Wearable blood pressure sensor and method of calibration
First Claim
1. A method for performing a circulatory measurement on an extremity of a subject, the method comprising:
- measuring a plethysmographic signal of a plethysmographic sensor disposed on the extremity of the subject at a plurality of heights of the sensor, relative to the heart of the subject, and at a plurality of externally applied pressures at each height of the sensor;
while measuring the plethysmographic signal, using a solid protrusion to externally apply a focal pressure to the extremity of the subject, the focal pressure having a value that may vary;
determining a relationship characterizing variation of the plethysmographic signal with the plurality of heights of the sensor and the plurality of externally applied pressures; and
deriving an arterial blood pressure feature based on at least the relationship characterizing variation of the plethysmographic signal with the plurality of heights of the sensor and the plurality of externally applied pressures, and on an instantaneously measured plethysmographic signal and height of the sensor relative to the heart of the subject.
1 Assignment
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Accused Products
Abstract
Methods and apparatus for measuring arterial blood pressure at an extremity of a subject. Arterial blood pressure is derived from a circulatory measurement performed on an extremity of a subject and the circulatory measurement is normalized to account for the instantaneous vertical displacement of the extremity. The vertical displacement of the extremity relative to the heart of the subject is obtained using the angular orientation of the subject'"'"'s extremity. An improved photoplethysmograph can discriminate light traversing the extremity from ambient light on the basis of differential response. The apparatus may have a conducting polymer actuator for applying pressure to the extremity of the subject. A pulsatile waveform from the photoplethysmographic signal may be obtained at a plurality of externally applied pressures to calibrate the photoplethysmograph.
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Citations
56 Claims
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1. A method for performing a circulatory measurement on an extremity of a subject, the method comprising:
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measuring a plethysmographic signal of a plethysmographic sensor disposed on the extremity of the subject at a plurality of heights of the sensor, relative to the heart of the subject, and at a plurality of externally applied pressures at each height of the sensor; while measuring the plethysmographic signal, using a solid protrusion to externally apply a focal pressure to the extremity of the subject, the focal pressure having a value that may vary; determining a relationship characterizing variation of the plethysmographic signal with the plurality of heights of the sensor and the plurality of externally applied pressures; and deriving an arterial blood pressure feature based on at least the relationship characterizing variation of the plethysmographic signal with the plurality of heights of the sensor and the plurality of externally applied pressures, and on an instantaneously measured plethysmographic signal and height of the sensor relative to the heart of the subject. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An improved blood pressure measurement device of the type having a plethysmographic sensor disposed on an extremity of a subject capable of sensing a plurality of plethysmographic signals at a plurality of heights of the sensor relative to the heart of the subject, and at a plurality of externally applied pressures at each height of the sensor, the improvement comprising:
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a solid protrusion for externally applying a focal pressure to the extremity of the subject, the focal pressure having a value that may vary; and a processor receiving the plurality of plethysmographic signals from the sensor, the processor determining a relationship characterizing variation of the pelthymographic signal with the plurality of heights of the sensor and the plurality of externally applied pressures, deriving an arterial blood pressure feature based on at least the relationship characterizing variation of the plethysmographic signal with the plurality of heights of the sensor and the externally applied pressures, and on an instantaneously measured plethysmographic signal and height of the sensor relative to the heart of the subject. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A method for performing a circulatory measurement on an extremity of a subject, the method comprising:
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measuring a plethysmographic signal of a plethysmographic sensor disposed on the extremity of the subject at a plurality of heights of the sensor, relative to the heart of the subject, and at a plurality of externally applied pressures at each height of the sensor; determining a relationship characterizing variation of the plethysmographic signal with the plurality of heights of the sensor and the plurality of externally applied pressures; and deriving an arterial blood pressure feature based on at least the relationship characterizing variation of the plethysmographic signal with the plurality of heights of the sensor and the plurality of externally applied pressures, and on an instantaneously measured plethysmographic signal and height of the sensor relative to the heart of the subject. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
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44. An improved blood pressure measurement device of the type having a plethysmographic sensor disposed on an extremity of a subject capable of sensing a plurality of plethysmographic signals at a plurality of heights of the sensor relative to the heart of the subject, and at a plurality of externally applied pressures at each height of the sensor, the improvement comprising:
a processor receiving the plurality of plethysmographic signals from the sensor, the processor determining a relationship characterizing variation of the plethysmographic signal with the plurality of heights of the sensor and the plurality of externally applied pressures, and deriving an arterial blood pressure feature based on at least the relationship characterizing variation of the plethysmographic signal with the plurality of heights of the sensor and the externally applied pressures, and on an instantaneously measured plethysmographic signal and height of the sensor relative to the heart of the subject. - View Dependent Claims (45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56)
Specification