METHOD AND APPARATUS FOR BLOOD WITHDRAWAL AND INFUSION USING A PRESSURE CONTROLLER
First Claim
1. A method to control blood flow in an extracorporeal blood system that withdraws blood from a vascular system of a patient, said method comprising:
- a. withdrawing blood from the vascular system into the extracorporeal blood system;
b. determining a withdrawal pressure of the withdrawn blood in the extracorporeal blood system;
c. comparing the withdrawal pressure to a withdrawal pressure target;
d. adjusting the flow rate if the withdrawal pressure is less than a withdrawal pressure target;
e. temporarily ceasing the flow if the adjusted flow rate becomes less than a predefined flow rate limit, andf. automatically restarting the flow after the temporary cessation.
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0 Petitions
Accused Products
Abstract
A method and apparatus for controlling blood withdrawal and infusion flow rate with the use of a pressure controller. The pressure controller uses pressure targets based upon occlusion limits that are calculated as a function of flow. The controller has the ability to switch from controlling withdrawal pressure to controlling infusion pressure based upon the detection of an occlusion. The controller distinguishes between partial and total occlusions of the withdrawal vein providing blood access. Depending on the nature of occlusion, the controller limits or temporarily reverses blood flow and, thus, prevents withdrawal vessel collapse or reverses blood flow to quickly infuse blood into the vessel without participation from operator.
75 Citations
25 Claims
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1. A method to control blood flow in an extracorporeal blood system that withdraws blood from a vascular system of a patient, said method comprising:
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a. withdrawing blood from the vascular system into the extracorporeal blood system; b. determining a withdrawal pressure of the withdrawn blood in the extracorporeal blood system; c. comparing the withdrawal pressure to a withdrawal pressure target; d. adjusting the flow rate if the withdrawal pressure is less than a withdrawal pressure target; e. temporarily ceasing the flow if the adjusted flow rate becomes less than a predefined flow rate limit, and f. automatically restarting the flow after the temporary cessation. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system for controlling blood flow withdrawn from and infused back into a patient comprising:
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an extracorporeal circuit having a blood passage including a blood withdrawal tube, a blood treatment device and an infusion tube; a withdrawal pressure sensor sensing a blood pressure in the withdrawal tube and an infusion pressure sensor sensing a blood pressure in the infusion tube; a pump coupled to the circuit and adapted to move blood through the circuit at a controlled flow rate, and a pump controller receiving blood pressure signals from the withdrawal and infusion pressure sensors and using the pressure signals to control the pump to regulate the controlled flow rate, wherein the pump controller includes a processor and a memory storing a control algorithm of a withdrawal pressure target and an infusion pressure target, said controller reduces the controlled flow rate based on a difference between a withdrawal pressure sensed by the withdrawal pressure sensor and the withdrawal pressure target and based on a difference between an infusion pressure sensed by the infusion pressure sensor and the infusion pressure target. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method to control blood flow in an extracorporeal blood system that withdraws blood from a vascular system of a patient, wherein said extracorporeal blood system includes a blood passage, pump coupled to the blood passage and a controller, said method comprising:
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reducing a pressure in the blood passage by the pump applying a pumping action to the blood passage, wherein the pumping action of the pump is controlled by the controller; withdrawing blood from the vascular system into the blood passage due to the reduced pressure in the blood passage; sensing a withdrawal pressure of the withdrawn blood in the blood passage and providing the sensed withdrawal pressure to the controller; comparing the withdrawal pressure to a withdrawal pressure target, wherein the comparison is performed automatically by the controller; adjusting the flow rate if the withdrawal pressure is less than a withdrawal pressure target, wherein the adjustment is determined by the controller which effects a change to the pumping action; temporarily ceasing the flow if the adjusted flow rate becomes less than a predefined flow rate limit, wherein the temporary cessation of the flow is caused by the controller temporarily stopping the pumping action, and automatically restarting the flow after the temporary cessation, wherein the automatic restart of the flow is caused by the controller restarting the pumping action of the pump. - View Dependent Claims (21, 22, 23, 24, 25)
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Specification