|Publication number||US20050000882 A1|
|Application number||US 10/774,127|
|Publication date||Jan 6, 2005|
|Filing date||Feb 6, 2004|
|Priority date||Jul 12, 2001|
|Also published as||US7776219, US20030010718, US20080177215|
|Publication number||10774127, 774127, US 2005/0000882 A1, US 2005/000882 A1, US 20050000882 A1, US 20050000882A1, US 2005000882 A1, US 2005000882A1, US-A1-20050000882, US-A1-2005000882, US2005/0000882A1, US2005/000882A1, US20050000882 A1, US20050000882A1, US2005000882 A1, US2005000882A1|
|Inventors||James Brugger, Jeffrey Burbank, Martin Stillig|
|Original Assignee||Brugger James M., Burbank Jeffrey H., Martin Stillig|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (15), Referenced by (2), Classifications (20)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present invention relates generally to devices and methods useful in preventing coagulation in filtered blood during hemofiltration. More specifically, the devices and methods provide a cap having a port, the cap adapted for attachment to a blood filter housing to provide hemodilution of blood as it enters and/or exits the filter.
Undesired coagulation of blood often complicates blood-processing procedures such as hemofiltration, hemodialysis, and hemodiafiltration, particularly where a filter is used. Blood generally coagulates by transforming soluble fibrinogen into insoluble fibrin by activation of numerous circulating proteins that interact in a cascading series of limited proteolytic reactions. At each step of reaction, a clotting factor undergoes limited proteolysis and becomes an active protease that in turn activates the next clotting factor until finally a solid fibrin clot is formed. Fibrinogen (factor I) is activated by thrombin (factor IIa), which is converted from prothrombin by activated factor X. There are two separate coagulation pathways that activate factor X—the intrinsic system and the extrinsic system. Activation of the extrinsic system requires tissue thromboplastin (factor III), which is released from damaged tissue into the circulating blood to activate clotting. The intrinsic system, on the other hand, has all the factors necessary for coagulation contained in the circulating blood. The intrinsic system is, for example, partially responsible for clotting of blood in a test tube. Aggregation of platelets caused by stagnation of blood also facilitates blood coagulation.
During hemofiltration, for example, blood is removed from the patient, filtered through a filtering column to remove waste products, and returned to the patient's circulation. However, during removal of waste products, fluid is also removed, causing concentration of blood leaving the outflow tubing. As a result of hemoconcentration, hematocrit rises, and the intrinsic coagulation pathway and platelets are activated causing clotting of blood around the outlet of the filtering column, thereby compromising the hemofiltrating process.
What is needed are devices and methods that can be used with a filtering column during blood-processing procedures, such as hemofiltration, hemodialysis, hemodiafiltration, and peritoneal dialysis, to prevent clotting. Existing devices are inadequate for this purpose.
The present invention provides devices and methods that prevent clotting of blood during blood-processing procedures, such as hemofiltration, hemodialysis, and hemodiafiltration. More particularly, blood is diluted by replacement fluid, such as saline, Ringer's lactate, or other physiological solutions, as it enters and/or exits the filter. In a first embodiment, the device, also known as a filter, is comprised of a bundle of hollow fiber membrane made of resins such as polysulfone that is fixed in a cylindrical housing with a potting material. The interior of the fibers is the blood flow path. The exterior of the fibers is the dialysate and/or waste space. The potting material is typically a polyurethane material. The cylindrical housing may have one or two access ports. One port is for the hemofiltration filter, and two ports allow dialysate to flow through the housing contacting the exterior surface of the membrane for hemodialysis or hemodiafiltration. In one embodiment, the open fibers at the end of the cylindrical housing are covered at both ends with a cap. One cap is the blood entry cap, the other is the blood exit cap. In other embodiments, the housing includes end plates at one or both ends, the end plates integral with the housing.
The exit cap is attached to the housing, in some cases removably attached, and generally at a position opposite the inlet cap. The exit cap has an outlet for blood and a port adjacent the outlet for receiving replacement fluid. In certain embodiments, the blood outlet, the replacement fluid port, the blood inlet, and/or the waste outlet of the filter assembly communicate with bond sockets adapted to receive flexible tubing.
In another embodiment, the filter has an outlet or exit cap for blood at one end and an inlet or inlet cap at the other end, the cap having an inlet for blood and a port adjacent to the inlet for receiving dilution fluid, such as saline, Ringer's lactate, or other physiological solutions. The housing also includes access ports for waste and ultrafiltrate.
In still another embodiment, the housing includes first and second caps at opposite ends and an outlet for waste and ultrafiltrate. The first cap has an inlet for blood and a port adjacent to the inlet for receiving dilution fluid. The second cap has an outlet for blood and a port adjacent to the outlet for receiving dilution fluid.
In use, blood is passed through the blood inlet of the entry cap, through the filter membrane fibers, and through the blood outlet of the exit cap. Replacement fluid or dilution fluid, such as saline, Ringer's lactate, or other physiological solutions, is infused into the port adjacent the blood outlet to produce hemodilution at the blood outlet. Alternatively, the fluid is infused into the port adjacent the blood inlet of the entry cap to produce hemodilution at the inlet. In still another alternative method, fluid is infused into the port adjacent the blood inlet of the entry cap and into the port adjacent the blood outlet of the exit cap to produce hemodilution as blood enters and exits the filter housing. In certain constrictions the replacement fluid swirls in a circular pattern in a headspace that is defined by the gap between the filter and the cap. Swirling of the replacement fluid facilitates mixing of the fluid and the blood, thereby preventing hemoconcentration and stasis of blood, and sweeping any particles of thrombus away from the filter.
The advantages associated with the hemodilution cap described herein include (1) preventing coagulation during blood processing procedures, (2) manufacturing efficiency, i.e., reducing plastic used in disposable components, (3) eliminating up to two bonds and up to two components, (4) less expense in materials costs and manufacturing costs, (5) more robust system, not subject to tolerances like bonding two rigid parts, and (6) integration of parts saves labor, materials, and precious resources.
During blood-processing procedures, such as hemofiltration, hemodialysis, and hemodiafiltration, blood has a tendency to clot as it passes through processing equipment, particularly where it exits the outlet of a filter, due to hemoconcentration. In
Infusion port 33 includes bond socket 34, and outlet 32 includes bond socket 35. Each bond socket is adapted to receive flexible tubing. Where the tubing is generally constructed of PVC and the bond socket is constructed of any one of a number of thermoplastic resins including PVC, polycarbonate, ABS, etc., PVC being preferable as it is solvent bonded to the housing, the tubing may be fused to the bond socket by brief immersion in cyclohexanone or other suitable organic solvent before inserting the tubing in the bond socket. Soft PVC is flexible, allowing the cap to have an interference fit when solvent bonded. This makes it less susceptible to tolerance problems.
Although the foregoing invention has, for the purposes of clarity and understanding, been described in some detail by way of illustration and example, it will be obvious that certain changes and modifications may be practiced which will still fall within the scope of the appended claims. For example, it will be understood that any feature of any device or method disclosed herein can be used with any of the other devices or methods, even though any given figure might depict only a particular combination.
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|U.S. Classification||210/321.79, 210/321.8|
|International Classification||B01D61/30, A61M1/36, B01D61/20, A61M1/18, B01D63/02, A61M1/34|
|Cooperative Classification||B01D2313/21, A61M1/3672, B01D63/02, B01D61/30, B01D61/20, A61M1/342, A61M1/3434|
|European Classification||B01D61/20, B01D63/02, A61M1/34E, B01D61/30, A61M1/36H|