Patent ID: 8070707

Claim:
A device for continuously measuring osmotic pressure of blood flowing through an extracorporeal blood circuit comprising: a blood passage further comprising a withdrawal blood passage connectable to a blood vessel in a patient, and an infusion blood passage connectable to a blood vessel in a patient and a filter in fluid communication with the withdrawal blood passage and the infusion blood passage; an osmotic pressure measurement device including a filtrate chamber, a blood chamber and a permeable membrane separating the filtrate chamber and blood chamber, wherein the blood chamber is in fluid communication with the blood passage; a filtrate pressure sensor sensing a pressure of the filtrate in the filtrate chamber while no filtrate flows from the filtrate chamber, and a blood pressure sensor sensing a pressure of the blood flowing through the blood chamber, and a controller receiving pressure signals from the filtrate pressure sensor and the blood pressure sensor, applying the pressure signals to determine an osmotic pressure, and adjusting a rate of removal of fluid from blood in the filter if the determined osmotic pressure varies from an osmotic pressure threshold.