Patent ID: 9028415
Filing Date: 2015-05-12
Classification: A61B

Abstract:
1. A blood flow monitor for detecting a blood flow rate down to zero flow, within a single blood vessel, comprising: a transducer probe directly contactable on a single blood vessel, a visual display, and a speaker; a probe monitoring circuit in electrical communication with said probe, where the probe monitoring circuit is configured to transmit a burst signal at a predetermined first frequency and receive a reflected signal at a second frequency; a mixer comprising an input in electrical communication with the probe monitoring circuit and an output in electrical communication with a first signal path and a second signal path, where the mixer is configured to compare the difference between the first frequency and the second frequency to determine a frequency shift, the frequency shift representative of a blood flow rate within the single blood vessel, wherein the frequency shift has a range between zero to indicate a zero flow rate and an upper limit frequency with a threshold frequency therebetween, where the threshold frequency is a frequency that is at least audible in said speaker, the mixer further configured to output a signal at a frequency of the frequency shift to each of the first and second signal paths; the first signal path including the speaker in electric communication with the output of the mixer, the speaker configured to produce an audible sound in response to the frequency shift signal having a frequency between the threshold frequency and the upper limit frequency to audibly indicate said blood vessel having a blood flow rate; and the second signal path including a signal processing circuit comprising an input in electrical communication with the output of the mixer and an output in electrical communication with the visual display, where the signal processing circuit is configured to drive the visual display with a signal in response to the frequency shift signal having a frequency between zero and the threshold frequency to visually indicate the blood vessel having a blood flow, wherein the visual display is configured to provide incremental visual indication of the blood flow rate when said blood flow rate is within a range from a blood flow rate associated with said threshold frequency down to said zero flow rate.