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 2012
Comparative study between Sample Entropy and Detrended Fluctuation Analysis performance on EEG records under data loss.
This study compares two signal entropy measures, Sample Entropy (SampEn) and Detrended Fluctuation Analysis (DFA) over real EEG signals after a randomized sample removal. Both measures have demonstrated their ability to discern between, among others: control and pathologic EEG signals, seizure free or not, control and opened eyes EEG, and side of brain signals. Results show that SampEn behaves better when analyzing control signals, while DFA provides better segmentation results between epileptic signals, in the context of sample loss, particularly when discerning between seizure and seizure free signal intervals.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2012
Stroke volume obtained from the brachial artery using transbrachial electrical bioimpedance velocimetry.
Stroke volume (SV) is the quantity of blood ejected by the cardiac ventricles per each contraction. When SV is multiplied by heart rate, cardiac output is the result. Cardiac output (CO), in conjunction with hemoglobin concentration and arterial oxygen saturation are the cornerstones of oxygen transport. ⋯ The technique involves passage of a constant magnitude, high frequency, and low amperage ac from the upper arm to the antecubital fossa. In all other respects, the operational aspects of TBEV are consistent with ICG. There is good evidence suggesting that the TBEV waveform and its derivatives are generated by blood resistivity changes only.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2012
Effect of arching spine on deformation of the ligamentum flavum during epidural needle insertion.
When administering epidural anesthesia, anesthesiologists ask patients to arch their back. Arching the spine is thought to enlarge the gap between neighboring vertebral bones. The author hypothesized that tension inside the ligamentum flavum generated by arching the spine would reduce deformation of the ligamentum flavum during epidural needle insertion. ⋯ For the maximum reaction force the coefficient of variance decreased by dividing raw data with thickness of the ligamentum flavum, which meant that the maximum reaction force correlated with thickness of the ligamentum flavum. Less effect on deformation was observed. Hypothesis was correct in the porcine study, while the difference between the porcine and the patient's spine should be examined in the next research.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2012
Clinical TrialEffects of propofol anesthesia induction on the relationship between arterial blood pressure and heart rate.
This paper presents the analysis of autonomic nervous system (ANS) control of heart rate (HR) and of cardiac baroreflex sensitivity (BRS) in patients undergoing general anesthesia for major surgery through spectral analysis techniques and with the Granger causality approach that take into account the causal relationships between HR and arterial blood pressure (ABP) variability. Propofol produced a general decrease in ABP due to its vasodilatory effects, a reduction in BRS, while HR remained unaltered with respect to baseline values before induction of anesthesia. The bivariate model suggests that the feedback pathway of cardiac baroreflex could be blunted by propofol induced anesthesia and that the feedforward pathway could be unaffected by anesthesia.
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Sternal seismocardiogram (SCG) is the assessment of microvibrations produced by the beating heart as detected by an accelerometer positioned on the sternum. This signal reflects mechanical events of the heart contraction, including the opening and closure of mitral and aortic valves and maximal blood flow acceleration. Traditionally, SCG has been detected in a laboratory setting with the subject lying at rest in supine position. ⋯ A large number of SCG estimates could be obtained over the 24 hours. In particular, more than 100 estimates per hour were available during the day; at night this rate was three times higher. Thus our study indicates that not only the 24h SCG monitoring in daily life is feasible but also that possible changes over time in SCG and its derived parameters may be tracked with an extreme temporal detail.