DISINFECTION ARRANGEMENT FOR DIALYSIS MACHINES

Abstract: Disinfection arrangement for a dialysis machine consisting of a clean side and dirty side. The clean side comprises an inlet (2) for water, a valve (4), a heat exchanger (6) as well as a water vessel (5) containing a heater (9). A feed conduit (11) leads from the water vessel (5) to a tube (13) which is normally connected to the clean side of the dialyser but, during disinfection, is connected to a recirculation conduit (40) via a valve (23) in order to perform a first recirculation circuit. A second recirculation circuit is constituted by a recirculation conduit (42), a valve (41), a tube (25), which is normally connected to the dirty side of a dialyser, a return conduit (28) as well as a pump (30). A heat exchanger (6) heats up the fluid in the second circuit with help of the fluid in the first circuit, which is heated up by the heater (9) in the water vessel (5). A small amount of fluid is transferred from the first circuit to the second circuit via a shunt conduit (27).

Description: TITLE DISINFECTION ARRANGEMENT FOR DIALYSIS MACHINES FIELD OF THE INVENTION The present invention relates to a disinfection arrangement for a dialysis machine. In particular the invention relates to a heat disinfection arrangement for a haernodialysis machine where the disinfection occurs in two separate circuits, one for the clean side of the dialysis machine and one for the dirty side of the dialysis machine. PRIOR ART A disinfection arrangement for a haernodialysis machine is described in DE-C2-34 47 989. This haernodialysis machine is provided with an inner shunt conduit which, in principle, connects the machine's used dialysis solution outlet with the inlet of the machine or, more specifically, a mixing chamber for the dialysis solution. A disinfectant is supplied to the dialysis machine and is made to circulate in the closed circuit through the machine and through the aforementioned shunt conduit. The disadvantage with this disinfection arrangement is that the same solution circulates on the clean side as well as on the dirty side of the dialysis machine. By the terminology "dirty side" of the machine is meant the side which, during normal operation, is positioned after the dialyser and contains the dialysis solution which comes from the dialyser, which can contain blood plasma (ultrafiltrate) . Another disinfection arrangement for a dialysis machine is described in EP-Bl-208 090. The machine is provided with a shunt conduit which extends from a dialyser coupling (the clean side of the dialyser) to the inlet of the dialysis machine. In this way a recirculation circuit is formed which only includes the clean side of the dialysis machine. Additionally, a heating element is included, said element being positioned in a water vessel in the recirculation circuit. The heating element is used to successively heat up the fluid, normally water, circulating in the circuit to a high temperature, for example above 95°C. In this way a heated disinfection and/or sterilisation is achieved. A small part of the warm fluid is tapped off to the dirty side of the dialysis machine and passes through this and out to the outlet, whereby the dirty side of the machine is also disinfected. The temperature of the fluid, however, falls during this passage, which results in the disinfection of the dirty side being less effective. SUMMARY OF THE INVENTION The object of the present invention is to achieve a disinfection arrangement corresponding to EP-Bl-208 090, but in which the dirty side is also effectively disinfected and/or sterilised. Another object of the present invention is to achieve a heat disinfection arrangement for a dialysis machine where the required heat energy is used effectively. Thus, there is provided a disinfection arrangement for a dialysis machine, whereby the dialysis machine comprises, a feed arrangement which constitutes a clean side of the dialysis machine, for normally supplying a dialysis solution to a dialyser; a return arrangement which constitutes a dirty side of the dialysis machine for normally removing the dialysis solution from the dialyser; and means for circulating a first fluid in a first recirculation circuit within the clean side of the dialysis machine for disinfection of the clean side of the dialysis machine. According to the invention, the disinfection arrangement comprises means for circulation of a second fluid in a separate second recirculation circuit within the dirty side of the dialysis machine, said second circuit comprising a heating arrangemen . Said heating arrangement is preferably a heat exchanger arranged to transfer heat energy from the first circuit to the second circuit. There may alternatively or additionally be included a heating member in the second circuit for heating of the second fluid. According to a preferred embodiment of the invention, the disinfection arrangement comprises a recirculation conduit which connects the inlet of the return arrangement with its outlet for recirculation of said second heated fluid. In another embodiment of the invention, the disinfection arrangement comprises a shunt conduit between the first circuit and the second circuit for transfer of fluid from the first circuit to the second circuit. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail with reference to the accompanying drawings which depict preferred embodiments of the invention. Fig. 1 is a schematic view which shows a dialysis machine of the general type disclosed in EP-Bl-208 090. Fig. 2 is a schematic view similar to Fig. 1, showing a preferred embodiment of the invention. Fig. 3 is a schematic view similar to Fig. 2 and shows an alternative embodiment of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Fig. 1 shows a dialysis machine 1 substantially in accordance with EP-Bl-208 090. Several components of the dialysis machine which are not necessary for an understanding of the invention have been omitted. The dialysis machine comprises an inlet 2 for clean water, which normally comes from a water purification unit (reverse osmosis unit) . The inlet 2 is connected to a water vessel 5 via an inlet conduit 3 and an inlet valve 4. A heat exchanger 6 may be located in the conduit 3, but this heat exchanger is in some machines only an accessory (optional) . The water vessel 5 is provided with a level detector 7 which controls the inlet valve 4 (indicated in dashed line 8) so that the level in the water vessel 5 is substantially constant. The water vessel 5 is normally connected to the surrounding atmosphere as shown.. Additionally the water vessel comprises an immersion heater 9. A temperature sensor 10 detects the temperature of the water in the water vessel 5 and regulates the power supply to the immersion heater 9 so that the correct water temperature is attained, normally about 37°C. A feed conduit 11 extends from the water vessel 5 to a tube 13 for connection to a dialyser 50. The conduit 11 comprises various arrangements 14, such as a dearator device, pH-sensor, flow meter, e t c, as well as two mixing points 15, 16. The water in the conduit 11 is mixed with a concentrate at the mixing point 15, which concentrate can be an A-concentrate (Acid-concentrate) via a metering pump 17. A B-concentrate (Bicarbonate-concentrate) is supplied at the second mixing point 16 via a metering pump 18. Supply of a substantially saturated bicarbonate solution from a cartridge filled with bicarbonate powder (BICART ) is shown on Fig. 1. Additionally, there are measurement cells 19, 20 in the conduit 11 in order to measure the conductivity of the mixture obtained. The measurement cells 19, 20 control the metering pumps 17, 18 so that the correct metering is obtained. The conduit 11 also comprises a pump 21 which ensures that a predetermined flow is maintained in the conduit 11, for example 500 millilitre/minute. The tube 13 is normally connected to the first side (the clean side) of the dialyser 50. When no dialyser is connected, the tube is instead connected with a bypass- conduit 27 via a coupling 22 as shown in Fig. 1. The coupling 22 is connected with a three-way valve 23, one end of which is connected to the water vessel 5 via a recirculation conduit 24. The above-described part of the dialysis machine 2-24 is constituted by its clean side (only half of the heat exchanger 6), as indicated with the dashed line 12. The dialysis machine is connected with the other side (dirty side) of the dialyser 14 via a tube 25. When the tube 25 is not connected to the dialyser 50 it is connected with a coupling 26 which, in turn, is connected with the three-way valve 23 by means of the bypass-conduit 27. The other end of the tube 25 is connected with an outlet conduit 28 which comprises various arrangements 29, such as blood leakage detectors, flow meter devices, e t c, as well as a pump 30. The outlet conduit passes through the other side of the heat exchanger 6, if such is present, and to an outlet coupling 31. During normal operation with the dialyser 50 connected, the pumps 21 and 30 are operated according to a mutual relationship such that a desired pressure is maintained on the dialysis side of the dialysers' 14 membrane so that a desired ultrafiltration is obtained. The part of the dialysis machine described above with reference numerals 25-31 forms the dirty side of the dialysis machine below the dashed line 12 in Fig. 1. When disinfecting the dialysis machine according to Fig. 1, the tubes 13 and 25 are placed in the position shown with solid lines, connected to the couplings 22 and 26 respectively. The valve 23 is adjusted so that substantially all the solution flowing through tube 13 is recirculated through the conduit 24. The heating element 9 is activated and successively heats up the water which is circulating through the conduit 11, the tube 13, the valve 23, the conduit 24 and the water vessel 5 to a higher and higher temperature until the temperature reaches at least 95°C, which is detected by the temperature sensor 10. Then, the valve 23 is adjusted (or is already in a position) so that a certain part of the water going through the tube 13 passes out through the shunt conduit 27, the tube 25, the conduit 28 and the connection 31 to the drain. The part which passes through the shunt conduit 27 and to the drain is only a small part, for example 10% of the amount which is circulating in the shunt conduit 24. Of course, valve 23 can be a three-way valve or a valve arrangement or combination having two distinct positions, one for normal operation and one for heat disinfection. In this way the clean side of the dialysis machine will be heat-disinfected and/or sterilised whilst the dirty side of the machine is disinfected with water as successively lower temperature towards the outlet 31. The level detector 7 in the water vessel 5 ensures that the level in the water vessel 5 is kept constant which means that the valve 4 allows a small amount of water in depending on how large the amount is which passes out through the outlet 31. Disinfection of the concentrate inlet at the pumps 17 and 18 also occurs, which is not explained in detail here. Disinfection occur with pure water or with the addition of some disinfection medium, as well as possibly also decalcification medium such as citric acid (CLEANCART ) in any suitable combination. In accordance with the present invention it is desirable to disinfect also the dirty side of the dialysis machine to a greater extent than that which occurs in the dialysis machine according to Fig. 1. The dialysis machine according to Fig. l is therefore provided with a second separate recirculation circuit on the dirty side. Such an embodiment is shown on more detail in Fig. 2. The same components as in Fig. 1 have been given the same reference numerals in Fig. 2. From Fig. 2 it is clear that the recirculation conduit 24 in Fig. 1 has been extended and is connected with the inlet conduit 3 immediately after the inlet valve 4. In this way the first recirculation circuit for the clean side is extended so that the clean side is disinfected to a maximum extent. Additionally, the water passes through the heat exchanger 6 in the first circuit. The shunt conduit 27 is provided with a recirculation valve 41, the one end of which is connected with a second recirculation conduit 42 which extends from the valve 41 to just before the outlet 31. In this way a second recirculation circuit is formed from the tube 25 through the outlet conduit 28 and the pump 30, through the heat exchanger 6, through the second recirculation conduit 42 to the valve 41 as well as to the coupling 26 and the tube 25, as clearly visible from Fig. 2. This second circuit has been obtained essentially by adding the valve 41 and the recirculation conduit 42. A function of the disinfection arrangement according to Fig. 2 is according to the following. The valve 23 is adjusted so that substantially all the solution which passes through the tube 13 is diverted to the first recirculation conduit 40 and, by means of the pump 21, is circulated in the first circuit through the water vessel 5. The water in the first circuit is heated up by means of the heat coil 9. At the same time the valve 41 is adjusted so that substantially all the fluid in the tube 25, the conduit 28 as well as the second recirculation conduit 42, is circulated by means of the pump 30 in the second circuit. Heat energy is transferred through the heat exchanger 6 from the first circuit to the second circuit for which reason the temperature rises successively also in the second circuit until a high temperature in the area of 95°C is reached in both circuits. The valves 23 and 41 are adjusted (or are already positioned) so that a small amount of fluid passes through the shunt conduit 27 from the first circuit to the second circuit. In order to keep the first circuit filled, the inlet valve 4 is at the same time automatically opened somewhat and the water comes in through the conduit 2. At the same time surplus amounts of fluid are given off into the second circuit by means of the outlet 31. By means of the arrangement which is described in Fig. 2, no additional heat coil is required apart from the heat coil 9 which is located in the water vessel 5, since the heat exchanger 6 is sufficiently effective in raising the temperature in the second circuit by a sufficient amount. As a complement, the second circuit can however also be provided with an immersion heater or other heater 43 as shown with dashed lines in Fig. 2. In certain cases it is desired to avoid the use of the heat exchanger 6 in the normal circuit in the dialysis machine, for example due to the risk of contamination of the inlet of the dialysis machine with bacteria which enters into the machine via the outlet 31. For this the emotion heater 43 is used by itself for heating the second circuit. It is also possible to place the heat exchanger in another position, for example between the two recirculation conduits 40 and 42, as indicated with the dashed block 44 in Fig. 2. In order to transfer a certain amount of fluid from the first circuit to the second circuit one of the metering pumps 17, 18 can be used instead of the valves 23, 41 and the bypass-conduit 27, which pump transfers fluid by means of a valve 45 and a conduit 46 from the first to the second circuit, as shown by dashed lines in Fig. 2. Since the water vessel 5 is connected with atmosphere, the temperature therein cannot rise above 100°C. If, despite everything, this should occur, nothing serious happens apart from the water in the vessel 5 boiling and steam being given off through its connection with atmosphere. The remainder of this first circuit has a lower temperature, this also including the heat exchanger. As an extra safety measure, the first circuit has a pressure sensor 47. The second circuit is heated via the heat exchanger and cannot reach a higher temperature than the first circuit. For additional monitoring a pressure sensor 48 is likewise used. Especially when a heater 43 is used, there may also be a temperature sensor 49, for example at the outlet 31. These sensors are connected with a monitoring system which produces an alarm signal in the event of dangerous or incorrect conditions. Fig. 2 shows a cartridge 51 connected in the holder which, during normal operation, contains a bicarbonate cartridge. The cartridge 51 contains citric acid and/or any other disinfection medium as is described in more detail in EP-A1-458 041 (CLEANCART ) . This cartridge 51 is optional and need not be used in normal operation. Certain dialysis machines lack the bypass-conduit 27 which is replaced by a shunt conduit directly from the outlet of the supply conduit 11 to the inlet of the return conduit 28. In this case the valves 23 and 41 are arranged in the manner shown in Fig. 3. The feed conduit 11 is provided with a three-way valve 52 corresponding to the valve 23, whic directly connects the feed conduit 11 with the first recirculation conduit 40 in order to form the first circuit. Additionally, the return conduit 28 is provided with a three-way valve 53 corresponding to the valve 41, which directly connects the return conduit 28 with the second recirculation conduit 42. A shunt conduit 54 connects a feed outlet 55, where the tube 13 is normally connected, with a return inlet 56 where the tube 25 is normally connected. The shunt conduit 54 can be constituted by the tubes 13 and 25 coupled together, or an outer or inner shunt conduit. The operation of this embodiment is the same as described above. Some dialysis machines have closed or substantially closed systems which allow pressure to be built up in either or both circuits. In such a case the temperature can be raised to above 100°C, for example to 121°C, which normally means an over-pressure of about 1 atmosphere. Preferred embodiments of the invention have been described above with reference to the drawings. These embodiments can be modified in many ways by a skilled man upon reading this description. Such modification which are obvious for the skilled man are intended to be encompassed within the scope of the present invention. The different parts which are described with reference to the drawings can be combined in different ways than those shown in the drawings. The invention is only limited by the appended claims.

Claims: PATENT CLAIMS 1. Disinfection arrangement for a dialysis machine, whereby the dialysis machine comprises, a feed arrangement (2-24) which constitutes a clean side of the dialysis machine, for normally supplying a dialysis solution to a dialyser (50) ; a return arrangement (25-31) which constitutes a dirty side of the dialysis machine for normally removing the dialysis solution from the dialyser; means (23, 24) for circulating a first fluid in a first recirculation circuit within the clean side of the dialysis machine for disinfection of the clean side of the dialysis machine, characterized by means (41, 42) for circulation of a second fluid in a separate second recirculation circuit within the dirty side of the dialysis machine, said second circuit comprising a heating arrangement (6, 43, 44) . 2. Disinfection arrangement according to claim 1, whereby the first circuit includes a heating arrangement (9) for heating of the first fluid, characterized by a heat exchanger (6, 44) arranged to transfer heat energy from the first circuit to the second circuit. 3. Disinfection arrangement according to claim 1 or 2, characterized by a heating member (43) in the second circuit for heating of the second fluid. 4. Disinfection arrangement according to any of the preceding claims, characterized by a recirculation conduit (42) which connects the inlet (26) of the return arrangement with its outlet (31) for recirculation of said second heated fluid. 5. Disinfection arrangement according to claim 4, characterized in that said heat exchanger (44) is connected to said recirculation conduit (42) . 6. Disinfection arrangement according to any of the preceding claims, characterized by a shunt conduit (27, 45, 46) between the first circuit and the second circuit for transfer of fluid from the first circuit to the second circuit. 7. Disinfection arrangement according to any of the preceding claims, characterized by an inlet arrangement (17, 18, 51) for supply of a disinfecting medium. 8. Disinfection arrangement according to any of the preceding claims, characterized by a shunt conduit (27, 46, 54) for transferring a portion of the fluid in the first circuit to the second circuit. 9. Disinfection arrangement according to claim 8, characterized in that said shunt conduit (46) comprises a pump (17) .

Inventors: GILLERFALK BJOERN, HOBRO STURE, JOENSSON JOERGEN, LINDERUP ERIK, GILLERFALK, BJOERN, HOBRO, STURE, JOENSSON, JOERGEN, LINDERUP, ERIK
Applicants: GAMBRO AB, GILLERFALK BJOERN, HOBRO STURE, JOENSSON JOERGEN, LINDERUP ERIK, GILLERFALK, BJOERN, HOBRO, STURE, JOENSSON, JOERGEN, LINDERUP, ERIK
Application year: 1995
Main classification: A61M1
IPC codes: A61M1