Apparatus, method, and non-transitory computer-readable recording medium having stored therein program for blood pressure estimating program
An apparatus for estimating a blood pressure includes a first pulse wave information detector configured to detect first pulse wave information at a first position of a living body, a second pulse wave information detector configured to detect second pulse wave information at a second position of the living body, the second position being spaced a distance in a vertical direction from the first position; and a blood pressure estimator configured to estimate, based on pulse wave amplitude information at the first position and the second position obtained from the first pulse wave information obtained by the first pulse wave information detector and the second pulse wave information obtained by the second pulse wave detector and the distance in the vertical direction, a blood pressure of the living body.
1 . An apparatus for estimating a blood pressure comprising:
a video camera configured to obtain a video signal of a predetermined part of a body of a living body;
a memory;
a processor having processor circuitry coupled to the memory; and
a display configured to display a video obtained by the video camera and information representing a result of processing performed by the processor circuitry in the processor, the processor circuitry in the processor comprising video signal obtaining processor circuitry, measuring region detector processor circuitry, video pulse wave signal detector processor circuitry, and blood pressure estimating processor circuitry, wherein
the video signal obtaining processor circuitry obtains the video signal of the predetermined part of the body of the living body from the video camera,
the measuring region detector processor circuitry specifies, from the video signal obtained by the video signal obtaining processor circuitry, a part of skin region from which video pulse wave signal in the predetermined part is obtained,
the video pulse wave signal detector processor circuitry comprises:
first video pulse wave signal detector processor circuitry configured to detect first video pulse wave signal from the video signal obtained at a first position of the living body, the first position being included in the specified skin region, and
second video pulse wave signal detector processor circuitry configured to detect second video pulse wave signal from the video signal obtained at a second position of the living body, the second position being included in the specified skin region and being spaced a distance in a vertical direction from the first position, and
the blood pressure estimating processor circuitry estimates, based on first pulse wave amplitude, which is a difference between the maximum value and the minimum value within a beat, at the first position obtained from the first video pulse wave signal obtained by the first video pulse wave signal detector processor circuitry, second pulse wave amplitude, which is a difference between the maximum value and the minimum value within a beat, at the second position obtained from the second pulse wave signal obtained by the second pulse wave detector processor circuitry, and the distance between the first position and the second position in the vertical direction, the blood pressure of the living body, wherein
the blood pressure estimating processor circuitry estimates the blood pressure of the living body using an expression
P=gh /(1− R )+α
where, q represents a density; h represents the distance in the vertical direction; R represents a ratio of the first pulse wave amplitude at the first position to the second pulse wave amplitude at the second position; and a represents a bias coefficient.
2 . The apparatus according to claim 1 , wherein
the blood pressure estimating processor circuitry estimates the blood pressure of the living body by inputting a value calculated from the first pulse wave amplitude and the second pulse wave amplitude into the expression, the expression being a blood pressure function derived from a basic function and using the value as a variable and further including the bias coefficient,
the bias coefficient being stored in the memory and depending on a characteristic of a blood vessel of the living body, and
the basic function including the bias coefficient and representing a relationship between the blood pressure of the living body and a cross-section of the blood vessel of the living body.
3 . The apparatus according to claim 2 , further comprising bias coefficient determining processor circuitry configured to determine the bias coefficient based on the first pulse wave amplitude, the second pulse wave amplitude, a blood pressure measurement of the living body at a reference position of the living body and a pulse wave amplitude at the reference position of the living body.
4 . The apparatus according to claim 1 , wherein
the blood pressure estimating processor circuitry estimates, based on the ratio of the first pulse wave amplitude to the second pulse wave amplitude and the distance between the first position and the second position in the vertical direction, the blood pressure of the living body.
5 . The apparatus according to claim 1 , wherein
the first pulse wave amplitude is obtained at a predetermined region of the living body, and
the second pulse wave amplitude is obtained at the predetermined region being moved.
6 . The apparatus according to claim 1 , wherein
the first pulse wave amplitude is obtained at a first hand of the living body at the first position, and
the second pulse wave amplitude is obtained at a second hand of the living body at the second position.
7 . The apparatus according to claim 1 , wherein
the first pulse wave amplitude is obtained at a first hand of the living body at the first position, and
the second pulse wave amplitude is obtained at a second hand of the living body, the second hand being moved to the second position.
8 . The apparatus according to claim 1 , wherein
a correction coefficient is obtained from two pulse wave amplitudes obtained at two different predetermined regions of the living body, the predetermined regions being at a same level in the vertical direction, and
at least one of the two pulse wave amplitudes is corrected by using the correction coefficient.
9 . A method for estimating blood pressure in an apparatus for estimating a blood pressure comprising a video camera configured to obtain a video signal of a predetermined part of a body of a living body,
the apparatus comprising:
a memory; a processor including processor circuitry coupled to the memory; and a display configured to display a video obtained by the video camera and information representing a result of processing performed by the processor circuitry in the processor, the processor circuitry in the processor comprising video signal obtaining processor circuitry, measuring region detector processor circuitry, video pulse wave signal detector processor circuitry, and blood pressure estimating processor circuitry,
the method comprising:
obtaining, by the video signal obtaining processor circuitry, the video signal of the predetermined part of the body of the living body from the video camera;
specifying, by the measuring region detector processor circuitry, a part of skin region from which video pulse wave signal in the predetermined part is obtained, from the video signal obtained in the obtaining;
detecting, by the video pulse wave signal detector processor circuitry, first video pulse wave signal from the video signal obtained at a first position of the living body, the first position being included in the specified skin region;
detecting, by the video pulse wave signal detector processor circuitry, second video pulse wave from the video signal obtained at a second position of the living body, the second position being included in the specified skin region and being spaced a distance in a vertical direction from the first position; and
estimating, by the blood pressure estimating processor circuitry, the blood pressure of the living body based on:
first pulse wave amplitude, which is a difference between the maximum value and the minimum value within a beat, at the first position obtained from the first video pulse wave signal obtained in the detecting the first video pulse wave signal,
second pulse wave amplitude, which is a difference between the maximum value and the minimum value within a beat, at the second position obtained from the second pulse wave signal obtained in the detecting the second video pulse wave signal, and
the distance between the first position and the second position in the vertical direction,
the method further comprising:
estimating, by the blood pressure estimating processor circuitry, the blood pressure of the living body using an expression
P=gh /(1− R )+α
where, q represents a density; h represents the distance in the vertical direction; R represents a ratio of the first pulse wave amplitude at the first position to the second pulse wave amplitude at the second position; and a represents a bias coefficient.
10 . A non-transitory computer-readable recording medium having stored therein a blood pressure estimating program that, when executed by an apparatus for estimating a blood pressure comprising a video camera configured to obtain a video signal of a predetermined part of a body of a living body; a memory; a processor including processor circuitry coupled to the memory; and a display configured to display a video obtained by the video camera and information representing a result of processing performed by the processor circuitry in the processor, processor circuitry in the processor comprising video signal obtaining processor circuitry, measuring region detector processor circuitry, video pulse wave signal detector processor circuitry and blood pressure estimating processor circuitry, causes the processor to execute a process comprising:
obtaining, by the video signal obtaining processor circuitry, the video signal of the predetermined part of the body of the living body from the video camera;
specifying, by the measuring region detector processor circuitry, a part of skin region from which video pulse wave signal in the predetermined part is obtained, from the video signal obtained in the obtaining;
detecting, by the video pulse wave signal detector processor circuitry, first video pulse wave signal from the video signal obtained at a first position of the living body, the first position being included in the specified skin region;
detecting, by the video pulse wave signal detector processor circuitry, second video pulse wave from the video signal obtained at a second position of the living body, the second position being included in the specified skin region and being spaced a distance in a vertical direction from the first position; and
estimating, by the blood pressure estimating processor circuitry, the blood pressure of the living body based on:
first pulse wave amplitude, which is a difference between the maximum value and the minimum value within a beat, at the first position obtained from the first video pulse wave signal obtained in the detecting the first video pulse wave signal,
second pulse wave amplitude, which is a difference between the maximum value and the minimum value within a beat, at the second position obtained from the second pulse wave signal obtained in the detecting the second video pulse wave signal, and
the distance between the first position and the second position in the vertical direction
the process further comprising:
estimating, by the blood pressure estimating processor circuitry, the blood pressure of the living body using an expression
P=gh /(1− R )+α
where, q represents a density; h represents the distance in the vertical direction; R represents a ratio of the first pulse wave amplitude at the first position to the second pulse wave amplitude at the second position; and a represents a bias coefficient.