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  • 1
    ISSN: 1741-0444
    Keywords: Cardiac interference ; Digital filter ; Dolph-Chebyshev ; Dynamic lung compliance ; Lung volume ; Transpulmonary pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Description / Table of Contents: Sommaire La conformité dynamique des poumons est une mesure des propriétés élastiques de ceux-ci, dans la gamme de respiration normale, et, est interprétée comme étant la relation entre les changements de pression transpulmonaire et ceux correspondants du volume des poumons. Cette relation est établie comme une anse pression/volume, à partir de laquelle on calcule la conformité comme étant la ligne de descente joignant les extrémités de l'anse. A cause de l'interférence cardiaque qui se superpose aux signaux normaux de volume et de pression, les anses de conformité se trouvent souvent sérieusement déformées, ce qui rend difficile l'établissement des extrémités de l'anse. Par conséquent, il est nécessaire de traiter au préalable les données mesurées afin d'éliminer les pulsations cardiaques superposées. Au cours des recherches décrites dans cet essai, nous avons appliqué des techniques de filtrage digital afin de récupérer les anses de conformité résultant uniquement d'une origine respiratoire. La conception d'un filtre digital, basée sur une technique “d'affichage”, est à l'étude. La méthode est appliquée pour filtrer les données de volume des poumons et de pression pulmonaire, obtenues grâce à des expériences réalisées sur des chats et des nouveaux-nés. On démontre ainsi l'efficacité du filtrage digital à récupérer les anses de conformité qui sont contaminées par la présence de pulsations cardiaques.
    Abstract: Zusammenfassung Die dynamische Lungencompliance ist eine Messung der elastischen Eigenschaften der Lunge im normalen Atembereich und wird als die Beziehung zwischen den transpulmonarischen Druckveränderungen und den korrespondierenden Veränderungen im Lungenvolumen gemessen. Diese Beziehung wird als Druckvolumenschleife dargestellt, aus der die Compliance als Steigung der Linie, die die Endpunkte der Schleife zusammenfügt, kalkuliert wird. Aufgrund der herzbezüglichen Interferenzen, die den normalen Druck und Volumensignalen übergelagert sind, sind die Complianceschleifen oft ernsthaft enstellt, was es sehr schwierig macht, die Endpunkte in der Schleife zu erkennen. Aus diesem Grund ist es erforderlich, die gemessenen Daten so vorzufertigen, daß die übergelagerten Herztöne beseitigt werden. In den in diesem Papier beschriebenen Nachforschungen haben wir eine digitale Filtertechnik zur Wiedergewinnung der Complianceschleifen, die allein aus der Atmung stammen, angewandt. Es wird die Konstruktionsmethode eines auf der “windowing”-Technik basierenden Digitalfilters beschrieben. Die Methode wird zum Filtern von transpulmonaren Druck- und Lungenvolumendaten aus Experimenten mit Katzen und Neugeborenen verwendet.
    Notes: Abstract Dynamic lung compliance is a measure of the elastic properties of the lungs in the normal breathing range and is measured as the relationship between the transpulmonary pressure changes and the corresponding changes in lung volume. This relationship is given as a pressure-volume loop, from which the compliance is calculated as the slope of the line joining the end points of the loop. Owing to cardiac interference, which is superimposed on the normal pressure and volume signals, the compliance loops are often severely distorted, making it difficult to establish the end points in the loop. Therefore it is necessary to preprocess the measured data so that the superimposed cardiac pulsations are eliminated. In the investigations that are described in this paper, we have applied digital filtering techniques to recover compliance loops resulting solely from respiratory origin. The design method of a digital filter based on ‘windowing’ technique is discussed. The method is applied for filtering transpulmonary-pressure and lung-volume data obtained from experiments with cats and neonates. The effectiveness of digital filtering in recovering the compliance loops which are contaminated by the presence of cardiac pulsations is shown.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1741-0444
    Keywords: Apnoeas ; Expired CO2 ; Near-miss infant ; Online respiratory monitoring ; Polygraphic recordings ; Sudden infant death syndrome ; Walsh transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract It has been postulated that the sudden infant death syndrome (s.i.d.s.) may sometimes be due to abnormal maturation or injury to the brain stem centres that regulate respiration. This functional abnormality of the brain stem respiratory centres may result in the interruption of the automatic inspiratory/expiratory cycle by recurrent periods of apnoea. There is a subgroup of infants known as ‘near-miss’ for s.i.d.s., who survived a prolonged apnoeic episode during sleep which may have resulted in death. In a number of recent studies, the near-miss infant has been clearly identified as an infant at high risk for s.i.d.s. Clinical studies conducted by using polygraphic and behavioural monitoring of near-miss infants have revealed numerous apnoeic episodes during sleep. Consequently, the clinical necessity of monitoring these babies in a paediatric care unit has become well established both for diagnostic purposes and for subsequent outpatient care. In view of these findings, it has become increasingly more important to develop advanced sophisticated computer methods for the on-line detection and processing of apnoeas during in-hospital monitoring of infants. This paper describes a digital computer method of on-line apnoea processing for application during the in-hospital monitoring of infants. The method is based on the application of Walsh transformations to the expired CO2 signal measured in infants using a Beckman CO2 analyser.
    Type of Medium: Electronic Resource
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