Controlling an apparatus for production of medical fluid for use in dialysis therapy

A control device for operating an apparatus for producing a medical fluid for use in dialysis therapy, said control device being configured to operate, in a respective production phase, the apparatus to generate a mixture of a base fluid and one or more concentrate fluids, and produce the medical fluid based on the mixture, wherein each of the one or more concentrate fluids is stored in a respective container, said control device being further configured to:

• operate the apparatus, in an initialization phase, to pump the one or more concentrate fluids to a sensor device for measuring a composition-related parameter,
• determine, based on an output signal of the sensor device during the initialization phase, a reference concentration of the respective concentrate fluid at a reference time point, and
• estimate, by use of the reference concentration and at least one calculation function for calculation of evaporative loss of water from the respective container over time, a momentary concentration of the respective concentrate fluid as a function of time,
• wherein the control device is configured to, at one or more time points before or during the respective production phase and based on the momentary concentration, adjust a mixing ratio between the base fluid and the one or more concentrate fluids in the mixture so as to produce the mixture with a target composition.

An apparatus for producing a medical fluid for use in dialysis therapy, said apparatus comprising:

• an inlet for a base fluid,
• an inlet for a respective concentrate fluid,
• a mixing arrangement operable to mix the base fluid with the respective concentration fluid,
• a fluid distribution arrangement operable to selectively supply the base fluid and the respective concentration fluid to the mixing arrangement,
• a sensor device for measuring a composition-related parameter, and
• a control device configured to operate the apparatus for producing the medical fluid, said control device being configured to operate, in a respective production phase, the apparatus to generate a mixture of a base fluid and one or more concentrate fluids, and produce the medical fluid based on the mixture, wherein each of the one or more concentrate fluids is stored in a respective container, said control device being further configured to:
• operate the apparatus, in an initialization phase, to pump the one or more concentrate fluids to a sensor device for measuring a composition-related parameter,
• determine, based on an output signal of the sensor device during the initialization phase, a reference concentration of the respective concentrate fluid at a reference time point, and
• estimate, by use of the reference concentration and at least one calculation function for calculation of evaporative loss of water from the respective container over time, a momentary concentration of the respective concentrate fluid as a function of time,
• wherein the control device is configured to, at one or more time points before or during the respective production phase and based on the momentary concentration, adjust a mixing ratio between the base fluid and the one or more concentrate fluids in the mixture so as to produce the mixture with a target composition.

A computer-implemented method of operating an apparatus to produce a medical fluid for use in dialysis therapy by mixing a base fluid with one or more concentrate fluids, wherein each of the one or more concentrate fluids is stored in a respective container, said method comprising:

• operating the apparatus, in an initialization phase, to pump the one or more concentrate fluids to a sensor device for measuring a composition-related parameter;
• determining, based on an output signal of the sensor device during the initialization phase, a reference concentration of the respective concentrate fluid at a reference time point;
• operating, in a respective production phase, the apparatus to generate a mixture of a base fluid and one or more concentrate fluids at a mixture ratio and to produce the medical fluid based on the mixture;
• estimating, by use of the reference concentration and at least one calculation function for calculation of evaporative loss of water from the respective container over time, a momentary concentration of the respective concentrate fluid as a function of time;
• and
• adjusting, at one or more time points before or during the respective production phase and based on the momentary concentration, the mixing ratio between the base fluid and the one or more concentrate fluids in the mixture so as to produce the mixture with a target composition.