The first man/machine interaction in medicine: the pulsilogium of Sanctorius

This article, published in lieu of the customary feature, artifact, describes one of the earliest medical devices--a device to measure pulse rate. A close examination of the pulsilogium of Sanctorius of Padua (1561--1636) reveals it to be something more than the first measuring device in medical history; it is also the first man/machine system in medicine. Using a systems approach, pulsilogium and physician interaction is found to contain important dynamic characteristics. The device is operated in a negative feedback mode, employs the concept of transduction, and measures pulse through another dimension--length. More than 100 years after its invention, the pulsilogium found useful application by de la Croix in measurements of cardiac function during "electrification."