Patent ID: 7957927

Claim:
A method of compensating for temperature error in a pneumatic pumping system of a peritoneal dialysis system, the peritoneal dialysis system including a pumping mechanism with a disposable cassette and at least one disposable chamber, wherein fluid communication is established between the peritoneal dialysis system and a peritoneal cavity of a patient, the method comprising: (i) calculating a corrected volume of air in a disposable chamber, V d = V r * ( Pr 2 - Pr 1 ) ( Pd 1 - Pd 2 ) wherein V d is the corrected volume, V r is a reference volume of the chamber, and (Pr 2 −Pr 1 ) is a pressure difference between a high pressure in the reference chamber and a pressure in the reference chamber after equalization, and (Pd 1 −Pd 2 ) is a pressure difference between a high pressure in the disposable chamber and a pressure in the delivery chamber after equalization, wherein pressures after equalization comprise pressure measurements after the delivery and reference chambers are connected; (ii) multiplying the result of (i) by a ratio of a temperature in the disposable chamber to a temperature in the reference chamber T d /T r ; and (iii) multiplying the result of (ii) by a ratio of Tr cal /Td cal to determine a correction factor, wherein Tr cal is a temperature in the reference chamber during a calibration procedure and Td cal is a temperature in the disposable chamber during the calibration procedure, wherein the temperature during a calibration procedure is constant in the reference and disposable volumes; (iv) calculating a corrected volume of air delivered by the disposable chamber of the system by applying the correction factor; and (v) correcting a volume of dialysate pumped by the dialysis system using the corrected volume of air.