Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Patent
1990-03-26
1992-03-03
Isabella, David J.
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
A61F 204
Patent
active
050928864
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a national phase application of PCT/HU88/00064 filed Sept. 29, 1988 based upon a U.K. national application 8722854 filed Sept. 29, 1987 under the International Convention.
FIELD OF THE INVENTION
The invention relates to an implantable artificial kidney having a blood inlet for connection to the renal artery of a living human body, a blood outlet for connection to the renal vein of the living human body and at least one glomerulus provided with blood tubes connected to the blood inlet separated from the filtrate tubes by permeable porous walls allowing ultra-filtration therethrough.
BACKGROUND OF THE INVENTION
As is known, the kidneys of the living human body are important excretory organs whose main functions are to excrete both the biologically useless materials accumulated in the blood and the superfluous water and to remove them in the form of urine. The living kidney is composed of about 1-1.5 million microscopic subunits called nephrons. Each nephron is composed of two parts: the glomerulus and the tubules. The glomerulus is built up of capillary vessels, and blood plasma is filtrated from blood through the porous wall of these vessels. Then the filtrate drains from Bowman's capsule enclosing the glomerulus to the tube system forming the tubules. The blood follows the tubules in the capillary efferent vessels starting in the Bowman's capsule and reabsorbs such an amount of water and solutes from the filtrate passing through the tubules as is necessary to restore the oncotic pressure value satisfying the Gibbs-Donnan equilibrium. The filtrate then transforms further along the tubules into urine as a consequence of this reabsorption process. It drains into the central funnel of the renal pelvis and hence into the ureter and is stored in the urinary bladder. The process carried out in the glomerulus is an ultra filtration essentially during which a great deal of water and in it dissolved solids are filtered from the blood. The blood loses approximately 50% of its aqueous content at this stage. In the tubules, the major part --approximately 80-90%--of this filtrate is reabsorbed into the efferent blood vessels together with the dissolved materials therein necessary for the blood. The remaining liquid containing also all the biologically useless materials in a high concentration is the urine that passes through the ureter to the urinary bladder. Approximately 180 liters per day of blood passes through the kidneys producing only approximately 1.5 liters of urine.
When kidneys cannot operate properly, useless materials accumulate first in the blood, then in the body and can lead to death within 10-12 days. That is why several methods have long been being experimented with for replacing a kidney unable to perform its task.
One of the methods is the implantation of a healthy kidney replacing the ill one. The disadvantage of this method is that the body rejects the foreign organ and expels it. For preventing rejection the donor is preferably a near relative. If the donor is a stranger or if a removed kidney is transplanted from a recently deceased person then anti-rejection drugs are given to the recipient patient. These drugs can not be taken ad infinitum due to their harmful side-effects; therefore a transplated kidney cannot generally be expected to keep functioning for more than five years using this method.
Another method is dialysis performed by external dialyzers. This method basically replaces the filtration process taking place in the glomerulus. On the one hand the filtrate that is generated and contains several kinds of materials necessary for blood is removed together with water and on the other hand the thickened blood is returned into the body. This method is rather expensive, unpleasant and inconvenient for the patient and can be regarded only as a temporary solution. A patient must spend three or four periods of eight to twelve hours each week connected to the dialyzer. The patient will feel unwell both before and after dialysis.
REFERENCES:
patent: 2715097 (1955-08-01), Guarino
patent: 4222869 (1980-09-01), Kato
patent: 4354933 (1982-10-01), Lester
patent: 4634447 (1987-01-01), Isono et al.
patent: 4648865 (1987-03-01), Aigner
patent: 4769037 (1988-09-01), Midcalf
patent: 4770852 (1988-09-01), Takahara et al.
Dubno Herbert
Isabella David J.
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