DEVICE MEASURING CONCENTRATION OF CARBON DIOXIDE IN EXHALED AIR Russian patent published in 2001 - IPC

FIELD: medicine, diagnostics of some diseases. SUBSTANCE: device includes measurement chamber connected to respiratory tracts of patient which carries ultrasonic radiator and reflector of audio signal, pulse generator which first output is connected to radiator linked to first input of amplifier and channel processing output signal incorporating computation circuit. Device is fitted with thermostatting unit which input and first output are connected correspondingly to temperature-sensitive element and heater located in measurement chamber. Channel processing output signal has first amplitude detector which input is connected to first output of generator, second amplitude detector which input is connected to output of amplifier, single-shot multivibrator which input is connected to second output of generator and which output is connected to second input of amplifier. Device also has logarithmic converter which first and second signal inputs are connected correspondingly to outputs of first and second amplitude detectors, threshold unit which signal input is connected to output of logarithmic converter. First input of computation circuit is connected to output of threshold unit, its second input is connected to output of logarithmic converter, its third input is connected to second output of thermostatting unit, its fourth and fifth inputs are used correspondingly to set calibration points and to control operational conditions, first output of computation circuit is connected to control inputs of logarithmic converter and threshold unit and its second output is connected to input of unit of indicators. EFFECT: increased accuracy of determination of concentration of carbon dioxide in air exhaled by patient. 6 dwg