Fluid flow resistance monitoring system
First Claim
1. A system 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 system comprising:
- a pressure sensor coupled to the conduit for providing pressure signals in response to the pressure sensed in the conduit; and
a processor configured to output a pseudorandom code having a codelength, control the flow control device to cause flow in a pattern of flow variation in accordance with the pseudorandom code having a codelength, receive the pressure signals and determine average pressure values for at least some of the pressure signals, decode the average pressure values in accordance with the pseudorandom code, and process the decoded average pressure values to determine a flow parameter.
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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 at the conduit is averaged, and the averaged values are then decoded in accordance with the pseudorandom code. An estimate of the equilibrium pressure is generated from the decoded average 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.
143 Citations
37 Claims
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1. A system 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 system comprising:
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a pressure sensor coupled to the conduit for providing pressure signals in response to the pressure sensed in the conduit; and a processor configured to output a pseudorandom code having a codelength, control the flow control device to cause flow in a pattern of flow variation in accordance with the pseudorandom code having a codelength, receive the pressure signals and determine average pressure values for at least some of the pressure signals, decode the average pressure values in accordance with the pseudorandom code, and process the decoded average pressure values to determine a flow parameter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system for infusing fluid to a patient, comprising:
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a fluid source; a conduit for delivering fluid from the fluid source to the patient; a flow control device that acts on the fluid conduit to control the flow of fluid through the conduit; a flow control device processor configured to control the flow control device to act on the fluid conduit to cause flow in the conduit in a pattern of flow variation, said pattern encompassing a selected number of timeslots, wherein at least some of said timeslots are active timeslots, said pattern including in each active timeslot an infusion period during which fluid is infused in a trilled pattern of substantially equal volume fluid boluses delivered in rapid succession. - View Dependent Claims (11, 12, 13)
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14. 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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(a) controlling the flow control device to act on the fluid conduit to cause a pattern of flow variation in the conduit, said pattern encompassing a selected number of timeslots, wherein at least some of said timeslots are active timeslots, said pattern including in each active timeslot an infusion period during which fluid is infused in a trilled pattern of substantially equal volume fluid boluses delivered in rapid succession; (b) monitoring pressure response of the fluid in the conduit and generating pressure signals representing the pressure response; and (c) calculating the flow parameter as a function of the generated pressure signals. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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22. A system for monitoring impedance to flow in a fluid delivery assembly in which a flow control device acts on a fluid conduit to control the flow of fluid through the conduit, the system comprising:
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a selector for selecting a flow rate; a comparator configured to determine if the selected flow rate is a high, medium, or a low flow rate by comparing the selected flow rate to a high flow rate threshold and a low flow rate threshold; a sensor configured to monitor pressure in the conduit and provide pressure signals in response to the monitored pressure; and a processor that is configured to; control the flow control device to vary the flow rate about the selected flow rate, with the variation in flow rate a function of whether the flow rate is a high, medium, or low flow rate; receive the pressure signals; and calculate the system flow resistance as a function of the pressure signals. - View Dependent Claims (23, 24, 25, 26, 27)
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28. A method for determining flow resistance 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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(a) selecting a flow rate; (b) determining if the selected flow rate is a high, medium, or low flow rate by comparing the selected flow rate to a high flow rate threshold and a low flow rate threshold; (c) varying the flow rate about the selected flow rate, the variation in flow rate a function of various operational parameters that are varied depending on whether the flow rate is a high, medium, or low flow rate; (d) monitoring fluid pressure response in the conduit and generating pressure signals representing the pressure response; and (e) calculating system flow resistance as a function of the generated pressure signals. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37)
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Specification