An extracorporeal blood treatment apparatus comprises:
- a filtration unit;
- an extracorporeal blood circuit comprising a blood withdrawal line connected to an inlet of the filtration unit, and a blood return line connected to an outlet of the filtration unit;
- a main infusion line comprising an injection point located on the blood withdrawal line of the extracorporeal blood circuit upstream the filtration unit to transfer an infusion solution into blood, the main infusion line comprising an auxiliary injection point located on the extracorporeal blood circuit downstream from the injection point and a sorting point wherein the main infusion line forks into a first infusion branch in fluid communication with the injection point and a second infusion branch in fluid communication with the auxiliary injection point;
- an infusion fluid source of the infusion solution connected to the main infusion line;
- a main infusion pump active on the main infusion line drivable between an activated condition wherein the main infusion pump causes the infusion solution to flow from the infusion fluid source to the extracorporeal blood circuit, and an inactivated condition, wherein the main infusion pump is inactive and the infusion solution does not flow through the main infusion line;
- a switching arrangement operating on the at least one main infusion line and configured to direct the infusion solution flowing in the main infusion line to either of the injection point or the auxiliary injection point when the main infusion pump is activated, the switching arrangement being switchable between a first condition wherein the infusion solution flows towards the injection point through the first infusion branch and a second condition wherein the infusion solution flows towards the auxiliary injection point through the second infusion branch;
- a concentrate sensor placed on the blood withdrawal line between the injection point and the auxiliary injection point of the main infusion line, upstream of the filtration unit, the concentrate sensor configured to monitor a concentration of at least one substance detectable in blood flowing in the blood withdrawal line between the injection point and the auxiliary injection point of the main infusion line;
- a control unit operatively connected to the concentrate sensor, the main infusion pump, and the switching arrangement, the control unit configured to:
- control the main infusion pump of the main infusion line between the activated condition and the inactivated condition,
- control the switching arrangement of the main infusion line between the first condition and the second condition,
- receive a signal from the concentrate sensor to determine the concentration of the at least one substance in a first operating condition and in a second operating condition of the extracorporeal blood treatment apparatus,
- wherein the control unit is further configured to:
- (i) in the first operating condition-activate the main infusion pump of the main infusion line, bring or maintain the switching arrangement of the main infusion line to/at the first condition and acquire the signal from the concentrate sensor to determine the concentration of the at least one substance in the blood infused with the infusion solution upstream of the concentrate sensor;
- and,
- (ii) in the second operating condition-activate the main infusion pump, bring or maintain the switching arrangement to/at the second condition and acquire the signal from the concentrate sensor to determine the concentration of the at least one substance into blood when no infusion solution is infused into the blood upstream of the concentrate sensor.