Ultrasonic air-in-line detector for detecting entrained air in a medication infusion system
First Claim
1. A system for detecting the presence of a significant amount of entrained air in fluid passing through a fluid passageway, comprising:
- ultrasonic sensor means disposed adjacent said fluid passageway for providing an air-in-line output signal indicative of whether there is presently air or fluid in said fluid passageway at the location monitored by said ultrasonic sensor means;
monitoring means for monitoring the volume pumped through said fluid passageway, said monitoring means providing a volume output signal indicative of the volume pumped;
evaluating means, responsive to said air-in-line output signal and said volume output signal, for evaluating the volume of air contained in each of a succession of windows of at least a predetermined volume pumped through said fluid passageway, said evaluating means providing as an output a numerical value for each window characterizing which of a plurality of ranges the volume of air contained in each window is within;
calculating means for calculating the sum of the numerical values characterizing each of the last N windows, wherein N is a present number; and
means for providing an alarm signal if the sum of numerical values characterizing each of the last N windows from said calculating means is equal to or greater than a preselected threshold value.
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Accused Products
Abstract
An ultrasonic air-in-line detection system for use in detecting entrained air bubbles in the fluid line of a disposable cassette mounted on a main pump unit is disclosed which can accurately detect entrained air bubbles in any type of fluid, whether clear or opaque. The system uses multiple windowing and air volume number weighting to determine when a threshold count of entrained air in a predetermined number of windows of material pumped occurs, with the alarm being sounded only when this threshold count of air bubbles is present in the multiple window volume. The system of the present invention thus will detect entrained air while avoiding so-called nuisance alarms.
171 Citations
29 Claims
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1. A system for detecting the presence of a significant amount of entrained air in fluid passing through a fluid passageway, comprising:
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ultrasonic sensor means disposed adjacent said fluid passageway for providing an air-in-line output signal indicative of whether there is presently air or fluid in said fluid passageway at the location monitored by said ultrasonic sensor means; monitoring means for monitoring the volume pumped through said fluid passageway, said monitoring means providing a volume output signal indicative of the volume pumped; evaluating means, responsive to said air-in-line output signal and said volume output signal, for evaluating the volume of air contained in each of a succession of windows of at least a predetermined volume pumped through said fluid passageway, said evaluating means providing as an output a numerical value for each window characterizing which of a plurality of ranges the volume of air contained in each window is within; calculating means for calculating the sum of the numerical values characterizing each of the last N windows, wherein N is a present number; and means for providing an alarm signal if the sum of numerical values characterizing each of the last N windows from said calculating means is equal to or greater than a preselected threshold value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A system for detecting the presence of a significant amount of air in fluid passing through a fluid passageway, comprising:
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a first ultrasonic transducer located on one side of said fluid passageway; a second ultrasonic transducer located on the other side of said fluid passageway; means for driving said first ultrasonic transducer to generate ultrasonic vibrations which are transmitted to said one side of said fluid passageway, said ultrasonic vibrations passing through said fluid passageway and being received by said second ultrasonic transducer when there is fluid in said fluid passageway, said ultrasonic vibrations substantially not passing through said fluid passageway and not being received by said second ultrasonic transducer when there is an air bubble in said fluid passageway; receiver means for detecting the ultrasonic vibrations received by said second transducer and providing an air-in-line output signal indicative of whether there is presently air or fluid in said fluid passageway between said first and second transducers; means for monitoring the volume pumped through said fluid passageway, said monitoring means providing a volume output signal indicative of the volume pumped; evaluating means, responsive to said air-in-line output signal and said volume output signal, for evaluating the volume of air contained in each of a succession of windows of at least a predetermined volume pumped through said fluid passageway, said evaluating means providing as an output a numerical value for each window characterizing which of a plurality of ranges the volume of air contained in each window is within; calculating means for calculating the sum of the numerical values characterizing each of the last N windows, wherein N is a preset number; and means for providing an alarm signal if the sum of numerical values characterizing each of the last N windows from said calculating means is equal to or greater than a preselected threshold value.
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28. A system for detecting the presence of a significant amount of entrained air in fluid passing through a fluid passageway, comprising:
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evaluating means for evaluating the volume of air contained in each of a succession of windows of at least a predetermined volume pumped through said fluid passageway, said evaluating means providing as an output a numerical integer value for each window characterizing which of a plurality of ranges the volume of air contained in each window is within; calculating means for calculating the sum of the numerical values characterizing each of the last N windows, wherein N is a preset number; and means for providing an alarm signal if the sum of numerical values characterizing each of the last N windows from said calculating means is equal to or greater than a preselected threshold value.
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29. A method of detecting the presence of a significant amount of entrained air in fluid passing through a fluid passageway, comprising:
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providing an air-in-line output signal indicative of whether there is presently air or fluid in said fluid passageway at a particular location with an ultrasonic sensor means disposed adjacent said fluid passageway at said particular location; monitoring the volume pumped through said fluid passageway and providing a volume output signal indicative of the volume pumped; evaluating, from said air-in-line output signal and said volume output signal, the volume of air contained in each of a succession of windows of at least a predetermined volume pumped through said fluid passageway and providing as an output a numerical value for each window characterizing which of a plurality of ranges the volume of air contained in each window is within; calculating the sum of the numerical values characterizing each of the last N windows, wherein N is a preset number; and providing an alarm signal if the sum of numerical values characterizing each of the last N windows from said calculating means is equal to or greater than a preselected threshold value.
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Specification