Method for measuring absolute saturation of time-varying and other hemoglobin compartments
First Claim
1. A method of measuring absolute saturation of hemoglobin compartments, the method comprising the steps of:
- illuminating an area of tissue with intensity-modulated light at at least two wavelengths;
sensing diffusely reflected light caused by said illumination to acquire time-resolved measurement data; and
processing said time-resolved measurement data to determine the absolute saturation of a hemoglobin compartment, without calibration on a population of healthy subjects;
wherein the absolute saturation of hemoglobin determined by said processing step includes absolute arterial saturation; and
wherein an amplitude of pulsation-induced absorption oscillations are quantitatively determined in said processing step to perform absolute pulse oximetry.
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Abstract
The present invention involves a time-resolved measurement method for the real time, non-invasive, simultaneous measurement of time-varying and other hemoglobin compartment saturation. This capability achieves absolute pulse oximetry and oximetry for tissue, without calibration based on a population of healthy people. Calculations conducted by the invention use quantitative measurement of tissue absorption spectrum for tissue saturation, and an amplitude of absorption oscillations for the time-varying hemoglobin compartments at various wavelengths. The invention illuminates tissue and senses light at predetermined distances apart on the tissue to be measured. Intensity and phase data are acquired from source-detector pairs to calculate absolute tissue optical properties from time-resolved measurement data, namely, a reduced scattering coefficient and an absorption coefficient. To determine time-varying hemoglobin compartment saturation, an amplitude is quantitatively calculated of absorption oscillations correlating variations of an average intensity of the source and detector pair by using the time-resolved measurement data.
98 Citations
15 Claims
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1. A method of measuring absolute saturation of hemoglobin compartments, the method comprising the steps of:
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illuminating an area of tissue with intensity-modulated light at at least two wavelengths;
sensing diffusely reflected light caused by said illumination to acquire time-resolved measurement data; and
processing said time-resolved measurement data to determine the absolute saturation of a hemoglobin compartment, without calibration on a population of healthy subjects;
wherein the absolute saturation of hemoglobin determined by said processing step includes absolute arterial saturation; and
wherein an amplitude of pulsation-induced absorption oscillations are quantitatively determined in said processing step to perform absolute pulse oximetry. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of measuring absolute saturation of hemoglobin compartments, the method comprising the steps of:
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illuminating an area of tissue with intensity-modulated light at at least two wavelengths;
sensing diffusely reflected light caused by said illumination to acquire time-resolved measurement data; and
processing said time-resolved measurement data to determine the absolute saturation of a hemoglobin compartment, without calibration on a population of healthy subjects;
wherein said hemoglobin compartments include time-varying hemoglobin compartments, and said processing step includes a step of calculating the sum of amplitudes of a fast Fourier transformed absorption coefficient for a predetermined time period to determine an amplitude of absorption oscillations. - View Dependent Claims (11, 12)
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13. A method of measuring absolute saturation of hemoglobin compartments, the method comprising the steps of:
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illuminating at least two areas of tissue with intensity-modulated light at at least two wavelengths;
sensing diffusely reflected light at at least two locations of said illuminated tissue to acquire time-resolved measurement data; and
processing said time-resolved measurement data to simultaneously determine the absolute saturation of at least one hemoglobin compartment;
wherein the absolute saturation of hemoglobin determined by said processing step includes absolute arterial saturation;
wherein an amplitude of pulsation-induced absorption oscillations are quantitatively determined in said processing step to perform absolute pulse oximetry. - View Dependent Claims (14, 15)
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Specification