Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D63/00—Apparatus in general for separation processes using semi-permeable membranes
  • B01D63/02—Hollow fibre modules
  • B01D63/021—Manufacturing thereof
  • B01D63/0233—Manufacturing thereof forming the bundle
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M1/00—Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems
  • A61M1/14—Dialysis systems; Artificial kidneys; Blood oxygenators ; Reciprocating systems for treatment of body fluids, e.g. single needle systems for hemofiltration or pheresis
  • A61M1/16—Dialysis systems; Artificial kidneys; Blood oxygenators ; Reciprocating systems for treatment of body fluids, e.g. single needle systems for hemofiltration or pheresis with membranes
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M1/00—Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems
  • A61M1/14—Dialysis systems; Artificial kidneys; Blood oxygenators ; Reciprocating systems for treatment of body fluids, e.g. single needle systems for hemofiltration or pheresis
  • A61M1/16—Dialysis systems; Artificial kidneys; Blood oxygenators ; Reciprocating systems for treatment of body fluids, e.g. single needle systems for hemofiltration or pheresis with membranes
  • A61M1/1621—Constructional aspects thereof
  • A61M1/1623—Disposition or location of membranes relative to fluids
  • A61M1/1627—Dialyser of the inside perfusion type, i.e. blood flow inside hollow membrane fibres or tubes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
  • B01D61/14—Ultrafiltration; Microfiltration
  • B01D61/20—Accessories; Auxiliary operations
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M2202/00—Special media to be introduced, removed or treated
  • A61M2202/04—Liquids
  • A61M2202/0496—Urine
  • A61M2202/0498—Urea
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M2205/00—General characteristics of the apparatus
  • A61M2205/15—Detection of leaks
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2313/00—Details relating to membrane modules or apparatus
  • B01D2313/10—Specific supply elements
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2313/00—Details relating to membrane modules or apparatus
  • B01D2313/12—Specific discharge elements
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2313/00—Details relating to membrane modules or apparatus
  • B01D2313/21—Specific headers, end caps

Definitions

• the present invention relates generally to medical treatments. More specifically, the present invention relates to dialysis therapies and dialyzers.
• the renal system can fail. In renal failure of any cause, there are several physiological derangements. The balance of water, minerals (Na, K, Cl, Ca, P, Mg, SO ) and the excretion of daily metabolic load of fixed hydrogen ions is no longer possible in renal failure. During renal failure, toxic end products of nitrogen metabolism (urea, creatinine, uric acid, and others) can accumulate in blood and tissues.
• Dialysis processes have been devised for the separation of elements in a solution by diffusion across a semi-permeable membrane (diffusive solute transport) down a concentration gradient. Principally, dialysis comprises two methods: hemodialysis; and peritoneal dialysis.
• Hemodialysis treatment utilizes the patient's blood to remove waste, toxins, and excess water from the patient.
• the patient is connected to a hemodialysis machine and the patient's blood is pumped through the machine.
• Catheters are inserted into the patient's veins and arteries to connect the blood flow to and from the hemodialysis machine. Waste, toxins, and excess water are removed from the patient's blood and the blood is infused back into the patient.
• Hemodialysis treatments last several hours and are generally performed in a treatment center about three to four times per week.
• Hemodialysis typically involves the use of a dialyzer.
• Dialyzers generally comprise a housing or casing. Located within the interior of the casing is a fiber bundle.
• the fiber bundle is comprised of a number of membranes that are oriented parallel to each other.
• the membranes are designed to allow blood to flow therethrough with dialysate flowing on the outside of the membranes. Due to an osmotic gradient that is created, waste products are removed from the blood through the membranes into the dialysate.
• dialyzers typically include a blood inlet and a blood outlet.
• the blood inlet is designed to cause blood to enter the fiber membranes and flow therethrough through the blood outlet.
• Dialysate is designed to flow through an inlet of the dialyzer and out of the dialyzer through an outlet.
• the dialysate is designed to flow across the outside or exterior walls of the membranes.
• dialysate may not flow sufficiently around the entire fiber bundle. Rather shunts between the bundle and the case may occur. This can result in a reduced flow of dialysate around certain portions of membranes contained in the center of the fiber bundle. The clearance of the dialyzer will therefore be reduced.
• the present invention provides improved dialyzers and methods for providing dialysis.
• the present invention provides a dialyzer having an improved perfusion of dialysate into the fiber bundle.
• a dialyzer comprising a casing defining an interior and including a dialysate inlet and a dialysate outlet.
• a plurality of fibers are located in the interior of the casing and define a fiber bundle.
• a dialysate inlet fluid channel is provided in fluid communication with the dialysate inlet and includes a plurality of flutes that extend into a portion of the fiber bundles, the flutes define an opening for allowing dialysate to flow from the inlet fluid channel into the interior of the casing.
• the dialyzer includes a dialysate outlet fluid channel in fluid communication with the dialysate outlet that includes a plurality of flutes that extend into a portion of the fiber bundle.
• the flutes define openings for allowing dialysate to flow from the interior of the casing into the dialysate outlet fluid channel.
• the outlet fluid channel and inlet fluid channel have substantially the same structure.
• the casing is constructed from plastic.
• the dialyzer includes eight flutes.
• a top portion of the dialysate inlet is defined by potting material.
• the flutes circumscribe an entire circumference of a first end of the dialyzer.
• the opening in the flutes is a slot.
• each flute defines a separate opening.
• a dialyzer comprising a casing defining an interior and having a first end having a dialysate inlet and a second end having a dialysate outlet.
• a fiber bundle including a plurahty of fibers is located within the interior and extends from the first end to the second end.
• a fluid inlet channel in fluid communication with the dialysate inlet is provided, the fluid inlet channel being defined, in part, by a portion of the casing that defines an exterior surface of the first end and an inner wall that circumscribes a portion of the interior.
• the inner wall includes portions that extend into the fiber bundle. At least one of the portions includes an aperture for allowing fluid to flow from the channel into the interior.
• a fluid outlet channel in fluid communication with the dialysate outlet is provided.
• the fluid outlet channel is defined, in part, by a portion of the casing that defines an exterior surface of the first end and an inner wall that circumscribes a portion of the interior.
• the inner wall includes portions that extend into the fiber bundle, at least one of the portions including an aperture for allowing fluid to flow from the channel into the interior.
• the inner wall defines a pluality of semicircular structures.
• the fluid inlet channel and fluid outlet channel includes at least six separate portions that extend into the fiber bundle each including an aperture.
• a dialyzer comprising a casing defining an interior having a fiber bundle located therein and including a first end having a dialysate inlet and a second end having a dialysate outlet.
• the casing including a dialysate inlet in fluid communication with an inlet fluid channel, the inlet fluid channel defined, at least in part, by an interior wall of the casing, a potting material and an inner wall circumscribing the interior of the first end.
• the inner wall includes a plurality of members defining areas for receiving fibers of the fiber bundle and a portion that extends into the fiber bundles. Each of the portions of the inner wall that extend into the fiber bundles and include an aperture for allowing dialysate to flow into the interior of the casing.
• the portions define flutes.
• a method for providing dialysis to a patient comprising the steps of passing blood through fiber bundles of a dialyzer and passing dialysate through the dialyzer such that the dialyzer includes portions that separate a portion of the fiber bundle causing more dialysate to flow to an interior of the fiber bundle.
• a further advantage of the present invention is to provide an improved method of providing dialysis to a patient.
• an advantage of the present invention is to provide an improved housing design for a dialyzer. Furthermore, an advantage of the present invention is to provide improved fluid flow characteristics in a dialyzer.
• an advantage of the present invention is to provide a dialyzer having improved efficiency.
• Another advantage of the present invention is to provide an improved dialyzer for hemodialysis.
• an advantage of the present invention is to provide an improved dialyzer that can be used in a number of therapies.
• Figure 1 illustrates a perspective view of an embodiment of a dialyzer of the present invention.
• Figure 2 illustrates a top elevation view of an embodiment of the dialyzer of the present invention.
• Figure 3 illustrates the dialyzer of Figure 2 with the fiber bundle removed.
• Figure 4 illustrates a side elevation view of the dialyzer of Figure 3.
• Figure 5 illustrates a cross-sectional view of the dialyzer of Figure 4.
• the present invention provides improved dialyzers and methods of using same.
• the dialyzer is designed for use in hemodialysis, it should be noted that the dialyzer can be used in a number of different therapies.
• the dialyzer can be used in non-traditional hemodialysis methods. Such methods include, for example, regeneration and continuous flow therapies which may or may not include hemodialysis, for example, continuous flow peritoneal dialysis.
• the present invention in an embodiment, can be utilized in methods of providing dialysis for patients having chronic kidney failure or disease, the present invention can be used for acute dialysis needs, for example, in an emergency room setting. Referring now to Figure 1, a dialyzer 10 is generally illustrated. The dialyzer 10 is generally illustrated. The dialyzer
• the 10 includes a body member 12 that generally comprises a casing.
• the casing includes a core section 14 as well as two bell members 16 and 18 located at each end of the dialyzer 10.
• Located within the core or casing is a fiber bundle 20.
• the fiber bundle 20 includes a plurality of hollow fiber membranes.
• the membranes are semi-permeable having a selective permeability.
• the membranes are bundled together and assembled in the casing in a manner allowing blood to flow simultaneously in a parallel manner through the lurnina of the fibers while a blood cleansing liquid (dialysate) is simultaneously passed through the casing. In theory, this allows the dialysate to bathe the exterior surface of the hollow fibers.
• a variety of compounds can be used to produce selective permeable membranes including polymers such as: cellulose; cellulose acetate; polyamide; polyacrylonitearliest; polyvinyl alcohol; polymethacrylate; polysulfone; and polyolefin.
• the fiber bundle 20 is encapsulated at each end of the dialyzer to prevent blood flow around the fibers.
• a fluid inlet 22 Located at a first end of the dialyzer is a fluid inlet 22 and at a second end a fluid outlet 24 defined by a fluid inlet header 26 and a fluid outlet header 28.
• a variety of header designs can be utilized.
• the inlet header 26 and outlet header 28 have designs such as those set forth in U.S. Patent Application Serial No. entitled “Hemodialyzer Headers” being filed herewith, the disclosure of which is hereby incorporated by reference.
• any header design can be utilized.
• the dialyzer body 10 also includes a dialysate inlet 30 and a dialysate outlet 32.
• the dialysate inlet 30 and dialysate outlet 32 define fluid flow channels that are in a radial direction, i.e., perpendicular to the fluid flow path of the blood.
• the dialysate inlet 30 and dialysate outlet 32 are designed to allow dialysate to flow into an interior 34 of the dialyzer bathing the exterior surfaces of the fibers and the fiber bundle 20 and then out through the outlet 32. This, as is known in the art, causes waste and other toxins to be removed from the blood through the semipermeable membrane of the fibers and carried away by the dialysate.
• an improved inlet and/or outlet design is provided. This provides for improved perfusion of the dialysate through the fiber bundle.
• three mass transfer resistances must be minimized. These mass transfer resistances include: 1) blood resistance; 2) membrane resistance; and 3) dialysate resistance.
• the dialysate resistance is dictated, in part, by the case design, fiber packing density, and effective shape of the fluid flow path.
• the bells and dialysate inlet and outlet have straight walls that surround the hollow fiber.
• the dialysate inlet 30 and dialysate outlet 32 of the dialyzer of the present invention provide a design that reduces shunting.
• the design also improves dialysate perfusion into the bundle 20.
• the fiber ends do not deflect outwardly into the chamber of the larger inner diameter of the bell of the core as in prior art designs. Instead, structures are provided causing the outer fibers to be pulled away from the bundle. This provides improved access to the bundle core.
• the present invention provides an inlet fluid flow channel 38 defined by an outer wall 40, an inner wall 42 and the top wall (not shown) defined by potting material that seals the fiber bundle, as is known in the art.
• the inlet fluid channel 34 preferably extends below and above the dialysate inlet 30. Thus, dialysate will enter the inlet fluid channel 34 through the dialysate inlet 30 and flow around the channel into the dialyzer.
• the outer wall 40 also defines the exterior of the casing of the dialyzer 10.
• the interior wall 42 with the outer wall 40, defines the inlet flow channel 38.
• the inner wall also includes a plurality of flutes, in the illustrated embodiment eight flutes 50, 52, 54, 56, 58, 60, 62, and 64. In the preferred embodiment illustrated, these flutes 50, 52, 54, 56, 58, 60, 62, and 64 define semicircular structures.
• the flutes define openings 51, 53, 55, 57, 59, 61, 63, and 65. In the preferred embodiment illustrated, the opening is a slot shape. However, a variety of openings can be utilized. The openings allow the dialysate that flows through the inlet flow channel 38 to enter an interior 34 of the dialyzer 10.
• the space between the outer wall 40 of the dialyzer 10 and the inner wall 42 that defines the flutes 50, 52, 54, 56, 58, 60, 62, and 64 is sufficient to allow ample dialysate to flow through the slots 51, 53, 55, 57, 59, 61, and 63 without a significant pressure drop.
• the slot widths can be varied depending on the position and order of the slots to account for circumferential differences in potting depth that may occur from the potting procedure. This allows the flow rate to be equal at all slot locations.
• flutes 50, 52, 54, 56, 58, 60, 62, and 64 are provided, and therefore eight openings or slots 51, 53, 55, 57, 59, 61, and 63, more or less flutes can be provided. However, it is believed that eight may be the ideal number.
• the outlet end 70 of dialyzer 10 includes a structure similar to that of the dialysate inlet.
• the dialysate outlet 70 will include a dialysate outlet channel (not shown) similar to the dialysate inlet flow channel 38.
• the dialysate outlet 70 can be of a standard bell structure as is known in the prior art. But, certain advantages are achieved by creating the dialysate outlet that is substantially identical to the dialysate inlet, including ease of manufacturing.
• Tables 1 and 2 show the reduction in urea clearance with dialysate shunts for a 2.0 square meter and a 2.4 square meter dialyzer.
• the overall mass transfer coefficient has been adjusted downward to account for the lower dialysate side mass transfer coefficient due to the reduced effective dialysate flow caused by the shunt. It can be seen from these two tables that a large dialysate shunt can dramatically reduce the clearance of a dialyzer.
• Urea clearance as a function of percentage dialysate shunt for a 2.0 square meter dialyzer with 300 ml/min blood flow and 500 ml min dialysate flow is reduced from 269 ml/min to 229 ml/min by a 40% dialysate shunt.
• the clearance drops from 278 ml min to 238 ml/min due to a 40% shunt.
• This analysis can also be used to predict the increase in clearance of a dialyzer if a shunt of known magnitude is eliminated. From a measured or calculated clearance value and an assumed shunt magnitude, the overall mass transfer coefficient of the dialyzer can be determined from the preceding equations. Using this calculated value of K and assuming the elimination of the assumed shunt, the improved clearance can be calculated. Table 3 shows the predicted urea clearances of 1.3, 1.6, 1.8 and 2.0 square meter dialyzers where 0%, 10%, 15 % and 20% shunt have been eliminated for a blood flow of 300 ml/min and dialysate flow rate of 500 ml/min.
• Line 1 provides the urea clearance of a dialyzer without maladistributions.
• Line 2 provides the urea clearance of a dialyzer with blood flow 10% higher.
• Line 3 is the urea clearance with 10% lower blood flow.
• the clearance of this dialyzer will be the average of the clearances on lines 2 and 3 which is shown on line 4.
• the urea clearance is only reduced from 268.8 to 267.6 ml/min., a minor reduction.
• Lines 5, 6 and 7 of Table 4 set forth a 10% variation in dialysate flow that was added to the 10% blood flow variation with the higher blood flow occurring where the dialysate flow is lower (as what might occur near the center of the bundle).
• the urea clearance dropped further to 265.8 ml/min.
• Table 6 provides similar results for 500ml/min blood flow and 800 ml/min dialysate flow. Here a 20% dialysate maldistribution results in a clearance reduction from 409.6 ml/min (line 4) to 402.7 ml/min (line 10).
• dialysate flow distributions are quite non-uniform for the regions adjacent to the flow inlet and outlet.
• the distributions of dialysate flow for the dialyzer header designs of the present invention are more uniform than the conventional dialyzer.
• a porous medium model is used here for modeling the over-all flow and pressure distributions in the fiber-bundle. The model assumes that there is a local balance between pressure and resistance forces in the flow domain such that:
• Kj is the permeability and Uj is the superficial velocity in direction ⁇ ,-. (The volume flow rate divided by the total cross-sectional area.)
• the permeability Kj is computed by the following equation:
• Ki cti lu l + ⁇ ,- where CCJ and ⁇ ,- are constants for a particular flow, U is the superficial velocity vector. It is noted that the permeability in Darcy's law is defined as: where K J is the permeability and is equal to ⁇ /Kj.
• the flow in the dialyzer is assumed to be laminar, steady state, incompressible, and Newtonian.
• the permeability for the porous-medium flow model should be derived from the flow pressure drop in the fiber-bundle measured experimentally. However, the experimental data are not available.
• the other alternative is to solve for the pressure distributions numerically. First it is assumed that the fibers are arranged in a fixed staggered pattern. The space in between the fibers is computed from the given fiber packing factor. The blood flow in a dialyzer is inside the hollow fibers.
• the porous medium flow permeability along the axial-direction is computed based on the pressure drop for a fully developed laminar pipe flow. The permeability is infinite for cross flow.
• the pressure drop is computed numerically for flow in several layers of fibers. Then the flow permeability is calculated from the computed pressure gradient for the particular fiber configuration.
• the axial flow pressure drop is different from the cross-flow pressure drop and the flow in each direction is computed separately.
• porous medium model is only an approximation for the actual complicated flow problem.
• the fiber distributions in a dialyzer are usually non-uniform and the flow permeability varies spatially.
• dialyzer design was analyzed. The first is an elongated version of the prior art dialyzer and the second is the present invention dialyzer.
• the input parameters for both cases are presented in Table 7.
• dialysate is introduced to the bundle in the inlet bell, where all the fibers along the bundle perimeter are exposed.
• dialyzer there are eight slots in the inlet bell region through which dialysate is introduced to adjacent sections of the fiber bundle. The width and length of the slots are 0.031" and 0.294", respectively.
• the bell configurations for the opposite (outlet) end of each dialyzer are the same as the respective inlets.
• dialyzer at a dialysate flow rate of 500 ml/min, the dialysate flow velocity is uniform adjacent to the flow inlet and outlet showing a 6% difference between the maximum and the minimum values. In the mid-section of the bundle, there exists a 0.5% flow variation. Flow characteristics for this dialyzer are also shown for a dialysate flow rate of 1000 ml/min.

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• 2001
  • 2001-06-01 US US09/871,864 patent/US6623638B2/en not_active Expired - Lifetime
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