EP0230407A1 - Dispositif de controle de la respiration chez les nouveau-nes - Google Patents

Dispositif de controle de la respiration chez les nouveau-nes

Info

Publication number
EP0230407A1
EP0230407A1 EP19850903888 EP85903888A EP0230407A1 EP 0230407 A1 EP0230407 A1 EP 0230407A1 EP 19850903888 EP19850903888 EP 19850903888 EP 85903888 A EP85903888 A EP 85903888A EP 0230407 A1 EP0230407 A1 EP 0230407A1
Authority
EP
European Patent Office
Prior art keywords
microphone
respiration
circuit
sounds
breathing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP19850903888
Other languages
German (de)
English (en)
Inventor
Dag Linnarsson
Bo Tedner
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
KAROLINSKA INSTITUTET
Original Assignee
KAROLINSKA INSTITUTET
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by KAROLINSKA INSTITUTET filed Critical KAROLINSKA INSTITUTET
Publication of EP0230407A1 publication Critical patent/EP0230407A1/fr
Pending legal-status Critical Current

Links

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/103—Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
    • A61B5/11—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb
    • A61B5/113—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb occurring during breathing
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B7/00—Instruments for auscultation
    • A61B7/003—Detecting lung or respiration noise

Definitions

  • This invention relates to a device for supervision of the respiration of infants by determination of the breathing sounds in the respiratory system.
  • Irregular breathing and breaks of respiration are usual with infants, both infants born too early and older infants. It is calculated that each fourth child with a birth weight of below 1750 g often has apnoeas. Almost all children with a birth weight of below 1000 g have apnoeas. The apnoeas can be dangerous to life and lead to grave handicaps. As moreand more infants born too early now survive (more than 50 % of those having a birth weight of below 1000 g) and will be quite sound the need of an adequate supervision of apnoea on departments for new- born babies will increase.
  • SIDS sudden unexpected infant death
  • Apnoeas or stopping of breathing can be either central (no breathing movements are initiated from the centrum of respiration in the brain) or obstructive (the upper respiratory system will collapse or contract). In the latter case fruitless breathing movements can be carried out by abdomen and thorax.
  • supervision of breathing of infants born too early and infants having an irregular respiration pattern is provided.
  • detection of breathing movements where the alarm is sounded if no such movements are detected within a certain time, e.g. 15 or 30 seconds.
  • This impedance varies with breathing and can be measured by passing a weak high-frequency current through thorax by means of electrodes.
  • the method is simple but has the disadvantage that simultaneously occurring heart synchronous impedance variations cannot always be distinguished from the respiration synchronous impedance variations.
  • transcutaneous P O2 means with a great certainty normal respiration conditions, while a low value need not necessarily be caused by a bad respiration but may also be due to bad bleed-through of the skin or even an electrode error. in addition, the electrode may be difficult to apply and may In certain cases cause local injuries.
  • the invention is based on the fact that the breathing sound is supervised which is a specific magnitude of the respiratory flow in the resplratory system.
  • the throat has been selected as a suitable place for detection of the breathing sound.
  • One microphone (the signal microphone) is then preferably placed straight at the front of the throat to receive the sound generated when breathing air streams through trachea and larynx.
  • the other microphone (the reference microphone) is placed so that substantially no breathing sounds are picked up e.g.
  • This reference microphone will then register the other sounds from the body whereas the sound from the flow of the respiratory air has essentially lower strength or can be neglected. Both the microphones register outer sounds from the surroundings with about the same signal strength, both direct sounds and outer sounds transmitted via the body. These sounds can then be eliminated by subtraction of the microphone signals, which will minimize the risk of outer sounds with the same frequency range as the breathing sounds being interpreted as respiration sounds.
  • two microphones are used for absorbing sounds, viz. a signal microphone 10, which is preferably adapted straight at the front of the throat to receive the sounds in trachea and larynx caused by the respiration air and a reference microphone 12 which is applied, as mentioned above, for example at the side of the throat, in the neck or behind the ear and which picks up substantially the same disturbing sounds as the signal microphone.
  • the two microphones consist preferably of miniature microphones of electret type and are preferably attached by means of an adhesive plaster or a thin elastic band around the throat.
  • the supervisory device On its input side the supervisory device has two identically built channels 14 and 16, i.e. one for each microphone. Each channel contains an amplifier 18 and 20, respectively, a band-pass filter 22 and 24, respectively, connected after these and a circuit 26 and 28, respectively, for rectification and mean value formation of the output signal of the filter.
  • the amplification factor of the amplifiers 18 and 20 is of the order of 1000 times and can be adjusted with a ganged potentiometer 21 indicated in the figure for optimal signal Level.
  • the band-pass filters 22, 24 should have the approximate pass band 300-1000 Hz and can for example consist of the filter of the fourth order with the damping 24 dB/octave outside the pass band.
  • the filters are matched to each other to give an identical signal actuation in the two channels.
  • the sound from the activity of the heart has been found to have a frequency content similar to that of the breathing sounds. However, the energy content of the heart sounds decreases with the frequency above about 200 Hz which means that the two sound types can be separated by means of the filters.
  • the heart sounds are strong if the microphone is placed in the vicinity of the heart. The heart sounds are normally weaker than the breathing sounds when the microphone is placed on the throat. The strength of the heart sounds, when the microphone is placed on the throat, decreases rapidly with increasing age of the infants.
  • the signals of the two channels must be rectified.
  • the microphones 10, 12 are very sensitive to the phase position of the absorbed sound, and therefore the signal phase can be changed as much as 180 at an extremely small change of the micro- phone position ( 5 mm). This might result in that an additional sound registered in the two channels and having frequencies within the pass band of the filters 22, 24 is summed instead of being subtracted and then interpreted as a respiration sound.
  • the signals are rectified and formed to mean values in the circuits 26, 28 before they are subtracted from each other in a differential amplifier 30 the influence from phase differences between the signals is quite eliminated.
  • the circuits 26, 28 perform a full-wave rectification of the signals and form mean values of the rectified signals with a time constant of about 0.1 s.
  • the low value of the time constant also results in a detection of relatively rapid changes of the sound.
  • the rectified and mean value formed signals are subtracted and further amplified about 10 times in the differential amplifier 30.
  • the output signal from the differential amplifier 30 will be close to zero in the absence of breathing sounds. If there are breathing sounds the result will be a positive output signal from the differential amplifier.
  • the output signal, from the differential amplifier 30 is fed to a threshold circuit 32 detecting if the output signal exceeds a predetermined level (e.g. 0.5 V), i.e. if there are breathing sounds.
  • a predetermined level e.g. 0.5 V
  • the output of the circuit 32 lies at a high level and maintains a time circuit 34 inactive. As soon as the output of the circuit 32 changes into a low level corresponding to a break of the breathing sounds the time circuit 34 is however released. If the breathing sounds return so that the output signal of the circuit 32 returns to a high level the time circuit 32 is immediately restored. If, however, the breathing sounds do not appear the time circuit 32 will after an adjustable time interval (e.g. 1-60 seconds) activate an alarm circuit 35 which, in turn, remains activated until a restoration button 38 is depressed.
  • the alarm circuit can be connected to a warning lamp 30, a summer 42 etc. and to another outer alarm device via a relay output 44.
  • the output of the time circuit 34 is also connected to an accumulating memory circuit 46 which registers past time from the activation of the alarm until respiratory signals return or until the restoration button 38 of the alarm is depressed, and corresponding alarm times accumulated for 24 hours. Moreover, the memory circuit 46 registers the total number of alarms for 24 hours.
  • the information stored in the memory can be presented on a digital display unit 48.
  • a pulse counter 50 can be connected to the output of the differential amplifier 30 for registration of the respiration frequency and display of the resulting value on a digital display unit 52.

Landscapes

  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Medical Informatics (AREA)
  • Molecular Biology (AREA)
  • Surgery (AREA)
  • Animal Behavior & Ethology (AREA)
  • Veterinary Medicine (AREA)
  • Engineering & Computer Science (AREA)
  • Pulmonology (AREA)
  • Physiology (AREA)
  • Dentistry (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Physics & Mathematics (AREA)
  • Biophysics (AREA)
  • Pathology (AREA)
  • Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)

Abstract

Les sons produits par la respiration sont détectés à l'aide d'un microphone de signaux (10) appliqué sur la gorge du nouveau-né. Afin d'éliminer l'influence des sons perturbateurs émis par l'environnement un microphone de référence (12) est positionné sur le nouveau-né de sorte qu'il capte essentiellement les mêmes sons perturbateurs que le microphone de signaux (10) mais essentiellement aucun son produit par la respiration. En soustrayant le signal provenant du microphone de référence du signal de sortie du microphone de signaux, par exemple dans un amplificateur différentiel (30), on obtient un signal de sortie indiquant la respiration, qui est essentiellement insensible aux sons perturbateurs et qui peut provoquer le déclenchement d'une alarme via des circuits de traitement de signaux appropriés (32, 34) lorsque les sons provoqués par la respiration cessent pendant un laps de temps prédéterminé.
EP19850903888 1984-01-30 1985-07-19 Dispositif de controle de la respiration chez les nouveau-nes Pending EP0230407A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE8400449A SE452946B (sv) 1984-01-30 1984-01-30 Anordning for overvakning av andningen hos spedbarn

Publications (1)

Publication Number Publication Date
EP0230407A1 true EP0230407A1 (fr) 1987-08-05

Family

ID=20354510

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19850903888 Pending EP0230407A1 (fr) 1984-01-30 1985-07-19 Dispositif de controle de la respiration chez les nouveau-nes

Country Status (3)

Country Link
EP (1) EP0230407A1 (fr)
SE (1) SE452946B (fr)
WO (1) WO1987000415A1 (fr)

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2609623B1 (fr) * 1987-01-15 1990-08-03 Abensour David Detecteur d'apnee pour enfant
GB8729881D0 (en) * 1987-12-22 1988-02-03 Zone Technology Ltd Detector unit & system
ES2119150T3 (es) * 1992-12-07 1998-10-01 Andromed Inc Estetoscopio electronico.
FI94287C (fi) * 1993-04-29 1995-08-10 Kari Hannu Kallio Häiriönvaimennusmenetelmä ja anturikonstruktio signaalin mittaamiseksi kiinteän aineen pinnalta
DE9409320U1 (de) * 1994-06-08 1995-07-06 Berlin Florence Atemschutzmaske und Mikrofonhalter zur Verwendung darin
US6026170A (en) * 1995-11-27 2000-02-15 Minnesota Mining And Manufacturing Company Electronic stethoscope with idealized bell and idealized diaphragm modes
FR2847796B1 (fr) * 2002-11-28 2005-04-01 Dispositif pour surveiller la respiration d'un patient
NZ591256A (en) * 2006-01-06 2012-06-29 Resmed Ltd Measuring sounds during expiration and inspiration and signalling if a ratio of the two exceeds a value
ES2351831B1 (es) * 2009-03-13 2011-07-11 Sergio Villaplana Garcia Dispositivo de monitorización de respiración infantil.
US9277892B2 (en) 2013-07-17 2016-03-08 Xerox Corporation Device for monitoring sleeping individuals
CN109276788A (zh) * 2018-08-24 2019-01-29 广州康智件科技有限公司 一种用于吸氧监测的呼吸频率采集方法及其装置

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4161945A (en) * 1977-10-25 1979-07-24 Cambridge Instrument Company, Inc. Selective interference filter
US4289142A (en) * 1978-11-24 1981-09-15 Kearns Kenneth L Physiological occurrence, such as apnea, monitor and X-ray triggering device
US4438772A (en) * 1982-04-08 1984-03-27 Intech Systems Corp. Differential stethoscope

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8700415A1 *

Also Published As

Publication number Publication date
SE452946B (sv) 1988-01-04
WO1987000415A1 (fr) 1987-01-29
SE8400449D0 (sv) 1984-01-30
SE8400449L (sv) 1985-07-31

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