Patent ID: 8394321

Claim:
An extracorporeal blood treatment apparatus, comprising: a membrane exchanger for an extracorporeal blood treatment comprising a blood chamber and a fluid chamber, separated from one another by a semipermeable membrane; an extracorporeal blood circuit connected to the blood chamber; and a medical fluid circuit configured for infusing the medical fluid in the blood circuit or in the fluid chamber, the medical fluid circuit comprising: a batch container for a medical fluid; a fluid supply line connected to the batch container for supplying the medical fluid; an expansion chamber arranged along the supply line; a first sensor configured to send at least a first signal indicating an emptying of the batch container; a second sensor configured to send at least a second signal indicating a parameter in the expansion chamber, the parameter being a pressure in the expansion chamber; and a control unit configured to perform a control procedure of a situation in the expansion chamber, the control procedure comprising following operations: detecting a situation of emptying of the batch container from the first signal; detecting at least a value of said parameter inside the expansion chamber during the emptying situation; performing a control on whether the at least a value of the parameter is in a determined relation with at least a reference value, comprising determining a variation in the parameter in the expansion chamber during a variation of a further predetermined parameter, and controlling whether the variation of the parameter is in a determined relation with at least a reference value; recognising a faulty situation of a too low liquid level in the expansion chamber based on said control, wherein the faulty situation is recognised if the variation in the parameter does not exceed a predetermined threshold value.