Method for measuring venous oxygen saturation
First Claim
1. A method for measuring the venous oxygen saturation comprising the steps of:
- illuminating an area of tissue of a subject with intensity modulated light at at least two wavelengths, said subject being free from mechanical ventilation devices and free from venous perturbationssensing 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 the venous compartment, said processing comprising at least determining an amplitude of respiration induced absorption oscillations.
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Accused Products
Abstract
A method for measuring venous oxygen saturation levels has steps of measuring optical absorption oscillation data at the respiratory frequency at a plurality of wavelengths (2). A reduced scattering coefficient and an absorption coefficient are determined for the tissue, with the result that an effective path length can be determined (6). Data processing is performed to calculate amplitudes for the absorption oscillation data that are translated into oxygenated and deoxygenated hemoglobin concentrations for the venous compartment (8). A method of the invention does not required mechanical ventilation devices or venous perturbation. Additional method steps may entail verifying that the measured absorption oscillation data results from the venous compartment.
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Citations
27 Claims
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1. A method for measuring the venous oxygen saturation comprising the steps of:
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illuminating an area of tissue of a subject with intensity modulated light at at least two wavelengths, said subject being free from mechanical ventilation devices and free from venous perturbations 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 the venous compartment, said processing comprising at least determining an amplitude of respiration induced absorption oscillations. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method for measuring a venous oxygen saturation comprising the steps of:
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illuminating an area of tissue of a subject with intensity modulated light in the visible and near infrared spectral range at at least two wavelengths on a common side of said area of tissue; sensing diffusely reflected light caused by said illumination to acquire time resolved measurement data for each of said at least two wavelengths; and processing said time resolved measurement data at each of said at least two wavelengths to determine the absolute saturation of the venous compartment, said processing comprising determining a reduced scattering coefficient and an oscillation absorption coefficient, quantifying an amplitude of respiration induced absorption oscillations using said reduced scattering coefficient and said oscillation absorption coefficient and using one of either a Fourier transformation or a band pass filter, and fitting said amplitude of respiration induced absorption oscillations with a linear combination of extinction spectra of oxygenated and deoxygenated hemoglobin. - View Dependent Claims (19)
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20. A method for measuring the venous oxygen saturation comprising the steps of:
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illuminating an area of tissue with a probe generating intensity modulated light at a plurality of wavelengths; sensing diffusely reflected light caused by said illumination to acquire time resolved measurement data; processing said time resolved measurement data to determine the absolute saturation of the venous compartment, said processing comprising at least determining an amplitude of respiration induced absorption oscillations; and verifying that said measurement data is accurate. - View Dependent Claims (21, 22, 23, 24)
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25. A computer program product for causing a computer to measure the venous oxygen saturation, the program product comprising computer executable instructions stored on a computer readable medium, the program instructions when executed causing the computer to:
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illuminate an area of tissue using a probe generating intensity modulated light at a plurality of wavelengths; sense diffusely reflected light caused by said illumination to acquire time resolved measurement data; process said time resolved measurement data to determine the absolute saturation of the venous compartment, said processing comprising at least determining an amplitude of respiration induced absorption oscillations; and verify that said time resolved measurement data represents venous compartment data. - View Dependent Claims (26, 27)
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Specification