Patent ID: 7734322

Claim:
A method for calibrating a blood property sensor, the method comprising: (a) connecting an arterial tubing portion of a dialysis system to withdraw blood from a patient and connecting a venous tubing portion of the dialysis system to deliver blood to the patient; (b) passing diluted blood having a dilution indicator past the blood property sensor in the venous tubing portion; (c) determining at least one property of the diluted blood passing the blood property sensor in the venous tubing portion; and (d) determining a calibration coefficient K of the blood property sensor based on the determined blood property of the diluted blood passing the blood property sensor in the venous tubing portion and the relationship K = - V Inj V + V Inj * Δ ⁢ ⁢ U Inj where V inj is a volume of the dilution indicator; V=(Q B −Q UF )*ΔT inj where Q B is a blood flow rate in the arterial tubing portion. Q UF is an ultrafiltration rate of the dialysis system, ΔT inj is the transit time of the dilution indicator; and ΔU inj relates to the determined blood property and is integrated over ΔT inj .