The NICO100C easily measures the change in thoracic impedance that occurs as the heart beats. As blood is forced out of the aorta during ventricular ejection, the impedance through the torso drops momentarily. The derivative of this waveform (dZ/dt) can be processed to record pulse rate (BPM) on a cycle-by-cycle basis in real time. The dZ/dt waveform is directly related to the aortic ejection velocity. The Macintosh version of AcqKnowledge includes a fully automated scoring and measurement system for bioimpedance data.