Surgery – Means for introducing or removing material from body for... – Material introduced into and removed from body through...
Reexamination Certificate
1999-06-28
2002-06-25
Bockelman, Mark (Department: 3762)
Surgery
Means for introducing or removing material from body for...
Material introduced into and removed from body through...
Reexamination Certificate
active
06409699
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to devices and methods for treating patients suffering from renal insufficiency and/or hepatic insufficiency. More particularly, the invention relates to devices and methods for performing continuous flow-through peritoneal dialysis.
2. Discussion of Related Technology
Irreversible end-stage kidney disease was recently reported to occur with an annual frequency of about 1 in 5000 to 10,000 in the general population, with this rate increasing. Until the 1960s, such disease was universally fatal. In the last four decades, various interventions have been developed and implemented for preserving life after loss of all or most of a patient's own kidney function.
The normal function of the mammalian kidney includes such activity as maintaining a constant acid-base and electrolyte balance, removing excess fluids and removing undesirable products of the body's metabolism from the blood. In an individual with end stage renal disease, this functioning of the kidney may be reduced to as low as 5% or less of the normal level. When renal function has decreased to this point, artificial means must then be employed to substitute for the kidney activity, if life is to be sustained. This is accomplished clinically by the use of dialysis.
One of the most common methods for achieving this is hemodialysis, in which the patient's blood is moved outside of the patient's body and passed through an artificial kidney dialysis machine. In the machine, a synthetic non-permeable membrane acts as an artificial kidney with which the patient's blood is contacted on one side; on the opposite side of the membrane is a dialyzing fluid or dialysate, the composition of which is such that the undesirable products in the patient's blood will naturally pass across the membrane by diffusion, into the fluid. The blood is thus cleansed, in essentially the same manner as the kidney would have done, and the blood is returned to the patient's body.
There are, however, a number of disadvantages inherently associated with hemodialysis. For instance, poor peripheral vasculature in some patients makes removal of the patient's blood for hemodialysis unfeasable. Additionally, extracorporeal handling of blood is inherently dangerous due to the risk of introducing, for example, bacterial or other contaminants or air bubbles into the blood. Further, equipment needed for performing hemodialysis is guide complicated and expensive.
Some of the disadvantages associated with extracorporeal treatment of blood by hemodialysis are overcome by the use of techniques which utilize the patient's own peritoneum as the required semipermeable membrane. Presently, a great deal of interest is being given to the development of improved methods for removing undesirable products from the blood through the peritoneum, an intricate membrane-like tissue that lines the abdominal cavity and covers the liver, kidneys, intestine and other internal organs. The peritoneum contains large numbers of blood vessels and capillaries and is thus capable of acting as a natural semipermeable membrane. In a peritoneal dialysis procedure, dialysis solution, or “dialysate” is introduced into the peritoneal cavity, via a catheter in the abdominal wall, and a suitable period of residence time for the dialysate is typically allowed to permit the exchange of solutes between it and the blood. The waste products removed from the patient's blood in this manner typically consist of solutes like sodium and chloride ions, and the other compounds normally excreted through the kidneys like urea, creatinine, and water. Fluid removal is achieved by providing a suitable osmotic gradient from the blood to the dialysate to permit water outflow from the blood. The diffusion of water across the peritoneal membrane during dialysis is called ultrafiltration. Conventional peritoneal dialysis solutions include glucose in concentrations sufficient to generate the necessary osmotic pressure to remove water from the patient's blood. Thus, the proper acid-base, electrolyte and fluid balance is returned to the blood and the dialysis solution is simply drained from the body cavity through the catheter.
Continuous Ambulatory Peritoneal Dialysis (CAPD) is a popular form of peritoneal dialysis (PD). A patient performs CAPD manually about four times a day. During CAPD, the patient drains spent peritoneal dialysis solution from his/her peritoneal cavity. The patient then infuses fresh peritoneal dialysis solution into his/her peritoneal cavity. This drain and fill procedure usually takes about 1 hour.
Automated Peritoneal Dialysis (APD) is another popular form of PD. APD uses a machine, called a cycler, to automatically infuse, dwell, and drain peritoneal dialysis solution to and from the patient's peritoneal cavity. APD is particularly attractive to a PD patient, because it can be performed at night while the patient is asleep. This frees the patient from the day-to-day demands of CAPD during his/her waking and working hours. The APD sequence typically lasts for several hours. It often begins with an initial drain cycle to empty the peritoneal cavity of spent dialysate. The APD sequence then proceeds through a succession of fill, dwell, and drain phases that follow one after the other. Each fill/dwell/drain sequence is called a cycle.
During the fill phase, the cycler transfers a predetermined volume of fresh, warmed dialysate into the peritoneal cavity of the patient. The dialysate remains (or “dwells”) within the peritoneal cavity for a time. This is called the dwell phase. During the drain phase, the cycler removes the spent dialysate from the peritoneal cavity. The number of fill/dwell/drain cycles that are required during a given APD session depends upon the total volume of dialysate prescribed for the patient's APD regime.
Continuous Cycling Peritoneal Dialysis (CCPD) is one commonly-used APD modality. During each fill/dwell/drain phase of CCPD, the cycler infuses a prescribed volume of dialysate. After a prescribed dwell period, the cycler completely drains this liquid volume from the patient, leaving the peritoneal cavity empty, or “dry.” Typically, CCPD employs 6 fill/dwell/drain cycles to achieve a prescribed therapy volume. After the last prescribed fill/dwell/drain cycle in CCPD, the cycler infuses a final fill volume. The final fill volume dwells in the patient through the day. It is drained at the outset of the next CCPD session in the evening. The final fill volume can contain a different concentration of glucose than the fill volume of the successive CCPD fill/dwell/drain fill cycles the cycler provides.
Intermittent Peritoneal Dialysis (IPD) is another APD modality. IPD is typically used in acute situations, when a patient suddenly enters dialysis therapy. IPD can also be used when a patient requires PD, but cannot undertake the responsibilities of CAPD or otherwise do it at home. Like CCPD, IPD involves a series of fill/dwell/drain cycles. The cycles in IPD are typically closer in time than in CCPD. In addition, unlike CCPD, IPD does not include a final fill phase. In IPD, the patient's peritoneal cavity is left free of dialysate (or “dry”) in between APD therapy sessions.
Tidal Peritoneal Dialysis (TPD) is another APD modality. Like CCPD, TPD includes a series of fill/dwell/drain cycles. Unlike CCPD, TPD does not completely drain dialysate from the peritoneal cavity during each drain phase. Instead, TPD establishes a base volume during the first fill phase and drains only a portion of this volume during the first drain phase. Subsequent fill/dwell/drain cycles infuse then drain a replacement volume on top of the base volume, except for the last drain phase. The last drain phase removes all dialysate from the peritoneal cavity. There is a variation of TPD that includes cycles during which the patient is completely drained and infused with a new fill base volume of dialysis. TPD can include a final fill cycle, like CCPD. Al
Bockelman Mark
Patent and Trademark Attorneys
Renal Solutions, Inc.
Woodward, Emhardt, Naughton Moriarty & McNett
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