Fluid flow resistance monitoring system
First Claim
1. A method for monitoring a flow parameter in a fluid delivery system in which a flow control device acts on a fluid conduit to control the flow of fluid through the conduit, the method comprising the steps of:
- outputting a pseudorandom code;
controlling the flow control device to act on the fluid conduit to cause a pattern of flow variation in the conduit in accordance with the pseudorandom code;
monitoring pressure of the fluid in the conduit and generating pressure signals representing said monitored pressure;
decoding the pressure signals in accordance with the pseudorandom code; and
processing the decoded pressure signals to determine the flow parameter.
12 Assignments
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Accused Products
Abstract
Flow parameters in a fluid delivery assembly are determined by monitoring pressure responses and processing those responses along with information regarding the fluid flow. In one aspect, a processor controls the pump to pump flow quantities in accordance with a pseudorandom code. Portions of the resulting pressure signal sensed are then decoded in accordance with the pseudorandom code. An estimate of the equilibrium pressure is generated from the decoded pressure values, while a summation of the pressure samples is generated from the undecoded pressure signals. The resistance to fluid flow of the system is determined from the estimated equilibrium pressure and pressure summation. For low flow rates, a processor controls the pump to pump fluid in a series of fluid boluses, with each fluid bolus delivered in the beginning of a separate timeslot. The equilibrium pressure is measured at the end of each timeslot, and a summation of the pressure samples is generated from the pressure signals. For high flow rates, the pump is controlled to vary the flow rate and the change in pressure is divided by the change in flow to directly determine the resistance. A resistance display continuously displays the resistance of the system. The pseudorandom coding and decoding can be used to filter out pressure-response crosstalk caused by multiple fluid infusion segments feeding into a common line.
135 Citations
22 Claims
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1. A method for monitoring a flow parameter in a fluid delivery system in which a flow control device acts on a fluid conduit to control the flow of fluid through the conduit, the method comprising the steps of:
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outputting a pseudorandom code; controlling the flow control device to act on the fluid conduit to cause a pattern of flow variation in the conduit in accordance with the pseudorandom code; monitoring pressure of the fluid in the conduit and generating pressure signals representing said monitored pressure; decoding the pressure signals in accordance with the pseudorandom code; and processing the decoded pressure signals to determine the flow parameter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for infusing fluid to a patient through a conduit, the system comprising:
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an infusion pump acting on the conduit and having a plurality of movement steps per cycle, each step causing a step volume of fluid to flow through the conduit; a pressure sensor coupled to the conduit for providing pressure signals in response to pressure sensed in the conduit; a processor configured to output a PRBS code having a codelength and a plurality of elements, assign a timeslot to each element of the PRBS code, control the infusion pump to cause flow in the conduit in a pattern of flow variation in accordance with the PRBS code, receive the pressure signals, decode the pressure signals in accordance with the PRBS code, and process the decoded pressure signals to determine a flow parameter. - View Dependent Claims (10, 11, 12)
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13. A system for infusing fluid to a patient through a conduit, the system comprising:
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a first infusion device acting on a first segment of the conduit; a pressure sensor coupled to the conduit and providing pressure signals in response to pressure sensed in the conduit; a processor configured to output a first pseudorandom code having a codelength, control the first infusion device to cause flow in accordance with the first pseudorandom code, receive the pressure signals, decode the pressure signals in accordance with the first pseudorandom code to create first decoded pressure values, and process the first decoded pressure values to determine a first flow parameter; and a second infusion device acting on a second segment of the conduit. - View Dependent Claims (14, 15, 16, 17, 18)
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19. A method for monitoring a flow parameter in a fluid conduit in which a first infusion device acts on a first segment of the conduit, and a second infusion device acts on a second segment of the conduit to control the flow of fluid through the conduit, wherein the first and second segments are separate branches of the conduit that are joined at a point downstream of both the first and second infusion devices, the method comprising the steps of:
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outputting a first pseudorandom code having a codelength; controlling the first infusion device to act on the first segment of the conduit to control fluid flow in a pattern of flow variation in accordance with the first pseudorandom code; monitoring pressure in the conduit and generating pressure signals representing said monitored pressure; decoding the pressure signals in accordance with the first pseudorandom code to create first decoded pressure values; and processing the first decoded pressure values to determine a first flow parameter. - View Dependent Claims (20, 21, 22)
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Specification