Patent GB-1417570-A (GB)
Title: Artificial kidney and a method of ultrfiltering liquid
IPC: A61M1/16
Filed: 1972-12-05
Abstract: 1417570 Dialysis; ultra filtration; artificial kidneys RHONE-POULENC SA 5 Dec 1972 [6 Dec 1971] 56118/72 Heading B1X Haemodialysis by a procedure wherein blood is contacted with one face of a membrane the other face of which forms part of the wall of a constant volume closed system substantially filled with dialysis liquid which is circulated through the system and along the membrane, at a rate of flow conventionally used in haemodialysis, is characterized in that the rate of flow of ultrafiltrate through the membrane is regulated precisely, dialysis liquid being withdrawn from the system at a predetermined rate so that the volume of dialysis liquid in the system is maintained constant and, preferably, the pressure of the dialysis liquid in the system being maintained between predetermined limits, for example between two predetermined values lower than the pressure of the blood being treated. The blood may be treated in an artificial kidney comprising a haemodialyser which has two chambers separated by a membrane capable of permitting simultaneous dialysis and ultrafiltration, one of the chambers being connectable to the bloodstream of a patient and the other of the chambers forming part of a constant volume closed system for containing dialysis liquid, which system further includes means for circulating dialysis liquid through the system and along the membrane at a rate of flow conventionally used in haemodialysis, means for withdrawing dialysis liquid from the system at a predetermined rate so that the volume of dialysis liquid in the system is maintained constant and, optionally, means for heating and regulating the temperature of the dialysis liquid, a dialysis liquid regenerator and a dialysis liquid reservoir, which reservoir may be associated with a manometer and co-operating alarm means for giving a warning when the pressure within the reservoir deviates from a predetermined range. The means for circulating dialysis liquid may be a pump; the means for withdrawing dialysis liquid may include means for pumping dialysis liquid from the reservoir and means for measuring the rate of withdrawal of dialysis liquid. A suitable artificial kidney is schematically illustrated in the Figure and comprises a haemodialyser 1 having a membrane 2 separating a blood compartment 3 from a dialysis liquid compartment 4 which forms part of a constant volume closed system 5 also comprising a pump 6 for circulating dialysis liquid through the system, a vessel 12 for heating and regulating the temperature of the dialysis liquid, a cartridge 7 containing material effective to regenerate the dialysis liquid and a dialysis liquid reservoir 11 provided with an inspection window 14, the artificial kidney further comprising an extraction pump 8 of the volumetric type for withdrawing dialysis liquid from the system, a graduated receptacle 9 for measuring the amount of dialysis liquid withdrawn from the system, a manometer 10 having maximum and minimum contacts and, connected to the contacts, an alarm device 13, for example an acoustic alarm device, for indicating deviation of the pressure in the system outside predetermined limits. The regenerant material in the dialysis liquid regenerator may be absorbent charcoal or urease/ammonia absorber complex (resin or zirconium phosphate) or a source of hypochlorite; specified materials from which the membrane is made are regenerated cellulose and acrylonitrile/sodium methallyl sulphonate copolymer; the haemodialyser may be of the type disclosed in French Specification 1597874.