Patent ID: 7706870

Claim:
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 (SD 1 ), semi-minor axis (SD 2 ), SD 1 /SD 2 of said Poincaré plot, as well as Poincaré plot area; wherein the semi-major axis (SD 1 ) and semi-minor axis (SD 2 ) of said Poincaré plot are calculated as following: defining a new axis as X 1 and X 2 ; [ x ⁢ ⁢ 1 x ⁢ ⁢ 2 ] = [ cos ⁢ ⁢ θ - sin ⁢ ⁢ θ sin ⁢ ⁢ θ cos ⁢ ⁢ θ ] ⁡ [ RR n RR n + 1 ] defining SD 1 and SD 2 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 ΔRR n ; wherein said Poincaré plot area is Π×SD 1 ×SD 2 ; wherein said R-R intervals is detected through one of method A and method B; wherein method A is First Derivative (FD 1 ) method, and said FD 1 method comprising: X(n): ECG raw data; Y ( n )=−2 X ( n− 2)− X ( n− 1)+ X ( n+ 1)+2 X ( 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 <1000 whereby 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 (AF 2 method), said AF 2 method comprising: amplitude threshold=0.4max [ X ( n )],0< n <1000 transforming original data into Y0(n): Y 0( n )= X ( n ) if X ( n )≧0,0 <n <1000 Y 0( n )=− X ( n ) if X ( n )<0,0 <n <1000 and based on said amplitude threshold, obtaining Y1(n) Y 1( n )= Y 0( n ) if Y 0( n )≧Amplitude threshold Y 1( n )=Amplitude threshold if Y 0( n )<Amplitude threshold Then, by conducting First Derivative, obtaining Y2(n): Y 2( n )= Y 1( n+ 1)− Y 1( n− 1),1 <n <2 wherein, 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 <1000 whereby 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.