Pulse curve analyser

Claim 1

A pulse curve analyser comprising, in combination, light-responsive transducer means for sensing a patient's continuous physiological circulatory activity by responding to light modulated by changes in capillary blood micro-circulation and producing a voltage waveform which is an analog of said patient's body tissue pulsatile blood color and/or density changes, means for processing said waveform to produce an output signal proportional to the time rate of change of the amplitude of said waveform, and means for displaying quantitatively and instantaneously data representing at least one of the rise time and the fall time of a transient cycle of said waveform as a function of the period of said cycle, said means for processing including a circuit wherein the output of said transducer means is fed to a notch filter, the output of which is fed to a operational amplifier whose output is buffered and then passed to a differentiator which in turn feeds a low pass filter having linear phase, the latter being offset whereby its output voltage is negative when said voltage waveform is rising, and positive when said voltage waveform is falling, and has a magnitude which is proportional to both the amplitude of said voltage waveform and its time rate of change.