Method and apparatus for making a rapid measurement of the hematocrit of blood
First Claim
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1. Method for making a non-invasive, non-destructive, rapid, relatively accurate measurement in vivo of the hematocrit of undiluted blood including the steps of:
- passing the undiluted blood through a liquid confining means having a light transmitting portion;
passing intense, coherent, monochromatic light through the light transmitting portion and undiluted blood;
sensing the transmittance of light passed through the light transmitting portion and undiluted blood;
producing an output signal related to the amount of transmitted light sensed and indicative of the light absorbed by the red blood cells; and
multiplying the output signal by a proportionality factor determined from a curve function obtained from an approximated curve fit of absorbance v. hematocrit measurements for measurements of light absorbance by blood having known hematocrits to produce a corrected output signal which is indicative of the hematocrit of the undiluted blood and which can be used to control the flow rate of at least one pump pumping whole blood or a fluid component thereof in a blood processing apparatus.
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Abstract
The method includes the steps of: placing blood in a transparent tubing; passing intense, coherent light through the tubing and blood; sensing the light passed through the tubing and blood; and, producing a signal related to the amount of transmitted light sensed and indicative of the hematocrit of the blood. The apparatus includes a laser light source for generating the intense, coherent light beam at a wavelength in the red spectrum and an optical photodetector including a silicon diode positioned to receive the transmitted light and an amplifier circuit.
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Citations
22 Claims
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1. Method for making a non-invasive, non-destructive, rapid, relatively accurate measurement in vivo of the hematocrit of undiluted blood including the steps of:
- passing the undiluted blood through a liquid confining means having a light transmitting portion;
passing intense, coherent, monochromatic light through the light transmitting portion and undiluted blood;
sensing the transmittance of light passed through the light transmitting portion and undiluted blood;
producing an output signal related to the amount of transmitted light sensed and indicative of the light absorbed by the red blood cells; and
multiplying the output signal by a proportionality factor determined from a curve function obtained from an approximated curve fit of absorbance v. hematocrit measurements for measurements of light absorbance by blood having known hematocrits to produce a corrected output signal which is indicative of the hematocrit of the undiluted blood and which can be used to control the flow rate of at least one pump pumping whole blood or a fluid component thereof in a blood processing apparatus. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
- passing the undiluted blood through a liquid confining means having a light transmitting portion;
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12. An apparatus for making a non-invasive, non-destructive, rapid, relatively accurate measurement in vivo of the hematocrit of undiluted blood including:
- liquid confining means having a light transmitting portion and being adapted to receive undiluted blood therein;
means for generating an intense, coherent, monochromatic light beam and for directing said light beam through said light transmitting portion of said liquid confining means and the undiluted blood;
light sensing means arranged to detect the transmittance of light that passes through said light transmitting portion and through the undiluted blood from said light generating means and to produce an output signal related to the amount of transmitted light sensed and indicative of the light absorbed by the red blood cells; and
means for multiplying the output signal generated by the transmitted light sensed by a proportionality factor determined from a curve function obtained from an approximated curve fit of absorbance v. hematocrit measurements for measurements of light absorbance by blood having known hematocrits thereby to produce a corrected output signal which is indicative of the hematocrit of the undiluted blood in said liquid confining means and which can be used to control the flow rate of at least one pump pumping whole blood or a fluid component thereof in a blood processing apparatus. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
- liquid confining means having a light transmitting portion and being adapted to receive undiluted blood therein;
Specification