Coefficent determination for blood oxygen saturation and total hemoglobin concentration indices
First Claim
1. A method for monitoring a patient condition using an implantable medical device including an optical sensor, the method comprising:
- obtaining a first concentration measurement of a chromophore in a vicinity of a measurement volume of the optical sensor, the chromophore present in a first form and a second form;
performing an intervention to cause at least one of a change in a total concentration of the chromophore and a change in a relative concentration of the first form of the chromophore to the total concentration of the chromophore in the measurement volume;
obtaining a second concentration measurement of the chromophore in the vicinity of the measurement volume after performing the intervention;
obtaining a first measurement of light remittance comprising a first light wavelength and a second light wavelength, the first light remittance measurement corresponding to the first concentration;
obtaining a second measurement of light remittance comprising the first light wavelength and the second light wavelength, the second light remittance measurement corresponding to the second concentration;
solving for a coefficient for computing an index of a change in the chromophore concentration using a difference between the first and second chromophore concentration measurements and the first and second light remittance measurements;
measuring remittance at the first light wavelength and the second light wavelength; and
computing an index of the change in chromophore concentration using the measured remittance and the coefficient.
1 Assignment
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Accused Products
Abstract
A first concentration of a chromophore corresponding to a measurement volume of an optical sensor is determined. A second concentration of the chromophore is obtained in the vicinity of the measurement volume corresponding to a change in at least one of a total concentration of the chromophore and a relative concentration of a first form of the chromophore to the total concentration of the chromophore in the measurement volume. Light remittance measurements including a first light wavelength and a second light wavelength are obtained corresponding to the first chromophore concentration and the second chromophore concentration. A coefficient for computing an index of a change in the chromophore concentration is computed using the difference between the first and second chromophore concentrations and the first and second light remittance measurements.
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Citations
23 Claims
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1. A method for monitoring a patient condition using an implantable medical device including an optical sensor, the method comprising:
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obtaining a first concentration measurement of a chromophore in a vicinity of a measurement volume of the optical sensor, the chromophore present in a first form and a second form; performing an intervention to cause at least one of a change in a total concentration of the chromophore and a change in a relative concentration of the first form of the chromophore to the total concentration of the chromophore in the measurement volume; obtaining a second concentration measurement of the chromophore in the vicinity of the measurement volume after performing the intervention; obtaining a first measurement of light remittance comprising a first light wavelength and a second light wavelength, the first light remittance measurement corresponding to the first concentration; obtaining a second measurement of light remittance comprising the first light wavelength and the second light wavelength, the second light remittance measurement corresponding to the second concentration; solving for a coefficient for computing an index of a change in the chromophore concentration using a difference between the first and second chromophore concentration measurements and the first and second light remittance measurements; measuring remittance at the first light wavelength and the second light wavelength; and computing an index of the change in chromophore concentration using the measured remittance and the coefficient. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An implantable medical device for monitoring a patient condition, comprising:
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an optical sensor to emit light and measure remitted light; and a processor and associated memory configured to obtain a first concentration of a chromophore in a vicinity of a measurement volume of the optical sensor, the chromophore present in a first form and a second form, obtain a second concentration of the chromophore in the measurement volume corresponding to at least one of a change in a total concentration of the chromophore and a change in a relative concentration of the first form of the chromophore to the total concentration of the chromophore in the vicinity of the measurement volume, obtain a first measurement of light remittance comprising a first light wavelength and a second light wavelength, the first light remittance measurement corresponding to the first concentration, obtain a second measurement of light remittance comprising the first light wavelength and the second light wavelength, the second light remittance measurement corresponding to the second concentration, solve for a coefficient for computing an index of a change in the chromophore concentration using the difference between the first and second chromophore concentrations and the first and second light remittance measurements, measure remittance at the first light wavelength and the second light wavelength, and compute an index of the change in chromophore concentration using the measured remittance and the coefficient. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A computer-readable medium storing instructions which cause a processor of an implantable medical device system comprising an optical sensor to:
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obtain a first concentration of a chromophore in a vicinity of a measurement volume of the optical sensor, the chromophore present in a first form and a second form; obtain a second concentration of the chromophore in the vicinity of the measurement volume corresponding to a change in at least one of a total concentration of the chromophore and a relative concentration of the first form of the chromophore to the total concentration of the chromophore in the measurement volume; obtain a first measurement of light remittance comprising a first light wavelength and a second light wavelength, the first light remittance measurement corresponding to the first concentration; obtain a second measurement of light remittance comprising the first light wavelength and the second light wavelength, the second light remittance measurement corresponding to the second concentration; solve for a coefficient for computing an index of a change in the chromophore concentration using the difference between the first and second chromophore concentrations and the first and second light remittance measurements; measure remittance at the first light wavelength and the second light wavelength; and compute an index of the change in chromophore concentration using the measured remittance and the coefficient.
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Specification