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 2014
Wearable seismocardiography for the beat-to-beat assessment of cardiac intervals during sleep.
Seismocardiogram (SCG) can be detected during sleep by a textile-based wearable system. This pilot study preliminarily explores the feasibility of a beat-to-beat estimation of cardiac mechanical features (RR interval, RRI, Pre-Ejection Period, PEP, Isovolumic Contraction Time, ICT, Left Ventricular Ejection Time, LVET, Isovolumic Relaxation Time, IRT) from the joint ECG and SCG assessment during sleep. ⋯ These findings represent the very first description of the beat-to-beat variability of cardiac mechanical indexes. Further investigations on a larger population are in progress to confirm the present results.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2014
Prediction of mortality from respiratory distress among long-term mechanically ventilated patients.
With the advent of inexpensive storage, pervasive networking, and wireless devices, it is now possible to store a large proportion of the medical data that is collected in the intensive care unit (ICU). These data sets can be used as valuable resources for developing and validating predictive analytics. In this report, we focus on the problem of prediction of mortality from respiratory distress among long-term mechanically ventilated patients using data from the publicly-available MIMIC-II database. ⋯ We also find that variables related to respiration rate have more predictive accuracy than variables related to oxygenation status. Ultimately, we have developed a model which predicts mortality from respiratory distress in the ICU with a cross-validated area-under-the-curve (AUC) of approximately 0.74. Four methodologies are utilized for model dimensionality-reduction: univariate logistic regression, multivariate logistic regression, decision trees, and penalized logistic regression.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2014
Design and fabrication of a multi-electrode array for spinal cord epidural stimulation.
A detailed design, fabrication, characterization and test of a flexible multi-site platinum/polyimide based electrode array for electrical epidural stimulation in spinal cord prosthesis is described in this paper. Carefully designed 8.4 μm-thick structure fabrication flow achieves an electrode surface modification with 3.8 times enhanced effective surface area without extra process needed. Measured impedance and phase of two type of electrodes are 2.35±0.21 KΩ and 2.10±0.11 KΩ, -34.25±8.07° and -27.71±8.27° at 1K Hz, respectively. ⋯ The measured charge transfer resistance, double layer capacitance, and solution resistance are 1.9 KΩ, 220 nF and 15 KΩ, respectively. The results show that the fabricated array is applicable for electrical stimulation with well characterized parameters. Combined with a multichannel stimulator, this system provides a full solution for versatile neural stimulation applications.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2014
Computational modeling analysis of a spinal cord stimulation paddle lead reveals broad, gapless dermatomal coverage.
Spinal cord stimulation (SCS) is an effective therapy for treating chronic pain. The St. Jude Medical PENTA(TM) paddle lead features a 4 × 5 contact array for achieving broad, selective coverage of dorsal column (DC) fibers. ⋯ We found that across contact configurations used clinically in the sweep algorithm, the activation region shifted smoothly between left and right DC, and could achieve gapless medio-lateral coverage in dermatomal fiber tract zones. Increasing stimulation amplitude between the DC threshold and discomfort threshold led to a greater area of activation and number of dermatomal zones covered on the left and/or right DC, including L1-2 zones corresponding to dermatomes of the lower back. This work demonstrates that the flexibility in contact selection offered by the PENTA lead may enable patient-specific tailoring of SCS.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2014
Comparative StudyComparison of methods for determining pulse arrival time from Doppler and photoplethysmography signals.
The aim of this study was to compare three foot-finding methods applied to ultrasound Doppler and photoplethysmographic (PPG) signals: maximum 1st derivative, maximum 2nd derivative and an 'intersecting tangents' method. The pulse arrival times of each method were compared. ⋯ The results show that the maximum 1st derivative method produced significantly larger pulse arrival times than the other two methods. The intersecting tangents method produced greatest precision for cardiac periods compared with ECG than maximum 1st or 2nd derivatives for both Doppler (r(2) = 0.975) and PPG (r(2) = 0.987) signals.