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NON-INVASIVE ELECTROMAGNETIC BLOODFLOW MEASURING SYSTEM WITH REJECTION OF NOISES

  • US 3,809,070 A
  • Filed: 10/11/1972
  • Issued: 05/07/1974
  • Est. Priority Date: 07/01/1971
  • Status: Expired due to Term
First Claim
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1. A blood flow measuring system comprising:

  • first sensory means adapted to be positioned on the skin of a living being at such locations that a strong and sharp cardiogram can be repeatedly obtained to use as a synchronizing signal and as a clock;

    means for producing in the region of a blood vessel a stable and sufficiently homogeneous magnetic field having an intensity large enough to generate measurable blood flow signals in said region;

    second sensory means adapted to be placed on the skin or in the subcutaneous tissue of said living being at locations adjacent to said vessel;

    amplifying means for amplifying the composite pulsatile signals sensed by said second sensory means during successive heart cycles, said composite pulsatile signals generally including a blood flow waveform component which is proportional not only to the blood flow but also to the intensity of the magnetic field, and a random noise component;

    measuring means synchronized by said synchronizing signal derived from said first sensory means to average, in waveform, a predetermined number of composite pulsatile signals from said second sensory means accumulated during a series of heart cycles, said measuring means including a waveform averager having individual storage elements which accumulate voltage samples of said pulsatile signals taken at corresponding time intervals of all successive heart cycles of said series;

    signal selector means including comparator means connected at the input to said waveform averager for comparing each incoming pulsatile signal with predetermined acceptable signal characteristics, and gating means for enabling said incoming pulsatile signal to be accumulated by said waveform averager only if said pulsatile signal is within said acceptable signal characteristics; and

    means for indicating the waveform averaged blood flow signal.

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