A system and a method for detecting the presence of an occlusion in an intravenous (IV) line supplying a medicinal liquid to a patient. Two pressure occlusion sensors are employed to produce a value for the proximal and distal pressures within an IV pumping cassette that is disposed in the fluid path of the IV line. Each pressure occlusion sensor includes a strain gauge connected to a leaf spring that is fixed at one end within a pump chassis and a rod that is disposed transverse to the leaf spring. Each rod has one end that responds to the force of a portion of an elastomeric membrane inside the pumping cassette and another end that contacts a free end of the leaf spring. When a leaf spring is flexed by the movement of a rod, the strain gauge mounted on the leaf spring produces a differential voltage that corresponds to a fluid pressure within the pumping cassette. The distal pressure occlusion sensor automatically opens a flow stop on the pumping cassette when the pumping cassette is inserted into the pump chassis. The outputs from the distal and proximal pressure sensors are sampled at least once per second to ensure that maximum pressure values are not exceeded and that a pressure sensor failure is immediately detected.
