15 Fakultätsübergreifend / Sonstige Einrichtung

Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/16

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1975 - 197911980 - 19835

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Author: search.filters.author.Schaldach, MaxSubject: search.filters.subject.600

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    Die Korrelationstechnik zur Überwachung fetaler Vitalfunktionen
    (1975) Nagel, Joachim H.; Thull, Roger; Schaldach, Max
    Durch die Anwendung neuer Techniken, insbesondere der Korrelationstechnik, soll die Meßwertgewinnung fetaler Vitalfunktionen verbessert, und damit die Effektivität elektronischer Überwachungsgeräte in der Perinatalmedizin gesteigert werden. Im folgenden werden die grundlegenden Untersuchungen über die Erkennung des fetalen QRS-Komplexes im vom Abdomen der Mutter abgeleiteten feto-maternellen EKG dargelegt.
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    Recording of uterine activity from the abdominal lead EMG
    (1980) Nagel, Joachim H.; Schaldach, Max
    With external tocography some form of pressure or force transducer is fastened to the abdominal wall by means of an elastic belt. Uterine contractions produce changes in the displacement of a sensor pin which acts on the transducer, producing an electrical signal that corresponds to the relative uterine pressure. External tocography, however, has the drawback that it is subject to many factors which may influence the results of the measurement. We feel that the limitations of tocography cannot be eliminated by technical improvements of the measuring equipment, and therefore the possibility of recording the uterine contractions from the abdominal lead electromyogram (EMG) without losing any information regarding tocography has been studied. As a result of the study it has become evident that the recording of uterine activity using the EMG is more reliable than tocography and offers even additional information about the excitation and propagation of the contractions. The basic methods that have been developed and the results of clinical tests are presented here.
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    The non-invasive assessment of the uterine activity
    (1983) Nagel, Joachim H.; Schaldach, Max
    All in all, uterine myographic recording has proved valuable in clinical trials. On account of the high information yield and the simplicity of handling, in particular for the simultaneous recording of fetal and maternal heart activity in addition to the uterine contraction curve, the procedure described is highly suitable for clinical routine work. The combined recording of the electrical activity of the myometrium and the intrauterine pressure will, it may be presumed, provide more information about the behaviour of the uterine musculature than either technique alone.
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    Entwurfsverfahren digitaler Filter
    (1982) Zhou, Li Gao; Kartmann, Peter; Nagel, Joachim H.; Schaldach, Max
    Die Anwendung digitaler Filter in der biomedizinischen Technik bringt gegenüber Analogfiltern wesentliche Vorteile. Vor allem erleichtert die große Flexibilität digitaler Systeme die Anpassung an das jeweilige Meßproblem, wobei in der vorliegenden Arbeit die Optimierung des Signal-Rauschverhältnisses bei biologischen Summensignalen wie Elektrokardiogramm (EKG) und Phonokardiognunm (PKG) im Vordergrund steht. Während bei der Realisierung von digitalen Filtern im allgemeinen Filtercharakteristiken durch digitale Computeralgorithmen approximiert werden, die einen sehr hohen Rechenaufwand erfordern, werden in der vorliegenden Arbeit digitale Filterprinzipien vorgestellt, die ein Minimum an Rechenzeit, Zeitaufwand bei der Verwirklichung und geringe Anforderungen an Spezialkenntnisse digitaler Filteralgorithmen erfordern. Die Wirksamkeit des Verfahrens wird an der phonographischen Analyse der beat to beat-Bestimmung der fetalen Herzfrequenz demonstriert.
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    An implantable artificial pancreas
    (1980) Schubert, Wolfgang; Baurschmidt, Peter; Nagel, Joachim H.; Thull, Roger; Schaldach, Max
    The artificial implantable pancreas is seen as the optimal means of therapy in patients with severe diabetes mellitus. The implantable pancreas consists of three modules; (i) the dosing unit, (ii) the control circuit and (iii) a glucose sensor for the realisation of a feedback system. Intensive research has been devoted to essential items, such as a dosing valve with only minimal susceptibility to interference, the design of an electrochemical sensor for continuously monitoring the glucose level, and design criteria for data transfer between an external programmer/monitor and the implant.
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    Processing the abdominal fetal ECG using a new method
    (1980) Nagel, Joachim H.; Schaldach, Max
    The performance of the method described above has been assessed in clinical trials. Comparing the results with those obtained using the earlier techniques of abdominal ECG processing showed a mean increase in the detection rate of the fetal QRS complexes of about 60%. When compared to fetal heart frequency recordings using ultrasonocardiography or phonocardiography the new method shows an important improvement with respect to the evaluation of short term variations of heart frequency.In addition to a bad signal to noise ratio the analysed abdominal signal showed a high rate of coincidence between maternal and fetal QRS complexes. Using simple threshold logic the measurement is obtained if the maternal ECG is subtracted prior to the threshold analysis of the signal. However, the necessary reliability is only achieved when both the maternal ECG is eliminated and a correlation analysis of the residual signal is performed. Comparing the FHF computed simultaneously from the scalp-lead ECG (A) and the abdominal ECG (8) shows that in most cases there is no loss of information when using the new non-invasive technique. In conclusion, it can be stated that the reliability of 'beat-to-beat' measurement of the fetal heart frequency could be significantly improved by employing the new analysis procedure. the resulting FHF curve cannot be employed clinically. An improvement of the measurement is obtained if the maternal ECG is subtracted prior to the threshold analysis of the signal. However, the necessary reliability is only achieved when both the maternal ECG is eliminated and a correlation analysis of the residual signal is performed.