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DOPPLER DEVICE FOR MEASURING BLOOD FLOW AT TIME OF HEART LUNG BYPASS AND CARDIAC VENTRICLE ASSISTANCE
DOPPLER DEVICE FOR MEASURING BLOOD FLOW AT TIME OF HEART LUNG BYPASS AND CARDIAC VENTRICLE ASSISTANCE
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机译:用于心脏通气和心室辅助时血流测量的多普勒装置
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摘要
An ultrasonic Doppler flow measurement system for measuring blood flow in a polymer conduit includes an ultrasonic transmitter transducer, an ultrasonic receiver transducer, an amplifier/detector circuit for producing a Doppler signal which varies in frequency as a function of blood velocity, a clipping circuit, an automatic gain control circuit, and a frequency-to-voltage converter which produces an output signal having a voltage which is a function of flow velocity. The automatic gain control circuit accomodates variations in Doppler signal strength due to varying red blood cell concentration. The clipping circuit prevents an inordinate reduction of gain by the automatic gain control circuit due to extremely large, occasional gas bubbles or fat globules in the blood.
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