Biomedizinische Technik. Biomedical engineering
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Medical research confirmed the relevance of diagnosis and therapy of sleep-related breathing disorders, revealing prevalence and patho-physiological mechanisms [1-10]. Reliable sleep assessment currently demands examinations in the sleep-lab, which is very technical and time-consuming. ⋯ As a solution, the authors present telemetric system concepts for the unattended assessment of a patient's sleep profile and cardio-respiratory parameters. Taking initial experience with home polysomnography into consideration, the presented research work focuses on easily applicable sensors, the corresponding sleep profile assessment rules, wireless data recording, intelligent signal processing algorithms and telemedical information logistics to include sleep-labs in the diagnosis and treatment process as competence centers.
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Impacts of hypnotic drugs on brain function are reflected in the EEG. The EEG monitor Narcotrend performs an automatic classification of the EEG using a scale which was proposed by Kugler for visual evaluation of the EEG. ⋯ The correlation between visual and automatic assessment was high (Spearman rank correlation r = 0.90, prediction probability Pk = 0.90) and a sufficient agreement between visual and automatic assessment was achieved for 92% of the analysed EEG epochs. The results of the study suggest that the automatic classification algorithms implemented in the EEG monitor Narcotrend yield a reliable assessment of the depth of hypnosis.
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Magnetic resonance imaging (MRI) is still contraindicated in patients with implanted active medical devices, as the applied radiofrequency (RF) fields can lead to significant heating of the implants and the electrodes. A head model with an implanted deep brain stimulation electrode (DBS) was exposed to a continuous RF-field similar to the excitational field used in MRI at a frequency of 64 MHz. ⋯ Then a thermodynamic algorithm taking heat transfer mechanisms into account was used. The applied method showed to be numerically stable and gave more accurate results than first calculated using a simple worst-case approximation.
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An important question during the intensive care of patients with subarachnoid hemorrhage and craniocerebral trauma is the evaluation of the cerebral autoregulation (CA). The so called Aaslid-Test is a standard method which allows the cerebral autoregulation to be classified. As the results under repetitive conditions show a high variation, it has not been yet possible to draw statistically proved conclusions concerning the performance of the CA. ⋯ The algorithms of the Aaslid-Test have been implemented to an online measuring system. The error bandwidth has been estimated. To avoid systematically occurring errors an enhanced measuring protocol is provided.
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During extracorporeal circulation, many important circulatory parameters are unknown, being inaccessible for measuring probes, as e.g. the perfusion of the brain. An observer system, which estimates such patient variables continuously throughout the operation, can extend the information basis for the decisions of the perfusionist regarding the control of the heart-lung machine and thus contribute to adjust this operation procedure to the actual patient situation. ⋯ Beside the classical Luenberger observer design, a rule-based approach has been tested, which is also based on the structure of a Luenberger observer, however instead of an observer matrix a correction algorithm has been used in the feedback loop. A prototype of this system for animal experimental and clinical evaluation has been realised.