×

Method for analyzing irreversible apneic coma (IAC)

  • US 7,706,870 B2
  • Filed: 07/10/2007
  • Issued: 04/27/2010
  • Est. Priority Date: 07/10/2007
  • Status: Expired due to Fees
First Claim
Patent Images

1. A method of analyzing heart rate variability for the presence of irreversible apneic coma (IAC), comprising following steps:

  • step 1 recording electrocardiogram (ECG) from a subject using a patient monitor;

    step 2 analyzing R-R interval in said electrocardiogram (ECG);

    step 3 plotting said R-R interval into Poincaré

    plot, wherein the X coordinate of said Poincaré

    plot represents R-R interval(n), n is a 1˜

    data number; and

    Y coordinate of said Poincaré

    plot represents RR(n+1); and

    step 4 quantifying said Poincaré

    plot, and obtaining semi-major axis (SD1), semi-minor axis (SD2), SD1/SD2 of said Poincaré

    plot, as well as Poincaré

    plot area;

    wherein the semi-major axis (SD1) and semi-minor axis (SD2) of said Poincaré

    plot are calculated as following;

    defining a new axis as X1 and X2;

    [ x



    1
    x



    2
    ]
    = [ cos



    θ

    - sin



    θ

    sin



    θ

    cos



    θ

    ]


    [ RR n RR n + 1 ]
    defining SD1 and SD2 as;

    SD



    1 2
    = Var

    ( x 1 )
    = Var ( 1 2

    RR n
    - 1 2

    RR n + 1
    )
    = 1 2

    Var

    ( RR n - RR n + 1 )
    = 1 2

    SDSD 2
    SD



    2 2
    = 2

    SDRR 2
    - 1 2

    SDSD 2
    wherein SDRR is the standard deviation of R-R interval and SDSD is the standard deviation of Δ

    RRn;

    wherein said Poincaré

    plot area is Π

    ×

    SD1×

    SD2;

    wherein said R-R intervals is detected through one of method A and method B;

    wherein method A is First Derivative (FD1) method, and said FD1 method comprising;

    X(n);

    ECG raw data;


    Y(n)=−

    2X(n−

    2)−

    X(n−

    1)+X(n+1)+2X(n+2),2<

    n
    <

    1000;

    wherein, for detecting the position of R wave in Y(n), a slope threshold value is defined as;


    Slope threshold=0.7max[Y(n)],2<

    n
    <

    1000whereby if Y(i)>

    slope threshold, Y(i) becomes a region for comparison, and positions of each peaks is selected from Y(i), and wherein the distance between adjacent peaks is the R-R intervals;

    wherein method B is an amplitude threshold plus a First Derivative method (AF2 method), said AF2 method comprising;


    amplitude threshold=0.4max [X(n)],0<

    n<

    1000transforming original data into Y0(n);


    Y0(n)=X(n) if X(n)≧

    0,0<

    n
    <

    1000
    Y0(n)=−

    X(n) if X(n)<

    0,0<

    n
    <

    1000and based on said amplitude threshold, obtaining Y1(n)
    Y1(n)=Y0(n) if Y0(n)≧

    Amplitude threshold
    Y1(n)=Amplitude threshold if Y0(n)<

    Amplitude thresholdThen, by conducting First Derivative, obtaining Y2(n);


    Y2(n)=Y1(n+1)−

    Y1(n−

    1),1<

    n
    <

    2wherein, in order to detect the position of R wave in Y2(n), a slope threshold value is defined as;


    Slope threshold=0.7max[Y(n)],2<

    n
    <

    1000whereby if Y(i)>

    slope threshold, Y(i) becomes the region for comparison, and positions of each peaks is selected from Y(i), and wherein the distance between adjacent peaks is the R-R intervals;

    step 5 determining a reference index from said quantification of said Poincaré

    plot and providing said reference index to a physician for determining whether brain death has occurred;

    wherein steps 2-5 are done using a computing device.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×