Patent Issued for Apparatus for Monitoring and Controlling Peritoneal Dialysis

By a News Reporter-Staff News Editor at Biotech Week -- A patent by the inventor Cazzini, Karl H. (Lindenhurst, IL), filed on January 29, 2010, was cleared and issued on December 25, 2012, according to news reporting originating from Alexandria, Virginia, by NewsRx correspondents (see also Baxter International Inc.).

Patent number 8337448 is assigned to Baxter International Inc. (Deerfield, IL).

The following quote was obtained by the news editors from the background information supplied by the inventors: "The present disclosure relates to medical fluid delivery and in particular to peritoneal dialysis fluid delivery.

"Due to disease or other causes, a person's renal system can fail. In renal failure of any cause, there are several physiological derangements. The balance of water, minerals and the excretion of daily metabolic load 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.

"Kidney failure and reduced kidney function have been treated with dialysis. Dialysis removes waste, toxins and excess water from the body that would otherwise have been removed by normal functioning kidneys. Dialysis treatment for replacement of kidney functions is critical to many people because the treatment is life saving. One who has failed kidneys could not continue to live without replacing at least the filtration functions of the kidneys.

"One type of dialysis is peritoneal dialysis. Peritoneal dialysis uses a dialysis solution or 'dialysate', which is infused into a patient's peritoneal cavity through a catheter implanted in the cavity. The dialysate contacts the patient's peritoneal membrane in the peritoneal cavity. Waste, toxins and excess water pass from the patient's bloodstream through the peritoneal membrane and into the dialysate. The transfer of waste, toxins, and water from the bloodstream into the dialysate occurs due to diffusion and osmosis, i.e., an osmotic gradient occurs across the membrane. The spent dialysate drains from the patient's peritoneal cavity and removes the waste, toxins and excess water from the patient. This cycle is repeated.

"There are various types of peritoneal dialysis therapies, including continuous ambulatory peritoneal dialysis ('CAPD') and automated peritoneal dialysis ('APD'). CAPD is a manual dialysis treatment, in which the patient connects an implanted catheter to a drain and allows a spent dialysate fluid to drain from the patient's peritoneal cavity. The patient then connects the catheter to a bag of fresh dialysate and manually infuses fresh dialysate through the catheter and into the patient's peritoneal cavity. The patient disconnects the catheter from the fresh dialysate bag and allows the dialysate to dwell within the cavity to transfer waste, toxins and excess water from the patient's bloodstream to the dialysate solution. After a dwell period, the patient repeats the manual dialysis procedure.

"In CAPD the patient performs several drain, fill, and dwell cycles during the day, for example, about four times per day. Each treatment cycle typically takes about an hour. APD is similar to CAPD in that the dialysis treatment includes a drain, fill, and dwell cycle. APD machines, however, perform three to four cycles of peritoneal dialysis treatment automatically, typically overnight while the patient sleeps. Like CAPD, APD machines connect fluidly to an implanted catheter, to one or more sources or bags of fresh dialysate and to a fluid drain.

"The APD machines pump fresh dialysate from the dialysate source, through the catheter, into the patient's peritoneal cavity and allow the dialysate to dwell within the cavity so that the transfer of waste, toxins and excess water from the patient's bloodstream to the dialysate solution can take place. The APD machines then pump spent dialysate from the peritoneal cavity, though the catheter, to the drain. APD machines are typically computer controlled so that the dialysis treatment occurs automatically when the patient is connected to the dialysis machine, for example, when the patient sleeps. That is, the APD systems automatically and sequentially pump fluid into the peritoneal cavity, allow for a dwell, pump fluid out of the peritoneal cavity and repeat the procedure. As with the manual process, several drain, fill, and dwell cycles will occur during APD. A 'last fill' is typically used at the end of APD, which remains in the peritoneal cavity of the patient when the patient disconnects from the dialysis machine for the day.

"For both APD and CAPD it is desirable to optimize dwell time such that the dialysis solution remains inside the patient for as long as the fluid is efficiently absorbing waste or ultrafiltration ('UF'). When the discharge fluid becomes 'spent', that is, it is not efficiently absorbing waste or UF, the dwell should be ended and a drain of the spent fluid should begin. It is desirable, especially for CAPD, to have a way to control the dwell time to be the optimized time and to notify the patient the dwell time has expired. In the case of APD, such information is also useful especially when the patient has disconnected himself or herself from the APD machine."

In addition to the background information obtained for this patent, NewsRx journalists also obtained the inventor's summary information for this patent: "The present disclosure sets forth an apparatus and method for determining, indicating and controlling an end of a patient dwell period for peritoneal dialysis ('PD'). The apparatus and method may be used to control an APD machine and is especially useful with CAPD. In general, a material is used, such as a hydrogel material, which increases in volume in a controlled and predictable way as the material absorbs water or dialysis fluid over time. The polymer material or hydrogel absorbs the liquid causing the material to expand predictability. The exterior of the material is fitted with an electrical contact or contacts. As the material expands, the contact moves outwardly. Eventually the contact is moved enough, such that it contacts a stationary contact. The material is specifically configured such that the duration of the expansion up until the contacts mate coincides with the patient's optimal dwell time.

"Once the contacts are mated, a circuit is completed and a signal is delivered to an APD machine, which can signal a switch from a dwell phase to a drain phase. Alternatively, the contact closure sounds an alarm or alert to a patient performing CAPD. The alert tells the CAPD patient to end a dwell phase and begin draining. The apparatus therefore acts as a timer to time out an optimal dwell, without the need for a power source for its movement.

"The hydrogel material needs to be in contact with fluid over the course of treatment. It is contemplated to place the hydrogel apparatus in the patient line or in combination with the patient's transfer set, so that fresh fluid remains in contact with the material during the entire dwell. In an APD application, the apparatus may be incorporated with a disposable cassette assuming that at least the apparatus associated portion of the cassette remains primed during the entire dwell.

"The timing of the apparatus is controlled via a number of parameters, such as, material type, porosity or percent open, and size. For example, a certain polymer hydrogel material may swell more quickly than other polymer hydrogels. A hydrogel that is more open than another hydrogel may swell more quickly. A hydrogel material that is larger than another hydrogel material may swell more slowly because it requires more water to become saturated.

"In an alternative embodiment, the electrical contact is not a physical contact. For example, the hydrogel material could be configured to change a capacitance ('.DELTA.C') between two parallel (or concentric) plates to form a parallel plate capacitor. As the hydrogel material hydrates, the distance between capacitor plates decreases and the resulting capacitance increases.

"It is accordingly an advantage of the present disclosure to provide a device and method for optimizing a dwell period for peritoneal dialysis.

"It is another advantage of the present disclosure to provide a device and method that times out or alarms or alerts when a patient's dwell period has ended.

"It is a further advantage of the present disclosure to provide a dwell period timer or alerting apparatus that does not require external power for its movement.

"It is still another advantage of the present disclosure to provide dwell period timer or alerting apparatus that can be incorporated readily into a CAPD or APD disposable and sterilized via a preferred method.

"Additional features and advantages are described herein, and will be apparent from the following Detailed Description and the figures."

URL and more information on this patent, see: Cazzini, Karl H.. Apparatus for Monitoring and Controlling Peritoneal Dialysis. U.S. Patent Number 8337448, filed January 29, 2010, and issued December 25, 2012. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=95&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=4735&f=G&l=50&co1=AND&d=PTXT&s1=20121225.PD.&OS=ISD/20121225&RS=ISD/20121225

Keywords for this news article include: Kidney, Alcohols, Hydrogel, Nephrology, Organic Chemicals, Polyethylene Glycols, Baxter International Inc..

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