Respiratory state estimating device, portable device, wearable device, medium, respiratory state estimating method and respiratory state estimator

Abstract

Provided is a respiratory state estimating device including a pulse wave signal acquiring unit that acquires a pulse wave signal from a portion of a living subject, a pulse rate calculating unit that calculates a pulse rate of the living subject based on the pulse wave signal, and a respiratory state estimating unit that estimates a respiratory state of the living subject based on the pulse rate. Also, provided is a respiratory state estimating method including optically acquiring a pulse wave signal from a portion of a living subject, calculating a pulse rate of the living subject based on the pulse wave signal, estimating a respiratory state of the living subject from the pulse rate.

What is claimed is: 
     
         1 . A respiratory state estimating device comprising:
 a pulse wave signal acquiring unit that acquires a pulse wave signal from a portion of a living subject;   a pulse rate calculating unit that calculates a pulse rate of the living subject based on the pulse wave signal; and   a respiratory state estimating unit that estimates a respiratory state of the living subject based on the pulse rate.   
     
     
         2 . The respiratory state estimating device according to  claim 1 ,
 wherein the respiratory state estimating unit   estimates the respiratory state from change in the pulse rate.   
     
     
         3 . The respiratory state estimating device according to  claim 2 ,
 wherein the respiratory state estimating unit   estimates at least one of an inspiration state, an expiration state, and an apneic state of the living subject as the respiratory state.   
     
     
         4 . The respiratory state estimating device according to  claim 1 ,
 wherein the pulse rate calculating unit   calculates pulse rates at predetermined intervals, and   wherein the respiratory state estimating unit   estimates the respiratory state of the living subject based on comparison of the calculated pulse rate with a next calculated pulse rate.   
     
     
         5 . The respiratory state estimating device according to  claim 1 ,
 wherein the respiratory state estimating unit   estimates that the respiratory state is an inspiration state when an amount of change in the pulse rate is more than or equal to a predetermined positive inspiration estimation threshold.   
     
     
         6 . The respiratory state estimating device according to  claim 5 ,
 wherein the respiratory state estimating unit   estimates that the respiratory state is the inspiration state when a difference between a value of the pulse rate at a first clock time and a value of the pulse rate at a second clock time prior to the first clock time is more than or equal to zero, a difference between the value of the pulse rate at the second clock time and a value of the pulse rate at a third clock time prior to the second clock time is more than or equal to zero, and a difference between the value at the first clock time and the value at the third clock time is more than or equal to the inspiration estimation threshold.   
     
     
         7 . The respiratory state estimating device according to  claim 6 , wherein a time period from the third clock time to the first clock time is shorter than a respiratory period of the living subject. 
     
     
         8 . The respiratory state estimating device according to  claim 1 ,
 wherein the respiratory state estimating unit   estimates that the respiratory state is an expiration state when an amount of change in the pulse rate is less than or equal to a predetermined negative expiration estimation threshold.   
     
     
         9 . The respiratory state estimating device according to  claim 8 ,
 wherein the respiratory state estimating unit   estimates that the respiratory state is the expiration state when a difference between a value of the pulse rate at a fourth clock time and a value of the pulse rate at a fifth clock time prior to the fourth clock time is less than or equal to zero, a difference between the value of the pulse rate at the fifth clock time and a value of the pulse rate at a sixth clock time prior to the fifth clock time is less than or equal to zero, and a difference between the value at the fourth clock time and the value at the sixth clock time is less than or equal to the expiration estimation threshold.   
     
     
         10 . The respiratory state estimating device according to  claim 9 , wherein a time period from the sixth clock time to the fourth clock time is shorter than a respiratory period of the living subject. 
     
     
         11 . The respiratory state estimating device according to  claim 1 ,
 wherein the respiratory state estimating unit   estimates that the respiratory state is an instantaneous apneic state when an amount of change in the pulse rate is not more than or equal to a predetermined positive inspiration estimation threshold, and is not less than or equal to a predetermined negative expiration estimation threshold.   
     
     
         12 . The respiratory state estimating device according to  claim 11 ,
 wherein the respiratory state estimating unit   estimates that the respiratory state is an apneic state when the estimated instantaneous apneic state continues for a predetermined time.   
     
     
         13 . The respiratory state estimating device according to  claim 3 ,
 wherein the pulse wave signal acquiring unit   outputs window signal including first sample data of the pulse wave signal, and   wherein the pulse rate calculating unit   has an integrating and outputting unit that outputs integrated window signal obtained by integrating second sample data before, after, or before and after the window signal, and   a discrete frequency transforming unit that calculates a pulse wave feature amount by performing a discrete frequency transformation on the integrated window signal.   
     
     
         14 . The respiratory state estimating device according to  claim 13 ,
 wherein the pulse rate calculating unit   further has a window function multiplying unit that multiplies the window signal by a window function, and   wherein the integrating and outputting unit   outputs the window signal obtained by integrating the second sample data before, after, or before and after the window signal after multiplication by the window function.   
     
     
         15 . The respiratory state estimating device according to  claim 14 , wherein the window function is the Hanning window. 
     
     
         16 . The respiratory state estimating device according to  claim 13 , wherein the second sample data is zero. 
     
     
         17 . The respiratory state estimating device according to  claim 13 ,
 wherein the integrating and outputting unit   outputs the integrated window signal obtained by integrating the second sample data into the first sample data so that a sum of the number of samples of the first sample data and the number of samples of the second sample data is a power of two, and   wherein the discrete frequency transforming unit performs FFT on the window signal.   
     
     
         18 . The respiratory state estimating device according to  claim 13 ,
 wherein the pulse wave signal acquiring unit   outputs window signals so that each of the window signals overlaps at predetermined time intervals.   
     
     
         19 . The respiratory state estimating device according to  claim 18 , wherein a time width of the window signal is larger than or equal to a pulse period of the living subject. 
     
     
         20 . The respiratory state estimating device according to  claim 13 ,
 wherein the integrated window signal output by the integrating and outputting unit has, at both ends, sample data having an equal value.   
     
     
         21 . The respiratory state estimating device according to  claim 13 ,
 wherein the pulse wave signal acquiring unit   has a video acquiring unit that acquires a video of a portion of the living subject, and   based on a reference signal indicating time, outputs the window signal a sampling rate of which is fixed at a sampling rate predetermined according to the video.   
     
     
         22 . The respiratory state estimating device according to  claim 21 , wherein the reference signal is a timestamp included in a frame constituting the video. 
     
     
         23 . The respiratory state estimating device according to  claim 21 , wherein the video is a video including light emitted by a lighting apparatus driven by an AC power source, and
 wherein the reference signal is a signal according to a luminance frequency of the lighting apparatus.   
     
     
         24 . The respiratory state estimating device according to  claim 3 , wherein the pulse wave signal acquiring unit optically acquires the pulse wave signal. 
     
     
         25 . A portable device comprising:
 the respiratory state estimating device according to  claim 21 ; and   a display that displays information indicating the respiratory state.   
     
     
         26 . A portable device comprising:
 the respiratory state estimating device according to  claim 3 ;   a video acquiring unit that acquires a video of a portion of the living subject; and   a display that displays information indicating the respiratory state.   
     
     
         27 . A wearable device comprising:
 the respiratory state estimating device according to  claim 3 ; and   a display that displays information indicating the respiratory state.   
     
     
         28 . A computer readable medium having a program recorded thereon that causes a computer to function as the respiratory state estimating device according to  claim 3 . 
     
     
         29 . A respiratory state estimating method comprising:
 acquiring a pulse wave signal from a portion of a living subject optically;   calculating a pulse rate of the living subject based on the pulse wave signal; and   estimating a respiratory state of the living subject from change in the pulse rate.   
     
     
         30 . A respiratory state estimator comprising:
 a video acquiring unit that acquires a video of skin of a living subject; and   a respiratory state estimating unit that estimates a respiratory state of the living subject based on the video.   
     
     
         31 . The respiratory state estimator according to  claim 30 ,
 wherein the respiratory state estimating unit   estimates the respiratory state based on blood flow information included in the video.   
     
     
         32 . The respiratory state estimator according to  claim 30 ,
 wherein the respiratory state estimating unit   estimates the respiratory state based on change in contrasting density of the video.   
     
     
         33 . The respiratory state estimator according to  claim 30  further comprising a display that displays information indicating the respiratory state. 
     
     
         34 . The respiratory state estimator according to  claim 33 ,
 wherein the display displays the information indicating the respiratory state live.   
     
     
         35 . A respiratory state estimating device comprising:
 a pulse wave signal acquiring unit that acquires a pulse wave signal from a portion of a living subject optically;   a pulse wave lag time calculating unit that calculates a pulse wave lag time of the living subject based on the pulse wave signal; and   a respiratory state estimating unit that estimates a respiratory state of the living subject based on the pulse wave lag time.   
     
     
         36 . The respiratory state estimating device according to  claim 35 ,
 wherein the pulse wave lag time calculating unit has:   an autocorrelation calculating unit that calculates an autocorrelation of the pulse wave signal; and   a lag time calculating unit that calculates the pulse wave lag time based on the autocorrelation.   
     
     
         37 . The respiratory state estimating device according to  claim 35 ,
 wherein the respiratory state estimating unit   estimates that the respiratory state is an inspiration state when an amount of change in the pulse wave lag time is less than or equal to a predetermined negative inspiration estimation threshold.   
     
     
         38 . The respiratory state estimating device according to  claim 37 ,
 wherein the respiratory state estimating unit   estimates that the respiratory state is the inspiration state when a difference between a value of the pulse wave lag time at a first clock time and a value of the pulse wave lag time at a second clock time prior to the first clock time is less than or equal to zero, a difference between the value of the pulse wave lag time at the second clock time and a value of the pulse wave lag time at a third clock time prior to the second clock time is less than or equal to zero, and a difference between the value at the first clock time and the value at the third clock time is less than or equal to the inspiration estimation threshold.   
     
     
         39 . The respiratory state estimating device according to  claim 38 , wherein a time period from the third clock time to the first clock time is shorter than a respiratory period of the living subject. 
     
     
         40 . The respiratory state estimating device according to  claim 35 ,
 wherein the respiratory state estimating unit   estimates that the respiratory state is an expiration state when an amount of change in the pulse wave lag time is more than or equal to a predetermined positive expiration estimation threshold.   
     
     
         41 . The respiratory state estimating device according to  claim 40 ,
 wherein the respiratory state estimating unit   estimates that the respiratory state is the expiration state when a difference between a value of the pulse wave lag time at a fourth clock time and a value of the pulse wave lag time at a fifth clock time prior to the fourth clock time is more than or equal to zero, a difference between the value of the pulse wave lag time at the fifth clock time and a value of the pulse wave lag time at a sixth clock time prior to the fifth clock time is more than or equal to zero, and a difference between the value at the fourth clock time and the value at the sixth clock time is more than or equal to the expiration estimation threshold.   
     
     
         42 . The respiratory state estimating device according to  claim 41 , wherein a time period from the sixth clock time to the fourth clock time is shorter than a respiratory period of the living subject. 
     
     
         43 . The respiratory state estimating device according to  claim 35 ,
 wherein the respiratory state estimating unit   estimates that the respiratory state is an instantaneous apneic state when an amount of change in the pulse wave lag time is not less than or equal to a predetermined negative inspiration estimation threshold, and is not more than or equal to a predetermined positive expiration estimation threshold.   
     
     
         44 . The respiratory state estimating device according to  claim 43 ,
 wherein the respiratory state estimating unit   estimates that the respiratory state is an apneic state when the estimated instantaneous apneic state continues for a predetermined time.   
     
     
         45 . The respiratory state estimating device according to  claim 36 ,
 wherein the pulse wave lag time calculating unit   further has a bias variation eliminating unit that eliminates bias variation of the pulse wave signal, and   wherein the autocorrelation calculating unit   calculates the autocorrelation based on the pulse wave signal after elimination of the bias variation.