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 2009
Hemodynamic models of cerebral aneurysms for assessment of effect of vessel geometry on risk of rupture.
Surgical decisions on treatment of cerebral aneurysms are based predominantly on aneurysm size. This study has assessed the influence of parent vessel geometry on intra-aneurysmal flow patterns and mass flow rate using computational fluid dynamics and finite element modeling of straight and curved vessels feeding saccular aneurysms of varying size and aspect ratio. ⋯ The dependency of parent vessel geometry is a function of aneurysm aspect ratio and shows minimal dependency at an aspect ratio of 1.68. These findings could be used for improved quantification of risk of rupture of cerebral aneurysms detected from clinical imaging modalities and to aid surgical decision making.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2009
Noninvasive cardiac output estimation using a novel photoplethysmogram index.
Cardiac output (CO) monitoring is essential for indicating the perfusion status of the human cardiovascular system under different physiological conditions. However, it is currently limited to hospital use due to the need for either skilled operators or big, expensive measurement devices. Therefore, in this paper we devise a new CO indicator which can easily be incorporated into existing wearable devices. ⋯ After least squares linear regression, the precision between CO(imp) and CO estimated from IHAR (CO(IHAR)) was 1.40 L/min. The total percentage error of the results was 16.2%, which was well below the clinical acceptance limit of 30%. The results suggest that IHAR is a promising indicator for wearable and noninvasive CO monitoring.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2009
Critiquing treatment and setting ventilatory parameters by using physiological modeling.
A modeling system is presented that can be used to predict the effects of ventilatory settings on the blood gases of patients on mechanical ventilation. The system uses a physiological model of the patient that includes lungs, body tissue, and brain tissue compartments. The model includes the effects of changes in the cardiac output and cerebral blood flow and lung mechanical factors. The system has applications in critiquing different treatment options and can be used alone or in combination with decision support systems to set ventilatory parameters and optimize treatment for patients on mechanical ventilation.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2009
Using A-weighting for psychoacoustic active noise control.
Conventional adaptive active noise control (ANC) methods aim to attenuate the acoustic noise over the frequency band of interest indiscriminately using the sound pressure level (SPL) measurement (or the measurement of the residual error variance). However, SPL does not correctly reflect the human perception of attenuated noise due to the frequency selective sensitivity of human hearing system. A-weighting is a commonly used weighting filter for measuring the noise. ⋯ In this paper, we aim to improve the performance of adaptive noise cancellation method from the psychoacoustic point of view by incorporating the A-weighting into the ANC system design. Loudness is used as the psychoacoustic criterion for evaluating the ANC system performance. Simulation results illustrate the effectiveness of the proposed method.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2009
Revisiting the video stethoscope: an application of digital signal processing software (Goldwave) to monitoring ventilation in intubated patients.
Problems with tracheal intubation and mechanical ventilation are potentially important causes of perioperative morbidity and mortality. We have developed a method of monitoring the ventilation of both lungs during general anesthesia that is an advanced digital version of a more primitive analog technique developed over two decades ago. We used two miniature electret microphones connected to regular chest pieces, placing the assemblies on the anterior chest wall about 4 inches below the clavicle in the midclavicular line. ⋯ We also hypothesized that as a result of noise and anatomical variations that under conditions of bilateral mechanical ventilation the obtained plot would be very different from a simple 45 degree line. The data obtained supports these hypotheses. This preliminary study suggests that our technique may help provide a practical real-time warning system for detecting endotracheal tube malpositions, and may help build on the work of other investigators.