초록 ▼

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 clip

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.

대표청구항 ▼

An ultrasonic flow measurement system for measuring velocity of blood flow through a conduit, the system comprising: means for producing a Doppler signal having a frequency which varies as a function of the velocity of blood flow; means for controlling amplification of the Doppler signal to compensa

An ultrasonic flow measurement system for measuring velocity of blood flow through a conduit, the system comprising: means for producing a Doppler signal having a frequency which varies as a function of the velocity of blood flow; means for controlling amplification of the Doppler signal to compensate for variations in Doppler signal strength due to variations in red blood cell concentration in the blood; and means for preventing inordinate reduction in amplification of the Doppler signal due to presence of particulates in the blood having higher ultrasonic reflectivity than red blood cells.