A Simple Calibrator for Measuring the First Derivative of Pressure Waveforms

A small, inexpensive, integrated circuit, asymmetric, triangle generator for the calibration of cardiovascular waveform differentiators is described. The calibrator produces a simulated pressure waveform in which the slopes of the leading and trailing edges are precisely and stably set to represent specific values of dP/dt in millimeters of mercury per second. The waveform is clipped to give a zero output when differentiated, facilitating setting the baseline and the gain of the differentiating amplifier used to record the first derivative.