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
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.
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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
Estimation of the aortic pressure waveform from a radial artery pressure waveform via an adaptive transfer function: Feasibility demonstration in swine.
We previously proposed a new technique to estimate the physiologically and clinically more relevant central aortic pressure (AP) waveform from a conveniently and safely measured peripheral artery pressure (PAP) waveform distorted by wave reflections. In contrast to conventional generalized transfer function (GTF) techniques, the technique is able to adapt the transfer function relating PAP to AP to the inter-patient and temporal variability of the arterial tree by defining it through a tube model and invoking the fact that aortic flow is negligible during diastole to estimate the unknown model parameters. We conducted feasibility testing of this adaptive transfer function technique here with respect to radial artery pressure (RAP) waveforms, for the first time, as well as femoral artery pressure (FAP) waveforms from four swine instrumented with AP catheters during several hemodynamic conditions. Our results showed that the AP waveforms estimated by the technique from the RAP and FAP waveforms were in superior agreement to the measured AP waveforms (overall respective errors of 4.1 and 4.8 mmHg) than the two unprocessed PAP waveforms (9.1 and 8.1 mmHg) and a previous GTF technique trained on a subset of the same data (5.0 and 5.8 mmHg).
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Conf Proc IEEE Eng Med Biol Soc · Jan 2009
Evaluation of three automatic oxygen therapy control algorithms on ventilated low birth weight neonates.
Neonates with under developed lungs often require oxygen therapy. During the course of oxygen therapy, elevated levels of blood oxygenation, hyperoxemia, must be avoided or the risk of chronic lung disease or retinal damage is increased. ⋯ All 3 automatic control algorithms demonstrated their ability to improve manual oxygen therapy by increasing periods of normoxemia and reducing the need for manual FiO(2) adjustments. Of the three control algorithms, the adaptive model showed the best performance with 0.25 manual adjustments per hour and 73% time spent within target +/- 3% SpO(2).
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Conf Proc IEEE Eng Med Biol Soc · Jan 2009
FDA regulation of clinical high intensity focused ultrasound (HIFU) devices.
In the U. S., medical devices are regulated under the authority of the 1976 Medical Device Amendments to the Food, Drug, and Cosmetic Act, with the Food and Drug Administration's Center for Devices and Radiological Health having primary responsibility. The Act defines several regulatory paths to market depending on the complexity of the device and indications for use. ⋯ Pre-clinical testing generally comprises ultrasound power measurements and field characterization, in vitro and in vivo temperature measurements, thermal computational modeling, and demonstrating the accuracy for targeting the region of interest and monitoring treatment progress. Protocols for clinical trials are developed by the device sponsor in conjunction with FDA medical and scientific staff. Currently there are no recognized guidance or standards documents for HIFU testing that could be used in the regulatory review process, but such work is underway within the International Electrotechnical Commission.