SE508439C2 - Measuring device for simultaneous determination of flow of a flowing gas mixture and concentration of a specific gas in the gas mixture. - Google Patents

Measuring device for simultaneous determination of flow of a flowing gas mixture and concentration of a specific gas in the gas mixture.

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Publication number
SE508439C2
SE508439C2 SE9701477A SE9701477A SE508439C2 SE 508439 C2 SE508439 C2 SE 508439C2 SE 9701477 A SE9701477 A SE 9701477A SE 9701477 A SE9701477 A SE 9701477A SE 508439 C2 SE508439 C2 SE 508439C2
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gas
acoustic
measuring
measuring device
concentration
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SE9701477A
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Swedish (sv)
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SE9701477D0 (en
SE9701477L (en
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Lars Wallen
Rolf Castor
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Siemens Elema Ab
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Priority to SE9701477A priority Critical patent/SE9701477L/en
Publication of SE9701477D0 publication Critical patent/SE9701477D0/en
Priority to EP98104172A priority patent/EP0874238A1/en
Publication of SE508439C2 publication Critical patent/SE508439C2/en
Publication of SE9701477L publication Critical patent/SE9701477L/en

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/08—Detecting, measuring or recording devices for evaluating the respiratory organs
    • A61B5/087—Measuring breath flow
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/08—Detecting, measuring or recording devices for evaluating the respiratory organs
    • A61B5/082—Evaluation by breath analysis, e.g. determination of the chemical composition of exhaled breath
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/02—Analysing fluids
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/02—Analysing fluids
    • G01N29/032—Analysing fluids by measuring attenuation of acoustic waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04—Analysing solids
    • G01N29/11—Analysing solids by measuring attenuation of acoustic waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/34—Generating the ultrasonic, sonic or infrasonic waves, e.g. electronic circuits specially adapted therefor
    • G01N29/348—Generating the ultrasonic, sonic or infrasonic waves, e.g. electronic circuits specially adapted therefor with frequency characteristics, e.g. single frequency signals, chirp signals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/08—Detecting, measuring or recording devices for evaluating the respiratory organs
    • A61B5/083—Measuring rate of metabolism by using breath test, e.g. measuring rate of oxygen consumption
    • A61B5/0836—Measuring rate of CO2 production
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/01—Indexing codes associated with the measuring variable
    • G01N2291/015—Attenuation, scattering
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/021—Gases
    • G01N2291/0215—Mixtures of three or more gases, e.g. air
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/028—Material parameters
    • G01N2291/02809—Concentration of a compound, e.g. measured by a surface mass change

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  • Health & Medical Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Pathology (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • Immunology (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Pulmonology (AREA)
  • Animal Behavior & Ethology (AREA)
  • Veterinary Medicine (AREA)
  • Biophysics (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Medical Informatics (AREA)
  • Molecular Biology (AREA)
  • Surgery (AREA)
  • Physiology (AREA)
  • Public Health (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Electromagnetism (AREA)
  • Fluid Mechanics (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
  • Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)
  • Investigating Or Analysing Biological Materials (AREA)

Abstract

A device for simultaneously measuring the flow of a gas mixture and a concentration of a specific gas in the mixture comprises a measuring chamber through which the mixture can flow, an acoustic transmitter (26) which generates and emits an acoustic signal that passes through the chamber, an acoustic receiver (28) for measuring the transmitted acoustic signal, and a first processor (36) linked to the receiver for determining the flow of gas through the chamber, based on the effect that the flow has on the acoustic signal. A second processor (38) is linked to the receiver for determining the concentration of the specific gas in the mixture, based on the effect of this gas on the signal. Preferably the second processor is used to measure carbon dioxide content.

Description

10 15 20 25 30 35 508 439 2 endast en del av det totala andningsgasflödet skall ledas igenom mätkammaren för bestämning av syrgashalten. Själva konstruktionen av nátkamaren medför dessutom att det flöde av gas som strömar in i, eller igenom màtkamaren pâverkas starkt. Den kända mätanordningen är således konstruerad och begränsad till enbart koncentrationsmätningar. för koncentrationsbestämning medelst ultraljud är beskriven i US-4,6l6,50l. kända mätanordningen omfattar ett sensorsystem där ultraljud vid ett flertal olika frekvenser genereras och transmitteras En annan känd mätanordning Den andra genom en provkammare. Därefter mäts amplituden på olika platser i provkammaren, vid de olika frekvenserna. De sà erhållna mätvärdena jämförs sedan med en matematisk modell som är experimentellt framtagen för specifika gassamansättningars amplitudrespons för de akustiska signalerna. Genom att matcha den framtagna amplitudresponsen med de kända lagrade amplitudresponserna, kan koncentrationen av en specifik gas bestämas. Mätanordningen är främst avsedd bestäma koncentrationen av en steriliserings- för att komponent (etylenoxid) i en steriliseringskammare. 10 15 20 25 30 35 508 439 2 only a portion of the total respiration gas flow shall be conducted through the measuring chamber to determine the oxygen content. Themselves the construction of the boiler chamber also causes it to flow of gas flowing into or through the measuring chamber is affected strong. The known measuring device is thus designed and limited to concentration measurements only. for concentration determination by ultrasound is described in US-4,6l6,50l. known measuring device comprises a sensor system in which ultrasound at a number of different frequencies are generated and transmitted Another known measuring device The other one through a test chamber. Then the amplitude is measured at different places in the test chamber, at the different frequencies. De sa the measured values obtained are then compared with a mathematical model which is experimentally developed for specific gas amplitude amplitude response for the acoustic the signals. By matching the generated amplitude response with the known stored amplitude responses, the concentration can of a specific gas is determined. The measuring device is primarily intended determine the concentration of a sterilizing in order to component (ethylene oxide) in a sterilization chamber.

Mätanordningen utför en metod som är komplicerad och kräver en mängd utrustning och datakraft att amplituderna och matcha de uppmätta amplituderna med en för kunna mäta datamodell. Dessutom krävs att för varje specifik gas som skall omfattande analyseras i en specifik gasblandning, krävs en datasamling pá kända koncentrationer i olika blandningsvarianter. Själva mätmetoden begränsar till gasflöden av varierande gassammansättning. användbarheten isolerade mätkamrar utan passerande Ett syfte med uppfinningen är att frambringa en mätanordning enligt ett enkelt sätt möjliggör samtidig bestämning av flödet av en strömande ingressen, som på och smidigt gasblandning och koncentrationen av en specifik gas i gasblandningen. 10 15 20 25 30 35 508 439 Detta syfte ernås i enlighet med uppfinningen genom att mät- anordningen är 'utformad 1ned en andra analysenhet ansluten till den akustiska mottagaren för att bestämma koncentra- tionen av den specifika gasen i gasblandningen genom att be- specifika inverkan på den akustiska stäma den gasens signalen.The measuring device performs a method that is complicated and demanding a variety of equipment and computing power to the amplitudes and match the measured amplitudes with one to be able to measure data model. In addition, for each specific gas required shall Extensive analyzed in a specific gas mixture, one is required data collection at known concentrations in different mixed variants. The measurement method itself is limiting to gas flows of varying gas composition. the usefulness of insulated measuring chambers without passing An object of the invention is to provide a measuring device in a simple way enables simultaneous determination of the flow of a flowing the preface, as on and smooth gas mixture and the concentration of a specific gas in the gas mixture. 10 15 20 25 30 35 508 439 This object is achieved in accordance with the invention by measuring the device is designed with a second analysis unit connected to the acoustic receiver to determine the concentration the specific gas in the gas mixture by specific impact on the acoustic sue that gas the signal.

Genom att utnyttja den signal som erhålls i samband med kan mätanordningen mini- stabil flödesmätningen av gasblandningen, meras med avseende pá komponenter och göras billig, och noggrann.By utilizing the signal obtained in connection with the measuring device can be stable the flow measurement of the gas mixture, more in terms of components and made cheap, and careful.

I princip kan analysen av den transmitterade signalen göras digitalt varvid information av flöde och koncentration snabbt och enkelt erhålls i form av digitala signaler som sedan kan behandlas eller presenteras pà känt sätt.In principle, the analysis of the transmitted signal can be done digitally whereby information of flow and concentration quickly and easily obtained in the form of digital signals which can then treated or presented in a known manner.

Ett flertal fördelaktiga vidareutvecklingar av mätanordningen framgår av de underordnade kraven till kravet 1.A number of advantageous further developments of the measuring device is apparent from the dependent claims to claim 1.

Mätanordningen enligt uppfinningen är synnerligen lämpad att användas i ventilator/anestesisystem, varvid de företrädesvis placeras i exspirationsledningen.The measuring device according to the invention is particularly suitable for be used in ventilator / anesthesia systems, preferably placed in the expiration line.

För att ytterligare möjliggöra exakta och snabba mätningar med ett minimum av elektronik och ansättning av matematiska modeller, kan mätanordningen alternativt placeras i en trakealtub eller motsvarande, genom vilken andningsgas flöder under både inspiration och exspiration. Under inspiration kan därvid det ett inspirerade inspirerade andningsgasflödet bestämmas, samtidigt som referensvärde för gassammansättningen i den andningsgasen bestäms. Under exspiration kan sedan det exspirerade andningsgasflödet mätas, samtidigt som koldioxid enkelt detta fall gaskomponenter sàsom bestäms.To further enable accurate and fast measurements with a minimum of electronics and employment of mathematics models, the measuring device can alternatively be placed in a tracheal tube or equivalent, through which respiratory gas flows during both inspiration and expiration. Under inspiration can thereby it one inspired inspired respiratory gas flow is determined, at the same time as a reference value for the gas composition in it the respiratory gas is determined. During expiration can then the exhaled respiratory gas flow is measured, at the same time as carbon dioxide easily this case gas components as determined.

Koncentrationsbestämningen blir i synnerligen 10 15 20 25 30 35 508 439 4 enkel eftersom den huvudsakliga skillnaden i gassammansättning mellan den inandade gasen och den utandade gasen består i just halten av koldioxid. Koldioxidhalten i utandningsgasen kan mätas genom att filterera ut en specifik frekvens ur den. akustiska signalen. och. bestäma amplitud- förändringen.The concentration determination becomes in particular 10 15 20 25 30 35 508 439 4 simple because the main difference in gas composition between the inhaled gas and the exhaled one the gas consists in precisely the content of carbon dioxide. Carbon dioxide content in the exhaled gas can be measured by filtering out a specific frequency from it. acoustic signal. and. determine amplitude the change.

I anslutning till figurerna skall mätanordningen enligt uppfinningen beskrivas närmare, varvid Fig. 1 visar mätanordningen placerad i ett ventilatorsystem, Fig. 2 visar en första utförandeform av mätanordningen, Fig. 3 visar en styranordning i mätanordningen enligt upp- finningen, Fig. 4 visar en andra utförandeform av mätanordningen, och Fig. 5 visar en alternativ placering av mätanordningen i ett ventilatorsystem.In connection with the figures, the measuring device according to the invention is described in more detail, wherein Fig. 1 shows the measuring device placed in a fan system, Fig. 2 shows a first embodiment of the measuring device, Fig. 3 shows a control device in the measuring device according to the finding, Fig. 4 shows a second embodiment of the measuring device, and Fig. 5 shows an alternative placement of the measuring device in one fan system.

Fig. 1 visar ett ventilatorsystem 2, vilket förser en patient 4 med en andningsgas. Ventilatorsystemet 2 omfattar en ven- tilatorenhet 6 till vilken en eller flera gaser kan anslutas via en första gasanslutning 8A, en andra gasanslutning 8B och en tredje gasanslutning 8C. Den anslutna gasen eller gaserna blandas i en blandningsenhet 10 och regleras även sä att den färdigblandade gasen erhåller en förutbestämd sammansättning samt följer ett viss ttryck- och flödesmönster. Parametrarna regleras via en styranordning 12. Den färdiga gasblandningen tillförs patienten 4 via en inspirationsledning 16 och en patientslang 18, exempelvis en trakealtub. Utandad gas från via patientslangen 18 och en exspira- patienten gär tionsledning 20 tillbaka till ventilatorenheten 6, varefter den evakueras via en evakueringsutgàng 24. Den utandade gasen kan pà känt sätt ventilatorenheten 6 (ej visat i figuren). I exspirationsdelen regleras avseende exempelvis tryck i är en mätanordning 22 för samtidig bestämning av flöde och koncentration anordnad. 10 15 20 25 30 35 508 439 5 Mätanordningen 22 innefattar, som framgår av fig. 2, en genom vilken all utandad gas strömmar, en mätkamare 23, akustisk sändare 26, exempelvis en piezoelektrisk kristall, en akustisk mottagare 28, vilken även den kan utgöras av en kristall, härvid piezoelektrisk och en analysanordning 30.Fig. 1 shows a ventilator system 2, which provides a patient 4 with a breathing gas. The fan system 2 comprises a fan tilator unit 6 to which one or more gases can be connected via a first gas connection 8A, a second gas connection 8B and a third gas connection 8C. The connected gas or gases is mixed in a mixing unit 10 and is also regulated so that it ready-mixed gas obtains a predetermined composition and follows a certain pressure and flow pattern. The parameters is controlled via a control device 12. The finished gas mixture is supplied to the patient 4 via an inspiration line 16 and a patient tubing 18, for example a tracheal tube. Exhaled gas from via the patient tube 18 and an expiratory the patient does line 20 back to the fan unit 6, after which it is evacuated via an evacuation outlet 24. The exhaled gas can in a known way the fan unit 6 (not shown in the figure). In the expiration part regulated with regard to, for example, pressure in is a measuring device 22 for simultaneous determination of flow and concentration arranged. 10 15 20 25 30 35 508 439 5 The measuring device 22 comprises, as shown in Fig. 2, a through which all exhaled gas flows, a measuring chamber 23, acoustic transmitter 26, for example a piezoelectric crystal, an acoustic receiver 28, which may also be a crystal, hereby piezoelectric and an analyzer 30.

Analysanordningen nátenheten 22 eller anordnas i exempelvis styrenheten 12 i kan vara integrerad i själva ventilatorenheten 6.The analysis device the wetting unit 22 or arranged in, for example, the control unit 12 in can be integrated into themselves the fan unit 6.

Den akustiska sändaren 26 avger en akustisk signal 32 som via ett antal reflexioner i väggarna i mätkamaren 23 trans- mitteras igenom den strömmande gasblandningen och träffar sedan den akustiska mottagaren 28, vilken mottagerr den transmitterade akustiska signalen. Utformningen av mätkammaren 23 för att erhålla reflexionerna kan ske pá något sätt som finns inom området för akustisk av de kända flödesmätning.The acoustic transmitter 26 emits an acoustic signal 32 as via a number of reflections in the walls of the measuring chamber 23 emitted through the flowing gas mixture and hits then the acoustic receiver 28, which receives it transmitted acoustic signal. The design of the measuring chamber 23 to obtain the reflections can be done on something ways found in the field of acoustic of the known flow measurement.

Analysanordningen 30 behandlar den mottagna signalen och bestämmer ur denna flödet av gasblandningen samt koncentra- tionen av åtminstone en :L gasblandningen ingående gaskom- ponent, exempelvis koldioxid.The analyzer 30 processes the received signal and determines from this the flow of the gas mixture and the of at least one gas mixture contained in the gas mixture. component, such as carbon dioxide.

I fig. 3 visas en utformning av analysanordningen 30. Den uppmätta akustiska signalen omvandlas i den akustiska mottagaren 28 till en elektrisk signal, vilken överförs till en förförstärkare 34 i analysanordningen 30. Den förstärkta signalen leds dels till en första analysenhet 36 och dels till en andra analysenhet 38. I den första analysenheten 36 bestäms det momentana flödet och dessa uppgifter överförs kontinuerligt till en beräkningsenhet 40. Pâ motsvarande sätt bestäms den momentana koncentrationen i den andra analysenheten 38 och motsvarande information överförs kontinuerligt till beräkningsenheten 40. 10 15 20 25 30 35 508 439 6 Den första analysenheten 36 innefattar åtminstone ett filter fram de som är 42 för signalfrekvenser lämpligast för flödet. De filtrerade signalerna överförs till en första bestämningsenhet 46 i Den första att filtrera bestämningen av vilken själva flödesbestämningen sker. bestämningsenheten 46 kan härvid även motta en referenssignal från beräkningsenheten 40 som exempelvis anger den avgivna frekvens. Med utgångspunkt från den akustiska signalens avgivna akustiska signalen och den uppmätta akustiska signalen. kan den flödande gasblandningens inverkan pà den akustiska signalen bestämmas och därigenom kan även flödet bestämmas.Fig. 3 shows a design of the analysis device 30. It measured acoustic signal is converted into the acoustic the receiver 28 to an electrical signal which is transmitted to a preamplifier 34 in the analyzer 30. The amplified the signal is routed partly to a first analysis unit 36 and partly to a second analysis unit 38. In the first analysis unit 36 the instantaneous flow is determined and this data is transmitted continuously to a calculation unit 40. Correspondingly the instantaneous concentration in the other is determined analysis unit 38 and the corresponding information is transmitted continuously to the calculation unit 40. 10 15 20 25 30 35 508 439 6 The first analysis unit 36 comprises at least one filter bring forth those who are 42 for signal frequencies most suitable for the flow. They filtered the signals are transmitted to a first determining unit 46 i The first to filter the determination of which the actual flow determination takes place. the determining unit 46 can in this case also receive a reference signal from the calculation unit 40 which, for example, indicates the output frequency. Based on it acoustic signal emitted acoustic signal and the measured acoustic the signal. the effect of the flowing gas mixture on it the acoustic signal is determined and thereby also the flow determined.

Pâ motsvarande sätt innefattar den andra analysenheten 38 ett andra bandpassfilter 48 för att filtrera fram de frekvenser i mätsignalen som är av intresse för koncentrationsmätningen.Correspondingly, the second analysis unit 38 comprises one second bandpass filter 48 to filter out the frequencies in the measurement signal which is of interest for the concentration measurement.

Dessa signaler överförs till en andra bestämningsenhet 50 i vilken koncentrationen av den specifika gasen bestäms. Även här kan en referenssignal överföras via beräkningsenheten 40 till den andra bestämningsenheten 50. Beräkningsenheten 40 kan även fungera som styrenhet för den akustiska sändaren 26.These signals are transmitted to a second determining unit 50 i which the concentration of the specific gas is determined. Also here, a reference signal can be transmitted via the computing unit 40 to the second determination unit 50. The calculation unit 40 can also act as a control unit for the acoustic transmitter 26.

Det bör här noteras att den akustiska sändaren 26 kan vara utformad att samtidigt eller sekventiellt avge ett flertal olika frekvenser och att den akustiska nmttagaren på nwt- svarande sätt är utformad att parallellt eller seriellt mäta ett flertal olika frekvenser. Den akustiska sändaren 26 res- pektive akustiska mottagaren 28 kan för detta syfte innefatta flera piezoelektriska element för generering av de olika frekvenserna.It should be noted here that the acoustic transmitter 26 may be designed to emit a plurality simultaneously or sequentially different frequencies and that the acoustic receiver on the nwt- corresponding way is designed to measure in parallel or in series a number of different frequencies. The acoustic transmitter 26 res- the respective acoustic receiver 28 may for this purpose include several piezoelectric elements for generating the different ones the frequencies.

I fig. 4 visas ett andra utföringsexempel av mätanordningen 22. I detta fall är den första akustiska sändaren 26 och akustiska mottagaren 28 placerade på motstående sidor av mät- kammaren 23 och mätsignalen 32 sänds diagonalt igenom mät- kammaren. 23. Även. här' kan signalen fås att reflekteras en eller flera gånger i mätkammarens 23 väggar. 10 15 20 25 508 439 För att öka noggrannheten i framför allt bestämningen av kon- centrationen av den ingående gaskomponenten kan en identisk mätanordning placeras pá inspirationssidan av ventilator- systemet, såsom framgår av fig. 1 med den ytterligare mätan- ordningen l4. Härigenom erhålles en ytterligare referens- signal för den gasblandning som tillförs patienten. Ur denna referens kan sedan .bestämningen. av' koncentrationen av' den specifika gasen på ett enklare sätt bestämmas säkert.Fig. 4 shows a second embodiment of the measuring device 22. In this case, the first acoustic transmitter is 26 and acoustic receiver 28 located on opposite sides of the measuring the chamber 23 and the measuring signal 32 are transmitted diagonally through the measuring the chamber. 23. Also. here 'the signal can be made to reflect one or several times in the walls of the measuring chamber 23. 10 15 20 25 508 439 In order to increase the accuracy of, in particular, the determination of the concentration of the constituent gas component can be identical measuring device is placed on the inspiration side of the fan system, as shown in Fig. 1 with the additional measurement scheme l4. This provides an additional reference signal for the gas mixture supplied to the patient. From this reference can then .determination. of the 'concentration of' it specific gas in a simpler way is determined safely.

I fig. 5 visas en alternativ placering av mätanordningen 22, nämligen i patientslangen 18. Detta medför flera fördelar, dels kan flöde och koncentration bestämmas under báde inspiration och exspiration medelst en och samma mätanordning. Dessutom bestäms dessa parametrar nära patienten 4, vilket innebär att exempelvis koldioxidproduktionen i patienten snabbt och säkert kan bestämmas genom att integrera produkten av uppmätt flöde och koncentration under exspirationsfaserna. Denna och andra bestämningar kan göras i berâkningsenheten 40, exempelvis bestämning av maximalt flöde under inspiration/exspiration, maximal koncentration av inspirerad resp. exspirerad volym, den specifika gasen, ändexspiratorisk koncentration av den specifika gasen m.Fig. 5 shows an alternative location of the measuring device 22, namely in the patient tube 18. This has several advantages, on the one hand, flow and concentration can be determined under both inspiration and expiration by one and the same measuring device. In addition, these parameters are closely determined patient 4, which means that for example carbon dioxide production in the patient can quickly and safely determined by integrating the product of measured flow and concentration during the expiration phases. This and others determinations can be made in the calculation unit 40, for example determination of maximum flow during inspiration / expiration, maximum concentration of inspired resp. expired volume, the specific gas, end-expiratory concentration of it specific gases m.

Kombinationer av de visade utföringsexemplen kan göras där sá är tillämpligt.Combinations of the embodiments shown can be made there is applicable.

Claims (10)

10 15 20 25 30 35 508 439 Krav10 15 20 25 30 35 508 439 Requirements 1. Mätanordning (22) för samtidig bestämning av flödet av en strömmande gasblandning och koncentrationen av en specifik gas i gasblandningen, innefattande en mätkanunare (23) , genom (26) igenom mät- vilken gasblandningen kan strönuna, en akustisk sändare för att generera och avge en akustisk signal kammaren (23), en akustisk mottagare (28) för att mäta en transmitterad akustisk signal och en första analysenhet (36) ansluten till den akustiska mottagaren (28) för att bestämma gasflödet igenom mätkammaren (23) utifrân gasflödets inverkan på den akustiska signalen, kännetecknad av en andra analysenhet (38) ansluten till den akustiska mottagaren (28) för att bestämma koncentrationen av den specifika gasen i gasblandningen genom att bestämma den specifika gasens inverkan pà den akustiska signalen. 'Measuring device (22) for simultaneously determining the flow of a flowing gas mixture and the concentration of a specific gas in the gas mixture, comprising a measuring cannon (23), through (26) through measuring which the gas mixture can scatter, an acoustic transmitter for generating and an acoustic signal chamber (23), an acoustic receiver (28) for measuring a transmitted acoustic signal and a first analysis unit (36) connected to the acoustic receiver (28) for determining the gas flow through the measuring chamber (23) from the effect of the gas flow on the acoustic signal, characterized by a second analysis unit (38) connected to the acoustic receiver (28) to determine the concentration of the specific gas in the gas mixture by determining the effect of the specific gas on the acoustic signal. ' 2. Mätanordning enligt krav 1, kännetecknad av att den första analysenheten (36) och/eller den andra analys- enheten (38) är anslutna till den akustiska sändaren (26) för att erhålla en referenssignal för den avgivna akustiska signalen.Measuring device according to Claim 1, characterized in that the first analysis unit (36) and / or the second analysis unit (38) are connected to the acoustic transmitter (26) in order to obtain a reference signal for the emitted acoustic signal. 3. Mätanordning enligt krav l eller 2, kännetecknad av att den andra analysenheten (38) är utformad att bestämrna koncentrationen av den specifika gasen i gasblandningen genom att bestämma dämpningen av den transmitterade akustiska sig- nalens amplitud.Measuring device according to Claim 1 or 2, characterized in that the second analysis unit (38) is designed to determine the concentration of the specific gas in the gas mixture by determining the attenuation of the amplitude of the transmitted acoustic signal. 4. Mätanordning enligt krav 3, kännetecknad av att (26) samtidigt generera och avge akustiska signaler med ett fler- (36, 38) är (28) upp- mätta transmitterade akustiska signalerna filtrera fram en den akustiska sändaren är utformad att' seriellt eller tal olika frekvenser och att analysenheterna utformade att ur den av den akustiska mottagaren 10 15 20 25 30 35 508 439 9 eller flera specifika frekvenser för bestämning av flöde respektive koncentration. av att (42, 48)Measuring device according to claim 3, characterized in that (26) simultaneously generating and emitting acoustic signals with a multi- (36, 38) measured (28) transmitted acoustic signals filter out an acoustic transmitter is designed to 'serial or speech different frequencies and that the analysis units designed that from that of the acoustic receiver 10 15 20 25 30 35 508 439 9 9 or more specific frequencies for determining flow and concentration respectively. of that (42, 48) 5. Mätanordning enligt krav 4, kännetecknad analysenheterna (36, 38) innefattar bandpassfilter för att filtrera ut signalerna med de specifika frekvenserna." ovanstående krav, (2 3 ) utsänd från den akustiskaMeasuring device according to claim 4, characterized in that the analysis units (36, 38) comprise bandpass filters for filtering out the signals with the specific frequencies. "The above claims, (2 3) emitted from the acoustic 6 . Mät anordning enligt något av av att mätkammaren är så utformad, att den akustiska signalen (32), (26), reflekteras ett flertal gånger i mätkammaren (23) , innan den träffar den akustiska mottagaren (28) . kännetecknad sändaren ovanstående krav, (23) (2 0) i varvid gasblandningen utgörs av6. Measure device according to any one of the measuring chambers in such a way that the acoustic signal (32), (26) is reflected several times in the measuring chamber (23), before it hits the acoustic receiver (28). characterized in the transmitter above claim, (23) (20) in which the gas mixture consists of 7 . Mät anordning enligt något av kännetecknad av att mätkammaren är utformad att till en exspirationsledning ett ventila- (2), utandad gas som flödar igenom mätkammaren (23). anslutas tor/anestesi-system7. Measure device according to one of the features characterized in that the measuring chamber is designed to supply a valve (2), exhaled gas which flows through the measuring chamber (23) to an expiration line. connected tor / anesthesia system 8. Mätanordning enligt något av kraven 1 - 6, k ä n n e - t e c k n a d (23) av en gasledning i ett ventilator/anestesi-system (2), av att mätkammaren utgör en integrerad del (18) varvid gasblandningen utgörs av in- och/eller utandad gas som flödar igenom mätkammaren (23) .Measuring device according to one of Claims 1 to 6, characterized (23) by a gas line in a ventilator / anesthesia system (2), in that the measuring chamber forms an integral part (18), the gas mixture consisting of in- and / or exhaled gas flowing through the measuring chamber (23). 9. Mätanordning enligt krav 7 eller 8, kännetecknad av att den andra analysenheten (38) bestämmer koncentra- tionen av C02 i den utandade gasen.Measuring device according to Claim 7 or 8, characterized in that the second analysis unit (38) determines the concentration of CO 2 in the exhaled gas. 10. Mätanordning enligt något av kraven 7 - 9, känne- (40) och den andra analysenheten t e c k n a d a v en beräkningsenhet ansluten till den (36) (38) för att bestämma ett antal parametrar relaterade till den första analysenheten utandade gasen, såsom maximalt utandat flöde, utandad total volym, utandad volym av den specifika gasen och max kon- centration av den specifika gasen.Measuring device according to any one of claims 7 to 9, the sensing (40) and the second analysis unit drawn by a calculation unit connected to the (36) (38) for determining a number of parameters related to the first analysis unit exhaled gas, such as maximum exhaled flow , exhaled total volume, exhaled volume of the specific gas and maximum concentration of the specific gas.
SE9701477A 1997-04-21 1997-04-21 Measuring device for simultaneous determination of flow of a flowing gas mixture and concentration of a specific gas in the gas mixture. SE9701477L (en)

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SE9701477A SE9701477L (en) 1997-04-21 1997-04-21 Measuring device for simultaneous determination of flow of a flowing gas mixture and concentration of a specific gas in the gas mixture.
EP98104172A EP0874238A1 (en) 1997-04-21 1998-03-09 A measuring device for simultaneous determination of the flow in a circulating gasmixture and the concentration of a specific gas in the gas mixture

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