Nocturnal penile tumescense monitor

Abstract

Apparatus for generating and recording signals from two separate sensors on a patient adapted to provide an indication of the condition of an anatomical member to be monitored. A control cabinet having an integral strip chart recorder is provided with plug in inputs for two externally connected strain gauges. Each strain gauge makes up one leg of a bridge circuit. The bridge outputs are amplified and multiplexed into a single channel strip chart recorder having a single, heated stylus which records two separate traces based on the signals received from the two sensors. Heat to the recordinng pen or stylus is turned off during switching excursions of the pen between the two traces so as to eliminate shading and marking which would otherwise occur on the recording chart between the traces at slow chart speeds. In the nocturnal penile tumescence monitoring application for which the apparaus is primarily intended, two mercury strain gauges in the form of elastomer rings are positioned at the base and tip of the penis. Minute variations in penile size occurring during the Rapid Eye Movement stages of sleep are sensed by the strain gauges, amplified, through bridge circuits and recorded in two separate traces.