Method and apparatus for noninvasive prediction of hematocrit

Claim 1

An apparatus for the noninvasive prediction of hematocrit within mammalian tissue, comprising: (a) a light source adapted to noninvasively interrogate the mammalian tissue with light of at least two wavelengths, wherein the at least two wavelengths are selected according to wavelength selection criteria, and wherein the wavelength selection criteria comprise: (1) a wavelength where absorbance of water is at or near a measurable peak; (2) at least one wavelength where absorbance of oxyhemoglobin and deoxyhemoglobin are predictable and represent total hemoglobin content; (3) a wavelength where the absorbance of water greatly exceeds the absorbance of all forms of hemoglobin; and (4) a wavelength where the absorbance of all forms of hemoglobin greatly exceeds the absorbance of water; wherein each of the wavelength selection criteria must be satisfied, wherein each selected wavelength can satisfy one or more than one of the wavelength selection criteria, and wherein at least one of the selected wavelengths is in the range 1150-2100 nm; (b) at least one detector adapted to receive light of the selected wavelengths transmitted through the mammalian tissue, the detector further adapted to convert the transmitted light of each selected wavelength from optical signals into electrical signals; and (c) processing means, connected to receive the electrical signals from the detector, the processing means for: determining the intensity of at least one peak, the intensity of at least one valley, and the intensity of at least one direct current value for the transmitted light of each selected wavelength; determining at least one pseudo-absorption H Value for each selected wavelength, wherein each H Value is based on the intensities of the at least one peak, at least one valley, and the at least one direct current value; and determining a prediction equation for the noninvasive prediction of hematocrit, wherein the prediction equation is based on true hematocrit values and the pseudo-absorption H Values determined for each selected wavelength.

Claim 2

An apparatus for the noninvasive prediction of hematocrit within mammalian tissue, comprising: (a) a light source adapted to noninvasively interrogate the mammalian tissue with light of at least two wavelengths, wherein the at least two wavelengths are selected according to wavelength selection criteria, and wherein the wavelength selection criteria comprise: (1) a wavelength where absorbance of water is at or near a measurable peak; (2) at least one wavelength where absorbance of oxyhemoglobin and deoxyhemoglobin are predictable and represent total hemoglobin content; (3) a wavelength where the absorbance of water greatly exceeds the absorbance of all forms of hemoglobin; and (4) a wavelength where the absorbance of all forms of hemoglobin greatly exceeds the absorbance of water; wherein each of the wavelength selection criteria must be satisfied, wherein each selected wavelength can satisfy one or more than one of the wavelength selection criteria, and wherein at least one of the selected wavelengths is in the range 1150-2100 nm; (b) at least one detector adapted to receive light of the selected wavelengths transmitted through the mammalian tissue, the detector further adapted to convert the transmitted light of each selected wavelength from optical signals into electrical signals; and (c) processing means, connected to receive the electrical signals from the detector, the processing means for: determining the intensity of at least one peak, the intensity of at least one valley, and the intensity of at least one direct current value for the transmitted light of each selected wavelength; determining at least one pseudo-absorption H Value for each selected wavelength, wherein each H Value is based on the intensities of the at least one peak, at least one valley, and the at least one direct current value; and determining a prediction equation for the noninvasive prediction of hematocrit, wherein the prediction equation is based on true hematocrit values and the pseudo-absorption H Values determined for each selected wavelength.