Blood Treatment Dialyzer/Filter Design to Remove Entrained Gas and Add Medicaments
A configuration of a blood microtubular filter/dializer used in many kinds of renal replacement therapy systems can provide highly a effective mechanism for removing air from the blood circuit of such systems. In embodiments, for example, the invention takes advantage of the slow flow rate that usually occurs where blood exits the microtubules into a header area of the filter to provide a settling area and an auxiliary port with a multi-way valve allowing gas to be drawn out from the header and for medicaments to be injected into said header.
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One 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 forming 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.
BRIEF DESCRIPTION OF THE DRAWINGS
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
Referring to
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. A blood treatment apparatus, comprising:
- a blood purifier including microtubular filter membranes in a bundle with one end of said bundle terminating in a first manifold at a lower end of said blood purifier and a second end of said bundle terminating in a second manifold, blood flowing in an upward direction through said filter media during use;
- said purifier having first and second header chambers forming respective passages where flow divides and coalesces in said first and second manifolds, respectively;
- said second header having an outlet where a coalesced flow from said second manifold flows out of said second header;
- said purifier being of generally cylindrical construction with a longitudinal axis parallel to said microtubular membranes;
- a holder configured to hold said purifier in a preferred orientation in which said longitudinal axis forms an angle with respect to a direction of gravitation force and with said auxiliary port at a highest point of said second header and said outlet being positioned remote from said port, said highest point being determined with respect to said preferred orientation;
- said second header having an auxiliary port;
- said auxiliary port having a multi-way valve connected thereto.
2. Apparatus as in claim 1, wherein said multi-way valve is connected to a syringe to allow selective flow communication between said auxiliary port and said syringe, whereby gas may be manually drawn from said second header using said syringe.
3. Apparatus as in claim 1, wherein said multi-way valve has a syringe port and a medicament port, and is connected to a syringe by said syringe port and to a container of medicament by said medicament port to allow selective flow communication between said auxiliary port and said syringe and between said syringe and said container of medicament, whereby gas may be manually drawn from said second header using said syringe and injected into said medicament container and medicament can be selectively withdrawn from said medicament container and injected into said second header.
4. A blood treatment apparatus, comprising:
- a blood dialyzer or hemofilter processing element including filter media into which blood comes in contact during use;
- said processing element having a header chamber where multiple flows of blood combine;
- said header chamber being at a position where blood exits a treatment portion of said blood purifier, said header chamber having at least one blood outlet and at least one auxiliary port;
- a holder configured to support said dialyzer or hemofilter in a position and orientation such that air can accumulate in said header chamber in a position in said header space that is adjacent and in communication with said auxiliary port;
- said auxiliary port having a multi-way valve connected thereto.
5. Apparatus as in claim 4, wherein said multi-way valve is connected to a syringe to allow selective flow communication between said auxiliary port and said syringe, whereby gas may be manually drawn from said second header using said syringe.
6. Apparatus as in claim 4, wherein said auxiliary port is opposite said blood outlet.
7. Apparatus as in claim 4, further comprising a valve connected to said auxiliary port and pre-connected and sterilized together with said blood purifier.
8. Apparatus as in claim 4, further comprising a multi-way multi-way valve valve connected to said auxiliary port and pre-connected and sterilized together with said blood purifier.
9. Apparatus as in claim 4, wherein said multi-way valve has a syringe port and a medicament port, and is connected to a syringe by said syringe port and to a container of medicament by said medicament port to allow selective flow communication between said auxiliary port and said syringe and between said syringe and said container of medicament, whereby gas may be manually drawn from said second header using said syringe and injected into said medicament container and medicament can be selectively withdrawn from said medicament container and injected into said second header.
10. Apparatus as in claim 4, further comprising a multi-way multi-way valve valve connectable to said auxiliary port and a syringe connectable to said multi-way valve, said valve, syringe, and said blood purifier forming a kit.
11. Apparatus as in claim 4, further comprising a holder, said blood purifier having a longitudinal axis and said holder being configured to support said blood purifier with said longitudinal axis at an angle with respect to the vertical, as defined with respect to the force of gravity.
12. A blood treatment apparatus, comprising:
- a blood purifier including filter media into which blood comes in contact during use;
- said processing element having a header chamber at a position where blood exits a portion of said blood purifier, said header chamber having at least one blood outlet and one auxiliary port remote from said at least one blood outlet;
- said auxiliary port being configured to permit the removal of gas accumulated in said header chamber and addition and removal of medicament.
13. Apparatus as in claim 12, further comprising a valve connected to said auxiliary port and pre-connected and sterilized together with said blood purifier.
14. Apparatus as in claim 12, further comprising a multi-way valve connected to said auxiliary port and pre-connected and sterilized together with said blood purifier.
15. Apparatus as in claim 12, further comprising a syringe connected to said auxiliary port.
16. Apparatus as in claim 12, further comprising a holder configured to orient said blood purifier such that said at least one blood outlet is lower, with respect to a direction of gravity, than said auxiliary port.
17. Apparatus as in claim 12, wherein said multi-way valve has a syringe port and a medicament port, and is connected to a syringe by said syringe port and to a container of medicament by said medicament port to allow selective flow communication between said auxiliary port and said syringe and between said syringe and said container of medicament, whereby gas may be manually drawn from said second header using said syringe and injected into said medicament container and medicament can be selectively withdrawn from said medicament container and injected into said second header.
18. A method of using a multi-way valve connected to a filter of a blood circuit, comprising the steps of:
- configuring to draw gas from the venous header of a blood filter, a multi-way valve that selectively bilaterally connects any pair of at least three connections, one connection being to the venous header of a blood filter, one connection being to a container, and one connection being to a positive displacement device configured to suck and push fluid;
- drawing gas from said venous header into said positive displacement device;
- configuring said multi-way valve to inject gasin said container;
- injecting gasinto said container.
19. A method as in claim 18, further comprising the steps of:
- drawing a medicament from said container into said positive displacement device;
- configuring said multi-way valve to inject fluid into said header;
- injecting medicament into said header.
20. A method as in claim 18, wherein said medicament includes blood-normal saline.
21. A method of using a multi-way valve connected to a blood circuit, comprising the steps of:
- configuring to draw gas from the venous header of a blood filter, a multi-way valve that selectively bilaterally connects any pair of at least three connections, one connection being to the blood line of a blood circuit of an extracorporeal blood treatment device, one connection being to a container, and one connection being to a syringe configured to suck and push fluid;
- drawing gas from said blood circuit into said syringe;
- configuring said multi-way valve to inject gas into said container;
- injecting gas into said container;
- configuring said multi-way valve corresponding to draw a medicament from said container into said positive displacement device and so drawing;
- configuring said multi-way valve to inject fluid into said blood circuit;
- injecting medicament into said blood circuit.
Type: Application
Filed: Oct 27, 2005
Publication Date: May 4, 2006
Applicant: NXSTAGE MEDICAL, INC. (Lawrence, MA)
Inventors: James BRUGGER (Newburyport, MA), Martin STILLIG (Dransfeld)
Application Number: 11/163,708
International Classification: B01D 63/04 (20060101);