Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference
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Conf Proc IEEE Eng Med Biol Soc · Jan 2008
Comparative StudyPower analysis of gamma frequencies (30 - 47Hz), adjusting for muscle activity (80 - 97Hz), in anesthesia: a comparison between young adults, middle-aged and the elderly.
This study looks at the role of EEG gamma activity, and the influence of facial EMG (80-97 Hz), in predicting consciousness during anesthesia. It also studies the association between the conventional depth of anesthesia index, BIS (Aspect Medical Systems), and EEG gamma and EMG activity. Data has been collected from 21 adult patients and grouped into young adults (18 - 39 yrs, n=3), middle-aged (40 - 64 yrs, n=10) and the elderly (65+ yrs, n=8). ⋯ There are two exceptions to this. In the young adults group there is a stronger association between BIS index and EEG gamma than there is between BIS index and EMG. In the elderly group, the state of consciousness is equally associated with EEG gamma and EMG recorded from the Masseter, but not with the EMG recorded from Fpz.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2008
Imaging of simulated crackle sounds distribution on the chest.
Crackles sounds have been associated with several pulmonary pathologies and diverse algorithms have been proposed for extracting and counting them from the acquired lung sound. These tasks depend among other factors, of the relation between the magnitude of the crackle and the background lung sound. In this work, we explore multivariate signal processing to deal with the tasks and propose a new concept, the discontinuous adventitious sounds imaging. ⋯ In the first case, the AR coefficients feed an artificial neural network (ANN) to classify temporal acoustic information as healthy or sick and; in the second case, a time-variant AR (TVAR) model, obtained by the RLS algorithm, permits to detect changes in the TVAR coefficients to be associated with the number of crackles. For AR-ANN, the ratio of the temporal windows classified as sick to the classified as healthy is used as an index to form the adventitious image, while for TVAR-RLS, an estimation of the number of crackles is obtained to form the corresponding image. The results indicated that fine and coarse crackles could be detected and counted even with very low crackle magnitude so that the formation of a crackle distribution image was consistent.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2008
EEG spectral changes and onset of burst suppression pattern in propofol/remifentanil anesthesia.
This paper studies how remifentanil, a commonly used intraoperative opioid, affects the relation of the onset of burst suppression pattern (BSP) and the spectral changes of EEG during anesthesia. The onsets of BSP were detected using both manual and the automatic method proposed from the EEGs of twenty-seven patients who had received different amount of remifentanil with the anesthetic. ⋯ The results showed that remifentanil significantly affects the relation of EEG spectral changes and the onset of BSP. The finding is important since the current EEG-based assessment of the depth of anesthesia basically relies on the analysis of the spectral features and BSP.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2008
Automatic identification of lumbar level with ultrasound.
An ultrasound-based system is created to label the lumbar vertebrae for the purpose of percutaneous needle insertion. Many lumbar punctures have a preferable vertebral level for needle insertion, but the traditional method of manual palpation is known to be inaccurate for determining the level. Needle insertion for epidural anesthesia in obstetrics is preferably performed at the L3-L4 interspace and miscalculation can lead to complications such as nerve damage and paralysis. ⋯ The vertebrae are labeled with a novel image processing algorithm. Since the coccyx is relatively easy to locate by palpation, the labels of the vertebrae from the panorama can be converted to skin location on the subject. The method is validated against independent measurements by a sonographer.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2008
Predicting ICU hemodynamic instability using continuous multiparameter trends.
Identifying hemodynamically unstable patients in a timely fashion in intensive care units (ICUs) is crucial because it can lead to earlier interventions and thus to potentially better patient outcomes. Current alert algorithms are typically limited to detecting dangerous conditions only after they have occurred and suffer from high false alert rates. Our objective was to predict hemodynamic instability at least two hours before a major clinical intervention (e.g., vasopressor administration), while maintaining a low false alert rate. ⋯ Area under receiver-operating curve (ROC) 0.83+/-0.03, sensitivity 0.75+/-0.06, and specificity 0.80+/-0.07; if the specificity is targeted at 0.90, then the sensitivity is 0.57+/-0.07. Based on our preliminary results, we conclude that the algorithms we developed using HR and BP trend data may provide a promising perspective toward reliable predictive alerts for hemodynamically unstable patients.