SELF CALIBRATING BLOOD CHAMBER
First Claim
1. A method of optically monitoring a blood constituent, the method comprising:
- filling an internal volume of a blood chamber with blood so as to provide first and second blood layers within respective first and second optical paths of a light source, the second Hood layer having a thickness along the second optical path that is substantially greater than a thickness of the first blood layer along the first blood path;
emitting light of substantially identical intensities along the first and second optical paths so as to pass the light through the respective first and second blood layers within the Hood chamber;
capturing light passing through the first and second blood layers using respective first and second light sensors respectively disposed in the first and second optical paths;
comparing the captured light; and
determining a characteristic of the blood constituent from the captured light.
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Accused Products
Abstract
An optical blood monitoring system and corresponding method avoid the need to obtain a precise intensity value of the light impinging upon the measured blood layer during the analysis. The system is operated to determine at least two optical measurements through blood layers of different thickness but otherwise substantially identical systems. Due to the equivalence of the systems, the two measurements can be compared so that the bulk extinction coefficient of the blood can be calculated based only on the known blood layer thicknesses and the two measurements. Reliable measurements of various blood parameters can thereby be determined without certain calibration steps.
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Citations
10 Claims
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1. A method of optically monitoring a blood constituent, the method comprising:
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filling an internal volume of a blood chamber with blood so as to provide first and second blood layers within respective first and second optical paths of a light source, the second Hood layer having a thickness along the second optical path that is substantially greater than a thickness of the first blood layer along the first blood path; emitting light of substantially identical intensities along the first and second optical paths so as to pass the light through the respective first and second blood layers within the Hood chamber; capturing light passing through the first and second blood layers using respective first and second light sensors respectively disposed in the first and second optical paths; comparing the captured light; and determining a characteristic of the blood constituent from the captured light. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An optical blood monitor for use in a hemodialysis system operable to monitor at least one blood constituent, the optical blood monitor comprising:
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a blood chamber including a body defining an internal volume for receiving blood to be monitored by the hemodialysis system, an inlet for supplying blood to the internal volume, and an outlet for withdrawing blood from the internal volume; and an optical blood sensor assembly including a light source that emits light along first and second optical paths, the first optical path extending through the blood chamber to a first sensor and passing through a first section of the internal volume of the blood chamber that has a first thickness, and the second optical path extending through the blood chamber to a second sensor and passing through a second section of the internal volume of the blood chamber that has a second thickness, the second thickness being substantially greater than the first thickness. - View Dependent Claims (8, 9, 10)
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Specification