Backflow detection method in ultrasonic Doppler blood flow measurement and ultrasonic Doppler blood flow meter

摘要

PPROBLEM TO BE SOLVED: To provide a regurgitation detecting method which is immune to external noise from an electric knife or the like and reduces a malfunction in a measurement of the circulation of blood utilizing the ultrasonic Doppler effect to be used for the extracorporal circulating blood circuit of a heart-lung machine. PSOLUTION: This method has a first decision step 431 for deciding whether or not a Doppler frequency fd representing the frequency deviation of an echo signal is greater than a first constant A, second decision step 432 for deciding whether or not a minus side Doppler frequency fdn representing the frequency deviation in the case of regurgitation is greater than the first constant, third decision step 433 for deciding whether or not the minus side Doppler frequency is greater than the product of a second constant B and the Doppler frequency, step 434 for deciding that the circulating direction of blood is reverse when all the decided results of the first to third decision steps are positive, and step 435 for deciding that the circulating direction of blood is forward when at least one of the decided results of the first to third decision steps is negative. PCOPYRIGHT: (C)2003,JPO