Abstract: A cassette useful for measuring one or more parameters of blood in, for example, a cardiopulmonary bypass circuit has a convex coupling for releasable connection with a mating, concave coupling of a measuring device. The coupling of the cassette includes flexible leg portions that can be moved toward each other under the influence of finger pressure to detach the cassette from the measuring device. Optionally, the cassette includes a body carrying one or more sensors, and also includes a casing that can be detached from the body when desired. A shunt circuit arrangement enables the cassette to be connected to the bypass circuit either before or during a surgical procedure.

Abstract: A sensor cassette for use in measuring a compositional parameter of blood comprising a housing having a wall defining a passage which is adapted to receive blood. The wall is at least somewhat permeable to the compositional parameter. A support element, which is less permeable to the compositional parameter of blood than the housing, is carried by a region of the wall. A sensor is carried by the support element and provides a signal in response to the compositional parameter. The support element separates the sensor from at least a portion of such region of the wall so that the affect of the permeability of the housing to the compositional parameter on the signal from the sensor is reduced.

Abstract: An assembly useful in conjunction with a signal transmission means for the measurement of a compositional parameter of the blood of a patient is disclosed. This assembly comprises a housing adapted and sized to be located outside the body of a patient and having a fluid flow passage therethrough into which blood from the patient is passed from a hollow tube, the fluid flow passage being defined by a wall which is substantially impermeable to blood, the housing being adapted to be removeably secured to a signal transmission system such that the housing is capable of being removed from the signal transmission system without disrupting the fluid flow passage; and a sensing element located in the housing in or near the fluid flow passage for providing a signal directly to the signal transmission system in response to a compositional parameter of blood located in the fluid flow passage.