Medical & biological engineering & computing
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Med Biol Eng Comput · Jul 2008
A novel autonomic activation measurement method for stress monitoring: non-contact measurement of heart rate variability using a compact microwave radar.
We developed a novel method for non-contact monitoring of stress-induced autonomic activation through the back of a chair, using a compact 24 GHz microwave radar (8 x 5 x 3 cm), without large-scale equipment and placing a heavy burden on the monitored individual. Following a silent period of 120 s, audio stimuli using a composite tone of 2,120 and 2,130 Hz sine-waves at 95 dB were conducted for 120 s. ⋯ Maximum cross-correlations between contact and non-contact measurements averaged 0.73 +/- 0.10. Our method appears to be promising for future monitoring of stress-induced autonomic activation of operators and may reduce stress-induced accidents.
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Med Biol Eng Comput · Dec 2007
Development of a biofeedback tilt-table for investigating orthostatic syncope in patients with spinal cord injury.
The purpose of this study was to develop a biofeedback tilt-table for automatic tilt-table training, helping patients with spinal cord injury (SCI) to recover more rapidly from orthostatic hypotension, and increasing safety to avoid syncope during training. This biofeedback tilt-table implemented automatic training maneuvers and included three closed feedback loops to monitor the acquisition of physiological signals from patients and the feedback of presyncope symptoms (PS) to regulate the angle of tilt. The results of clinical testing revealed that the mean blood pressure and oxygen saturation represented the most useful physiological signals for determining PS feedback and the quantitative criteria adopted were practicable and useful in describing the level of PS. This novel biofeedback tilt-table system offered higher patient throughput, faster training and safety in training of SCI patients to overcome their orthostatic hypotension than traditional tilt-table training, and could provide quantitative information of PS to assist medical staff in studying the mechanism of orthostatic syncope.
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Med Biol Eng Comput · Aug 2007
Simulation of an anterior spine instrumentation in adolescent idiopathic scoliosis using a flexible multi-body model.
Anterior spinal instrumentation is an alternative option to posterior instrumentation for surgical treatment of adolescent idiopathic scoliosis (AIS). However, optimal instrumentation configuration and strategies are not yet clearly defined. A biomechanical kinematic model using flexible mechanism was developed to study instrumentation strategies. ⋯ The validated model was used to find optimal instrumentation configurations for one patient prior to surgery. Six strategies were tested out of which the optimal one was identified while two were not recommended for surgery since screw forces exceeded published pullout forces. This study demonstrates the possibility to simulate anterior spine instrumentations.
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Med Biol Eng Comput · Jul 2007
Predicting survival in critical patients by use of body temperature regularity measurement based on approximate entropy.
Body temperature is a classical diagnostic tool for a number of diseases. However, it is usually employed as a plain binary classification function (febrile or not febrile), and therefore its diagnostic power has not been fully developed. In this paper, we describe how body temperature regularity can be used for diagnosis. ⋯ Our results indicate there is a correlation between the patient's condition and the regularity of the body temperature. This finding enabled us to design a classifier for two outcomes (survival or death) and test it on a dataset including 36 subjects. The classifier achieved an accuracy of 72%.
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Med Biol Eng Comput · Jun 2007
Analysis of intracranial pressure during acute intracranial hypertension using Lempel-Ziv complexity: further evidence.
We analyzed intracranial pressure (ICP) signals during periods of acute intracranial hypertension (ICH) using the Lempel-Ziv (LZ) complexity measure. Our results indicate the LZ complexity of ICP decreases during periods of ICH. ⋯ The mean decrease of the LZ complexity values during the ICH episodes was 19.5%. Additionally, we present preliminary evidence suggesting that periods of ICH may be detectable from non-invasive signals coupled with ICP, such as pulse oximetry (SpO2).