Machine for dialysis

(54) Name: Dialysis system

The present invention relates to a dialysis system comprising means for supplying water and saline concentrates as well as means for heating and mixing these liquids, which are intended to be passed through a dialyzer.

Such dialysis systems usually include agents for heat sterilization. Typically, these means are the ordinary heating means which are caused to heat the supplied water to a higher temperature than normal. The water is then caused to flow through systems in the same way that the dialysis fluid is otherwise conducted. The only difference is that the hoses or wires that are otherwise connected to the actual dialyzer are instead connected to a safety bypass.

However, there has long been a desire to be able to sterilize at lower temperatures. The object of the present invention is to provide such an effective system for cold sterilization or chemical sterilization. For practical reasons, the following also includes disinfection in this concept, since between sterilization and disinfection there is rather a degree difference than a species difference. However, the system can also operate at higher temperatures.

The dialysis system according to the invention is characterized by a supply

7611388-5 conduit of sterilizing agent, which is coupled or connectable to a pump normally included in the system, which is arranged to pump the sterilizing agent through a special return line to a point near the water inlet of the system.

As a sterilizing agent can be used conventionally in market such as e.g. formalin or chloramine.

A very simple construction is obtained if said supply line for the sterilizing agent is the ordinary supply line for the brine concentrate. This is then arranged to be switchable from a source of such concentrate to a source of sterilizing agent.

Preferably, said return line is arranged to start from a point located relatively high in a bubble separator normally included in the system to thence return the sterilizing agent back into the system to a water vessel, in which there is normally a means for heating the water. Conveniently, the return line is thereby caused to emanate from the highest point of the bubble separator, so that it is always completely filled with sterilizing agents. The bubble separator can hereby be provided with a shut-off valve which is arranged to shut off the conduit which normally discharges from the liquid when the bubble separator is filled with sterilizing agent.

Extra great assurance that the whole system is truly sterilized is obtained if one or more shut-off valves are provided after said bubble separator and if these are arranged to be opened manually or

25 'automatically only after the system part before the bubble separator has been substantially completely filled with sterilizing agents.

Past one or more shunt lines, past the switching point of the actual dialyzer. All of these conduits are conveniently caused to flow through the sterilizing agent.

In said return line, a check valve is preferably arranged which partly prevents flow in the opposite direction and partly increases the pressure, whereby the sterilizing agent is pressed out to points which otherwise might not have been reached.

The invention will be described in more detail below with reference to the accompanying drawing, which in the form of a block diagram and as an example, describes a preferred embodiment of the dialysis system according to the invention.

1 is hereby designated an inlet line for fresh water. This conduit 1, which is provided with an inlet valve 2, leads to one

Water vessel 3. This vessel 3 is provided with a float valve 4, which is arranged to close the water inlet 5 by means of a shut-off cone 6, when the water vessel 3 is filled. The water vessel 3 further comprises means 7 for heating the water, e.g. in the form of a heating coil.

· This heating loop is controlled by a temperature control device 8, which is in turn controlled by a temperature sensor 9 in the outlet line 10 from the vessel 3. Furthermore, the vessel comprises schematically shown maximum and minimum controls 11 and 12 respectively for sensing the liquid level in the vessel. These level controls may, for example, be arranged to directly control the inlet valve 2. Finally, the vessel contains a schematically shown filter element 13, which is primarily intended to remove any solid particles from the water, but which in practice also removes a certain amount of gas, e.g. free gas bubbles.

After heating, the supplied fresh water is passed through the outlet line 10, the temperature sensor 9, a line 14 'with a shut-off valve 14a, and a throttle valve 15 to a branch point 16. Here, a branch line 17 is connected, which normally starts from a source 18 for brine concentrate. Usually, this source is simply a can of salt solution. For sterilization according to

In the present invention, however, this can is replaced by one with sterilizing agent, which is thus said source of sterilizing agent and designated (19) in the figure. This is the simplest solution in practice. But, of course, if special reasons so required, it would be possible to connect a further conduit 17 'to the system in parallel with the conduit 17 for connection of a separate vessel 19'. This is indicated by dashed lines in the figure.

From the point 16, the liquid flows through a pressure sensor 20 and a pump 21 to a bubble separator 22. The pressure sensor 20 hereby controls the pump 21 via a pressure regulator 23. The inlet line to the bubble separator 22 is hereby designated 24.

From the bubble separator 22, the ordinary conduit 25, and a conduit 26 for discharge of separated gas, and a return conduit 27. are provided, and the inlet 28 to the conduit 26 is controlled, hereby by a float valve 29, which closes this inlet, when the bubble separator 22 in conjunction with sterilization is filled with liquid. The return line 27 is provided with a spring-loaded check valve 30 and leads back to the liquid vessel 3.

The conduit 25 leads to a conductivity meter 31 which, via a control device 32, controls a throttle valve 33 in the conduit 17 for the saline concentrate. After the conductivity meter 31, the liquid flow reaches a new branch point 34 from which a shunt conduit 35 with a valve 36. This shunt conduit 35 is used when it is desired to quickly switch the liquid flow past the dialyzer 37, e.g. when errors are detected in the dialysis fluid on e.g. temperature or salinity. Normally, otherwise, the fluid flow to the dialyzer 37 flows through the conduit 38, which contains a valve 39 and a flow meter 40. The valve 39 is normally controlled simultaneously with the valve 36 for switching the fluid flow. Alternatively, of course, the two valves 36 and 39 may be exchanged for a three-way valve located at the junction point 34.

41 denotes the conduits or hoses normally coupled to the dialyzer 37. In sterilization, however, these hoses are coupled to a safety bypass 42, as indicated by dashed lines denoted by 41 '. An example of such a security by-pass is described, for example, in Swedish patent application 76.02455-3. Therefore, it need not be further described in connection with the present invention. With 43 and 44 respectively, the inlet and outlet respectively for the blood side of the dialyzer 37 are denoted.

45 denotes a blood detector, which gives alarm and possibly shuts down the entire system if blood is detected in the dialysate. This blood detector may, for example, be a transparent tube located in the middle of an otherwise shielded photocell device which directly senses the presence of any blood in the dialysate. After the blood detector, the fluid stream is fed through a pressure gauge 46, which via a regulator 47 controls a liquid pump 48. Then the liquid stream is finally fed to a drain. Unless part of the liquid stream is recycled. However, such recirculation is fully known to those skilled in the art and has therefore not been shown in detail in the drawing.

After sterilization, the system of the invention must normally be effectively rinsed. This is conveniently done by intake of water via the normal water intake 5. This water is fed through the various pipes of the system up to the liquid pump 48 shown and from there to a drain, and partly through the pipes 10, 14, 24 and 27 back to the liquid vessel 3. of the upper level sensor 11, this liquid vessel is not completely filled. It is therefore convenient to arrange conduit 27 in such a way that the entire liquid vessel 3 is still rinsed. This can be done, for example, by leading conduit 27 straight above the float 4, from which both the sterilizing fluid and the rinsing fluid splash during an effective flushing of the inside of the vessel 3. Alternatively, some type of sprinkler system may be provided in the vessel 3 to provide an effective rinse.

The invention is, of course, not limited solely to the example described above, but can be varied within the scope of the following claims. For example, the details contained in the system can be varied in both form and function, without exceeding the scope of the invention. Furthermore, the drawing does not show details which are not necessary for the understanding of the invention, but which are obviously part of the skilled person in a complete dialysis system.

Examples of dialyzers that can be included in the system are referred to Swedish patents 218 441, 314 167 and 365 119. As an example of pumps, which can be included in the system, reference is made to Swedish patent 341 453. Also, compare the simultaneously filed patent applications 76.11386 -9, 76.11387-7 and 76.11389-3.

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