A pumping cassette, the cassette includes a housing. The housing includes at least one fluid port and at least one air vent port. The air vent port vents a fluid source outside the housing. The pumping cassette also includes at least one reciprocating pressure displacement membrane pump within the housing....http://www.google.de/patents/US20080253912?utm_source=gb-gplus-sharePatent US20080253912 - Pumping Cassette
