CONTINUOUS MEASUREMENT OF TOTAL HEMOGLOBIN
First Claim
1. A method of determining total hemoglobin of blood, comprising:
- transmitting light of multiple wavelengths into the blood using a catheter;
receiving the light after interacting with the blood;
normalizing a spectral intensity of wavelengths of the received transmitted light using a first predetermined wavelength, wherein an intensity at the first predetermined wavelength is substantially insensitive to changes in levels of hemoglobin and oxygen saturation;
calculating the total hemoglobin of the blood using the normalized spectral intensity at a second predetermined wavelength, wherein the normalized intensity at the second predetermined wavelength is sensitive to changes in levels of hemoglobin, but substantially insensitive to changes in levels of oxygen saturation.
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Accused Products
Abstract
The present application relates to continuous measurement of total hemoglobin (tHb) in whole blood. In one embodiment, different wavelengths are used for normalization of the spectral intensity and calculation of the total hemoglobin. In particular, for normalization, a first wavelength is used wherein the wavelength is substantially insensitive to changes in levels of hemoglobin and oxygen saturation. For calculation of the total hemoglobin, a second wavelength is used. The second wavelength is sensitive to changes in levels of hemoglobin, but substantially insensitive to changes in levels of oxygen saturation. In another embodiment, a continuous measurement can be made using two wavelengths that are both sensitive to oxygen saturation, but they both are equally sensitive. In other words, the normalized intensities associated with the two wavelengths change equal amounts with equal changes in oxygen saturation levels.
18 Citations
17 Claims
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1. A method of determining total hemoglobin of blood, comprising:
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transmitting light of multiple wavelengths into the blood using a catheter; receiving the light after interacting with the blood; normalizing a spectral intensity of wavelengths of the received transmitted light using a first predetermined wavelength, wherein an intensity at the first predetermined wavelength is substantially insensitive to changes in levels of hemoglobin and oxygen saturation; calculating the total hemoglobin of the blood using the normalized spectral intensity at a second predetermined wavelength, wherein the normalized intensity at the second predetermined wavelength is sensitive to changes in levels of hemoglobin, but substantially insensitive to changes in levels of oxygen saturation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An apparatus for determining total hemoglobin of blood, comprising:
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a catheter including a transmit optical fiber and a receive optical fiber; a light source coupled to the transmit optical fiber for transmitting light into blood; one or more photodetectors coupled to the receive optical fiber for receiving the light after it interacts with the blood; and a controller coupled to the one or more photodetectors for receiving a spectral intensity of one or more wavelengths and for normalizing the spectral intensity of the wavelengths using a first predetermined wavelength, wherein an intensity at the first predetermined wavelength is substantially insensitive to changes in levels of hemoglobin and oxygen saturation and for calculating the total hemoglobin of the blood using the normalized spectral intensity at a second predetermined wavelength, wherein the normalized intensity at the second predetermined wavelength is sensitive to changes in levels of hemoglobin, but substantially insensitive to changes in levels of oxygen saturation.
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17. A method of determining total hemoglobin of blood, comprising:
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transmitting light at multiple wavelengths into the blood using a catheter; receiving the light after interacting with the blood; normalizing a spectral intensity of wavelengths of the received transmitted light using a first predetermined wavelength; calculating the total hemoglobin of the blood using the normalized spectral intensity at a second predetermined wavelength, different from the first predetermined wavelength, wherein the normalized intensity at the second predetermined wavelength changes an amount equal to the normalized intensity of the first predetermined wavelength with equal changes in the oxygen saturation levels.
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Specification