United States Patent [191
`Gangemi
`
`[11]
`
`[45]
`
`4,077,882
`Mar. 7, 1978
`
`[54]
`
`[76]
`
`ISOLATING AND BLOOD PRESSURE
`TRANSMfITING APPARATUS FOR
`EXTRACORPOREAL BLOOD TREATMENT
`SYSTEM
`Inventor: Ronald Gangemi, 17752 Amberton
`La., Huntington Beach, Calif. 92646
`[21] Appl. No.: 726,807
`[22] Filed:
`Sep. 27, 1976
`Int. Cl.2 .............................................. BOID 31/00
`[51]
`[52] U.S. CI •........................................ 210/90; 210/94;
`210/321 B
`[58] Field of Search .............. 73/406, 410; 128/214 E;
`210/90, 94, 321 B; 92/5 R; 138/30; 23/258.5 M
`References Cited
`U.S. PATENT DOCUMENTS
`Qulat .................................. 73/410 X
`9/1954
`2,689,481
`Madsen et al. ......................... 73/406
`1/1973
`3,713,341
`Parr ................................... 73/410 X
`12/1973
`3,780,693
`Kettering ........................... 210/90 X
`9/1975
`3,908,653
`Dunphy et al. ................... 73/410 X
`5/1976
`3,958,558
`Primary Examiner-Frank A. Spear, Jr.
`Attorney, Agent, or Firm-Gary Appel
`ABSTRACT
`[57]
`An isolating and blood pressure transmitting apparatus
`for use in an extracorporeal blood treatment system or
`the like comprises a generally cylindrical, transparent
`plastic chamber with a housing having axially opposing
`inlet and outlet portions. The inlet portion is connected
`to a blood pumping and purifying portion of the system
`for receiving pressurized blood therefrom; the outlet
`portion is connected to a conventional pressure trans-
`
`[56]
`
`ducer which, in response to blood pressure transmitted
`thereto, controls blood pumping valving to maintain
`blood pressure in the system within predetermined lim(cid:173)
`its. The chamber housing has a diameter and an axial
`length substantially greater than the diameter of the
`inlet and outlet portions, the chamber having an appre(cid:173)
`ciable volume to absorb pressure surges. A thin flexible
`membrane, formed in a frustoconical shape is disposed
`across the housing to physically isolate the pressure
`transducer from the blood pumping and purifying por(cid:173)
`tion of the system. A plurality of annular membrane
`wall segments, interconnected into a staircase-like
`structure, form the conical portion of the membrane
`and permit such portion to axially expand and contract
`or telescope in response to blood pressure variations at
`the inlet portion, pressure being the_reby transmitted to
`the transducer through a pressure transmitting media.
`In extreme variations of blood pressure the conical
`membrane can tum inside out and sweep out major
`portions of the chamber volume, enabling use of the
`apparatus with very sensitive transducers. Axial por(cid:173)
`tions of the conical membrane portion may be formed
`having an appearance contrasting with adjacent axial
`portions to enhance visual monitoring of membrane
`expansion and hence of blood pressure in the system.
`The membrane steps may be formed of varying thick(cid:173)
`ness to provide non-linear expansion and contraction of
`the conical membrane portion in response to linear
`blood pressure variations at the inlet portion and to
`provide pressure surge protection for the transducer.
`
`12 Claims, 7 Drawing Figures
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`14
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`lb
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`32
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`30
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`12
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`Nipro Ex. 1006
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`U.S. Patent
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`March 7, 1978
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`Sheet 1 of 2
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`4,077,882
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`lb
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`14
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`20
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`:
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`I
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`50
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`24
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`I
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`12
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`1
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`Z6
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`Nipro Ex. 1006
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`U.S. Patent
`
`March 7, 1978
`
`Sheet 2 of 2
`
`4,077,882
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`78
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`78
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`80
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`80tL
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`70a./
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`/pOa.
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`72tl.
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`000003
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`Nipro Ex. 1006
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`1
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`4,077,882
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`2
`their original state, nor do they provide a means of
`warning if the isolator is over pressurized, absorb air or
`other contaminants from the sensor portion into the
`blood being treated, and also because the response of
`5 the diaphragm to pressure fluctuations in the blood
`treatment portion is always relatively constant and can(cid:173)
`not readily be made to vary in a predetermined manner,
`as may be desirable in some applications.
`
`ISOLATING AND BLOOD PRESSURE
`TRANSMITI'ING APPARATUS FOR
`EXTRACORPOREALBLOODTREATMENT
`SYSTEM
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`The present invention relates generally to the field of
`extracorporeal blood treatment systems, and more spe- 10
`cifically to those portions of such systems relating to
`pressure sensing and pressure surge protection.
`2. Description of the Prior Art
`Various types of extra-corporeal blood treatment
`systems for humans, or external artificial kidneys, are, 15
`and have for some time, been available for removing
`waste products and impurities from the blood of pa(cid:173)
`tients having diseased, damaged, or impaired kidneys.
`In order to perform this life saving function in a satis(cid:173)
`factory manner, the systems must be provided with 20
`delicate system pressure sensing elements or transduc(cid:173)
`ers and associated electric or pneumatic controls for the
`system blood pump and valves. These transducers sense
`variations in system blood pressure as blood is pumped
`through the cleansing apparatus and, in response 25
`thereto, regulate the pump and valves to prevent high
`or low pressures which might cause damage to the
`patients' internal blood circulating system or delicate
`internal organs.
`However, when these transducers are connected 30
`directly to the blood treatment part of the system, sharp
`high pressure transients, caused, for example, by equip(cid:173)
`ment malfunction, may damage the transducers to the
`extent that they cannot later accurately sense, and
`hence control, system pressure. This may occur even if 35
`the pressure transient were such that the patient under(cid:173)
`going treatment was not injured. And even if a patient
`were injured, it might not be readily apparent that the
`transducer (or transducers) was damaged, and hence
`control of system pressure for future patients could be 40
`impaired.
`In addition, if the transducer is directly coupled to
`the blood treatment portion of the system, it may be a
`source of contamination to the blood being treated.
`Even though the various blood lines and purifying ap- 45
`paratus may be replaced or sterilized after each use, the
`transducer, which is a relatively permanent part of the
`system, may be contaminated and introduce particles of
`a previous patients blood into a next patients blood. Or,
`if the transducer is damaged by pressure transients, it 50
`may become a source of other types of contaminants,
`such as metal particles, air, or oil.
`Even ifthe transducer is not damaged by sharp blood
`pressure transients it may not be sufficiently responsive
`to control the system pressure within a pressure range 55
`not injurious to the patient.
`As a result of these and other problems, the pressure
`transducer should be effectively isolated from blood
`being pumped through the system and means should be
`provided to absorb pressure transients both to protect 60
`patients and the transducer from injury. Although in
`some instances diaphragm type apparatus have been
`employed to isolate the pressure transducers from other
`portions of the blood treatment apparatus through
`which flows a patient's blood, such diaphragms, whose 65
`action depends upon stretching, are generally unsatis(cid:173)
`factory because they prove to eventually crack in use
`and have not sufficient membrane memory to return to
`
`SUMMARY OF THE INVENTION
`In combination with an extracorporeal blood treat(cid:173)
`ment system or the like having a blood pumping and
`purifying portion for connecting to a patient, at least
`one pressure sensing transducer for sensing pressure in
`the pumping and purifying portion and control means
`responsive to the transducer for controlling blood pres(cid:173)
`sure in the pumping and purifying portion within prede(cid:173)
`termined limits, apparatus for isolating the transducer
`from the pumping and purifying portion while transmit(cid:173)
`ting pressure of the blood therein to the transducer, the
`apparatus comprising a pressure chamber including a
`housing with axially apposing inlet and outlet portions,
`means for connecting the inlet portion to the system
`pumping and purifying portion and the outlet portion to
`the transducer and membrane means disposed across
`the housing to physically isolate the inlet and outlet
`portions and preventing flow of blood therebetween.
`The membrane means includes a flexible, gas and
`liquid impermeable membrane formed in a frustoconical
`shape from a plurality of annular wall segments inter(cid:173)
`connected into a staircase-like structure which axially
`expands in either axial direction and contracts or tele(cid:173)
`scopes within the housing in response to blood pressure
`variations at the inlet portion, and thereby transmits
`system blood pressure, through a pressure transmitting
`media to the transducer.
`More particularly, the membrane wall segments are
`formed of a uniform thickness, thereby enabling gener(cid:173)
`ally linear expansion and contraction of conical portions
`of the membrane. The housing may be formed of sub(cid:173)
`stantially transparent material enabling an observer to
`visually monitor expansion and contraction of the mem(cid:173)
`brane and hence visually monitor blood pressures in the
`pumping and purifying portion of the system. Observa(cid:173)
`tion of membrane movement may be enhanced by con(cid:173)
`structing first portions of the membrane conical portion
`to have a contracting appearance relative to axially
`adjacent portions of the membrane. The contracting
`construction may be such that upon expansion the con(cid:173)
`tracting portion first becomes visible at a preselected
`pressure.
`The annular wall segments may be constructed to be
`of varying thickness, the segments closest to an outer
`edge of the membrane being thinner than those further
`from the outer edge. When contructed in this manner,
`the membrane axially expands and contracts in a non(cid:173)
`linear manner. This enables pressure surge protection of
`the transducer.
`Since the membrane, upon expansion and contrac(cid:173)
`tion, unfolds and folds rather than stretching like a
`conventional diaphragm, there is a reduced tendency
`for the membrane to crack or break in use. Also, this
`method of construction, in conjunction with a relatively
`large diameter, and axially long chamber, permits the
`membrane to sweep out large volumes of the chamber
`as it expands and contracts in response to system blood
`pressure variations and fluctuations, rather than small
`
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`4,077,882
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`3
`volumes as would a diaphragm. This adapts the appara(cid:173)
`tus for use with very sensitive transducers.
`Thus the apparatus performs the several important
`functions of physically separating the transducer from
`the blood pumping and purifying portion of the system 5
`to prevent contamination of the blood in the system, of
`transmitting system blood pressure in a linear or non(cid:173)
`linear manner, according to the type of membrane used,
`and protecting the transducer from possibly damaging
`blood pressure spikes.
`The apparatus is constructed in a relatively inexpen(cid:173)
`sive manner so that it can be di~posed of after a single
`use, if desired.
`
`4
`the transducer 18. Additionally, the means 22 functions
`as a small pressure surge chamber which dampens out
`pressure spikes in the portion 12 and protects the trans-
`ducer 18 from pressure surges.
`Included in the means 22 is,an isolation and pressure
`transfering or pressure chamber 24 which has an inlet
`portion 26, connected by a blood line 28 to the portion
`20, and an outlet portion 30, connected by a pressure
`·tube 32 to the transducer 18. (See also FIG. 2). The
`10 blood line 28 and tube 32 comprise conventional non(cid:173)
`toxic medical grade plastic tubing of a type commonly
`employed in extracorporeal blood treatment systems.
`The portions 26 and 30 are on the longitudinal axis of
`the chamber 24 in an apposing relationship.
`BRIEF DESCRIPTION OF THE DRAWINGS
`15 As best seen in FIGS. 2 and 3, the chamber 24 in-
`eludes a rigid, generally transparent medical grade plas-
`A better understanding of the present invention may
`tic housing formed of a first axial housing segment 40
`be had from a consideration of the following detailed
`and a second axial housing segment 42, the inlet portion
`description, taken in conjunction with the accompany-
`26 forming an inlet to the second segment and the outlet
`ing drawings in which:
`FIG. 1 is a drawing, partially in block diagram form, 20 portion 30 forming an outlet to the first segment. Prefer-
`of an extracorporeal blood treatment system using a
`ably the two housing segments 40 and 42 are substan-
`blood isolating and pressure transfering apparatus;
`tially identical, having outwardly projecting mating
`FIG. 2 is an exploded perspective drawing of the
`central flanges 44 and 46 respectively, slightly converg-
`blood isolating and pressure transfering apparatus,
`ing circular wall portions 48 and 50, connected to the
`showing elements thereof;
`25 flanges 44 and 46 respectively, and relatively steeply
`FIG. 3 is a side elevational view, partially cut away,
`converging, generally conical ends 50 and 52 respec-
`along line 3-3 of FIG. 1, showing features of the blood
`tively.
`As seen in FIG. 3, outer circular surfaces the inlet and
`isolating and pressure transfering apparatus;
`FIG. 4 is an end elevational view along line 4-4 of
`outlet portions 26 and 30 are slightly converging
`FIG. 2, showing, in an expanded configuration, a blood 30 towards exposed entrances and exit ends, respectively,
`enabling tubing to be tightly slipped thereover. How-
`isolating and pressure transfering membrane used in the
`apparatus,
`ever, each such such portion 26 and 30 is also formed
`FIG. 5 is a cross sectional view along line 5-5 of
`having an enlarged cylindrical bore 54 at the exposed
`FIG. 4, showing construction of the membrane;
`ends enabling ends of tubing to be received therein.
`FIG. 6 is a cross sectional view of the membrane of 35 That is, the portions 26 and 30 have combined male and
`FIGS. 4 and 5, showing the membrane in a collapsed or
`female tubing receiving characteristics.
`The housing, comprising segments 40 and 42 is, when
`telescoped configuration; and
`FIG. 7 is a cross sectional view of a variation of the
`assembled, impervious to gas or liquids, is non-porous
`membrane of FIG. 4-6, showing features of its con-
`and easy to clean and is resistant to shock and pressure
`40 changes therein. Generally cylindrical in shape, the
`struction.
`housing, and hence the chamber 24, has a transverse
`cross sectional diameter at any axial point substantially
`greater than that of the inlet and outlet portions 26 and
`30, and likewise has an axial length, exclusive of such
`portions 26 and 30, substantially greater than the diame(cid:173)
`ters of these portions. Thus, there is substantial volume
`in the chamber 24, thereby making it suitable for func(cid:173)
`tioning as a surge chamber.
`Installed within the chamber 24, between the housing
`segment flanges 44 and 46, is a strong thin, flexible
`blood isolating and pressure transmitting membrane 60.
`The outer circular periphery of the membrane .60 is
`formed with a siding bead 62 (FIGS. 3-5) which, upon
`assembly is received, in sealing relationship, into mating
`annular recesses 64 and 66 formed in aJmtting faces of
`the housing segment flanges 44 and 46 respectively
`(FIG. 3).
`As best seen in FIGS. 4 and 5, the membrane 60 is
`constructed having a hollow, generally frustoconical
`shape, a conical portion 70 thereof being formed contin(cid:173)
`uously with a circular flange portion 72, the latter of
`which includes the bead 62. The conical portion 70 is
`formed in a general stair-case or accordian-pleated man(cid:173)
`ner comprising a plurality (six being shown) of inter(cid:173)
`connected steps 74, each of which is formed of annular
`wall segments, a first, generally axial portion 76 of each
`segment being directed in a converging direction
`towards the closed end of the conical portion 70 and a
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`An extracorporeal blood treatment system for exam(cid:173)
`ple, a kidney dialysis machine or the like 10, as seen in 45
`FIG. 1, includes a blood pumping and purifying portion
`12 adapted for connecting to the blood stream of a
`patient (not shown) for cleansing the patient's blood and
`a control portion 14, connected to the pumping and
`purifying portion by connecting means 16 for pressure 50
`control of the system in a conventional manner. The
`control portion 14 includes at least one very sensitive
`pressure sensing transducer 18, of conventional design,
`which has electrical outputs proportional to the pres(cid:173)
`sure sensed. By means of these proportional electrical 55
`outputs, blood pressure in the pumping and purifying
`portion is controlled within preestablished limits.
`Connected between the transducers 18 and a portion
`20 of the pumping and purifying portion 12 through
`which flows, or which receives, pressurized blood, in a 60
`blood isolation and pressure transfering means 22. Such
`means 22 functions to transfer or transmit pressure of
`blood in the pumping and purifying portion 12 to the
`pressure transducer 18, which in turn, through the con(cid:173)
`trol portion 14, controls blood pumping and valving in 65
`the portion 12. At the same time, the means 22 isolates
`blood in the pumping and purifying portion 12 from air
`or other contaminants which may be associated with
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`4,077,882
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`second generally radial portion 78 being directed gener(cid:173)
`ally orthogonally to the first portion 76. The closed end
`of the cone portion 70, terminates in a flat small diame(cid:173)
`ter, transverse end segment 80.
`The staircase-type construction of the membrane 60 S
`permits the conical portion 70 to axially expand to the
`extended or nearly extended configuration of FIG. 5
`and to axially contract or telescope into an intermediate,
`generally folded configuration shown in FIG. 6 without
`any significant stretching. Such construction also ena- 10
`bles the conical portion 70 to tum inside out in response
`to a change from positive to negative blood pressure at
`the housing inlet portion 26. That is, the conical portion
`70 can axially contract or telescope in a uniform manner
`from the positive inlet pressure configuration illustrated 15
`in FIGS. 3 and 5, to the intermediate configuration of
`FIG. 6 as pressure in the inlet portion 26 is reduced. As
`pressure in the inlet portion 26 further decreases to a
`negative value, the conical portion 70 then axially ex(cid:173)
`tends the expands towards the inlet portion. Relatively 20
`uniform contraction and expansion of the cone portion
`70 is permitted by the staircase-type construction, and
`the degree of extension/contraction is a direct function
`of blood pressure at the housing inlet portion. The hous(cid:173)
`ing segment 44 to the transducer side of the membrane 25
`60, as well as the tube 32 leading to the transducer 18
`are filled with a pressure transmitting media, such as air
`or gaseous nitrogen. Axial movement of the membrane
`conical portion 70, in response to blood pressure fluctu(cid:173)
`ations in the inlet portion 26, transmits the blood pres- 30
`sure to the transducer 18 through the pressure transmit(cid:173)
`ting media. It is emphasized that the conical portion 70
`of the membrane 60, because of its manner of construc(cid:173)
`tion, is permitted to move axially to sweep out a large
`volume of the chamber 24 thereby making it particu- 35
`larly adapted for use with very sensitive transducers.
`A gas and liquid seal is provided between the housing
`segments 40 and 42, and hence between the transducer
`18 and the pumping and purifying portion 12 of the
`system 10, by the membrane 60. Because movement of 40
`the membrane conical portion 70 is by means of axial
`unfolding and folding, rather than by stretching, the
`membrane 60 is generally more resistant to cracking or
`breaking than a conventional diaphragm which must
`stretch to operate. The membrane 60 may, for example, 45
`be constructed of a thin film, approximately 0.020
`inches thick of a strong, flexible silicone rubber material
`such as Dow Coming.
`Because axial extending and contracting of the mem(cid:173)
`brane conical portion 70 is relatively uniformly related 50
`to the blood pressure at the housing inlet portion 26, the
`extent of extension and contraction, as well as the direc(cid:173)
`away from or towards the housing
`tion of extension -
`inlet portion -
`as can be seen through the transparent
`housing segments 40 and 44, provides an operator with 55
`a visible indicator of blood pressure in the pumping and
`purifying portion 12. A visual monitoring of the proper
`blood pressure in the system 10 is thereby provided
`which is in addition to any indicators which may be
`associated with the transducer 18. Since the membrane 60
`60 is directly operated by blood pressure in the system,
`such a visual indication of system blood pressure serves
`as an important check of, or back-up for, the system
`control portion 14.
`To enhance this visual monitoring of blood pressure 65
`by observing the degree and direction of extension of
`the conical portion 70, selected ones, for example step
`82, of the steps 74 may be formed having an appearance
`
`6
`which contrasts with that of adjacent steps. For exam(cid:173)
`ple, the selected steps 82 may be of a contrasting color.
`When the conical portion 70 is in the intermediate con(cid:173)
`figuration of FIG. 6 and even as some axial extension
`occurs, the selected step 82 remains hidden in the folds.
`As more pressure in the inlet portion 26 causes greater
`extension of the membrane conical portion 70, the con(cid:173)
`trast of the selected step 82 becomes visible. In this
`manner, the membrane 60 can be constructed so that
`when a preselected, for example, a near maximum al(cid:173)
`lowable, blood pressure in the system is reached, the
`contrasting selected step 82 becomes visible.
`By constructing the membrane 60 of a material of
`uniform thickness (except for the bead 62) the degree of
`axial expansion/contraction of the conical portion 70 is
`directly related, in a generally proportional manner, to
`the blood pressure at the housing inlet portion 26. Thus,
`if the axial expansion doubles, as an illustration, the
`blood pressure will also have had to about double.
`However, by constructing various portions of the
`membrane of different thicknesses, the generally di(cid:173)
`rectly proportional expansion can be caused to be
`changed. It can be changed so that, for example, a dou(cid:173)
`bling of blood pressure at the inlet portion 26 will cause
`either more or less than a doubling of extension of the
`conical portion 70. As an illustration, with no limitation
`intended or implied, the wall thickness of a conical
`portion 70a of a variation membrane 60a can be con(cid:173)
`structed to vary in a generally uniform manner, as seen
`in FIG. 7, from a flange 72a to a transverse end segment
`80a, steps 74a closest to the flange being for example,
`thinner than steps closest to the end portion. The coni(cid:173)
`cal portion wall thickness may, in this manner, vary
`from about 0.012 inches to 0.020 inches. Since those of
`the steps 74a closest to the flange 72a are thinner and
`hence more flexible than other steps closer to the end
`segment 80a, axial extension and telescoping or contrac(cid:173)
`tion in response to blood pressure at the inlet portion 26
`will start at the steps near the flange. This characteris(cid:173)
`tic, in combination with forming selected ones of the
`steps 74a to be of visually contrasting appearance, en(cid:173)
`hances the visual observation of preselected pressures,
`as described above.
`The variable thickness of the membrane 60a also
`enables the membrane to function as a dampening de(cid:173)
`vice, as well as a gas and liquid barrier and a pressure
`transmitter, to protect a sensitive transducer from oth(cid:173)
`erwise damaging high blood pressure spikes.
`As an illustrative example, the chamber 24 may be
`about 1 l inches in diameter and vary in axial length
`from about 2 to 2l inches, having a corresponding vol(cid:173)
`ume of from about 7-15 cc's and being adapted for
`maximum pressures of about 600 mm/mercury.
`The chamber 24 is constructed in a comparatively
`inexpensive manner to be disposable, if desired, after a
`single use.
`Although there has been described above specific
`arrangements of a blood isolating and pressure transfer(cid:173)
`ing apparatus for use in extracorporeal blood treatment
`systems and a variation thereof, in accordance with the
`invention for the purpose of illustrating the manner in
`which the invention may be used to advantage, it will be
`appreciated that the invention is not limited thereto.
`Accordingly, any and all modifications, variations or
`equivalent arrangements which may occur to those
`skilled in the art should be considered to be within the
`scope of the invention as defined in the appended
`claims.
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`2. The apparatus according to claim 1, wherein said
`annular wall segments are formed having a substantially
`uniform· thickness.
`3. The apparatus according to claim 1, wherein said
`annular wall segments are formed having substantially
`uniformly varying thickness, the wall segments Closest
`to the outer periphery being substantially thinner than
`the wall segments most remote from the outer periph(cid:173)
`ery.
`· 4. The apparatus according to claim 3, wherein the
`wall segment thickness varies from about 0.012 inches
`adjacent to the outer periphery to about 0.020 inches for
`wall segments most remote from the outer periphery.
`5. The apparatus according to claim 1, wherein the
`membrane is formed having about six steps, each step
`being of substantially the same size.
`6. The apparatus according to claim 1, wherein the
`housing is formed of substantially transparent material
`to thereby permit visual observation of the membrane.
`7. The apparatus according to claim 6, wherein first
`selected portions of the membrane are formed to be
`color contrasting to axially adjacent second portions of
`the membrane, axial expansion and telescoping of the
`membrane causing, respectively, the first portion to be
`visible and non-visible, a visual indication of a prese(cid:173)
`lected blood pressure being provided when the first
`portion is visible.
`8. The apparatus according to claim 1, wherein the
`housing is formed having an axial length substantially
`greater than transverse cross sectional dimensions of the
`inlet and outlet portions, the chamber thereby having a
`relatively substantial volume.
`9. The apparatus according to claim 8, wherein the
`membrane is generally axially centered in the chamber
`and wherein the membrane is operative for sweeping
`out substantially the entire volume of the chamber in
`response to extreme ranges of pressure in the blood
`pumping and purifying portion.
`10. The apparatus according to claim 1, wherein the
`housing is generally cylindrical in shape, the outer pe(cid:173)
`riphery of the membrane being substantially circular.
`11. The apparatus to claim 9, wherein the inlet and
`outlet portions are generally conical in shape, converg(cid:173)
`ing, respectively towards the pumping and purifying
`portion and the transducer.
`12. The apparatus according to claim 1, wherein the
`membrane is formed of a silicon rubber material having
`a substantially uniform thickness of about 0.020 inches.
`* * * * *
`
`What is claimed is:
`1. In combination with an extracorporeal blood treat(cid:173)
`ment system having a blood pumping and purification
`portion for connecting to a patient, at least one pressure
`sensing transducer for sensing pressure in the pumping 5
`and purifying portion and control means responsive to
`the pressure transducer for controlling blood pressure
`in the pumping and purifying portion within predeter(cid:173)
`mined limits, apparatus for isolating the transducer from
`blood flowing in the pumping and purifying portion 10
`while permitting the pressure of the blood therein to be
`transmitted to the transducer, the apparatus comprising:
`(a) a substantially rigid pressure chamber including a
`gas and liquid impermeable, non-toxic housing
`having relatively apposing, axial pressure inlet and 15
`outlet portions
`said housing having a transverse cross sectional
`area substantially greater than transverse cross
`sectional areas of the inlet and outlet portions,
`(b) means for connecting the inlet portion to a blood 20
`carrying portion of the pumping and purifying
`portion for receiving pressurized blood therefrom
`and for connecting the outlet portion to the trans(cid:173)
`ducer for transmitting pressure of the pressurized
`blood thereto, and
`(c) membrane means disposed transversely across the
`pressure chamber for physically isolating the outlet
`portion from the inlet portion and preventing the
`flow of pressurized blood therebetween
`said membrane means comprising a flexible gas and 30
`fluid impermeable membrane formed into a gen(cid:173)
`erally frustoconical configuration and having
`outer peripheral edge portions connected to
`walls of the housing
`said membrane being formed having a plurality of 35
`concentric, annular wall segments intercon(cid:173)
`nected to form a collapsible staircase-like struc(cid:173)
`ture permitting the membrane to be extended in
`either axial direction and being turned inside out
`as it passes through a central position between 40
`extension in opposite directions in response to
`positive and negative pressures transmitted to an
`inlet portion side thereof by the pressurized
`blood, the membrane thereby causing pressure of
`the pressurized blood to be transmitted to the 45
`transducer through the outlet portion and a pre(cid:173)
`selected pressure transmitting media contained
`between an outlet side of the membrane and the
`transducer.
`
`25
`
`50
`
`55
`
`60
`
`65
`
`000007
`
`Nipro Ex. 1006