Patent ID: 8721883

Claim:
A dialysis system, comprising: a dialysis machine defining a cassette compartment; and a dialysis fluid cassette configured to be disposed in the cassette compartment, the dialysis fluid cassette comprising a base defining a recessed region; and a flexible membrane attached to the base and configured to cooperate with the recessed region to define a first fluid channel when the flexible membrane is pressed against the base, wherein the base further comprises a member extending into the recessed region, the member defining a second fluid channel that extends to an opening in an end surface of the member, the recessed region and the member being configured such that when the membrane is pressed against the end surface of the member, fluid is permitted to flow around an outer contour of the member in the first fluid channel and through the first fluid channel and fluid is prevented from flowing through the second fluid channel, and when the membrane is spaced from the end surface of the member, fluid is permitted to flow around an outer contour of the member in the first fluid channel and through the first fluid channel and fluid is permitted to flow through the second fluid channel.