Method for obtaining blood pressure data from optical sensor
First Claim
1. A method for obtaining blood pressure data from a patient using an optical blood pressure sensor placed against a patient'"'"'s body, said sensor comprising a two-dimensional array of photo-sensitive elements, comprising the steps of:
- (1) calibrating said optical sensor, said step of calibrating comprising the steps of obtaining at least one digitized two-dimensional calibration image of a portion of said patient'"'"'s body using said optical sensor, substantially simultaneously obtaining a blood pressure measurement form said patient, and comparing said blood pressure measurement to at least one portion of said at least one calibration image to thereby obtain a calibration relationship between said at least one portion of said at least one calibration image and said blood pressure measurement;
(2) subsequently obtaining a second digitized two-dimensional image of said portion of said patient'"'"'s body during a period in which said blood pressure data is to be obtained from said patient;
(3) applying said calibration relationship derived for said at least one portion of said at least one calibration to a corresponding portion of said second image to thereby derive said blood pressure data; and
(4) performing validation checking of output signals from multiple photosensitive elements corresponding to said portion of said calibration and second two-dimensional images.
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Accused Products
Abstract
An optical sensor generates blood pressure data by obtaining two dimensional images of the surface of the patient'"'"'s body, such as in the vicinity of the radial artery in the wrist area. Blood flow in the patient causes light to be reflected off a flexible reflective surface applied against the patient with a hold down pressure, and the scattering of light is sensed with a two-dimensional array of photo-detectors. The output of the photo-detectors during systolic and diastolic events is calibrated against known blood pressure measurements taken with a conventional air-cuff sphygmomanometer. Linear calibration relationships between output signal and blood pressure are obtained during calibration for some set of the photo-detectors. When blood pressure data is obtained from the patient, the linear calibration relationship between output signals and blood pressure is applied to the output signals from the set of photo-detectors, resulting in blood pressure data. The method provides for compensation for changes in hold down pressure and translation or rotation of the optical sensor relative to the patient. A preferred optical sensor arrangement for use in performing the method is also described.
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Citations
52 Claims
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1. A method for obtaining blood pressure data from a patient using an optical blood pressure sensor placed against a patient'"'"'s body, said sensor comprising a two-dimensional array of photo-sensitive elements, comprising the steps of:
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(1) calibrating said optical sensor, said step of calibrating comprising the steps of obtaining at least one digitized two-dimensional calibration image of a portion of said patient'"'"'s body using said optical sensor, substantially simultaneously obtaining a blood pressure measurement form said patient, and comparing said blood pressure measurement to at least one portion of said at least one calibration image to thereby obtain a calibration relationship between said at least one portion of said at least one calibration image and said blood pressure measurement;
(2) subsequently obtaining a second digitized two-dimensional image of said portion of said patient'"'"'s body during a period in which said blood pressure data is to be obtained from said patient;
(3) applying said calibration relationship derived for said at least one portion of said at least one calibration to a corresponding portion of said second image to thereby derive said blood pressure data; and
(4) performing validation checking of output signals from multiple photosensitive elements corresponding to said portion of said calibration and second two-dimensional images. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 31, 32)
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2. A method for obtaining blood pressure data from a patient using an optical blood pressure sensor placed against a patient'"'"'s body, said sensor comprising a two-dimensional array of photo-sensitive elements, comprising the steps of:
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(1) calibrating said optical sensor, said step of calibrating comprising the steps of obtaining at least one digitized two-dimensional calibration image of a portion of said patient'"'"'s body using said optical sensor, substantially simultaneously obtaining a blood pressure measurement form said patient, and comparing said blood pressure measurement to at least one portion of said at least one calibration image to thereby obtain a calibration relationship between said at least one portion of said at least one calibration image and said blood pressure measurement;
(2) subsequently obtaining a second digitized two-dimensional image of said portion of said patient'"'"'s body during a period in which said blood pressure data is to be obtained from said patient;
(3) applying said calibration relationship derived for said at least one portion of said at least one calibration to a corresponding portion of said second image to thereby derive said blood pressure data;
(4) generating a multitude of digitized two-dimensional images over a data collection period of time and performing said step (3) for each of said multitude of images; and
(5) measuring blood flow rate from sequential images in said multitude of two-dimensional images over a measured interval of time.
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3. A method for obtaining blood pressure data from a patient using an optical blood pressure sensor placed against a patient'"'"'s body, said sensor comprising a two-dimensional array of photo-sensitive elements, comprising the steps of:
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(1) calibrating said optical sensor, said step of calibrating comprising the steps of obtaining at least one digitized two-dimensional calibration image of a portion of said patient'"'"'s body using said optical sensor, substantially simultaneously obtaining a blood pressure measurement form said patient, and comparing said blood pressure measurement to at least one portion of said at least one calibration image to thereby obtain a calibration relationship between said at least one portion of said at least one calibration image and said blood pressure measurement;
(2) subsequently obtaining a second digitized two-dimensional image of said portion of said patient'"'"'s body during a period in which said blood pressure data is to be obtained from said patient; and
(3) applying said calibration relationship derived for said at least one portion of said at least one calibration to a corresponding portion of said second image to thereby derive said blood pressure data;
wherein said portion of said calibration image comprises a single location in said calibration, wherein said calibration relationship is obtained for said single location in said calibration image, and wherein said corresponding portion in said second image comprises said single location in said calibration image.
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4. A method for obtaining blood pressure data from a patient using an optical blood pressure sensor placed against a patient'"'"'s body, said sensor comprising a two-dimensional array of photo-sensitive elements, comprising the steps of:
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(1) calibrating said optical sensor, said step of calibrating comprising the steps of obtaining at least one digitized two-dimensional calibration image of a portion of said patient'"'"'s body using said optical sensor, substantially simultaneously obtaining a blood pressure measurement form said patient, and comparing said blood pressure measurement to at least one portion of said at least one calibration image to thereby obtain a calibration relationship between said at least one portion of said at least one calibration image and said blood pressure measurement;
(2) subsequently obtaining a second digitized two-dimensional image of said portion of said patient'"'"'s body during a period in which said blood pressure data is to be obtained from said patient; and
(3) applying said calibration relationship derived for said at least one portion of said at least one calibration to a corresponding portion of said second image to thereby derive said blood pressure data;
wherein said portion of said calibration image comprises a set of locations in said calibration image having substantially different image intensity values, and wherein said calibration relationship is performed for said set of locations.
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5. A method for processing output signals from a two-dimensional array of photo-sensitive elements to generate blood pressure data, said two-dimensional array of photo-sensitive elements incorporated into an optical blood pressure sensor adapted to be placed on the surface of a patient and obtain optical information as to movement of the patient'"'"'s body in response to blood flow in the patient, comprising the steps of:
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generating a calibration relationship between output signals from a set of at least one of said photo-sensitive elements to known blood pressure measurements;
obtaining, via said optical blood pressure sensor, a two-dimensional image of the surface of a patient'"'"'s body during a period in which blood pressure information is sought for said patient;
digitizing said two-dimensional image to thereby obtain a two-dimensional array of digital output values, said output values including output values for said set of at least one of said photo-sensitive elements; and
applying said calibration relationship to a portion of said array of digital output values corresponding to said set of at least one of said photo-sensitive elements to thereby derive said blood pressure data;
wherein said set of at least one of said photo-sensitive elements comprises a single photo-sensitive element in said array.
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6. A method for obtaining blood pressure data from a patient using an optical blood pressure sensor placed against a patient'"'"'s body, said sensor comprising a two-dimensional array of photo-sensitive elements, comprising the steps of:
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(1) calibrating said optical sensor, said step of calibrating comprising the steps of obtaining at least one digitized two-dimensional calibration image of a potion of said patient'"'"'s body using said optical sensor, substantially simultaneously obtaining a blood pressure measurement form said patient, and comparing said blood pressure measurement to at least one portion of said at least one calibration image to thereby obtain a calibration relationship between said at least one portion of said at least one calibration image and said blood pressure measurement;
(2) subsequently obtaining a second digitized two-dimensional image of said portion of said patient'"'"'s body during a period in which said blood pressure data is to be obtained from said patient;
(3) applying said calibration relationship derived for said at least one portion of said at least one calibration to a corresponding portion of said second image to thereby derive said blood pressure data; and
(4) compensating for rotation or translation of said optical sensor relative to said patient occurring between the obtaining of said calibration and second images. - View Dependent Claims (7, 8)
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9. A method for obtaining blood pressure data from a patient using an optical blood pressure sensor placed against a patient'"'"'s body, said sensor comprising a two-dimensional array of photo-sensitive elements, comprising the steps of:
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(1) calibrating said optical sensor, said step of calibrating comprising the steps of obtaining at least one digitized two-dimensional calibration image of a portion of said patient'"'"'s body using said optical sensor, substantially simultaneously obtaining a blood pressure measurement form said patient, and comparing said blood pressure measurement to at least one portion of said at least one calibration image to thereby obtain a calibration relationship between said at least one portion of said at least one calibration image and said blood pressure measurement;
(2) subsequently obtaining a second digitized two-dimensional image of said portion of said patient'"'"'s body during a period in which said blood pressure data is to be obtained from said patient; and
(3) applying said calibration relationship derived for said at least one portion of said at least one calibration to a corresponding portion of said second image to thereby derive said blood pressure data;
wherein said portion of said calibration image comprises a set of locations in said calibration image having substantially the same image intensity values, wherein said calibration relationship is obtained for said set of locations.
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28. A method for processing output signals from a two-dimensional array of photo-sensitive elements to generate blood pressure data, said two-dimensional array of photo-sensitive elements incorporated into an optical blood pressure sensor adapted to be placed on the surface of a patient and obtain optical information as to movement of the patient'"'"'s body in response to blood flow in the patient, comprising the steps of:
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generating a calibration relationship between output signals from a set of at least one of said photo-sensitive elements to known blood pressure measurements;
obtaining, via said optical blood pressure sensor, a two-dimensional image of the surface of a patient'"'"'s body during a period in which blood pressure information is sought for said patient;
digitizing said two-dimensional image to thereby obtain a two-dimensional array of digital output values, said output values including output values for said set of at least one of said photo-sensitive elements; and
applying said calibration relationship to a portion of said array of digital output values corresponding to said set of at least one of said photo-sensitive elements to thereby derive said blood pressure data;
wherein said set of at least one of said photo-sensitive elements comprises a set of photo-sensitive elements having substantially similar output signals at said known blood pressure measurement. - View Dependent Claims (29, 30, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 52)
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48. A method for processing output signals from a two-dimensional array of photo-sensitive elements to generate blood pressure data, said two-dimensional array of photo-sensitive elements incorporated into an optical blood pressure sensor adapted to be placed on the surface of a patient and obtain optical information as to movement of the patient'"'"'s body in response to blood flow in the patient, comprising the steps of:
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generating a calibration relationship between output signals from a set of at least one of said photo-sensitive elements to known blood pressure measurements;
obtaining, via said optical blood pressure sensor, a two-dimensional image of the surface of a patient'"'"'s body during a period in which blood pressure information is sought for said patient;
digitizing said two-dimensional image to thereby obtain a two-dimensional array of digital output values, said output values including output values for said set of at least one of said photo-sensitive elements; and
applying said calibration relationship to a portion of said array of digital output values corresponding to said set of at least one of said photo-sensitive elements to thereby derive said blood pressure data;
wherein said calibration relationship comprises a linear scaling relationship between blood pressure and a digitized output signal from said set of at least one of said photo-sensitive elements;
wherein said calibration relationship comprises a plurality of linear scaling relationships between said known blood pressure and a plurality of output signals from a plurality of individual photo-sensitive elements in said array, said linear scaling relationships of the form ys,d(n, m)=an,ms,d X(n, m)+bn,ms,d, where Ys,d is blood pressure for systolic and diastolic events, (n, m) are one or more individual photo-sensitive elements in an n by m array of such elements, X(n, m) is an output signal value and an,ms,d and bn,ms,d are calibration coefficients during systolic and diastolic events for each photo-sensitive element, determined during calibration of the array.
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49. A method for processing output signals from a two-dimensional array of photo-sensitive elements to generate blood pressure data, said two-dimensional array of photo-sensitive elements incorporated into an optical blood pressure sensor adapted to be placed on the surface of a patient and obtain optical information as to movement of the patient'"'"'s body in response to blood flow in the patient, comprising the steps of:
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generating a calibration relationship between output signals from a set of at least one of said photo-sensitive elements to known blood pressure measurements;
obtaining, via said optical blood pressure sensor, a two-dimensional image of the surface of a patient'"'"'s body during a period in which blood pressure information is sought for said patient;
digitizing said two-dimensional image to thereby obtain a two-dimensional array of digital output values, said output values including output values for said set of at least one of said photo-sensitive elements;
applying said calibration relationship to a portion of said array of digital output values corresponding to said set of at least one of said photo-sensitive elements to thereby derive said blood pressure data; and
performing validation checking of output signals from multiple photo-sensitive elements corresponding to said portion of said two-dimensional image.
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50. A method for processing output signals from a two-dimensional array of photo-sensitive elements to generate blood pressure data, said two-dimensional array of photo-sensitive elements incorporated into an optical blood pressure sensor adapted to be placed on the surface of a patient and obtain optical information as to movement of the patient'"'"'s body in response to blood flow in the patient, comprising the steps of:
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generating a calibration relationship between output signals from a set of at least one of said photo-sensitive elements to known blood pressure measurements;
obtaining, via said optical blood pressure sensor, a two-dimensional image of the surface of a patient'"'"'s body during a period in which blood pressure information is sought for said patient;
digitizing said two-dimensional image to thereby obtain a two-dimensional array of digital output values, said output values including output values for said set of at least one of said photo-sensitive elements;
applying said calibration relationship to a portion of said array of digital output values corresponding to said set of at least one of said photo-sensitive elements to thereby derive said blood pressure data;
generating a multitude of digitized two-dimensional images over a data collection period of time and performing said steps of digitizing and applying for each of said multitude of images; and
measuring blood flow rate from sequential images in said multitude of two-dimensional images over a measured interval of time.
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51. A method for processing output signals from a two-dimensional array of photo-sensitive elements to generate blood pressure data, said two-dimensional array of photo-sensitive elements incorporated into an optical blood pressure sensor adapted to be placed on the surface of a patient and obtain optical information as to movement of the patient'"'"'s body in response to blood flow in the patient, comprising the steps of:
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generating a calibration relationship between output signals from a set of at least one of said photo-sensitive elements to known blood pressure measurements;
obtaining, via said optical blood pressure sensor, a two-dimensional image of the surface of a patient'"'"'s body during a period in which blood pressure information is sought for said patient;
digitizing said two-dimensional image to thereby obtain a two-dimensional array of digital output values, said output values including output values for said set of at least one of said photo-sensitive elements;
applying said calibration relationship to a portion of said array of digital output values corresponding to said set of at least one of said photo-sensitive elements to thereby derive said blood pressure data; and
compensating for rotation or translation of said optical sensor relative to said patient occurring between the obtaining of said calibration relationship and said two-dimensional image.
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Specification