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
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
In-vivo evaluation of a fiber-optic splanchnic photoplethysmographic sensor during open laparotomy.
There is a need for a reliable and continuous monitoring of abdominal organ oxygen saturation (SpO(2)). Splanchnic ischemia may ultimately lead to cellular hypoxia and necrosis and may well contribute to the development of multiple organ failures and increased mortality. A new prototype reflectance fiber optic photoplethysmographic sensor and signal processing system was evaluated on six anaesthetized patients undergoing elective laparotomy. ⋯ The normalized amplitudes of the splanchnic PPG signals were in good agreement with those obtained from the periphery using an identical fiber optic sensor. Furthermore, average SpO(2) values were in good agreement and showed correlation with those obtained from a commercial system. These preliminary results suggest that a miniaturized 'indwelling' fiber optic sensor may be a suitable method for pre-operative and post-operative evaluation of splanchnic organ SpO(2) and their health.
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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
Pulse rate analysis in case of central sleep apnea: a new algorithm for cardiac rate estimation.
This paper first describes the AM-FM demodulation of an arterial pressure signal. Although it is known to be efficient on signals modulated by breathing, we demonstrate that in case of lack of respiratory modulation (real or simulated central sleep apnea), the AM-FM algorithm doesn't perform well in heart rate extraction. ⋯ The error for cardiac frequency estimation is around 0.2 BPM (Beats Per Minute) versus 5.5 BPM for the AM-FM demodulation. Further experimentations will be performed (with this time both cardiac and respiratory assessments) and will deal with real sleep apnea cases.