Medical & biological engineering & computing
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Med Biol Eng Comput · Jan 2011
Acoustic thoracic image of crackle sounds using linear and nonlinear processing techniques.
In this study, a novel approach is proposed, the imaging of crackle sounds distribution on the thorax based on processing techniques that could contend with the detection and count of crackles; hence, the normalized fractal dimension (NFD), the univariate AR modeling combined with a supervised neural network (UAR-SNN), and the time-variant autoregressive (TVAR) model were assessed. The proposed processing schemes were tested inserting simulated crackles in normal lung sounds acquired by a multichannel system on the posterior thoracic surface. In order to evaluate the robustness of the processing schemes, different scenarios were created by manipulating the number of crackles, the type of crackles, the spatial distribution, and the signal to noise ratio (SNR) at different pulmonary regions. ⋯ Finally, the performance of the TVAR scheme was tested against a human expert using simulated and real acoustic information. We conclude that a confident image of crackle sounds distribution by crackles counting using TVAR on the thoracic surface is thoroughly possible. The crackles imaging might represent an aid to the clinical evaluation of pulmonary diseases that produce this sort of adventitious discontinuous lung sounds.
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Med Biol Eng Comput · Jan 2011
An endotracheal intubation confirmation system based on carina image detection: a proof of concept.
In this paper, a novel system for automatic confirmation of endotracheal intubation is proposed. The system comprises a miniature CMOS sensor and electric wires attached to a rigid stylet. Video signals are continuously acquired and processed by the algorithm implemented on a PC/DSP. ⋯ As an additional validation, the system was tested using a dataset of 231 video images recorded from five human subjects during intubation. The system correctly classified 120 out of 125 non-carina images (i.e. a sensitivity of 96.0%), and 100 out of 106 carina images (i.e. a specificity 94.3%). Using a 10th-order median filter, applied on the frame-based classification results, a 100% accuracy rate was obtained.
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Med Biol Eng Comput · Nov 2010
Improved breath alcohol analysis in patients with depressed consciousness.
Many patients in pre-hospital and emergency care are under the influence of alcohol. In addition, some of the more common pathological conditions can introduce a behaviour that can be mistaken to be related to alcohol inebriation. Fast quantitative determination of the breath alcohol concentration (BrAC) in emergency patients facilitates triage and medical assessment, but shallow expirations performed by non-cooperative patients reduce the measurement reliability. ⋯ With prototypes of a handheld breath alcohol analyser based on infrared transmission spectroscopy the alcohol and CO(2) concentration in expired breath from 37 cooperative and non-cooperative patients were measured. The results show that enhanced breath sampling with use of a pump and estimation of the end expiratory BrAC with use of the ratio between the measured partial pressure of CO(2) (PCO2) and a reference value of the alveolar PCO2, provided adequate correlation with the blood alcohol concentration (BAC). This pre-clinical study has shown that breath alcohol analysis in shallow expirations from non-cooperative patients can be improved with use of CO(2) as a tracer gas.
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Med Biol Eng Comput · Sep 2010
3D finite compartment modeling of formation and healing of bruises may identify methods for age determination of bruises.
Simulating the spatial and temporal behavior of bruises may identify methods that allow accurate age determination of bruises to assess child abuse. We developed a numerical 3D model to simulate the spatial kinetics of hemoglobin and bilirubin during the formation and healing of bruises. Using this model, we studied how skin thickness, bruise diameter and diffusivities affect the formation and healing of circular symmetric bruises and compared a simulated bruise with a natural inhomogeneous bruise. ⋯ The different spatio-temporal dynamics of hemoglobin and bilirubin allows age determination of model bruises. Combining our model predictions with individual natural bruises may allow optimizing our model parameters. It may particularly identify methods for more accurate age determination than currently possible to aid the assessment of child abuse.
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Med Biol Eng Comput · Aug 2010
Brain hypothermia induced by cold spinal fluid using a torso cooling pad: theoretical analyses.
Brain hypothermia induced by a temperature reduction of the spinal fluid using a torso-cooling pad is evaluated as a cooling alternative for traumatic injury patients. A theoretical model of the human head is developed to include its tissue structures and their contribution to local heat transfer. The Pennes bioheat equation and finite element analysis are used to predict the temperature distribution in the head region. ⋯ This approach is more effective during ischemia because it promotes deeper cooling penetration and results in larger temperature reductions; the average grey matter temperature decreases to 35.4 degrees C. Cooling in the white matter is limited and only occurs under ischemic conditions. The non-invasive nature of the torso-cooling pad and its ability to quickly induce hypothermia to the brain tissue are beneficial to traumatic injury patients.