known manner in the embodiment described above but not shown here in which the sensors are arranged in a circuit or a printed circuit within the housing the connection support 72 is connected with terminals arranged on the housing wall by means of the connecting conduits and the terminals are in turn connected to the blood carrying conduits fig3 shows a schematic view of the peristaltic pump 18 the peristaltic pump 18 comprises a pump housing 80 on which is arranged a motor of which only the motor axle 84 is shown moreover there are provided three freely rotating rolls 82 which are in direct contact with the motor axle 84 and are driven by same the connecting tube 26 is laid in the peristaltic pump 18 or the pump housing 80 in such a way that it can be squashed between the rolls 82 and the wall of the pump housing 80 in order to generate excess pressure in the connecting tube 26 the peristaltic pump 18 is started under control of the control or monitoring unit 40 not shown the motor axle 84 thus turns in the direction indicated by arrow 88 this causes rotation of the rolls.