Hematocrit sampling system
First Claim
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1. A method of determining the average hematocrit of a known volume of blood processed in a blood processing system during a blood processing procedure, the known volume of blood being equal to the total amount of blood processed during the blood processing procedure, the method comprising:
- providing a blood processing system having a blood inlet and a blood outlet, the blood processing system being sized to process the known volume of blood during the processing cycle;
providing a hematocrit measurement circuit connected to measure the hematocrit of blood flowing through the outlet of the blood processing system, the hematocrit measurement circuit having a display for reporting hematocrit values;
determining a minimum volume of the known volume of blood which must be measured for hematocrit in order for an average hematocrit value for the known volume of blood to be calculated within a predetermined degree of accuracy;
evacuating processed blood from the system through the blood outlet;
making a plurality of hematocrit measurements of a measured volume of the processed blood;
calculating from the plurality of hematocrit measurements an average hematocrit value for the measured volume of processed blood; and
comparing the measured volume to the minimum volume.
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Abstract
Accurate measurement of hematocrit during blood recovery or plasma sequestration processes by means of algorithms to account for the presence of air or other non-blood substances in salvaged or separated blood is described. A method of automatic start-up of the hematocrit measurement circuit and a method of determining the minimum volume of blood required to obtain an accurate measurement of the hematocrit also is described.
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Citations
18 Claims
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1. A method of determining the average hematocrit of a known volume of blood processed in a blood processing system during a blood processing procedure, the known volume of blood being equal to the total amount of blood processed during the blood processing procedure, the method comprising:
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providing a blood processing system having a blood inlet and a blood outlet, the blood processing system being sized to process the known volume of blood during the processing cycle;
providing a hematocrit measurement circuit connected to measure the hematocrit of blood flowing through the outlet of the blood processing system, the hematocrit measurement circuit having a display for reporting hematocrit values;
determining a minimum volume of the known volume of blood which must be measured for hematocrit in order for an average hematocrit value for the known volume of blood to be calculated within a predetermined degree of accuracy;
evacuating processed blood from the system through the blood outlet;
making a plurality of hematocrit measurements of a measured volume of the processed blood;
calculating from the plurality of hematocrit measurements an average hematocrit value for the measured volume of processed blood; and
comparing the measured volume to the minimum volume. - View Dependent Claims (2)
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3. A method of measuring hematocrit in processed blood comprising:
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providing a blood processing system having a blood inlet and a blood outlet, the blood processing system being sized to process a known volume of blood during each processing cycle;
providing a hematocrit measurement circuit having a hematocrit sensor connected to measure the hematocrit of blood flowing through the outlet of the blood processing system, the hematocrit measurement circuit having a known lock time after which the circuit first responds to the presence of blood sensed by the sensor;
evacuating processed blood from the system through the blood outlet;
making a plurality of hematocrit measurements of the processed blood;
assigning a hematocrit value to a first volume of processed blood passing the hematocrit sensor during the lock time; and
calculating from the plurality of hematocrit measurements and assigned hematocrit value an average hematocrit value of the known volume of processed blood evacuated from the system. - View Dependent Claims (4, 5, 6, 7, 8, 9)
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10. A method of measuring hematocrit in processed blood comprising:
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providing a blood processing system having a blood inlet and a blood outlet;
providing a hematocrit measurement circuit connected to measure the hematocrit of blood flowing through the outlet of the blood processing system;
evacuating processed blood from the system through the blood outlet;
making a plurality of hematocrit measurements, the hematocrit measurement including good hematocrit values and non-blood values;
determining the presence of a non-blood substance in the processed blood from the non-blood values;
assigning a hematocrit value to a first volume of processed blood flowing through the blood outlet after the non-blood substance based on hematocrit measurements of at least one good hematocrit value of the processed blood; and
calculating from the measured hematocrit and assigned hematocrit values an average hematocrit value of processed blood evacuated from the system. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A blood processing system for determining the average hematocrit of a known volume of blood processed in a blood processing system during a blood processing procedure, the known volume of blood being equal to the total amount of blood processed during the blood processing procedure, the system comprising:
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a blood processor having an inlet and an outlet, the blood processor being sized to process the known volume of blood during the processing cycle;
a hematocrit sensor connected to measure hematocrit of process blood flowing through the outlet of the blood processor at a predetermined sampling rate, the sensor being configured to provide data indicative of the hematocrit of the processed blood being sensed and to provide data indicative of non-blood substances when substances other than blood are being sensed; and
a controller connected to receive the data from the sensor and to calculate from the data an average hematocrit value of the known volume of processed blood, the calculation being performed in a manner that makes adjustments to the calculation depending on the presence of non-blood substances in the processed blood.
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17. A blood processing system comprising:
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a blood processor having an inlet and an outlet; and
a hematocrit sensing circuit including a hematocrit sensor configured to connect with a first connector when the blood processor is not in use and with a second connector when the blood processor is in use, the second connector being connected to the outlet of the blood processor, the hematocrit sensing circuit being switchable from an operational mode where the sensor is making hematocrit measurements and a non-operational mode where the sensor is not making hematocrit measurements, the hematocrit sensing circuit being further configured to be switched to the operational mode by disconnecting the sensor from the first connector.
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18. A blood processing system comprising:
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a blood processor having an inlet and an outlet; and
a hematocrit sensing circuit including a hematocrit sensor configured to connect with a first connector when the blood processor is not in use and with a second connector when the blood processor is in use, the second connector being connected to the outlet of the blood processor, the hematocrit sensing circuit being switchable from an operational mode where the sensor is making hematocrit measurements and a non-operational mode where the sensor is not making hematocrit measurements, the hematocrit sensing circuit being further configured to be switched to the operational mode by connecting the sensor to the second connector.
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Specification