Biomedizinische Technik. Biomedical engineering
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Approximate entropy, a measure of regularity, can be used to analyze the electroencephalogram of patients in general anesthesia to discriminate between different states of consciousness. EEG burst suppression patterns reflect a state of deep anesthesia. ⋯ Possible solutions to this problem may be limited by the demand of computing power for entropy calculation and the reaction time following changes in patient state. Different approaches for an online monitoring application are examined.
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Comparative Study
[Variability of ventilation parameters of home ventilation equipment].
The performance of pressure- and volume controlled ventilators used for invasive and non-invasive ventilation in the home were tested on a patient lung model. In order to determine the influence of tidal volume preset, breathing rate, resistance, compliance and leakage to the variability of delivered tidal volume and peak airway pressure a factorial plan with adapted analysis of variance was used. The influence of tidal volume preset, compliance and leakage to the delivered tidal volume is significant. ⋯ All tested ventilators meet the legal demands. But in some clinical situations there are considerable deviations of the breathing parameters depending on the brand. In conclusion ventilators of different brands are not interchangeable.
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Supplying organs and body tissues with sufficient oxygen is one of the most important vital human functions. Commercial pulse oximeters compute the functional oxygen saturation from relative values (reduced hemoglobin and oxyhemoglobin). Methemoglobin (MetHb) and carboxyhemoglobin (COHb) are not taken into account, since they are considered to be reduced hemoglobin and oxyhemoglobin (RHb, HbO2). ⋯ In this work, a non-invasive pulse oximeter is developed, which finds the entire hemoglobin concentration photometrically, and measures the fractional oxygen saturation and pulse rate. The signal of transmitted light I is processed according to the Lambert-Beer-law. The signal decays exponentially with the thickness d of the irradiated sample and its absorption coefficient alpha (I = I0 e -alpha d), where I0 is the incident light intensity.
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In this paper we present the medical augmented reality system INPRES for Intraoperative Presentation of surgical planning and simulation results. The system is based on a see-through head-mounted display for data visualization and overlay. ⋯ Further tasks are detection of occlusions, intuitive man-machine-cooperation and evaluation of the complete setup. The system configuration and the methods are shown, first results are given and future work is outlined.