AN APPARATUS SYSTEM FOR THE CONTROL OF A MEDICAL TREATMENT, E.G. DIALYSIS

Abstract: A system for the control of a medical treatment, e.g. dialysis, using a tempered fluid, comprising means for the control of the temperature (2) or rather the flow (18, 28) of this fluid and means (36, 37) for the connection of the system to a treating arrangement, e.g. a dialyzer (33), disinfection and/or sterilization being arranged so as to take place with the help of a fluid heated to a higher temperature than normal treatment temperature, this fluid being made to flow along the same path as the treatment fluid, except for being conducted past the said connecting means (36, 37) through a so-called by-pass arrangement (38-41 and/or 34, 35). The system is characterized in that a part of the fluid heated to the said higher temperature is made to recirculate in the system. The invention primarily relates to a system for the control of haemodialysis, that is to say for the purifying of the blood of patients with diminished renal function or wholly lacking such function.

Description: TECHNICAL FIELD The present invention relates to a system for the control of medical treatment, e.g. dialysis, using a tempered fluid, comprising means for the control of the temperature and the flow of this fluid, respectively, and means for the connection of the system to a treating arrangement, e. g. a dialyzer, disinfection and/or steril­ ization being arranged so as to take place with the help of a fluid heated to a higher temperature than normal treat­ ment temperature, this fluid being made to flow along the same path as the treatment fluid, except for being con­ ducted past the said connecting means through a so-called bypass arrangement. The invention primarily relates to a system for the control of haemodialysis, that is to say for the purifying of the blood of patients with diminished renal function or wholly lacking such function. It will be obvious, to those versed in the art that the system in accordance with the invention also may be used for the control of other medical treatments, such as peritoneal dialysis, haemofiltration, plasmaferes etc., that is to say systems comprising means for the tempering of a treatment fluid. BACKGROUND ART More particularly the invention relates to a further development of the system which is marketed by the Gambro Group, to which the applicant belongs, under the descrip­ tion "Gambro AK-10". Various details of this system form the subject of, for example the following US Patents: 4 122 010, 4 158 034, 4 293 409, 4 194 974 and 4 191 359, these descriptions being included hereby in the present description. Reference is made also to the further development according to European patent application EP 84.112914.1 and the inven­ tion according to the British patent 2 003 274 and the further development of this according to the European patent application published under number EP 0 106 940, and these too are included in the present description. Reference is made, furthermore, to EP 0 022 922 which describes in more detail the preparation of dialysis fluid from two concentrates, a preparation which is only touched upon in the following description of the present invention. Finally, reference is made to US patent 3 738 382 which describes a competing system for the preparation of dialysis fluid wherein the sterilization is achieved with the help of a heating element normally included in the system, at the same time as the heated sterilizing agent is made to recirculate through the system in its entirety. The said system is subject to the disadvantage, among other things, that the sterilizing fluid is caused to recirculate through less contaminated as well as more contaminated parts of the system. The result can be that impurities may be passed from the more contaminated parts to the less contaminated parts. Furthermore, the known system is designed to operate at a pressure above atmospheric which is adapted to a very special procedure for the preparation of dialysis fluid, as a result of which its applicability is limited. DISCLOSURE OF INVENTION The invention thus relates to a system of the above­ mentioned type which, more particularly, is characterized in that a part of the fluid heated to the said higher temperature is made to recirculate in the system. The advantage gained thanks to this design is that heating devices normally included in the system suffice, without overdimensioning, both for compensation of heat losses in the recirculating system and for the heating of a small amount of new fluid supplied continuously. At the same time an amount of fluid equal to that newly supplied may be allowed to flow through more contaminated parts of the system directly to an outlet. Preferably the said recirculation is arranged so as to take place with the help of a special return line from a point further on in the system to a point at the start of the system. Appropriately this special return line is adapted so that the recirculation takes place from the said bypass arrangement, that is to say within the part of the system which normally contains pure treatment fluid not affected by the treatment arrangement. Thereby it also ensured that no recirculation is occasioned in the part of the system through which flows normally treatment fluid which has been acted on and thus may also have been contaminated by the treating arrangement. If it is merely intended to procure disinfection, the normal heating device of the system may be adapted so as to raise the temperature in a fluid heating vessel to substan­ tially 90°C at the same time as the recirculation selected is such that the temperature in the recirculation circuit does not fall far short of 90°C. At the same time the temperature in the system, after the point of recircula­ tion, may be allowed gradually to drop, e.g. down to the order of magnitude of 80°C. Preferably the disinfection and/or the sterilization are adapted so as to take place at substantially normal atmospheric pressure. If it is desired to assure effective sterilization it may become necessary, though, either to increase the pressure and the temperature or supplement it by chemical means. In practice it has proved appropriate to allow the disinfection and/or the sterilization to take place with substantially maximum flow in the recirculation circuit, whilst the flow in the rest of the system is kept at a fraction of this, e.g. in the order of magnitude of one fifth. Any constrictions included in the recirculation circuit are arranged appropriately to be opened or wholly or partly bridged over during disinfection and/or sterilization so as to minimize flow resistance. BRIEF DESCRIPTION OF DRAWINGS The invention is described in more detail in the following with reference to the attached drawing which, by way of example, shows the most important components of a system in accordance with the invention. BEST MODE OF CARRYING OUT THE INVENTION In the system shown as an example in the attached drawing the water is fed via an inlet 1 to a heating device 2, where it is heated. The temperature is then measured in a temperature measuring device 3 before the water is conducted via a return vessel 4 to a constriction 5 and further via a bubble expansion tank 6, a pressure gauge 7 and a pump 8 to a vent tank 9. From the vent tank 9 a return duct 10 leads back to the return vessel 4 for the recycling of any air or other gases separated together with a small part of the fluid. A recycling would be possible instead to the heating vessel 2, but this would then require to be made from a more resistant material, since dialysis concentrate is being supplied to the point 11 via the duct 12 with the help of the pump 13. This part of the system corresponds in substantial parts to the system which is described, for example, in the US patents 4 158 034 and 4 293 409. The function of the expansion vessel 6 is described in detail in the European patent application 84.112914.1. From the vent tank 9 the fluid is passed further via a conductivity measuring cell 14 to another mixing point 15 where further concentrate is supplied possibly with the help of a pump 16 and a duct 17. This is done on the assumption that it is intended to work with so-called two-component-based dialysis concentrate, e.g. of the type which is described in EP 0 022 922. From the mixing point 15 the dialysis fluid is passed through a first constant flow arrangement 18 consisting of a constriction 19, a pump 20 and a pressure gauge 21. Before the constriction device 19 the pressure is substantially at atmospheric pressure as the duct is connected without any major resistance to the vent tank 9. Should it be found in practice that the pressure varies owing to the pump 16, the conductivity meter 14 and the mixing point 15 can be moved to a position before the vent tank 9. The pressure measured by the pressure gauge 21 is used for the control of the pump 20, so that a desired constant flow is obtained. After the pump 20 the flow is passed through a conductivity meter 22 and an ultrafiltra­ tion monitor 23 via a temperature measuring instrument 24 and a pressure gauge 25 to the dialyzer. From the dialyzer the flow is conducted via a pressure gauge 26, the said ultrafiltration monitor 23 and a blood detector 27 to a further constant flow arrangement 28 consisting of a pump 29, a pressure gauge 30 and a constriction device 31. Finally the dialysate is passed to an outlet 32. It is appropriate for the constant flow arrangement 28 to be identical with the arrangement 18. In the constriction 31, though, the pressure drop obtained is from a pressure above atmospheric to the pressure prevailing at the outlet which ought to be kept constant and, for example, may be equal to atmospheric pressure. The design and function of the ultrafiltration monitor are described in greater detail in the above­ mentioned publications GB 2 003 274 and EP 0 106 940. Numeral 33 designates the dialyzer which can be connected to the system in accordance with the invention, on the blood side of which the patient is connected up. The latter connection, however, is not shown in the drawing. The dialyzer 33 can be bridged over in two ways. It may be done either with the help of the by-pass duct 34 with the valve 35 which is opened if, for example, the temperature or the conductivity exceed, or fall short of, certain limit values. At the same time the flow to the dialyzer 33 is stopped with the help of a valve not shown in the drawing. Alternatively the bridging may be done in that the dialyzer connections 36 and 37 are coupled to a by-pass duct 38 via the couplings 39 and 40. This bridging arrange­ ment is designed appropriately in the main according to US patent 4 122 010 with a pressure monitoring device 41 which checks whether a suction pressure exists in the duct 38. In the present case, though, a pressure above atmos­ pheric is detected instead. If this is the case, and only then, sterilization may take place. In the example shown a return duct 42 with a valve 43 runs back from the bridging arrangement 38 to the heating vessel 2. Through this duct 42 recirculates a part of the flow, when the system is to be disinfected or sterilized. The remainder of the flow is passed instead from the duct 36, which is connected to the coupling 39 via the duct 38 and the coupling 40 to the duct 37 and from there through the ultrafiltration monitor 23 and further to the outlet 32. A small amount, however, is conducted directly from the duct 36 via the duct 34 with the valve 35 directly to the duct 37 for disinfection and/or sterilization of this bridging arrangement. Naturally the invention is not limited merely to the embodiment described above, but can be varied within the scope of the following claims. For example, the diverse components included in the system can be varied within wide limits without the scope of the invention thereby being exceeded. Compare, for example the publications cited above and the patent applications 85.02756-3 and 85.02757-1 with our references GA 139 and GA 140 submitted at the same time.

Claims: 1. A system for the control of a medical treatment, e.g. dialysis, using a tempered fluid, comprising means (2, 3) for the control of the temperature and the flow (18, 28) of this fluid, respectively, and means (36, 37) for the connection of the system to a treating arrangement, e.g. a dialyzer (33), disinfection and/or sterilization being arranged so as to take place with the help of a fluid heated to a higher temperature than normal treatment temperature, this fluid being made to flow along the same path as the treatment fluid, except for being conducted past the said connecting means (36, 37) through a so-called by-pass arrangement (38-41 and/or 34, 35), charac­ terized in that a part of the fluid heated to the said higher temperature is made to recirculate in the system. 2. A system in accordance with claim 1, charac­ terized in that the said recirculation is arranged so as to take place with the help of a special return line (42) from a point further on in the system to a point at the start of the system. 3. A system in accordance with claim 2, charac­ terized in that the recirculation is arranged to take place from the said by-pass arrangement (38-41), that is to say within the part of the system which normally contains a treatment fluid not affected by the treating arrangement (33). 4. A system in accordance with claim 3, charac­ terized in that no recirculation is occasioned in the part of the system through which flows normally treat­ ment fluid which has been acted on, and thus may also have been contaminated, by the treating arrangement (33). 5. A system in accordance with anyone of the preced­ ing claims, characterized in that the normal heating device (2) of the system in the case of disinfec­ tion is adapted to raise the temperature in a fluid heating vessel to substantially 90°C and that such a recirculation is selected that the temperature in the recirculation circuit does not fall far short of 90°C, whilst the tem­ perature in the system after the point of recirculation is allowed gradually to drop, e.g. down to the order of magniture of 80°C. 6. A system in accordance with anyone of the preceding claims, characterized in that the disinfection and/or the sterilization are adapted so as to take place at substantially normal atmospheric pressure. 7. A system in accordance with anyone of the pre­ ceding claims, characterized in that the disinfection and/or the sterilization are adapted so as to take place with substantially maximum flow in the recircu­ lation circuit, whilst the flow in the rest of the system is adapted so as to be kept to a fraction of this, e.g. in the order of magnitude of one fifth. 8. A system in accordance with anyone of the pre­ ceding claims, characterized in that any constrictions included in the recirculation circuit are arranged to be opened during disinfection and/or steril­ ization and/or are wholly or partly bridged over so as to minimize flow resistance.

Inventors: PETERSEN, PREBEN ALLAN, STERNBY, JAN PETER
Applicants: GAMBRO AB
Application year: 1986
Main classification: A61M1
IPC codes: A61M1, B01D61