Biomedical Signal Processing / Medical Signal Processing / Biosignal Processing
Mina Amiri; Edmond Zahedi; Fereydoun Behnia
Volume 7, Issue 1 , June 2013, , Pages 85-95
Abstract
It is proved that the endothelial (artery inner lumen cells) function is associated with cardiovascular risk factors. Among all the common non-invasive methods employed in the research setting for assessing endothelial function, flow-mediated dilation is the most widely used one. This technique measures ...
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It is proved that the endothelial (artery inner lumen cells) function is associated with cardiovascular risk factors. Among all the common non-invasive methods employed in the research setting for assessing endothelial function, flow-mediated dilation is the most widely used one. This technique measures endothelial function by inducing reactive hyperemia using temporary arterial occlusion and measuring the resultant relative increase in blood vessel diameter via ultrasound. In this paper, the limitations associated with the ultrasound technique are overcome by using the photoplethysmogram (PPG) signal recorded during FMD. The correctness of this approach is investigated by modeling the AC changes of PPG after FMD by a 2nd order autoregressive model. A sensitivity of 78.6%, specificity of 81.6% and total accuracy of 80% were achieved in classification of 16 healthy and 14 diabetic subjects.
Zahra sadat Hosseini; Mohadese Arabgari; Ali Farmad; Leili Goldoozian; Hamid Reza Maghari; Sara Aghajari; Edmond Zahedi
Volume 7, Issue 3 , June 2013, , Pages 277-285
Abstract
In this article a wireless patient monitoring system for vital signs (respiratory rate and heart beat) is presented. The recorded biosignal is the photoplethysmogram using a probe attached to the patient's finger. This signal is amplified, filtered and digitized by an on-board processor unit before finally ...
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In this article a wireless patient monitoring system for vital signs (respiratory rate and heart beat) is presented. The recorded biosignal is the photoplethysmogram using a probe attached to the patient's finger. This signal is amplified, filtered and digitized by an on-board processor unit before finally being sent wirelessly via a transmitter. The capacity of the current system is 16 patients whose data can be received through a common receiver by a central server which measures and displays the heart beat and respiratory rate for each patient on the monitor.
Biomedical Signal Processing / Medical Signal Processing / Biosignal Processing
Adib Keikhosravi; Edmond Zahedi
Volume 6, Issue 4 , June 2012, , Pages 307-317
Abstract
The photoplethysmogram (PPG) is a low cost and ubiquitous signal and has always had a great significance in cardiovascular parameter identification such as arterial dilation due to a stimulus. The PPG is generally recorded from the fingertip which is affected by the auto-regulation mechanism (ARM), preventing ...
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The photoplethysmogram (PPG) is a low cost and ubiquitous signal and has always had a great significance in cardiovascular parameter identification such as arterial dilation due to a stimulus. The PPG is generally recorded from the fingertip which is affected by the auto-regulation mechanism (ARM), preventing the results to be well correlated with standard methods based on imaging the brachial or radial artery. Based on the fact that the ARM has no effect on conduit arteries, the correlation between fingertip and radial artery PPG is investigated in this work. A custom made probe is fabricated using an array of photodiodes and a 960 nm LED for recording the wrist photoplethysmogram (PPG). The design is based on Monte-Carlo simulation of light propagation in tissues. Two series of experiments were carried-out: normal breathing and deep breathing. In both experiments, index finger and wrist PPG were simultaneously recorded. In the first series of experiments, signals from 9 subjects were recorded and the correlation coefficient for the raw signals (AC+DC), the AC and DC components of wrist and finger PPG were 62.5% ± 12.1%, 91.2% ± 6.9% and 61% ± 13.4% respectively. In the second series of experiment (deep breathing), signals from 6 subjects were recorded and the correlation coefficient for the raw signals (AC+DC), the AC and DC components were 89.7% ± 5.9%, 93.7% ± 3.3% and 89.9% ± 5.9% respectively. These results show that under normal breathing conditions, only the AC components of the PPG signals are highly correlated. When respiration becomes the dominant effect, both AC and DC parts become highly correlated.
