CA1122445A - Dialysis apparatus and technique - Google Patents
Dialysis apparatus and techniqueInfo
- Publication number
- CA1122445A CA1122445A CA363,894A CA363894A CA1122445A CA 1122445 A CA1122445 A CA 1122445A CA 363894 A CA363894 A CA 363894A CA 1122445 A CA1122445 A CA 1122445A
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- CA
- Canada
- Prior art keywords
- cap
- casing
- chamber
- flange
- skirt
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Separation Using Semi-Permeable Membranes (AREA)
Abstract
A process of securing a cap on the end of a tubular artificial kidney casing wherein the casing has an outwardly extending encircling flange of fusible plastic near said end, the cap is also of fusible plastic and has a body thickness of at least about 2 millimeters, and the cap has a skirt that is welded to the flange by applying a high-frequency vibrating member to the cap body while supporting the remote face of the flange.
Description
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This invention relates to a process of secur;ng a cap on the end of a t~bular artificial kidney casing, and to an artificial kidney produced using such a process.
Accordingly, the invention resi`des in one aspect in a process of securing a cap on the end of a tubular artificial kidney casing wherein the casing has an outwaLdly encircling flange of fusible plastic near said end, the cap is also of fusible plastic and has a body thickness of at least about 2 millimeters, and the cap has a skirt at the bottom edge of which is welded to the flange by applying a high frequency vibrating member to the cap body while supporting a face of the flange remote from the cap and holding it against the skirt body.
In the accompany;ng drawings, Figure 1 is a front elevation, partly in section, of an artificial k;dney produced using a process according to one example of the present invention, - Figure 2 is a view generally along the line 2-2 of Figure 1, illustrating the internal operation of the artificial kidney; and 2Q Figure 3 is a sectional view along the line 3-3 of Figure 2.
Referring to the drawings, an artificial kidney 10 has a plastics casing 12 formed, for example, of polystyrene with enlarged header end portions 14, 16 and with securing flanges 18 and 20 encircling each end portion.
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This invention relates to a process of secur;ng a cap on the end of a t~bular artificial kidney casing, and to an artificial kidney produced using such a process.
Accordingly, the invention resi`des in one aspect in a process of securing a cap on the end of a tubular artificial kidney casing wherein the casing has an outwaLdly encircling flange of fusible plastic near said end, the cap is also of fusible plastic and has a body thickness of at least about 2 millimeters, and the cap has a skirt at the bottom edge of which is welded to the flange by applying a high frequency vibrating member to the cap body while supporting a face of the flange remote from the cap and holding it against the skirt body.
In the accompany;ng drawings, Figure 1 is a front elevation, partly in section, of an artificial k;dney produced using a process according to one example of the present invention, - Figure 2 is a view generally along the line 2-2 of Figure 1, illustrating the internal operation of the artificial kidney; and 2Q Figure 3 is a sectional view along the line 3-3 of Figure 2.
Referring to the drawings, an artificial kidney 10 has a plastics casing 12 formed, for example, of polystyrene with enlarged header end portions 14, 16 and with securing flanges 18 and 20 encircling each end portion.
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-2-Z49~5 Ultrasonically welded to each flange is a plastics end cap 22, 24 which covers the casing ends and has a central nipple 26, 28 for introducing the liquid to be dialy~ed at one end and removing it at the other. The caps can be made of the same plastics material as the casingO
The interior of the casing contains partitioning that subdivides it into a plurality of chambers and passageways extending longitudinally through it, as more clearly seen in Figure 3. Thus parti-tioning 30 subdivides the interior of the casing into three large-bore chambers 31, 33 and 35 as well as two smallbore passageways 32, 34. The chamber and passageways extend the length of the casing and are only interconnected near the casing ends. Near the upper end a port 41 in the partitioning 30 establishes communi-cation between the upper portions of chamber 31 and pas-sageway 32. ~ similar port ~not shown) in the lower por--tion of the partitioning establishes communication between the lower portions of passageway 32 and chamber 33, a third port 43 in the upper portion of the partitioning establishes communication between the upper portions of chamber 33 and passageway 34, and a fourth port (also not shown) at the lower portion of the partitioning establishes communication between the lower portions of passageway 32 and chamber 35.
A dialyzate inlet connector 51 is moulded integrally with the enlarged lower end portion 14 of the casing and opens into the lower portion of chamber 31, while a dialyzer outlet connector 52 correspondingly provided in the upper enlarged casing end portion 16 opens into the upper portion of chamber 35 to complete the dialyzate flow path.
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A bundle of hollow dialysis fibres 48 i5 inserted in each chamber 31, 33, 35, the fibres extending the length of the casing. At or near each casing end the fibres are potted in an end wall 54 of a sealing resin that can project somewhat from the casing end as illustrated in Figures 1 and 2. End caps can be sealed against these end walls by gaskets such as 0-rings 56 shown in Figure 1 as fitted between short flanges 58 projecting from the end wall 60 of each end cap.
Potting resin 54 which can be a polyurethane, leaves the hollow interiors of the fibres 48 open so that the liquid to be dialyzed flows through these fibres, prefer-ably countercurrent to the flow of the dialyzate in cham-bers 31, 33 and 35. Thus blood or other liquid to be dialyzed can be introduced through upper nipple 28 and withdrawn from lower nipple 26, while dialyzate is intro-duced into connector 51 and withdrawn throuyh connector 52. The dialyzate flows upwardly through chamber 31 around and between the individual fibres in that chamber, then down through passageway 32, after which it flows upwardly through chamber 33 around and between the indi-vidual fibres there, then descends through passageway 34 for a final pass upwardly through chamber 35 around and between the individual ibres there. From the upper portion of chamber 35 the dialyzate flows out of the dialyzer 10 through the outlet connector 52.
The casing 12 is made of transparent plastic like polystyrene so that the contents of passageways 32, 34 as well as their side walls are clearly seen from outside the casing. Chambers 31, 33 and 35 are also seen from outside the casing, but these chambers are essentially filled with the hollow dialysis fibres ~8, and when a dark liquid like blood is being dialyzed very little detail can be made out visually other than the presence or absence of gas bubbles in front of the fibres.
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In one embodiment of the present invention the lengths of chambers 31l 33 and 35 between the enlarged casing ends :L4l 16 are cylindrical with diameters of about 2 1/3 centimeters so that each chamber can be packed with something over 3,000 hollow fibres to provide a total membrane dialysis surface oE about 1 s~uare meter per dialyzer or about 1/3 square meter per chamber. The pas-sageways 32, 34 in this embodiment are cylindrical with diameters of about 3/4 to about 4/5 centimeter. So dimen-sioned the standard dialyzate flow rates of 300 or 500 millimeters per minute will be rapid enough to flush out of the dialyzer essentially all gas bubbles that may appear in the dialyzate as the dialyzate passes through it.
For measuring the rate of ultrafiltration taking place in the artificial kidney a volume o:E gas such as air is deliberately introduced into -the dialyzate contained in the artificial kidney. To this end Figure 1 shows a gas-injecting attachment 70 that has a body 72 carrying a standard dialyzate connector 74, which connector is fitted to the dialyzer's dialyzate intake connector 51. Body 72 also carries another standard dialyzate connector 76 for connection to the dialyzate supply output of a source of dialyzate, and a bore 78 that establishes communication between the two connectors 74, 76~
Connector 74 is shown as of the female type having a socket 71 that receives connector 51 and an O-ring seal 73 against which a tapered tip 53 on connector 51 seats.
Connector 51 is latched in sealing engagement with the 0-ring by a set of balls 75 held in apertures around the wall of socket 71 and forced into a grocve 55 in connector 51 by a slide ring 77. The engagement is unlatched by sliding the slide ring toward the body 72 against the resistance of spring 791 far enough to bring a relieved ,.j..
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internal taper 57 of the slide around the walls thus per-mitting ~he balls to be moved outwardly in a radial direc-tion into the wall of socket 71 when the connectors are pulled apart. A locking snap ring 59 can be snapped into a groove on the outer face of the socket 71 to keep the slide ring 77 from coming off the connector when in use, but permitting disassembly when desired.
Also communicating with bore 78 is a branch 80 that leads to a nipple 82 projecting from the surface of body 74 and onto which is frictionally mounted a plastic or rubber outlet tube ~4 of a gas injector 86. This injector has a squeezable bulb 88 secured as by cementing or weld-ing to tube 84, and carrying an air inlet tube 90. Valves 91, 92 in tubes 81 and 90 control the air injection action, and a filter such as a plug 94 of foamed plastic or rubber can be used to make sure solid particles are kept out of the entering air.
Valves 91, 92 can be of any desired type, but are shown as balls of relatively inert material such as stainless steel very snugly held in encirclinq seats moulded into thick-walled portions of tubes 84 and 90. As in conven-tional laboratory pipette Eilling adaptors, by making the tube walls at least about 3 millimeters thick but still yieldable, the valve seats will deform when opposed portions of the tube around them are manually pinched toward each other, and in such deformation at least one section of the seat will be forced away from the valve ball~ This opens the valve. Releasing the pinch permits the valve seat to return to ball-gripping engagement over its entire periphery and this keeps the valve closed.
The apparatus of Figures 1 through 3 is placed in operation by connecting it to a source of dialyzate at 76 as well as to dialyzate removal means at 52, and to a source of blood or other liquid to be dialyzed at 28 as well as to return for such liquid at 26.
~L2;2~45 For measuring ultrafiltration, the dialyzer preferably has its dialysis chambers and passageways first filled with dialyzate, following which a volume of air is introduced into chamber 31 by operation of the air injector 70. Such operation is easily effected by pinching tube 84 at valve 91 and squeezing bulb 88. The bulb can be dimensioned so that one squeeze will inject a suitable quantity of air into bore 78 and from there by way of connector 51 into chamber 31. Valve 91 can then be released to cause it to close, and it is sometimes helpful to tilt the apparatus to help move the large air bubble into chamber 31. After valve 91 is closed, valve 92 can be opened momentarily to permit the bulb to expand and suck in a fresh supply of air through filter 94. This places the apparatus in condition for the next injection of air.
The connection between connector 76 and the dialyzate source is preferably closed as by a shut-off valve r when the air injection is taking place. This will assure that the injected air is not carried by incoming dialyzate too far through dialyzer 10 to permit the desired measurement of ultrafiltration rate. The introduction of dialyzate into the dialyzer is also shut off when that measurement is being made.
Immediately after the injected air reaches chamber 31 it rises to the top of that chamber. If the dialyzer is maintained generally upright the air will not only reach the top of chamber 31 but it will also move into the upper portion of passageway 32 and part way down that passageway until the height occupied by the air is about the same in that passageway as in that chamber. This leaves the liquid level in passageway 32 relatively low so that the volume of ultrafiltration that can be measured by downward movement of that water level is limited.
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If the volume of air lnjected is kept small 50 as to provide a high liquid level in passageway 32r then the liquid level in chamber 31 is also relatively high and liquid from that chamber will spill over into the passageway after a very limited amount oE ultrafiltration.
Such spill-over makes it impossible to subsequently measure ultrafiltration by liquid level changes.
To avoid such limitation the dialyzer can be tilted when the introduced air has risen. The degree of tilt is such that it causes 1 iqu id to flow from near the tilted upper end of chamber 31 into the -tilted upper end of passageway 32. In this way the liquid levels can be adjusted so that after restoring the dialyzer to its upright position, they are generally in positions such as shown at 37, 38 in Figure 2.
So long as the blood or other liquid being dialyzed flows through the hollow fibers, ultraEiltration takes place causing water to move from the liquid being dialyzed through the walls of the fibres. As a result there will be a gradual increase in volume of the dialyzate around the fibres in chamber 31 and the air bubble will move down into passageway 32. In Figure 2 the dialyzate level 37 in passageway 32 is starting its slow traverse through that passageway. That traverse is easily measured with an ordinary watch or clock having a seconds hand. A stop-watch can be used but is not necessary inasmuch as the measurement times can be 30 seconds or longer and split-second timing does not add much to the measurement accuracy.
The traverse of level 37 can be measured from the time it leaves the level of the floor 41 of header 16, to the time it reaches the top 42 of header 14. It is preferred however to apply a scale alongside passageway 32, as by means of a label 69 cemented onto the outside of ., the dialyzer casing. Inasmuch as a label is generally used to carry instructions as to the connections made to the dialyzer, the ultraEiltration-measuring scale can be conveniently added to such a label. The presence of a scale also enables the making of two or more successive measurements during a single traverse of the gas bubble through passageway 32.
Inasmuch as the ultra-filtration rate essentially depends on the difference between the pressures on the inside and outside of the hollow fibres, those pressures should be adjusted to the valves at which the ultrafiltration rate is to be measured, and should not be changed during the measurement. The presence of a gas bubble in chamber 31 and the traverse of part of the bubble into passageway 32 will not significantly affect either of the critical pressures.
Blood is generally under a superatmospheric pressure of a hundred or so tor when it is being dialyzed, although that pressure can range from a low of about 30 tor to a high of about 160 tor or even higher. The dialyzate is generally under a subatmospheric pressure of about minus 50 to about minus 100 tor but can range from almost zero to an extreme of about minus 350 tor. While it is not essential to have the dialyzate at subatmospheric pressure, the use of subatmospheric pressure speeds up ultrafiltration. As a matter of precaution the dialyzate pressure is substantially below the pressure at which the blood is supplied, to keep dialyzate from enterinq the blood stream in the event there is a lealc in the dialyzer.
To maintain subatmospheric pressure in the dialyzate the dialyzer's dialyzate outlet 52 is preferably maintained in connection with the dialyzate supply system that develops such negative pressure.
As previously stated, the plastics end caps 22, 24 are r.~
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ultrasonically welded to the Elanges 18, 20 respectively t this method producing a very sturdy structure which is inexpenslve to manufacture. To effect the welding opera-tionr the casiny 12 is placed in a holder which supports it by engaging the lower face of Elange 20. The cap 24 is then placed in position over the flange 20 and a cylindri-cal vibrating piston is then lowered onto the cap 24 so that the edge face of the cylinder engages the periphery of the cap end wall 60. The piston is hollowed out at its edge face to receive nipple 28 and the immediately sur-rounding portions of wall 60 that extend up higher than its periphery. The cylinder vibration is then actuated at about 20 to 25 kilohertz for about one second or less to complete the welding.
It has been found that the ultrasonic welding will not produce a good product unless wall 60 of the end cap is at least about 2 millimeters thick. Smaller thick-nesses are susceptible to damage during the ultrasonic welding. Preferred thicknesses are from about 3 to about ~ millimeters. The provision of a narrow ridge on the welding face of flange 20, as shown at 39, also helps with the ultrasonic welding process.
It is also very desirable to vent the portion of the end cap outside the seal effected by the gasket 56. In Figure 1 such venting is shown at a notch 40 on1y about 1 to 2 millimeters wide and about 2 millimeters deep, exten-ding across the lip of the cap's side wall. This simpli-fies testing of the seal between the end cap and the end wall 54 of the dialyzer body. Such testing can be simply accomplished by connecting nipple 2~3 to a source of pres-surized air, closing off nipple 26, momentarily applying pressure of about 300 tor through nipple 28 and permitting the pressurized assembly to stand with a pressure gauge attached to see whether there is a loss of pressure. No loss of pressure after about 10 - 15 seconds demonstrates 'A . ~Z,~
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that both end cap seals are satisfactory and also that there is no significant leakage through or around the dialysis fibres.
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The interior of the casing contains partitioning that subdivides it into a plurality of chambers and passageways extending longitudinally through it, as more clearly seen in Figure 3. Thus parti-tioning 30 subdivides the interior of the casing into three large-bore chambers 31, 33 and 35 as well as two smallbore passageways 32, 34. The chamber and passageways extend the length of the casing and are only interconnected near the casing ends. Near the upper end a port 41 in the partitioning 30 establishes communi-cation between the upper portions of chamber 31 and pas-sageway 32. ~ similar port ~not shown) in the lower por--tion of the partitioning establishes communication between the lower portions of passageway 32 and chamber 33, a third port 43 in the upper portion of the partitioning establishes communication between the upper portions of chamber 33 and passageway 34, and a fourth port (also not shown) at the lower portion of the partitioning establishes communication between the lower portions of passageway 32 and chamber 35.
A dialyzate inlet connector 51 is moulded integrally with the enlarged lower end portion 14 of the casing and opens into the lower portion of chamber 31, while a dialyzer outlet connector 52 correspondingly provided in the upper enlarged casing end portion 16 opens into the upper portion of chamber 35 to complete the dialyzate flow path.
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A bundle of hollow dialysis fibres 48 i5 inserted in each chamber 31, 33, 35, the fibres extending the length of the casing. At or near each casing end the fibres are potted in an end wall 54 of a sealing resin that can project somewhat from the casing end as illustrated in Figures 1 and 2. End caps can be sealed against these end walls by gaskets such as 0-rings 56 shown in Figure 1 as fitted between short flanges 58 projecting from the end wall 60 of each end cap.
Potting resin 54 which can be a polyurethane, leaves the hollow interiors of the fibres 48 open so that the liquid to be dialyzed flows through these fibres, prefer-ably countercurrent to the flow of the dialyzate in cham-bers 31, 33 and 35. Thus blood or other liquid to be dialyzed can be introduced through upper nipple 28 and withdrawn from lower nipple 26, while dialyzate is intro-duced into connector 51 and withdrawn throuyh connector 52. The dialyzate flows upwardly through chamber 31 around and between the individual fibres in that chamber, then down through passageway 32, after which it flows upwardly through chamber 33 around and between the indi-vidual fibres there, then descends through passageway 34 for a final pass upwardly through chamber 35 around and between the individual ibres there. From the upper portion of chamber 35 the dialyzate flows out of the dialyzer 10 through the outlet connector 52.
The casing 12 is made of transparent plastic like polystyrene so that the contents of passageways 32, 34 as well as their side walls are clearly seen from outside the casing. Chambers 31, 33 and 35 are also seen from outside the casing, but these chambers are essentially filled with the hollow dialysis fibres ~8, and when a dark liquid like blood is being dialyzed very little detail can be made out visually other than the presence or absence of gas bubbles in front of the fibres.
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In one embodiment of the present invention the lengths of chambers 31l 33 and 35 between the enlarged casing ends :L4l 16 are cylindrical with diameters of about 2 1/3 centimeters so that each chamber can be packed with something over 3,000 hollow fibres to provide a total membrane dialysis surface oE about 1 s~uare meter per dialyzer or about 1/3 square meter per chamber. The pas-sageways 32, 34 in this embodiment are cylindrical with diameters of about 3/4 to about 4/5 centimeter. So dimen-sioned the standard dialyzate flow rates of 300 or 500 millimeters per minute will be rapid enough to flush out of the dialyzer essentially all gas bubbles that may appear in the dialyzate as the dialyzate passes through it.
For measuring the rate of ultrafiltration taking place in the artificial kidney a volume o:E gas such as air is deliberately introduced into -the dialyzate contained in the artificial kidney. To this end Figure 1 shows a gas-injecting attachment 70 that has a body 72 carrying a standard dialyzate connector 74, which connector is fitted to the dialyzer's dialyzate intake connector 51. Body 72 also carries another standard dialyzate connector 76 for connection to the dialyzate supply output of a source of dialyzate, and a bore 78 that establishes communication between the two connectors 74, 76~
Connector 74 is shown as of the female type having a socket 71 that receives connector 51 and an O-ring seal 73 against which a tapered tip 53 on connector 51 seats.
Connector 51 is latched in sealing engagement with the 0-ring by a set of balls 75 held in apertures around the wall of socket 71 and forced into a grocve 55 in connector 51 by a slide ring 77. The engagement is unlatched by sliding the slide ring toward the body 72 against the resistance of spring 791 far enough to bring a relieved ,.j..
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internal taper 57 of the slide around the walls thus per-mitting ~he balls to be moved outwardly in a radial direc-tion into the wall of socket 71 when the connectors are pulled apart. A locking snap ring 59 can be snapped into a groove on the outer face of the socket 71 to keep the slide ring 77 from coming off the connector when in use, but permitting disassembly when desired.
Also communicating with bore 78 is a branch 80 that leads to a nipple 82 projecting from the surface of body 74 and onto which is frictionally mounted a plastic or rubber outlet tube ~4 of a gas injector 86. This injector has a squeezable bulb 88 secured as by cementing or weld-ing to tube 84, and carrying an air inlet tube 90. Valves 91, 92 in tubes 81 and 90 control the air injection action, and a filter such as a plug 94 of foamed plastic or rubber can be used to make sure solid particles are kept out of the entering air.
Valves 91, 92 can be of any desired type, but are shown as balls of relatively inert material such as stainless steel very snugly held in encirclinq seats moulded into thick-walled portions of tubes 84 and 90. As in conven-tional laboratory pipette Eilling adaptors, by making the tube walls at least about 3 millimeters thick but still yieldable, the valve seats will deform when opposed portions of the tube around them are manually pinched toward each other, and in such deformation at least one section of the seat will be forced away from the valve ball~ This opens the valve. Releasing the pinch permits the valve seat to return to ball-gripping engagement over its entire periphery and this keeps the valve closed.
The apparatus of Figures 1 through 3 is placed in operation by connecting it to a source of dialyzate at 76 as well as to dialyzate removal means at 52, and to a source of blood or other liquid to be dialyzed at 28 as well as to return for such liquid at 26.
~L2;2~45 For measuring ultrafiltration, the dialyzer preferably has its dialysis chambers and passageways first filled with dialyzate, following which a volume of air is introduced into chamber 31 by operation of the air injector 70. Such operation is easily effected by pinching tube 84 at valve 91 and squeezing bulb 88. The bulb can be dimensioned so that one squeeze will inject a suitable quantity of air into bore 78 and from there by way of connector 51 into chamber 31. Valve 91 can then be released to cause it to close, and it is sometimes helpful to tilt the apparatus to help move the large air bubble into chamber 31. After valve 91 is closed, valve 92 can be opened momentarily to permit the bulb to expand and suck in a fresh supply of air through filter 94. This places the apparatus in condition for the next injection of air.
The connection between connector 76 and the dialyzate source is preferably closed as by a shut-off valve r when the air injection is taking place. This will assure that the injected air is not carried by incoming dialyzate too far through dialyzer 10 to permit the desired measurement of ultrafiltration rate. The introduction of dialyzate into the dialyzer is also shut off when that measurement is being made.
Immediately after the injected air reaches chamber 31 it rises to the top of that chamber. If the dialyzer is maintained generally upright the air will not only reach the top of chamber 31 but it will also move into the upper portion of passageway 32 and part way down that passageway until the height occupied by the air is about the same in that passageway as in that chamber. This leaves the liquid level in passageway 32 relatively low so that the volume of ultrafiltration that can be measured by downward movement of that water level is limited.
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If the volume of air lnjected is kept small 50 as to provide a high liquid level in passageway 32r then the liquid level in chamber 31 is also relatively high and liquid from that chamber will spill over into the passageway after a very limited amount oE ultrafiltration.
Such spill-over makes it impossible to subsequently measure ultrafiltration by liquid level changes.
To avoid such limitation the dialyzer can be tilted when the introduced air has risen. The degree of tilt is such that it causes 1 iqu id to flow from near the tilted upper end of chamber 31 into the -tilted upper end of passageway 32. In this way the liquid levels can be adjusted so that after restoring the dialyzer to its upright position, they are generally in positions such as shown at 37, 38 in Figure 2.
So long as the blood or other liquid being dialyzed flows through the hollow fibers, ultraEiltration takes place causing water to move from the liquid being dialyzed through the walls of the fibres. As a result there will be a gradual increase in volume of the dialyzate around the fibres in chamber 31 and the air bubble will move down into passageway 32. In Figure 2 the dialyzate level 37 in passageway 32 is starting its slow traverse through that passageway. That traverse is easily measured with an ordinary watch or clock having a seconds hand. A stop-watch can be used but is not necessary inasmuch as the measurement times can be 30 seconds or longer and split-second timing does not add much to the measurement accuracy.
The traverse of level 37 can be measured from the time it leaves the level of the floor 41 of header 16, to the time it reaches the top 42 of header 14. It is preferred however to apply a scale alongside passageway 32, as by means of a label 69 cemented onto the outside of ., the dialyzer casing. Inasmuch as a label is generally used to carry instructions as to the connections made to the dialyzer, the ultraEiltration-measuring scale can be conveniently added to such a label. The presence of a scale also enables the making of two or more successive measurements during a single traverse of the gas bubble through passageway 32.
Inasmuch as the ultra-filtration rate essentially depends on the difference between the pressures on the inside and outside of the hollow fibres, those pressures should be adjusted to the valves at which the ultrafiltration rate is to be measured, and should not be changed during the measurement. The presence of a gas bubble in chamber 31 and the traverse of part of the bubble into passageway 32 will not significantly affect either of the critical pressures.
Blood is generally under a superatmospheric pressure of a hundred or so tor when it is being dialyzed, although that pressure can range from a low of about 30 tor to a high of about 160 tor or even higher. The dialyzate is generally under a subatmospheric pressure of about minus 50 to about minus 100 tor but can range from almost zero to an extreme of about minus 350 tor. While it is not essential to have the dialyzate at subatmospheric pressure, the use of subatmospheric pressure speeds up ultrafiltration. As a matter of precaution the dialyzate pressure is substantially below the pressure at which the blood is supplied, to keep dialyzate from enterinq the blood stream in the event there is a lealc in the dialyzer.
To maintain subatmospheric pressure in the dialyzate the dialyzer's dialyzate outlet 52 is preferably maintained in connection with the dialyzate supply system that develops such negative pressure.
As previously stated, the plastics end caps 22, 24 are r.~
29~4~
ultrasonically welded to the Elanges 18, 20 respectively t this method producing a very sturdy structure which is inexpenslve to manufacture. To effect the welding opera-tionr the casiny 12 is placed in a holder which supports it by engaging the lower face of Elange 20. The cap 24 is then placed in position over the flange 20 and a cylindri-cal vibrating piston is then lowered onto the cap 24 so that the edge face of the cylinder engages the periphery of the cap end wall 60. The piston is hollowed out at its edge face to receive nipple 28 and the immediately sur-rounding portions of wall 60 that extend up higher than its periphery. The cylinder vibration is then actuated at about 20 to 25 kilohertz for about one second or less to complete the welding.
It has been found that the ultrasonic welding will not produce a good product unless wall 60 of the end cap is at least about 2 millimeters thick. Smaller thick-nesses are susceptible to damage during the ultrasonic welding. Preferred thicknesses are from about 3 to about ~ millimeters. The provision of a narrow ridge on the welding face of flange 20, as shown at 39, also helps with the ultrasonic welding process.
It is also very desirable to vent the portion of the end cap outside the seal effected by the gasket 56. In Figure 1 such venting is shown at a notch 40 on1y about 1 to 2 millimeters wide and about 2 millimeters deep, exten-ding across the lip of the cap's side wall. This simpli-fies testing of the seal between the end cap and the end wall 54 of the dialyzer body. Such testing can be simply accomplished by connecting nipple 2~3 to a source of pres-surized air, closing off nipple 26, momentarily applying pressure of about 300 tor through nipple 28 and permitting the pressurized assembly to stand with a pressure gauge attached to see whether there is a loss of pressure. No loss of pressure after about 10 - 15 seconds demonstrates 'A . ~Z,~
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that both end cap seals are satisfactory and also that there is no significant leakage through or around the dialysis fibres.
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Claims (15)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process of securing a cap on the end of a tubular artificial kidney casing wherein the casing has an outwardly encircling flange of fusible plastic near said end, the cap is also of fusible plastic and has a body thickness of at least about 2 millimeters, and the cap has a skirt at the bottom edge of which is welded to the flange by applying a high frequency vibrating member to the cap body while supporting a face of the flange remote from the cap and holding it against the skirt body.
2. A process as claimed in Claim 1, wherein the casing end has an internal end wall and a resilient gasket is interposed between the wall and the inner face of the cap body before the welding.
3. A process as claimed in Claim 1, wherein the cap skirt has a transverse passageway that is not sealed by the welding.
4. An artificial kidney having a tubular casing and an end cap, the casing having an encircling flange to substantially the entire length of which the bottom edge of a skirt on the end cap is bonded, a ring-shaped gasket between the body of the end cap and an internal end wall near the end of the casing to enclose and seal-in a chamber between cap body and wall, and a passageway through the cap at a location outside the seal-in chamber.
5. A process as claimed in Claim 2 wherein the cap skirt has a transverse passageway that is not sealed by the welding and communicates with the periphery of the gasket.
6. An artificial kidney according to Claim 4 in which the passageway is a notch in the bottom of the skirt.
7. A process of securing a short end-cap on the end of a tubular artificial kidney casing, wherein the casing has an outwardly extending encircling flange of fusible plastic near said end and an inwardly extending end wall, the cap is also of fusible plastic and has a body that closes the casing end as well as a skirt the bottom edge of which is notched and welded to the flange by applying a high-frequency vibrating member to the cap body while supporting the remote face of the flange and holding it against the skirt bottom, the notch remaining unwelded.
8. The Process of Claim 7 in which a ring-shaped gasket is fitted between the cap body and the end wall to enclose and seal-in a chamber at the end of the casing, and the notch communicates with the outer aspect of the gasket ring.
9. An artificial kidney comprising a tubular casing having a first end, a second end, and an internal chamber;
a securing flange encircling, and extending outwardly from, said casing near one end thereof;
a bundle of hollow dialysis fibers in said internal chamber, said bundle of fibers having a first set of fiber ends and a second set of fiber ends, the first set of fiber ends being potted in a potting resin which defines a first internal wall near the first end of the casing, the second set of fiber ends being potted in a potting resin which defines a second internal wall near the second end of the casing, first and second end caps, said first end cap comprising a body portion and a skirt portion having an end edge;
first and second gaskets;
the end edge of the skirt portion of said first end cap being bonded to said securing flange and said first gasket being disposed in sealing relationship between said first internal end wall and said first end cap, whereby there is provided at the first end of said casing a first sealed end chamber in fluid communication with said first set of fiber ends, said first cap having a passageway therethrough at a location outside said first sealed-in chamber;
said second end cap being secured to said second end of said casing and said second gasket being disposed in sealing relationship between said second internal end wall and said second end cap, whereby there is provided at the second end of said casing a second sealed end chamber in fluid communication with said second set of fiber ends;
the lumens of said hollow fibers providing a path for the flow of blood between said first sealed end chamber and said second sealed end chamber;
said casing further comprising an inlet for liquids and an outlet for liquids, each said inlet and outlet being in fluid communication with the internal chamber of said casing and located between said first interior wall and said second interior wall one of said two end caps further comprising means for introducing blood into the artificial kidney and the other of said two end caps further comprising means for withdrawing blood from the artificial kidney.
a securing flange encircling, and extending outwardly from, said casing near one end thereof;
a bundle of hollow dialysis fibers in said internal chamber, said bundle of fibers having a first set of fiber ends and a second set of fiber ends, the first set of fiber ends being potted in a potting resin which defines a first internal wall near the first end of the casing, the second set of fiber ends being potted in a potting resin which defines a second internal wall near the second end of the casing, first and second end caps, said first end cap comprising a body portion and a skirt portion having an end edge;
first and second gaskets;
the end edge of the skirt portion of said first end cap being bonded to said securing flange and said first gasket being disposed in sealing relationship between said first internal end wall and said first end cap, whereby there is provided at the first end of said casing a first sealed end chamber in fluid communication with said first set of fiber ends, said first cap having a passageway therethrough at a location outside said first sealed-in chamber;
said second end cap being secured to said second end of said casing and said second gasket being disposed in sealing relationship between said second internal end wall and said second end cap, whereby there is provided at the second end of said casing a second sealed end chamber in fluid communication with said second set of fiber ends;
the lumens of said hollow fibers providing a path for the flow of blood between said first sealed end chamber and said second sealed end chamber;
said casing further comprising an inlet for liquids and an outlet for liquids, each said inlet and outlet being in fluid communication with the internal chamber of said casing and located between said first interior wall and said second interior wall one of said two end caps further comprising means for introducing blood into the artificial kidney and the other of said two end caps further comprising means for withdrawing blood from the artificial kidney.
10. An artificial kidney according to Claim 9 wherein said passageway is a notch in the bottom edge of said skirt.
11. An artificial kidney comprising a tubular casing having a first end, a second end, and an internal chamber;
first and second securing flanges, said first flange encircling, and extending outwardly from, said casing near the first end thereof and said second flange encircling, and extending outwardly from, said casing near the second end thereof;
a bundle of hollow dialysis tibers in said internal chamber, said bundle of fibers having a first set of fiber ends and a second set of fiber ends, the first set of fiber ends being potted in a potting resin which defines a first internal wall near the first end of the casing, the second set of fiber ends being potted in a potting resin which defines a second internal wall near the second end of the casing, first and second end caps, each of said end caps comprising a body portion and a skirt portion and each skirt portion having an end edge;
first and second gaskets;
the end edge of the skirt portion of said first end cap being bonded to said first securing flange and said first gasket being disposed in sealing relationship between said first internal end wall and said first end cap, whereby there is provided at the first end of said casing a first sealed end chamber in fluid communication with said first set of fiber ends, said first end cap further comprising means for introducing blood into said first sealed end chamber;
the end edge of the skirt portion of said second end cap being bonded to said second securing flange and said second gasket being disposed in sealing relationship between said second internal end wall and said second end cap, whereby there is provided at the second end of said casing a second sealed end chamber in fluid communication with said second set of fiber ends, said second end cap further comprising means for withdrawing blood from said second sealed end chamber; one of said caps having a passageway therethrough at a location outside the sealed-in chamber associated with said one of said caps;
the lumens of said hollow fibers providing a path for the flow of blood between said first sealed end chamber and said second sealed end chamber;
said casing further comprising an inlet for liquids and an outlet for liquids, each said inlet and outlet being in fluid communication with the internal chamber of said casing and located between said first interior wall and said second interior wall.
first and second securing flanges, said first flange encircling, and extending outwardly from, said casing near the first end thereof and said second flange encircling, and extending outwardly from, said casing near the second end thereof;
a bundle of hollow dialysis tibers in said internal chamber, said bundle of fibers having a first set of fiber ends and a second set of fiber ends, the first set of fiber ends being potted in a potting resin which defines a first internal wall near the first end of the casing, the second set of fiber ends being potted in a potting resin which defines a second internal wall near the second end of the casing, first and second end caps, each of said end caps comprising a body portion and a skirt portion and each skirt portion having an end edge;
first and second gaskets;
the end edge of the skirt portion of said first end cap being bonded to said first securing flange and said first gasket being disposed in sealing relationship between said first internal end wall and said first end cap, whereby there is provided at the first end of said casing a first sealed end chamber in fluid communication with said first set of fiber ends, said first end cap further comprising means for introducing blood into said first sealed end chamber;
the end edge of the skirt portion of said second end cap being bonded to said second securing flange and said second gasket being disposed in sealing relationship between said second internal end wall and said second end cap, whereby there is provided at the second end of said casing a second sealed end chamber in fluid communication with said second set of fiber ends, said second end cap further comprising means for withdrawing blood from said second sealed end chamber; one of said caps having a passageway therethrough at a location outside the sealed-in chamber associated with said one of said caps;
the lumens of said hollow fibers providing a path for the flow of blood between said first sealed end chamber and said second sealed end chamber;
said casing further comprising an inlet for liquids and an outlet for liquids, each said inlet and outlet being in fluid communication with the internal chamber of said casing and located between said first interior wall and said second interior wall.
12. An artificial kidney according to Claim 11 wherein said passageway is a notch in the bottom edge of said skirt.
13. A process for securing an end cap on an end of a tubular artificial kidney casing having an internal end wall and an outwardly extending encircling flange of fusible plastic near said end, said cap also being of fusible plastic and comprising a body and a skirt portion having an end edge, said cap also having a passageway therein, said process including the steps of:
placing said casing in a holder which engages the lower face of said flange;
placing a ring-shaped gasket against the outer face of said end wall;
placing said end cap in position over said flange so that the end edge of said skirt comes into contact with said flange;
bringing a high frequency vibrating member into engagement with said cap;
and actuating said high frequency vibrating member to secure the end edge of said skirt to said flange such that, after said securing process is completed, said passageway through said cap communicates with the outer aspect of said gasket.
placing said casing in a holder which engages the lower face of said flange;
placing a ring-shaped gasket against the outer face of said end wall;
placing said end cap in position over said flange so that the end edge of said skirt comes into contact with said flange;
bringing a high frequency vibrating member into engagement with said cap;
and actuating said high frequency vibrating member to secure the end edge of said skirt to said flange such that, after said securing process is completed, said passageway through said cap communicates with the outer aspect of said gasket.
14. A process according to Claim 13 in which the body of said end cap has a thickness of from three to four millimeters.
15. A process according to Claim 13 wherein said passageway is a notch in the bottom edge of said skirt.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA363,894A CA1122445A (en) | 1977-05-23 | 1980-11-03 | Dialysis apparatus and technique |
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US79958277A | 1977-05-23 | 1977-05-23 | |
| US05/827,565 US4218313A (en) | 1977-05-23 | 1977-08-25 | Dialysis apparatus and technique |
| CA301,363A CA1115989A (en) | 1977-05-23 | 1978-04-18 | Dialysis apparatus and technique |
| CA363,894A CA1122445A (en) | 1977-05-23 | 1980-11-03 | Dialysis apparatus and technique |
| US827565 | 1986-02-10 | ||
| US799582 | 1991-11-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1122445A true CA1122445A (en) | 1982-04-27 |
Family
ID=27426068
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA363,894A Expired CA1122445A (en) | 1977-05-23 | 1980-11-03 | Dialysis apparatus and technique |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1122445A (en) |
-
1980
- 1980-11-03 CA CA363,894A patent/CA1122445A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |