Biomedizinische Technik. Biomedical engineering
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Case Reports
Laser Doppler flowmetry--peripheral microcirculation during cessation of cerebral and cardiocirculatory function.
Laser Doppler flowmetry (LDF) is a noninvasive method to study the microcirculation. We studied the feasibility of the clinical use of LDF in the intensive care unit by continuously recording different LDF parameters during the cessation of cerebral and cardiocirculatory function. The LDF-Conc (concentration of red blood cells) reflected biological phenomena correlated with the heart rate and microvibration that could not be detected with conventional means (systemic blood pressure, peripheral oxygen saturation).
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Instrumental monitoring is being increasingly employed in the postoperative phase after microsurgery. For this purpose, laser Doppler flowmetry has proven to be very useful. ⋯ For this purpose, the software program "call-doc" was developed, which provides the necessary monitoring and control functions. A general perfusion-independent emergency call can also be triggered at the touch of a button.
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The effects of orthotopic heart transplantation on spontaneous fluctuations of the respiration rate and heart rate were studied with a computer-assisted system for neurovegetative monitoring in 22 patients (mean age +/- SD: 48.7 +/- 9.4 years) 19.5 +/- 14.4 months after transplantation. The control group consisted of 12 healthy volunteers (mean age +/- SD: 38.7 +/- 6.6 years). The mean (+/- SE) respiratory rate was higher in the transplantation group than in the control group (17.7 +/- 0.8/min vs. 14.6 +/- 1.1 breaths/min, P < 0.2). ⋯ A separate group of 7 transplant patients (mean age 51.0 +/- 7.7 years) had activated cardiac pacemakers and thus no spontaneous physiologic heart rate oscillations. The variability of the respiratory rate in these patients was lower than in the other 22 transplant patients (1.8 +/- 0.2 vs. 3.7 +/- 0.3, P < 0.001). The data provided by multiparametric neurovegetative monitoring support the evaluation of complex regulatory mechanisms of respiratory and cardiovascular function and their adaptability after orthotopic heart transplantation.
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In EEG analysis an automatic pattern recognition is of interest. In this paper the usefulness of autoregressive parameters to classify EEG segments recorded during anesthesia is examined. ⋯ The results show that AR parameters have high discriminating power and that the lowest error classification rate (smaller than 3%) is obtained by using quadratic discriminant functions. Consequently autoregressive parameters are efficient for classifying EEG segments into general stages of anesthesia.
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For the acquisition of subjective variables in outpatients and inpatients, a new device--the Rating Box--has been designed. The Rating Box provides a standardized, date- and time-logged documentation of symptoms by the patient and rapid transfer of data to a personal computer. ⋯ The acoustic alarm of the Rating Box reminds the patient to enter data at preselected times. The device is easy to handle, even by older patients, and has been successfully tested in the acquisition of pain variables in patients with a variety of painful conditions.