Method and apparatus for determining hemoglobin oxygenation such as in ocular and other vascular beds
First Claim
1. An oximetry method for determining hemoglobin oxygenation in optically-accessible tissue, comprising:
- probing a selected area of tissue with a source of collimated probe light of at least two predetermined wavelengths in an hemoglobin absorption band around an absorption isobestic wavelength of about 501 nm, with at least one wavelength being approximately the absorption isobestic wavelength, and at least one wavelength being non-isobestic;
detecting the probe light reflected from the tissue for each wavelength and providing corresponding reflection intensity signals; and
in response to said reflection intensity signals, determining appropriate oxygen saturation ratios of reflection intensity for the absorption isobestic and the non-isobestic wavelengths representative of hemoglobin oxygenation.
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Abstract
An oximetry technique permits determination of hemoglobin oxygenation in vascular beds such as the inner retinal capillary beds. For a retinal application, an oximeter (FIG. 2) uses as a probe light source a multiline argon laser (11) that operates at three wavelengths in the hemoglobin absorption band, preferably 488, 501, and 514 nm. The oximeter optics module (30) attaches to the output end of a conventional slit lamp microscope (20). Reflected probe light is separated (34) into its constituent wavelengths, and photon counters (38) are used to measure light intensity for each wavelength. Data acquisition and analysis are performed by an oximeter processor (40) that computes hemoglobin oxygenation ratios from the intensity measurements, and determines the corresponding percent oxygen saturation.
72 Citations
22 Claims
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1. An oximetry method for determining hemoglobin oxygenation in optically-accessible tissue, comprising:
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probing a selected area of tissue with a source of collimated probe light of at least two predetermined wavelengths in an hemoglobin absorption band around an absorption isobestic wavelength of about 501 nm, with at least one wavelength being approximately the absorption isobestic wavelength, and at least one wavelength being non-isobestic; detecting the probe light reflected from the tissue for each wavelength and providing corresponding reflection intensity signals; and in response to said reflection intensity signals, determining appropriate oxygen saturation ratios of reflection intensity for the absorption isobestic and the non-isobestic wavelengths representative of hemoglobin oxygenation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An oximeter for determining oxygen saturation in optically-accessible tissue, comprising:
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a source of collimated probe light of at least tow predetermined wavelengths in an hemoglobin absorption band around an absorption isobestic wavelength of about 501 nm, the probe light being directed to a selected area of tissue and partially reflected from the tissue; at least one wavelength being approximately the absorption isobestic wavelength, and at least one wavelength being non-isobestic; an intensity detector for detecting the probe light reflected form the tissue for each wavelength and providing corresponding reflection intensity signals; and an oximeter processor responsive to said reflection intensity signals for determining appropriate oxygen saturation ratios of reflection intensity for the absorption isobestic and non-isobestic wavelengths representative of hemoglobin oxygenation. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification