Biological information measuring apparatus and biological information measuring method, and computer program product
A biological information measuring apparatus according to an embodiment includes a calculating unit and a measuring unit. The calculating unit is configured to calculate information related to a pulse wave of a subject, on the basis of luminance information of a picture signal of the subject. The measuring unit is configured to measure a fluctuation of blood pressure of the subject based on an increase or a decrease in the information related to the pulse wave, in accordance with a site of the subject from which the picture signal was obtained.
1. A biological information measuring apparatus comprising a processor configured to:
calculate a difference, at a mutually same time, between an image-based photoplethysmogram extracted from luminance information of a picture signal of a designated region of interest that is a skin region on a face, an arm or a hand of a subject included in a picture and an image-based photoplethysmogram extracted from luminance information of a picture signal of a further designated region of interest that is a skin region on the face, the arm or the hand of the subject other than the designated region of interest;
calculate at least one of a pulse transit time or an instantaneous phase difference from the difference calculated; and
measure a fluctuation of a blood pressure of the subject on basis of the difference calculated, wherein
the processor performs, in the measuring, a measuring process in accordance with a combination of the regions of interests from which the image-based photoplethysmograms are extracted and based on a correlation between the at least one of the pulse transit time or the instantaneous phase difference and the fluctuation of the blood pressure, the correlation being a positive correlation or a negative correlation, and, when a combination of the regions of interests from which the image-based photoplethysmograms are extracted, the correlation is either a combination of any of first regions of interest, in which, due to a peripheral arteriole being under control of a sympathetic nerve when the blood pressure increases, a first delay in an arrival of a first pulse wave is greater than a threshold, or, when a combination of any of second regions of interest from which the image-based photoplethysmograms are extracted, in which, due to a peripheral arteriole being under control of the sympathetic nerve and a parasympathetic nerve when the blood pressure increases, a second delay in an arrival of a second pulse wave is less than the first delay in the first regions of interest.
2. The biological information measuring apparatus according to claim 1 , wherein the processor performs the measuring process including
measuring the fluctuation of the blood pressure based on the positive correlation when the designated region of interest and the further designated region of interest from which the image-based photoplethysmograms are extracted are one of the first regions of interest and one of the second regions of interest, and
measuring the fluctuation of the blood pressure based on the negative correlation when the designated region of interest and the further designated region of interest from which the image-based photoplethysmograms are extracted are both any of the first regions of interest or any two of the second regions of interest.
3. A biological information measuring method comprising:
calculating a difference, at a mutually same time, between an image-based photoplethysmogram extracted from luminance information of a picture signal of a designated region of interest that is a skin region on a face, an arm or a hand of a subject included in a picture and an image-based photoplethysmogram extracted from luminance information of a picture signal of a further designated region of interest that is a skin region on the face, the arm or the hand of the subject other than the designated region of interest;
calculating at least one of a pulse transit time or an instantaneous phase difference from the difference calculated; and
measuring a fluctuation of a blood pressure of the subject on basis of the difference calculated, wherein
the measuring includes performing a measuring process in accordance with a combination of the regions of interests from which the image-based photoplethysmograms are extracted and based on a correlation between the at least one of the pulse transit time or the instantaneous phase difference and the fluctuation of the blood pressure, the correlation being a positive correlation or a negative correlation, and, when a combination of the regions of interests from which the image-based photoplethysmograms are extracted, the correlation is either a combination of any of first regions of interest, in which, due to a peripheral arteriole being under control of a sympathetic nerve when the blood pressure increases, a first delay in an arrival of a first pulse wave is greater than a threshold, or, when a combination of any of second regions of interest from which the image-based photoplethysmograms are extracted, in which, due to a peripheral arteriole being under control of the sympathetic nerve and a parasympathetic nerve when the blood pressure increases, a second delay in an arrival of a second pulse wave is less than the first delay in the first regions of interest.
4. A computer program product having a non-transitory computer readable medium including a biological information measuring program, wherein the biological information measuring program, when executed by a computer, causes the computer to perform:
calculating a difference, at a mutually same time, between an image-based photoplethysmogram extracted from luminance information of a picture signal of a designated region of interest that is a skin region on a face, an arm or a hand of a subject included in a picture and an image-based photoplethysmogram extracted from luminance information of a picture signal of a further designated region of interest that is a skin region on the face, the arm or the hand of the subject other than the designated region of interest;
calculating at least one of a pulse transit time or an instantaneous phase difference from the difference calculated;
performing a measuring process in accordance with a combination of the regions of interests from which the image-based photoplethysmograms are extracted and based on a correlation between the at least one of the pulse transit time or the instantaneous phase difference and the fluctuation of the blood pressure, the correlation being a positive correlation or a negative correlation, and when a combination of the regions of interests from which the image-based photoplethysmograms are extracted, the correlation is either a combination of any of first regions of interest in which, due to a peripheral arteriole being under control of a sympathetic nerve when the blood pressure increases, a first delay in an arrival of a first pulse wave is greater than a threshold, or, when a combination of any of second regions of interest from which the image-based photoplethysmograms are extracted, in which, due to a peripheral arteriole being under control of the sympathetic nerve and a parasympathetic nerve when the blood pressure increases, a second delay in an arrival of a second pulse wave is less than the first delay in the first regions of interest; and
measuring the fluctuation of the blood pressure of the subject by processing the difference using the measuring process.
5. The biological information measuring method according to claim 3 , wherein the measuring includes
measuring the fluctuation of the blood pressure based on the positive correlation when the designated region of interest and the further designated region of interest from which the image-based photoplethysmograms are extracted are one of the first regions of interest and one of the second regions of interest, and
measuring the fluctuation of the blood pressure based on the negative correlation when the designated region of interest and the further designated region of interest from which the image-based photoplethysmograms are extracted are both any of the first regions of interest or any two of the second regions of interest.
6. The computer program product according to claim 4 , wherein performing the measuring process includes
measuring the fluctuation of the blood pressure based on the positive correlation when the designated region of interest and the further designated region of interest from which the image-based photoplethysmograms are extracted are one of the first regions of interest and one of the second regions of interest, and
measuring the fluctuation of the blood pressure based on the negative correlation when the designated region of interest and the further designated region of interest from which the image-based photoplethysmograms are extracted are both any of the first regions of interest or any two of the second regions of interest.