Patent ID: 7575564

Claim:
A dialysis machine under control of a processor, the machine comprising: an actuation unit configured to accept a disposable medical fluid cassette that includes a flexible membrane, the cassette arranged to receive a medical fluid; the actuation unit ant processor programmed to: in a first integrity test, and before liquid is admitted to the cassette, provide a positive pressure to first and second portions of an outer surface of the membrane of the cassette and simultaneously provide a negative pressure to third and fourth portions of the inner surface of the membrane of the cassette and measure a decay of the pressures, wherein at least three successive pressure readings are taken in a first time period; and in a second integrity test, and before liquid is admitted to the cassette, provide positive pressure to the inner surface of the first and third portions while providing negative pressure to the inner surface of the second and fourth portions of the membrane of the cassette and measure a decay of the pressures, wherein at least first, second and third successive positive pressure readings and at least first, second and third successive negative pressure readings are taken in a second time period, wherein differences between the successive positive pressure readings and differences between the successive negative pressure readings are used to determine whether the cassette passes or fails the second integrity test.