Hematocrit sampling system
AssigneeCobe Cardiovascular, Inc.
InventorsSteven Kenneth Hunley, Rainer Harald Koenig
Life of this patent
Estimating the term…
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.
Claims14
A method of determining the average hematocrit of blood processed in a blood processing system, comprising:
- 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 a 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 the processed blood;
- calculating from the plurality of hematocrit measurements an average hematocrit value for a first volume of processed blood;
- and
- comparing the first volume to the minimum volume.
A method of measuring hematocrit in processed blood comprising:
- 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.
A method of measuring hematocrit in processed blood comprising:
- 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;
- determining the presence of non-blood substances in the processed blood from the hematocrit measurements;
- assigning a hematocrit value to a first volume of processed blood based on hematocrit measurements of non-blood substances in the processed blood;
- and
- calculating from the measured hematocrit and assigned hematocrit values an average hematocrit value of process blood evacuated from the system;
- wherein the hematocrit measurement circuit includes a hematocrit sensor connected to measure the hematocrit of blood flowing throuah the outlet of the blood processing system and wherein the hematocrit measurement system has a known lock time after which the circuit first resnonds to the presence of blood sensed by the sensor, the method including assigning a hematocrit value to a second volume of recessed blood passing the hematocrit sensor during the lock time.
Dependencies are inferred from the claim text.