated 180 is pro-
`15 vided with an internally threaded portion 182 adapted
`to mate with the external threads 115 and to apply axiaJ
`sealing pressure to force blood diverter 141 into the
`position shown in FIG . 5 as the circumferential tapered
`ledge 184 bears against the correspondingly tapered
`20 ledge 155 d uring assembly. Cap 180 is an o pen ended
`cylindrical shell having a cavity 186 for receiving and
`supporting microporous vent membrane 188 on the
`upper end surface 190 of ledge 184. Vent membrane 188
`is secured in place by cover disc 192 having circumfer-
`25 ential projection 194. T he lower surface 196 of disc 192
`is also provided w ith additional supports for membrane
`188 in its central region to prevent collapse in the event
`of large pressure gradients across the membrane. These
`additional supports are circular and consist of two pro-
`30 jecting beads. Bead 196 has a diameter w hich bisects the
`central portion of fou r equally arcuately spaced aper(cid:173)
`tures 198 which extend through disc 192 and provide
`the escape route for part of the gases that exit to atmo(cid:173)
`sphere. The second bead 200 has a smaller diameter
`35 than bead 196 and supports membrane 188 immediately
`adjacent to three equally arcuately spaced apertures 202
`that similarly extend through disc 192.
`The lower surface 204 of disc 192 and the upper
`surface 206 of membrane 188 define a liquid tight cavity
`40 208 which during use is filled with water for the identi(cid:173)
`cal purpose described above in connection w ith cham(cid:173)
`ber 44 in the embodiment of F IG. 2. D isc 192 is main(cid:173)
`tained in pressure sealing contact with the portion of
`membrane 188 which overlies support surface 190 of
`45 cap 180 by upper closure 210. Tapered portion 212 of
`circumferential bead 213 of closure 210 bears against
`the upper tapered surface 214 of bead 216 which
`projects upwardly from the upper surface 218 in disc
`192 when closure 210 is inserted into opening 211 of cap
`so 180 and sealed thereto by any suitable means. The upper
`end of apertures 198 and 202 open into planar surface
`218 which is spaced downwardly from the lower sur(cid:173)
`face 220 in closure 210 and the space between surfaces
`218 and 220 provides a path for gases from apertures
`55 198, 202 to move toward centrall y located exit opening
`222 in closure 210.
`It will be apparent to one skilled in this art that the
`modified construction of subassembly 114 enables disas(cid:173)
`sembly by unscrewing cap 180 from the threaded por-
`60 tion 115 of wall portion 129. With the upper end of
`housing 128 thus opened. blood diverter 141 with at(cid:173)
`tached filter 132 is easily removed for discard and re(cid:173)
`placement of the cap, diverter and filter, or any one of
`them as elected. Filter 132 is also easily disassembled
`65 from diverter 141 and after cleaning each may be re(cid:173)
`placed in housing 128 for reuse after appropriate steril(cid:173)
`ization with, for example, a conventional fo rmaldehyde
`solution.
`
`Nipro Ex. 1015
`
`000008
`
`

`
`9
`
`4,412,916
`
`20
`
`l claim:
`1. An airless artificial kidney assembly comprising
`(1) an artificial kidney having inlet and outlet ports,
`(2) a liquid-tight subassembly having a filter, micro-
`porous vent means for venting to atmosphere gas 5
`bubbles separated from liquid in said subassembly
`and preventing gas entry through said vent means
`into said subassembly, pressure measuring means
`for continuously monitoring the pressure of liquid
`in said subassembly, a housing for blood having an 10
`upper region and an outlet connect