Abstract: Blood is treated externally to a human or animal body, the blood having been extracted from a first human or animal body for delivery to a second human or animal body. The temperature and/or composition of the blood are controlled.

Abstract: A rheometeris disclosed for determining flow characteristics of a fluid. The rheometer comprises a circuit in which the fluid is arranged to flow. The circuit comprises a duct and a plurality of flow elements, each comprising a flow environment arranged in fluid communication with the duct. The flow environment of each element is arranged to convey fluid from an up-stream position to a downstream position of the respective flow element. The rheometer further comprises pressure sensing means arranged to determine fluid pressure at the upstream position and the downstream position of each of the plurality of flow elements. At least two of the plurality of flow elements comprise different flow environments for the fluid such that the rheometer can determine the flow characteristics of the fluid at a particular instant in time.