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US 2009/0024012 A1Published application
Method and apparatus for measuring blood oxygen saturation
AssigneeShenzhen Mindray Bio-Medical Electronics Co., Ltd.
InventorsXu Li, Xu Zhang
Life of this patent
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Abstract
A method and apparatus are disclosed for measuring blood oxygen saturation by using spectrophotometry to improve the accuracy of the measurement under a condition of low perfusion.
Claims25
A method for measuring blood oxygen saturation, the method comprising:
- acquiring intensities of transmitted lights that are obtained by transmitting respectively a light of a first wavelength and a light of a second wavelength through organism tissues, and converting the intensities of the transmitted lights into corresponding signals for the light of the first wavelength and the light of the second wavelength;
- defining at least one interval on waveforms of the signals for the light of the first wavelength and the light of the second wavelength, and performing an area integral on the waveforms of the signals for the light of the first wavelength and the light of the second wavelength in the at least one interval to produce a total area integral of the signal for the light of the first wavelength and a total area integral of the signal for the light of the second wavelength;
- calculating a ratio of the total area integral of the signal for the light of the first wavelength to the total area integral of the signal for the light of the second wavelength as a blood oxygen content R;
- and
- calculating a blood oxygen saturation according to the following formula:
- SpO2=(A×R+B)/(C×R+D),
- where SpO2 is the blood oxygen saturation;
- B=−ε2;
- C=ε4−ε3;
- D=ε1−ε2;
- ε1, ε2 are respectively an absorption rate of oxyhemoglobin to the light of the first wavelength and an absorption rate of deoxyhemoglobin to the light of the first wavelength;
- and
- ε3, ε4 are respectively an absorption rate of oxyhemoglobin to the light of the second wavelength and an absorption rate of deoxyhemoglobin to the light of the second wavelength.
10 more elements
An apparatus for measuring blood oxygen saturation, the apparatus comprising:
- a signal generation component to acquire intensities of transmitted lights that are obtained by transmitting a light of a first wavelength and a light of a second wavelength through organism tissues and to convert the acquired intensities of the transmitted lights into corresponding signals for the light of the first wavelength and the light of the second wavelength;
- an interval determination component to define at least one interval on waveforms of the signals for the light of the first wavelength and the light of the second wavelength;
- an integral component to perform a natural logarithm operation on the signals for the light of the first wavelength and the light of the second wavelength in the at least one interval respectively;
- a first calculating component to calculate a ratio of the total area integral of the signal for the light of the first wavelength to the total area integral of the signal for the light of the second wavelength as the blood oxygen content R;
- and
- a second calculating component to calculate blood oxygen saturation according to the following formula:
- SpO2=(A×R+B)/(C×R+D),
- where SpO2 is the blood oxygen saturation;
- B=−ε2;
- C=ε4−ε3;
- D=ε1−ε2;
- ε1, ε2 are respectively an absorption rate of oxyhemoglobin to the red light and an absorption rate of deoxyhemoglobin to the red light;
- and
- ε3, ε4 are respectively an absorption rate of oxyhemoglobin to the infrared light and an absorption rate of deoxyhemoglobin to the infrared light.
11 more elements
A computer-readable medium comprising program code for performing a method for measuring blood oxygen saturation, the method comprising:
- acquiring intensities of transmitted lights that are obtained by transmitting respectively a light of a first wavelength and a light of a second wavelength through organism tissues, and converting the intensities of the transmitted lights into corresponding signals for the light of the first wavelength and the light of the second wavelength;
- defining at least one interval on waveforms of the signals for the light of the first wavelength and the light of the second wavelength, and performing an area integral on the waveforms of the signals for the light of the first wavelength and the light of the second wavelength in the at least one interval to produce a total area integral of the signal for the light of the first wavelength and a total area integral of the signal for the light of the second wavelength;
- calculating a ratio of the total area integral of the signal for the light of the first wavelength to the total area integral of the signal for the light of the second wavelength as a blood oxygen content R;
- and
- calculating a blood oxygen saturation according to the following formula:
- SpO2=(A×R+B)/(C×R+D),
- where SpO2 is the blood oxygen saturation;
- A=ε1;
- B=−ε2;
- C=ε4−ε3;
- D=ε1−ε2;
- ε1, ε2 are respectively an absorption rate of oxyhemoglobin to the light of the first wavelength and an absorption rate of deoxyhemoglobin to the light of the first wavelength;
- and
- ε3, ε4 are respectively an absorption rate of oxyhemoglobin to the light of the second wavelength and an absorption rate of deoxyhemoglobin to the light of the second wavelength.
11 more elements
A system for measuring blood oxygen saturation, the system comprising:
- means for acquiring intensities of a first light at a first wavelength and a second light at a second wavelength transmitted through organism tissues and for converting the acquired intensities of the transmitted lights into signals corresponding to the light of the first wavelength and the light of the second wavelength;
- means for defining at least one interval on waveforms of the signals for the light of the first wavelength and the light of the second wavelength;
- means for performing a natural logarithm operation on the signals for the light of the first wavelength and the light of the second wavelength in the at least one interval;
- first calculating means for calculating a ratio of the total area integral of the signal for the light of the first wavelength to the total area integral of the signal for the light of the second wavelength as the blood oxygen content R;
- and
- second calculating means for calculating blood oxygen saturation according to the following formula:
- SpO2=(A×R+B)/(C×R+D),
- where SpO2 is the blood oxygen saturation;
- A=ε1;
- B=−ε2;
- C=ε4−ε3;
- D=ε1−ε2;
- ε1, ε2 are respectively an absorption rate of oxyhemoglobin to the red light and an absorption rate of deoxyhemoglobin to the red light;
- and
- ε3, ε4 are respectively an absorption rate of oxyhemoglobin to the infrared light and an absorption rate of deoxyhemoglobin to the infrared light.
12 more elements
Dependencies are inferred from the claim text.