Device and method for measuring the variation of the diameter of a vein using Doppler effect

摘要

The equipment comprises an ultrasound transmitter/receiver (3) typically piezoelectric which is connected to a control/processing unit (4). The control/processing unit includes a variation unit (6) which measures the frequency difference of the emitted and received ultrasonic waves. The difference is used to determine blood speed at various vein levels and hence changes in vein diameter and the equipment includes loudspeaker and display (16,17). An Independent claim is made for the Doppler effect method of measurement.