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Method and apparatus for calculating blood pressure with signal transformation

  • US 20070049834A1
  • Filed: 12/20/2005
  • Published: 03/01/2007
  • Est. Priority Date: 08/31/2005
  • Status: Active Grant
First Claim
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1. A method for calculating blood pressure with signal transformation, wherein the method includes steps of:

  • a. winding a cuff connected with a pressure sensor around an arm of a human body being examined, inflating the cuff to a certain pressure, and then deflating the cuff to a determined pressure;

    b. maintaining the determined pressure for a predetermined time, continuously transforming both the pressure and a PW signal at the determined pressure into electric signals by the pressure sensor within the predetermined time, and transmitting the electric signals to an A/D converter circuit which converts the electric signals into a pressure value and a time sequence of a PW digital signal after the electric signals are amplified;

    c. carrying out the signal transformation of the time sequence of the PW digital signal, calculating a maximum amplitude value and a frequency value corresponding to the maximum amplitude value at the determined pressure based on the transformed signal, taking the maximum amplitude value as an amplitude value at the determined pressure, taking the frequency value corresponding to the maximum amplitude value as a pulse rate value at the determined pressure, continuing to deflate the cuff to another determined pressure, and then returning to the step b till predetermined times;

    d. constituting a PW amplitude value sequence and a pressure value sequence according to the amplitude value and the pressure value at each determined pressure, and then forming a PW amplitude-pressure curve according to the PW amplitude value sequence and the pressure value sequence;

    e. calculating a mean pressure and a PW amplitude value P0 corresponding to the mean pressure based on the PW amplitude-pressure curve, respectively calculating PW amplitude values PS and PD which are corresponding to a systolic pressure and a diastolic pressure to be measured with ratio method, wherein PS=α

    *P0, PD=β

    *P0, α and

    β

    are a systolic pressure amplitude coefficient and a diastolic pressure amplitude coefficient respectively, and finally obtaining the systolic pressure and diastolic pressure based on the PW amplitude-pressure curve according to the PW amplitude values PS and PD.

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