Feedback control of ultrafiltration to prevent hypotension
First Claim
1. A method for preventing hypotension in a mammalian patient whose blood is withdrawn, treated in a blood treatment device having an extracorporeal blood circuit for removal of ultrafiltrate fluid, and infused into the patient, said method comprising:
- a. withdrawing blood from a peripheral vein of the patient into the blood circuit, treating the withdrawn blood flowing through the circuit to remove the ultrafiltrate fluid from the blood, and infusing the treated blood into a peripheral vein of the patient;
b. monitoring oxygen concentration in the blood withdrawn from the peripheral vein and flowing through the circuit;
c. determining a baseline oxygen concentration level in the blood during an initial phase of the treatment;
d. automatically reducing filtrate flow from a first filtration rate of the ultrafiltrate fluid extracted from blood to a second filtration rate, if the oxygen concentration in blood varies from a predetermined target oxygen value below the baseline level, and e. automatically resuming the first filtration rate when the oxygen concentration level returns to the baseline level.
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Abstract
A method and system for the extracorporeal treatment of blood to remove fluid from the fluid overloaded patient is disclosed that non-invasively measures an oxygen level in the venous blood. The oxygen blood level is used to detect when hypotension is about to occur in a patient. The oxygen level measurements are used as feedback signals. These feedback signals are applied to automatically control the rate of fluid extraction to achieve the desired clinical outcome and avoid precipitating a hypotensive crisis in the patient.
138 Citations
22 Claims
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1. A method for preventing hypotension in a mammalian patient whose blood is withdrawn, treated in a blood treatment device having an extracorporeal blood circuit for removal of ultrafiltrate fluid, and infused into the patient, said method comprising:
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a. withdrawing blood from a peripheral vein of the patient into the blood circuit, treating the withdrawn blood flowing through the circuit to remove the ultrafiltrate fluid from the blood, and infusing the treated blood into a peripheral vein of the patient;
b. monitoring oxygen concentration in the blood withdrawn from the peripheral vein and flowing through the circuit;
c. determining a baseline oxygen concentration level in the blood during an initial phase of the treatment;
d. automatically reducing filtrate flow from a first filtration rate of the ultrafiltrate fluid extracted from blood to a second filtration rate, if the oxygen concentration in blood varies from a predetermined target oxygen value below the baseline level, and e. automatically resuming the first filtration rate when the oxygen concentration level returns to the baseline level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for preventing hypotension in a mammalian patient whose blood is being withdrawn, treated in a blood treatment device of an extracorporeal blood circuit for removal of ultrafiltrate fluid, and infused into the patient, said method comprising:
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a. monitoring oxygen concentration in blood flowing in a peripheral blood vessel;
b. automatically reducing a flow rate of the ultrafiltrate fluid extracted from blood if the oxygen concentration in blood drops to a predetermined target value, and c. automatically increasing the reduced flow rate of the ultrafiltrate fluid if the oxygen concentration in blood increases to a baseline value.
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13. A method for preventing hypotension in a mammalian patient whose blood is withdrawn, treated in a blood treatment device having an extracorporeal blood circuit for removal of ultrafiltrate fluid, and infused into the patient, said method comprising:
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a. withdrawing blood from a peripheral vein of the patient, treating the withdrawn blood flowing through the circuit to remove the ultrafiltrate fluid from the blood and infusing the treated blood into a peripheral vein of the patient;
b. monitoring oxygen concentration in the blood withdrawn from the peripheral vein and flowing through the circuit;
c. determining a baseline oxygen concentration level in the withdrawn blood during an initial phase of the treatment;
d. automatically reducing filtrate flow from a first rate of the ultrafiltrate fluid to a reduced rate if the oxygen concentration in blood varies from a predetermined target oxygen value, wherein the predetermined target oxygen value is a function of the baseline level, and wherein the oxygen concentration is a mixed venous oxygen saturation (SvO2) level. - View Dependent Claims (14, 15, 16, 17)
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18. A method of controlling an extracorporeal blood circuit comprising:
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a. withdrawing blood from a withdrawal blood vessel in a patient into the extracorporeal circuit;
b. filtering fluids from blood flowing through the circuit at a controlled filtration rate;
c. detecting a reduction in cardiac output level of the patient, wherein the reduction in cardiac output level is determined by monitoring oxygen level of venous blood in or taken from a peripheral vein of the patient;
d. automatically reducing the filtration flow rate if the measured cardiac output falls below a first threshold level, and e. automatically stopping the filtration flow rate if, after step d, the measured cardiac output falls below a second threshold level, wherein the second threshold level is below the first threshold level. - View Dependent Claims (19, 20, 21, 22)
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Specification