Patent ID: 8640703

Claim:
A patient cassette for use in a modular rebreathing circuit that provides breathing assistance to a patient, said modular rebreathing circuit being of a breathing circuit type, from among a plurality of different breathing circuit types, said patient cassette comprising: a cassette housing having a first inlet configured for connection to a drive circuit that forces gas through said first inlet, said drive circuit being of a drive circuit type, from among a plurality of different drive circuit types; a patient circuit in said cassette housing pneumatically connected to said first inlet, said patient circuit comprising a Y-branch having an expiratory line connected to a second inlet of said cassette housing configured to receive expiratory gas from the patient, and an inspiratory line connected to an outlet of said cassette housing configured to provide gas from said drive circuit to the patient, and a volume-varying arrangement connected between said first inlet and said Y-branch to form a part of said patient circuit in said cassette housing between said first inlet and said Y-branch, said volume-varying arrangement having a selectable volume that, when set, also sets a volume of said patient circuit to a set volume dependent on at least one of: the drive circuit type of the drive circuit currently connected to said first inlet, the breathing circuit type of the modular rebreathing circuit comprising said drive circuit currently connected to said first inlet, and a predetermined tidal volume of the patient currently connected to said outlet.