BLOOD TREATMENT DIALYZER/FILTER FOR PERMITTING GAS REMOVAL
A configuration of a blood microtubular filter/dialyzer used in many kinds of renal replacement therapy systems can provide a highly effective mechanism for removing air from the blood circuit of such systems. Air is removed from an outlet header space of the filter avoiding the need for a bubble trap or settling chamber such as a drip chamber.
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This application is a continuation of U.S. patent application Ser. No. 11/163708, filed Oct. 27, 2005, now pending, which claims the benefit of U.S. Provisional Application Ser. No. 60/622,863, filed Oct. 28, 2004, both of which are incorporated by reference herein in their entireties.
BACKGROUNDOne of the problems with fluid circuits in blood treatment systems is entrained air (bubbles) in treatment fluids, infusate, or blood. Treatment systems normally have air detectors to prevent air from being injected into a patient, either because a venous line carrying blood back to the patient contains air or because an infusate line, such as the replacement fluid line of a hemofiltration system, contains air. It is desirable for the air detectors to be made sufficiently sensitive to prevent the rare instances of long trains of air bubbles being injected into a patient. But sensitivity high enough to prevent long thin trains of bubbles may be high enough to alarm very small amounts of air which pose no risk. In other words, sensitive air detectors alarm on a lot of fall positives if they protect against all possible risks.
A prior art approach has been to remove as much air from a protected fluid circuit as possible. Putting air traps in fluid circuits, particularly blood lines, has drawbacks. Air-settling chambers necessarily involve stagnant flow, which creates a risk of fowling clots (e.g., for blood) or sedimentation or other concentration of entrained material (e.g. medication).
Another prior art problem is stagnant flow in the headers of microtubular filter used for most dialyzers and hemofilters. This is a particular problem in the venous header where flow from many microtubules coalesces into a single slow moving flow.
The inventive embodiments provide various other features and advantages in addition to or in lieu of those discussed above and below. Many of these features and advantages are apparent from the description below with reference to the following drawing.
The orientation of the filter 100 with respect to the pull of gravity is shown with the understanding that gravity is assumed to pull down with respect to the profile orientation of the drawing page. If any air is entrained in the blood, it may settle in pockets 151 and 153 in the arterial 160 and venous 155 head spaces as indicated by air/liquid interfaces 152 and 150. The flow of blood through the arterial 160 and venous 155 head spaces is extremely slow due to the very small cross-sectional areas of the filter fibers in the bundle 132. As a result, the arterial 160 and venous 155 head spaces are an idea place for air to settle out. With the indicated orientation, with blood outlet 124 pointing down and away from the pocket 151. Since the blood moves at a very slow rate in the arterial 160 and venous 155 head spaces, there is little risk of reentrainment and air settles out very effectively.
Air trapped in pocket 153 may travel through filter fibers in bundle 132 up to venous head space 155 and accumulate in pocket 151. Since the pocket 153 is located near the top of the arterial head space 160, air will tend to travel up a few of the fibers closest to the top and collect in the pocket 151 without mixing in with blood. This keeps the vast majority of fibers filled with blood.
Note that besides using the multi-way valve and bag 365 to draw air from the header of a filter and inject medicaments into the filter header, the same devices may be used in connection with an air trap or drip chamber. Referring to
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The filter fiber membrane bundle 420 may be inserted such that the fibers 415 extend beyond the end 407 of the tube 405 as indicated at 445. Referring now to
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A tension band 757 may be used to ensure a good seal and provide a final shape to the one-piece cap 725 if made of a somewhat compliant resin to allow it to be removed from an injection mold despite the recess defined by the dialysate manifold 740. Alternatively, the one-piece cap 725 may have a discontinuous dialysate manifold that allows it to be created without requiring the cap to yield, the cap could be machined rather than molded, or the cap could be made of two molded pieces that are assembled into a single cap. Many variations are possible.
It will be understood that while the invention has been described above in conjunction with a few exemplary embodiments, the description and examples are intended to illustrate and not limit the scope of the invention. That which is described herein with respect to the exemplary embodiments can be applied to the measurement of many different formation characteristics. Thus, the scope of the invention should only be limited by the following claims.
Claims
1-18. (canceled)
19. A system for removing gas from blood, the system comprising:
- a blood processing device including a microtubular fiber filter having a plurality of filter fibers with ends opening into an inlet header space and an outlet header space, the inlet header space including an inlet port and the outlet header space including an outlet port and a gas release port, the outlet port and the gas release port lying at opposite ends of the outlet header space,
- the blood processing device being configured to allow blood entering through the inlet port into the inlet header space to flow through the plurality of filter fibers into the outlet header space and out the outlet port, and further configured to allow gas to collect in a portion of the inlet header space so as to be conveyed through a subset of the plurality of filter fibers into the outlet header space,
- the inlet and outlet header spaces having sizes and shapes such that a shear rate of blood flow is sufficient to prevent stagnant flow regions from arising in the inlet and outlet header spaces; and
- a holder configured to support said blood processing device in a position and orientation such that gas in the outlet header space accumulates in a portion of the outlet header space which is adjacent the gas release port, the gas release port being configured to periodically release the accumulated gas.
20. The system of claim 19, wherein the filter has a longitudinal housing with a longitudinal axis and is supported by the holder so as to be at an angle with respect to the vertical.
21. The system of claim 19, further comprising a valve connected to said gas release port and pre-connected and sterilized together with said blood processing device, the valve being configured to permit gas to egress from the outlet header space without permitting blood to egress from the outlet header space.
22. The system of claim 19, further comprising a stopcock connected to said gas release port and pre-connected and sterilized together with said blood processing device.
23. The system of claim 19, further comprising a syringe connected to said gas release port and pre-connected and sterilized together with said blood processing device.
24. The system of claim 19, wherein the holder is configured to orient said blood processing device such that said outlet port is lower, with respect to a direction of gravity, than said gas release port.
25. The system of claim 19, wherein the inlet and outlet header spaces have a hydraulic shape to eliminate stagnant flow of blood.
26. The system of claim 19, wherein the gas release port further includes a microporous filter to prevent contamination from entering the outlet header space.
27. The system of claim 19, wherein the portion of the inlet header space where gas collects is connected to the portion of the outlet header space where gas accumulates before release by said subset of the filter fibers.
28. The system of claim 19, wherein the holder is configured to hold the blood processing device so that the inlet port and the outlet port are oriented below the gas release port.
29. The system of claim 19, wherein the holder is fixedly attachable to a blood treatment machine.
30. The system of claim 19, wherein the blood processing device is one of a blood dialyzer and a hemofilter processing element.
31. The system of claim 19, wherein the gas release port is further configured to permit adding or removing biocompatible non-blood fluid.
32. The system of claim 19, wherein the portion of the inlet header space where gas collects is opposite the inlet port.
33. A system for processing blood, the system comprising:
- a blood processing element including filter media, the filter media being configured to convey blood and air from an inlet header chamber into an outlet header chamber through the filter media,
- the blood processing element including the outlet header chamber at a position where blood and air exit said filter media, said outlet header chamber having at least one outlet; and
- a holder configured to support said processing element in a preferred position and orientation, wherein the preferred position and orientation is such that air can accumulate in said outlet header chamber in a position remote from said outlet,
- wherein the holder includes a flexible holding portion configured to accept the blood processing element only in the preferred position and orientation.
34. A holding device for holding a blood filtering element in a preferred orientation relative to a blood processing machine, the holding device comprising:
- a flexible holding portion to receive the blood filtering element in a predetermined orientation;
- an attachment portion to detachably attach the flexible holding portion to the blood processing machine, the blood processing machine including a fluid circuit,
- wherein when the attachment portion is attached to the blood processing machine, the blood filtering element is positioned in a preferred orientation relative to the blood processing machine, and
- wherein the preferred orientation is such that gas accumulates in a specific portion of the blood filtering element.
35. The holding device of claim 34, wherein the blood filtering element is connected to the fluid circuit before the attachment portion is attached to the blood processing machine.
36. The holding device of claim 34, wherein the fluid circuit includes a cartridge enclosed between two separate parts of the blood treatment machine, and the holding device is configured to be detachably attached to the cartridge so that the preferred orientation of the blood filtering element relative to the blood processing machine is determined by the attachment of the holding device to the cartridge.
37. The holding device of claim 34, wherein the holding device is integral with the blood processing machine.
38. The holding device of claim 34,
- wherein,
- the blood filtering element includes a microtubular fiber filter having a plurality of filter fibers with ends opening into an inlet header space and an outlet header space, the inlet header space including an inlet port and the outlet header space including an outlet port and a gas release port, the outlet port and the gas release port lying at opposite ends of the outlet header space, the blood filtering element being configured to allow blood entering through the inlet port into the inlet header space to flow through the plurality of filter fibers into the outlet header space and out the outlet port, and further configured to allow gas to collect in a portion of the inlet header space so as to be conveyed through a subset of the plurality of filter fibers into the outlet header space, the inlet and outlet header spaces having sizes and shapes such that a shear rate of blood flow is sufficient to prevent stagnant flow regions from arising in the inlet and outlet header spaces, and
- the preferred orientation is such that gas accumulates in a portion of the outlet header space adjacent the gas release port.
Type: Application
Filed: Feb 11, 2011
Publication Date: Jun 2, 2011
Applicant:
Inventors: James M. Brugger (Newburyport, MA), Martin Stillig (Dransfeld)
Application Number: 13/025,306
International Classification: B01D 63/02 (20060101); B01D 61/30 (20060101); B01D 19/00 (20060101);