Intravenous-line air-detection system
First Claim
1. A method for detecting the presence of a bubble in a liquid, the method comprising:
- providing an acoustically resonant system having a region, the region having a first portion containing a measurement gas and a second portion containing the liquid in which the presence of the bubble is to be detected, the sum of the first portion'"'"'s volume and the second portion'"'"'s volume being a constant volume;
determining the resonant frequency of the system at a first pressure of the measurement gas;
changing the pressure of the measurement gas to a second pressure;
determining the resonant frequency of the system at the second pressure;
determining, based on the resonant frequency measured at the first pressure and the resonant frequency measured at the second pressure, whether the volume of the first portion has changed due to the change in pressure; and
if the volumes at the first and second pressures are different, generating a signal indicating the presence of a bubble in the liquid.
1 Assignment
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Accused Products
Abstract
The flow of an intravenous (IV) fluid from a IV source through an IV line to a patient is controlled, while monitoring whether there is any bubble in the liquid being delivered to the patient. Disposed in the line is a region having a first portion containing a measurement gas and a second portion containing a segment of the liquid flowing through the line. The liquid in this region is tested for the presence of an air bubble. The sum of the first portion'"'"'s volume and the second portion'"'"'s volume should be a constant volume. The region is part of an acoustically resonant system, in the volume of the measurement gas in the first portion of the region can be determined from the resonant frequency. Preferably, the acoustically resonant system is tuned so as to prevent the presence of a bubble from significantly affecting the measurement of the volume of the region'"'"'s first portion. The region should be isolatable from pressure effects in the rest of the line, preferably by means of a first valve that controls flow from the source and a second valve that controls flow to the patient. The resonant system includes at least one speaker and one microphone, arranged so that the resonant frequency of the system can be detected. In addition, some means for changing the pressure of the measurement gas in the resonant system is provided.
227 Citations
20 Claims
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1. A method for detecting the presence of a bubble in a liquid, the method comprising:
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providing an acoustically resonant system having a region, the region having a first portion containing a measurement gas and a second portion containing the liquid in which the presence of the bubble is to be detected, the sum of the first portion'"'"'s volume and the second portion'"'"'s volume being a constant volume; determining the resonant frequency of the system at a first pressure of the measurement gas; changing the pressure of the measurement gas to a second pressure; determining the resonant frequency of the system at the second pressure; determining, based on the resonant frequency measured at the first pressure and the resonant frequency measured at the second pressure, whether the volume of the first portion has changed due to the change in pressure; and if the volumes at the first and second pressures are different, generating a signal indicating the presence of a bubble in the liquid. - View Dependent Claims (2)
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3. A method for controlling the flow of a liquid from a intravenous fluid source through an intravenous line to a patient and detecting the presence of a bubble in the liquid, the method comprising:
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providing in the line a region having a first portion containing a measurement gas and a second portion containing a segment of the liquid flowing through the line, the sum of the first portion'"'"'s volume and the second portion'"'"'s volume being a constant volume, the region being part of an acoustically resonant system, the region being isolatable from pressure effects in the rest of the line by means of a first valve that controls flow from the source and a second valve that controls flow to the patient; closing the second valve and opening the first valve to permit flow from the source into the region; after liquid has flowed from the source into the region, closing the first valve so as to isolate the region from pressure effects in the line; determining the resonant frequency of the system at a first pressure of the measurement gas; after closing the first valve, changing the pressure of the measurement gas to a second pressure; determining the resonant frequency of the system at the second pressure; determining, based on the resonant frequency measured at the first pressure and the resonant frequency measured at the second pressure, whether the volume of the first portion has changed due to the change in pressure; and if no change in volume is detected due to the change in pressure, opening the second valve to permit flow to the patient, and if a change in volume is detected, generating a signal indicating the presence of a bubble in the liquid. - View Dependent Claims (4, 5, 6, 7)
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8. An apparatus for detecting the presence of a bubble in a liquid, the apparatus comprising:
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an acoustically resonant system having a region isolated from extraneous pressure effects, the region having a first portion containing a measurement gas and a second portion containing the liquid in which the presence of the bubble to be detected, the sum of the first portion'"'"'s volume and the second portion'"'"'s volume being a constant volume; means for detecting the resonant frequency of the system; means for changing the pressure of the measurement gas in the system; and signal generating means for generating a signal indicating the presence of a bubble in the liquid, wherein the signal generating means is in communication with the means for detecting the resonant frequency and the means for changing the pressure of the measurement gas, wherein the signal is generated based upon a first and a second resonant frequency determined by the means for detecting the resonant frequency when the means for changing the pressure has caused the measurement gas to have a first and second pressure, respectively. - View Dependent Claims (9, 10, 11, 12, 13)
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14. An apparatus for controlling the flow of a liquid from a intravenous fluid source through an intravenous line to a patient and detecting the presence of a bubble in the liquid, the apparatus comprising:
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a region having a first portion containing a measurement gas and a second portion containing a segment of the liquid flowing through the line in which the presence of the bubble is to be detected, the sum of the first portion'"'"'s volume and the second portion'"'"'s volume being a constant volume, the region being part of an acoustically resonant system, the system having different frequencies of resonance for different volumes of the measurement gas in the first portion of the region, the region being isolatable from pressure effects in the rest of the line by means of a first valve that controls flow from the source and a second valve that controls flow to the patient; means for detecting the resonant frequency of the system; means for changing the pressure of the measurement gas; and a controller for controlling the valves, the resonance-detection means, and the pressure-changing means, for determining, based on the resonant frequencies measured at two different pressures, whether the volume of the first portion changes due to a change in pressure and for generating a signal indicating the presence of a bubble in the liquid if the first portion'"'"'s volume does change due to a change in pressure. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification