Measurement of a fluorescent analyte using tissue excitation
First Claim
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1. An apparatus for noninvasive measurement of a concentration of a fluorescent analyte in the blood of a patient comprising:
- a light source operatively associated with a tunable optical filter, such that the light source is adapted to excite an analyte and blood at alternating first and second wavelengths,one or more spectrometers for detecting a portion of the emission spectra of the fluorescent analyte at the first excitation wavelength and the second excitation wavelength; and
a processor adapted to determine a derived signal representative of the concentration of the analyte based on the difference between the portion of the emission spectra excited at the first excitation wavelength range and the second excitation wavelength range; and
determine whether the detected concentration of the fluorescent analyte is below a preselected concentration; and
provide an indication that the fluorescent analyte concentration is below the preselected concentration,wherein the analyte is selected from the group consisting of;
erythrocyte zinc protoporphyrin and erythrocyte protoporphyrin IX, or a combination thereof, and the first and second alternating wavelengths are selected such that the analyte exhibits first and second emission intensities at the first and second wavelengths, the first and second emission intensities being different, and the blood exhibits first and second absorbances at the first and second wavelengths, the first and second absorbances being similar.
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Abstract
An apparatus and method for noninvasive measurement of a fluorescent analyte concentration in the blood of a patient by exciting the blood and the analyte at two wavelength ranges and measuring the emission spectrum of the fluorescent analyte when (i) the difference of emission intensities at the excitation wavelength ranges of the fluorescent analyte is greater than that of background fluorophores, and (ii) when blood absorbance at the two excitation wavelength ranges is similar. An apparatus and method for measurement of a fluorescent analyte concentration in the blood of a patient is provided.
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Citations
20 Claims
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1. An apparatus for noninvasive measurement of a concentration of a fluorescent analyte in the blood of a patient comprising:
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a light source operatively associated with a tunable optical filter, such that the light source is adapted to excite an analyte and blood at alternating first and second wavelengths, one or more spectrometers for detecting a portion of the emission spectra of the fluorescent analyte at the first excitation wavelength and the second excitation wavelength; and a processor adapted to determine a derived signal representative of the concentration of the analyte based on the difference between the portion of the emission spectra excited at the first excitation wavelength range and the second excitation wavelength range; and
determine whether the detected concentration of the fluorescent analyte is below a preselected concentration; and
provide an indication that the fluorescent analyte concentration is below the preselected concentration,wherein the analyte is selected from the group consisting of;
erythrocyte zinc protoporphyrin and erythrocyte protoporphyrin IX, or a combination thereof, and the first and second alternating wavelengths are selected such that the analyte exhibits first and second emission intensities at the first and second wavelengths, the first and second emission intensities being different, and the blood exhibits first and second absorbances at the first and second wavelengths, the first and second absorbances being similar. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An apparatus for measurement of a concentration of erythrocyte zinc protoporphyrin (eZnPP) as the eZnPP/heme ratio in the blood of a patient comprising:
- a light source operatively associated with a tunable optical filter for providing alternating excitation of the tissue at a first wavelength of about 425 nm and a second wavelength of about 407 nm;
a detector for detecting a portion of the emission spectra excited at about 425 nm and about 407 nm; and
a processor for determining the concentration of eZnPP based on the difference between the portion of the emission spectra excited at about 425 nm and about 407 nm.
- a light source operatively associated with a tunable optical filter for providing alternating excitation of the tissue at a first wavelength of about 425 nm and a second wavelength of about 407 nm;
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18. A method for noninvasive measurement of a concentration of a fluorescent analyte in the blood of a patient comprising:
- exciting the tissue at an alternating first wavelength and second wavelength, the first and second excitation wavelengths selected such that the fluorescent analyte exhibits a difference in emission intensities at the first and second excitation wavelengths that is greater than that of background fluorophores and light absorbance by blood at the first and second excitation wavelength ranges is similar;
detecting a portion of the emission spectra at the first excitation wavelength range and the second excitation wavelength range; and
using a processor, determining the concentration of the fluorescent analyte based on the difference between the emission spectra excited at the first excitation wavelength range and the second excitation wavelength range;
determining whether the detected concentration of the fluorescent analyte is below a preselected concentration;
providing an indication that the fluorescent analyte concentration is below the preselected concentration, and determining whether the analyte concentrations are increasing or decreasing when successive analyte readings are obtained for a particular patient and providing an indication that the fluorescent analyte concentration is increasing or decreasing. - View Dependent Claims (19, 20)
- exciting the tissue at an alternating first wavelength and second wavelength, the first and second excitation wavelengths selected such that the fluorescent analyte exhibits a difference in emission intensities at the first and second excitation wavelengths that is greater than that of background fluorophores and light absorbance by blood at the first and second excitation wavelength ranges is similar;
Specification