Systems and methods for sensing red blood cell hematocrit
First Claim
1. A red blood cell sensing assembly comprisingan incident source of light having a wavelength of about 805 nm, an optical sensor, a blood collection tube to convey a blood suspension containing a quantity of red blood cells, the quantity of red blood cells in the blood suspension being expressed as a percentage of red blood cells present in the blood suspension (% RBC), and a holder to hold the blood collection tube at a radial distance of about 7.5 mm from the incident source of light where a linear relationship exists between sensed reflected light measured by the optical sensor and % RBC in a range of at least % RBC=10% to % RBC=90%.
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Abstract
Red blood cell sensing systems and methods rely upon straightforward measurement geometries. The systems and methods comprise an incident light source, an optical sensor, and a blood collection tube. The systems and methods hold the blood collection tube a predetermined radial distance from the incident light source where a linear relationship exists between sensed reflected light measured by the optical sensor and red blood cell hematocrit in a range of at least 10 to 90. The systems and methods make possible accurate red blood sensing without use of special optical cuvettes, mirrors, or focusing lenses. The systems and methods also make possible the use of standard transparent plastic tubing, without reliance upon special optical cuvettes.
131 Citations
30 Claims
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1. A red blood cell sensing assembly comprising
an incident source of light having a wavelength of about 805 nm, an optical sensor, a blood collection tube to convey a blood suspension containing a quantity of red blood cells, the quantity of red blood cells in the blood suspension being expressed as a percentage of red blood cells present in the blood suspension (% RBC), and a holder to hold the blood collection tube at a radial distance of about 7.5 mm from the incident source of light where a linear relationship exists between sensed reflected light measured by the optical sensor and % RBC in a range of at least % RBC=10% to % RBC=90%.
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7. A blood processing system comprising
a device for processing blood to obtain a blood suspension containing a quantity of red blood cells, the quantity of red blood cells in the blood suspension being expressed as a percentage of red blood cells present in the blood suspension (% RBC). a sensing assembly outside the device including an incident light source and an optical sensor to optically sense presence of red blood cells, and a fluid circuit coupled to the device and including a blood inlet tube for conveying a flow of blood into the device and a component collection tube for conveying a flow of the blood suspension from the device, and a fixture including a holder to hold the blood inlet tube and the component collection tube in an adjacent, spaced-apart relationship for handling as a bundle, the holder also being movable into releasable engagement with the sensing assembly to hold the component collection tube within the holder at a predetermined radial distance from the incident light source where a linear relationship exists between sensed reflected light measured by the optical sensor and % RBC in a range of at least % RBC=10% to % RBC=90%.
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16. A method for sensing red blood cells in a blood suspension containing a quantity of red blood cells, the quantity of red blood cells in the blood suspension being expressed as a percentage of red blood cells present in the blood suspension (% RBC), comprising the steps of
providing an incident source of light having a wavelength of about 805 nm, providing an optical sensor, holding a blood collection tube at a radial distance of about 7.5 mm from the incident source of light where a linear relationship exists between sensed reflected light measured by the optical sensor and % RBC in a range of at least % RBC=10% to % RBC=90%, and sensing red blood cells in the blood suspension within the blood collection tube.
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20. A blood separation system comprising
a device for separating whole blood into a blood suspension containing a quantity of red blood cells, the quantity of red blood cells in the blood suspension being expressed as a percentage of red blood cells present in the blood suspension (% RBC), a sensing assembly outside the device including an incident source of light having a wavelength of about 805 nm and an optical sensor to sense red blood cells, and a fluid circuit coupled to the device and including a component collection tube for conveying a flow of the blood suspension from the device, and a fixture movable into releasable engagement with the sensing assembly and including a holder to hold the component collection tube at a radial distance of about 7.5 mm from the incident source of light where a linear relationship exists between sensed reflected light measured by the optical sensor and % RBC in a range of at least % RBC=10% to % RBC=90%.
Specification