Method and apparatus for noninvasively monitoring hemoglobin concentration and oxygen saturation
First Claim
1. A method for noninvasively monitoring hemoglobin concentration and oxygen saturation comprising:
- (a) selecting at least two wavelengths from a region of wavelengths in which an extinction coefficient for water is smaller than an extinction coefficient for hemoglobin, the at least two wavelengths including at least two isobestic wavelengths;
(b) sequentially radiating incident light beams having the selected wavelengths onto a predetermined site of a body that includes a blood vessel;
(c) receiving, at another site of the body, light beams sequentially transmitted through the predetermined site and converting the received light beams into electrical signals;
(d) calculating the light attenuation variation caused by pulses of blood for the respective wavelengths from the electrical signals;
(e) obtaining at least one ratio of the light attenuation variation between the selected wavelengths; and
(f) calculating the hemoglobin concentration CHb in blood using the calculated at least one ratio of the light attenuation variation between the wavelengths.
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Abstract
A method and apparatus for noninvasively monitoring hemoglobin concentration and oxygen saturation, wherein the method includes selecting at least two wavelengths from a region of wavelengths in which an extinction coefficient for water is smaller that for hemoglobin, the at least two wavelengths including at least two isobestic wavelengths; sequentially radiating incident light beams having the selected wavelengths onto a predetermined site of a body which includes a blood vessel; receiving, at another site of the body, light beams sequentially transmitted through the predetermined site and converting the received light beams into electrical signals; calculating the light attenuation variation caused by pulses of blood for the respective wavelengths from the electrical signals; obtaining at least one ratio of the light attenuation variation between the selected wavelengths; and calculating the hemoglobin concentration CHb in blood using the calculated at least one ratio of the light attenuation variation between the wavelengths.
27 Citations
30 Claims
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1. A method for noninvasively monitoring hemoglobin concentration and oxygen saturation comprising:
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(a) selecting at least two wavelengths from a region of wavelengths in which an extinction coefficient for water is smaller than an extinction coefficient for hemoglobin, the at least two wavelengths including at least two isobestic wavelengths;
(b) sequentially radiating incident light beams having the selected wavelengths onto a predetermined site of a body that includes a blood vessel;
(c) receiving, at another site of the body, light beams sequentially transmitted through the predetermined site and converting the received light beams into electrical signals;
(d) calculating the light attenuation variation caused by pulses of blood for the respective wavelengths from the electrical signals;
(e) obtaining at least one ratio of the light attenuation variation between the selected wavelengths; and
(f) calculating the hemoglobin concentration CHb in blood using the calculated at least one ratio of the light attenuation variation between the wavelengths. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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17. An apparatus for noninvasively monitoring hemoglobin concentration and oxygen saturation, comprising:
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a light radiation unit for sequentially radiating incident light beams having at least two wavelengths selected from a region in which an extinction coefficient for water is smaller than an extinction coefficient for hemoglobin, onto a predetermined site of the body that includes a blood vessel;
a photodetector unit for receiving, at another site of the body, light beams transmitted through the predetermined site, converting the received light beams into an electrical signal, and outputting the converted electrical signal;
a variation calculation unit for calculating light attenuation variation for each of the selected at least two wavelengths from the electrical signal and outputting the calculated light attenuation variation;
a ratio calculation unit for calculating at least one ratio among the light attenuation variations sequentially input from the variation calculation unit and outputting the calculated at least one ratio of the light attenuation variations; and
a concentration calculation unit for calculating hemoglobin concentration in blood from the at least one ratio and outputting the calculated hemoglobin concentration, wherein the at least two wavelengths are externally selected to include at least two isobestic wavelengths.
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Specification