The present invention relates generally to the field of medical devices. More particularly, the present invention relates to a device and method to produce dialysate.
During the COVID-19 pandemic, it became apparent that major events could result in dialysate shortages. It is therefore desirable to provide a device and method for the production of dialysate.
The foregoing needs are met, to a great extent, by the present invention wherein in one aspect, a device for producing dialysate includes an adapter having an outer wall and having a first end and a second end. The outer wall defines an interior lumen that extends between the first and second ends of the adapter. The first end of the adapter is configured to be coupled to dialysis equipment and wherein the second end is configured to be coupled to a dialysate collection bag.
In accordance with an aspect of the present invention, the interior lumen includes couplings for the dialysis equipment and the collection bag. The couplings are threaded couplings. The adapter is formed from a plastic. The adapter is manufactured via three-dimensional printing. The present invention can also include a method of producing dialysate using the adapter of claim 1 to couple the dialysate collection bag to the dialysis equipment.
In accordance with another aspect of the present invention, a method includes generating an adapter having an outer wall and having a first end and a second end, wherein. The outer wall defines an interior lumen that extends between the first and second ends of the adapter. The first end of the adapter is configured to be coupled to dialysis equipment and wherein the second end is configured to be coupled to a dialysate collection bag.
In accordance with yet another aspect of the present invention, the interior lumen includes couplings for the dialysis equipment and the collection bag. The couplings are threaded couplings. The adapter is formed from a plastic. The method includes generating the adapter using three-dimensional printing generating the adapter using a molding process, and/or sculpting the adapter from a block of plastic. The adapter can be formed from one selected from a group of polylactic acid (PLA), nylon, and/or polycarbonate (PC).
Further objectives and advantages will become apparent from a consideration of the description, drawings, and examples.
The presently disclosed subject matter will now be described more fully hereinafter with reference to the accompanying Drawings, in which some, but not all embodiments of the inventions are shown. Like numbers refer to like elements throughout. The presently disclosed subject matter may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Indeed, many modifications and other embodiments of the presently disclosed subject matter set forth herein will come to mind to one skilled in the art to which the presently disclosed subject matter pertains having the benefit of the teachings presented in the foregoing descriptions and the associated Drawings. Therefore, it is to be understood that the presently disclosed subject matter is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims.
The present invention provides a novel device and method of generating and bagging dialysate for continuous veno-venous hemodialysis (CVVHD). The procedure involves the use of standard hemodialysis (HD) equipment and the device of the present invention. The device of the present invention is an adapter configured to be used with standard hemodialysis equipment.
A device according to the present invention allows for CVVHD dialysate to be produced by generating it from conventional hemodialysis (HD) machines. Testing of this dialysate demonstrates that its composition is comparable to the CVVHD bags that are available commercially. When the dialysate flow rate is set to 800 mL/min on the HD machine, approximately 400 mL/minute of dialysate can be produced, since the flow is pulsatile.
The adapter described above can be three-dimensionally printed, manufactured via molding, sculpting. or any other suitable method for manufacturing the adapter known to or conceivable to one of skill in the art. The adapter can be formed from polylactic acid (PLA), nylon, polycarbonate (PC), or any other suitable material known to or conceivable to one of skill in the art. The material should be sterilizable, and should exhibit low deformation.
Prototyping and testing was done for three materials: Polylactic Acid (PLA), Nylon, and Polycarbonate (PC). Ultimaker brand filament spools were used for all prints, to ensure compatibility with the Ultimaker 3 Extended printer that was used to manufacture all parts. These spools are widely available and perform consistently well under normal use.
PC: PC has superior mechanical and thermal properties than most common 3D printing materials. The adapter had no visible defects from the use of chlorhexidine swabs or EtO sterilization. But, they were significantly deformed after being autoclaved with a steam cycle. While Polycarbonate is a common material used for medical devices of similar nature, the Ultimaker PC is NOT medical grade and therefore, the adapter should not be assumed to be either biocompatible or to have adequate leaching properties. However, the non-contacting nature of the adapter design should help bypass any biocompatibility concerns, especially if EtO sterilization is performed and chlorhexidine swabs are used. A summary of the PC sterilization tests can be seen below. Tests are currently being performed to determine how many cycles an adapter can go through before it should be changed. Note: All diameters were measured between the threads on both ends. The steam cycle PC samples did not retain their shape and became elliptical on both ends. Failure mode for PC: Formal tests have not been performed on the effects of repeated use of chlorhexidine swabs on a PC adapter. If any visual anomalies are observed, switching out the adapter with a new one is recommended. The adapters of the present invention are also being tested for any visual anomalies.
PLA: PLA was only used for prototyping and it is NOT recommended to use PLA for functional parts. PLA is not compatible with most sterilization methods and does not have the adequate mechanical properties to be used for this purpose. However, PLA is a highly popular filament, and is recommended for the testing.
Nylon: Nylon has excellent mechanical properties. It showed significant changes on its surface when wiped with chlorhexidine swabs, but deformed under a single steam cycle in the autoclave. EtO sterilization tests were not performed for Nylon.
The method of using the adapter with standard dialysis equipment to produce dialysate in collection bags is described further herein with respect to
a) Repeated use of the same adapter may result in a loss of sterility. Remember to scrub the adapter with chlorhexidine prior to connecting a new bag.
The adapter of the present invention is configured to connect the dialyzer to a fluid storage bag. In particular, the examples used herein are the Fresenius Optiflux high-flux dialyzer and the Baxter Exactamix TPN bags. Both these devices have male threads on their ends that do not mate with each other. The generally cylindrical adapter of the present invention includes complementary female threads on each end to enable this connection in a way that allows the dialysate to pass from the dialyzer's effluent port directly to the TPN bag without touching the adapter.
In some embodiments the adapter of the present invention is three-dimensionally printed. A preferred process for printing follows. It should be noted that this printing process is included by way of example and is not meant to be considered limiting. Any printing or other manufacturing process known to or conceivable to one of skill in the art can also be used.
Print the adapter with the smaller diameter side of the adapter facing the build plate. All the testing and analysis has been performed using the “Ultimaker 3 (Extended)” printer, which uses the Fused Deposition Modeling (FDM) method to create parts. The adapter of the present invention is designed to work with single-extrusion printers and DO NOT need any support material. The Ultimaker family of printers is one option for equipment or any other printers with similar capabilities. The adapter of the present invention are PC sterilizable and PC has superior mechanical properties than most commonly available 3D printing materials. EtO sterilization is recommended for the adapters of the present invention and disinfection with chlorhexidine swabs between uses. Results from the sterilization tests can be found in Table 1. Use the standard latest version of Cura to set up the prints, if using an Ultimaker. The default Ultimaker PC profile on Cura as the baseline. Make the following changes and confirm that the temperatures in the default profile match.
Please DO NOT use glue or any other material to improve print adhesion on these parts to avoid affecting their potential sterility later on.
In order to determine the stability of the dialysate created, chemical analyses were performed to monitor key analyte concentrations over time. At the beginning of the experiment the procedure outlined in section 1 was used to collect two full bags of dialysate in the ExactaMix TPN bags. One was stored in a 4° C. refrigerator and the other was stored at room temperature. Samples were taken at hour 0, 6, 9, 12, and 23 to monitor the stability of the dialysate overtime. Specifically, the concentrations of 8 analytes were taken: calcium, chloride, bicarbonate, glucose, potassium, lactate, magnesium, and sodium. Both bags of dialysate remained reasonably stable for at least 23 hours. In the first 12 hours, no analyte concentration varied from the baseline by more than 5%. At the 23 hour mark, this was true for all analytes except for the refrigerated bicarbonate measurement which varied by about 10%. The full results can be found in Tables 2 and 3, below. The FDA guidelines suggest that generated dialysate should be used within 4 hours, so the generated dialysate will remain stable well past this time point.
At the beginning of the experiment the above procedure was used to collect two full bags of dialysate in the ExactaMix TPN bags. One was stored in a 4° C. refrigerator and the other was stored at room temperature. The following is the testing procedure used.
5) Using a sterile, individually wrapped pipette, one drop of the fluid was plated to blood agar and chocolate agar plates for the aerobic culture and one drop to a brucella blood agar plate for the anaerobic culture. Then, plates were streaked for isolation.
The results of the culture tests showed that there was no growth on any of the plates throughout the experiment, suggesting that the bagged dialysate fluid was safe for use. While the results are promising, the test does not prove that the fluid is sterile. Therefore, it is only suggested to use this method if non-sterile dialysate is appropriate. This method is not recommended for creating infusate, as sterility cannot be guaranteed. It is encouraged that microbiology tests are performed intermittently to instill confidence that this method continues to produce dialysate that is safe to use.
Visual inspection of the adapter was performed under normal operation and also the Dialyzer-TPNbag interface was analyzed under a microscope. These tests were performed on a special test version of the adapter of the present invention. The test adapter is dimensionally equivalent but has two diametrically opposite slots that enable visual inspection of the dialyzer-collection bag interface through the naked eye and a microscope.
To further check for leaks, the collection bag was filled with water and blue watercolor was added to enhance visibility under the microscope. Then the water was allowed to flow under gravity by raising the bag above the connection to check for leaks. This was repeated twice. One slot was used to obtain the images and the other was used to check for any leaks during the tests. A chromatography strip was placed under the connection, facing the diametrically opposite slot to collect any fluid, if it leaked. After the test, another chromatography strip was pressed against the outside of the dialyzer-collection bag screw's interface, through the slot, to check for leaks as well. Both chromatography papers were found to be dry,
Visual inspections of the slotted test adapters were also performed when connected to the dialysis machine and were monitored for leaks. No leaks were observed under normal operation. The non-contacting nature has only been verified in a limited setting, under normal operation. At high pressure, or in cases where the procedure is not followed, extra care should be taken to monitor for leaks. The adapter of the present invention is not expected to fail under normal operation. The adapter is designed to be intuitive to use, however, the user must ensure that both, the effluent port of the dialyzer and the male screw of the TPN bag are completely screwed in. If not done correctly, the fluid may either leak over the threads of either the connections and seep out or, if there is a large enough gap, the fluid might make contact with the inner wall of the adapter before entering the bag. To ensure a proper fit, it is recommended to screw the adapter over the dialyzer effluent port first. When it can no longer move, screw in the collection bag until the flange of the TPN bag's male screw is flush with the flat surface of the adapter. It is recommend that users to support their bags on a flat surface (like a chair or a table) as they are filled. While the adapters of the present invention can support the weight of a fully filled 1L collection bag, this is not recommended. The weight of the filled bags can cause tensile stress in the adapter and stretch it over time, jeopardizing its non-contacting nature.
The embodiments illustrated and discussed in this specification are intended only to teach those skilled in the art how to make and use the invention. In describing embodiments of the invention, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected. The above-described embodiments of the invention may be modified or varied, without departing from the invention, as appreciated by those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the claims and their equivalents, the invention may be practiced otherwise than as specifically described.
This application claims the benefit of U.S. Provisional Patent Application No. 63/168,452 filed on Mar. 31, 2021, which is incorporated by reference, herein, in its entirety.
Number | Date | Country | |
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63168452 | Mar 2021 | US |