Rosmina Jaafar

Finger photoplethysmogram pulse amplitude changes induced by flow-mediated dilation

This study was conducted to investigate the utility and efficacy of finger photoplethysmogram pulse amplitude (PPG-AC) in comparison with the standard Doppler ultrasound in assessing an endothelial function via flow-mediated dilation (FMD). High-resolution B-mode scanning of the right brachial artery (BA) of 31 healthy subjects aged 39.7 +/- 11.3 (range 22-64) years and 52 risk subjects aged 47.7 +/- 10.8 (range 30-65) years were performed before and after 4 min of upper arm occlusion. Concurrent with the ultrasound measurement (where color Doppler imaging was used to enhance arterial boundary detection), PPG signals were recorded from both index fingers for cross evaluation and comparison. Our results show that the finger PPG-AC exhibits a similar response to that of the well-known BA dilation: following the release of pressure (cuff around the BA), the PPG-AC increases abruptly before slowly decreasing toward the baseline. The peak PPG-AC is reached significantly faster than the peak FMD measured by ultrasound among healthy and risk groups (P < 0.001). The proposed technique using a finger photoplethysmogram can be applied in a rapid and non-invasive assessment of peripheral vascular functions as an alternative low-cost and less operator-dependent tool compared to ultrasound.

Photoplethysmographic Pulse Amplitude Response to Flow Mediated Dilation

In this paper, the photoplethysmographic (PPG) pulse amplitude response to flow-mediated dilation (FMD) is investigated. Vessel dilation is induced in the right-arm brachial artery (BA) in response to a shear force due to the sudden opening of the BA following supra-systolic blockage of blood supply for 4 minutes. The diameter of the BA is recorded through ultrasound imaging measurement before and after blockage. Concurrently, PPG of the left and right index fingers are recorded before blood occlusion (baseline) and after release. Results on ten human subjects (age 49.7 ± 10.4 years, range 34–64 years) show that the PPG pulse amplitude measured at the finger of the stimulated arm shows a very distinctive pattern associated to the FMD in the conducting artery. A potential application for the proposed technique is the evaluation of the vascular endothelial function, using a significantly lower-cost and less operator-dependent alternative to conventional ultrasound-FMD.

A study on EEG signals during eye-closed and eye-open using discrete wavelet transform

Analysis of the electroencephalogram (EEG) signal is a popular method for brain activity tracing. However, a precise experiment design is required in ensuring accuracy and reliability of the recorded signals. This includes the eye state whether to be in a closed or open position based on the experiment requirement. In this study, we have demonstrated significant difference between EC and EO in terms of sub-band frequencies using discrete wavelet transform (DWT). The average percentage energy for DWT coefficients related to delta and theta waves are significantly decreased while interestingly, the percentage energy for DWT coefficients related to alpha waves increased significantly from EO to EC. Meanwhile, there is no significant change in the DWT coefficients related to beta and gamma waves. The significant change is determined when p-value is less than 0.01 for an independent t-test. We conclude that this study has proven that it is important to maintain specific eye states during EEG recording to avoid misinterpretation on the analysis of the brain activities.

T100. Computerized Recognition of Epileptic Discharge (CREED) algorithm and its clinical application

Introduction Clinical examination and electroencephalography (EEG) testing remain the gold standards for diagnosis of epilepsy. Unfortunately, these techniques require experienced epileptologist and highly time consuming activity, adversely impacting treatment decisions and leading to delays in treatment. Until recently, software computation has been neglected in the assessment of epileptic discharge. The advancement in computational technology offers reliable method for evaluating the electrophysiological changes in EEG during epileptic discharge providing appropriate guidance for treatment. Methods The Computerized Recognition of Epileptic Discharge (CREED) algorithm comprise of adaptive segmentation algorithm and morphological pattern identifier that can assist in the diagnosis of epilepsy. The etiology of epileptic discharge (ED) is revealed through the presence of sharp and spike. 5 normal EEG and 5 interictal EEG data were acquired from Universiti Kebangsaan Malaysia Medical Centre (PPUKM) database and their number of ED were determined by three neurologists manually are use as reference to validate the performance of developed algorithm. CREED performance is evaluated using Bivariate Pearson’s Correlation Analysis to measure the strength and direction relationship of number of ED detected between CREED and the neurologists. Results CREED is helpful in improving our reviewing and reporting duration of the electrophysiology of these common conditions by providing number and location of ED in the recorded signal. CREED is able to distinguish between normal and interictal ED channel with 90% accuracy, 100% sensitivity and 83.3% specificity. ED detection between three neurologist and CREED has been analysed. A near identical result were produced by Neurologist 1 and 2 and were used for further validation using correlation analysis against CREED. CREED assessment on number of ED are positively correlated with neurologists 1 and 2 assessment with correlation of r = 0.86 (p  Conclusion Preliminary evidence prove that CREED has potential to be introduced in clinical environment as a standard aspect of evaluating epileptic discharge in neurology laboratories that offer EEG diagnosis. On-going research suggests that it may become an essential element in the evaluation of epilepsy patient diagnosis and treatment.

PVDF sensor design and FPGA implementation of ultrasound power measurement

Ultrasound devices provide either diagnostic or therapeutic purpose in biomedical application. To avoid unwanted power exposure to the patient for safety concern but at the same time maintaining optimum diagnostic and therapeutic effect, ultrasound power meter is used to measure and calibrate the output power and intensity of the ultrasound machine. Most of the current ultrasound power meters are limited for either high power therapeutic or low power diagnostic purposes but not both and it is expensive. To enable Polyvinylidene fluoride (PVDF) for low cost ultrasound power meter, a robust low cost casing has been designed for optimum ultrasound power capturing from both therapeutic and diagnostic ultrasound machine. The system has been designed to minimize interference effect and noise, as well as to stabilize mechanical construction of the sensor. This paper presents a PVDF sensor design of an ultrasound power measurement system that is compact and simple in construction, easy and user friendly, but at the same time provides a reliable power measurement result. The power meter is designed using PVDF sensor and Altera Cyclone II Field Programmable Gate Array (FPGA) technology. Results show that this in-house power measurement system is able to measure 0.5 MHz - 10 MHz of the frequency range and 1 mW/cm2 to 10 W/cm2 of the intensity range.

Definition and comparison of a new vascular index between young healthy and aged subjects

In an effort to identify a useful noninvasive screening tool for cardiovascular diseases (CVD) screening, photoplethysmograph (PPG) signals were acquired and analyzed. These PPG signals were recorded during reactive hyperemia experiments consisting of a 4-minute blood flow blockage of the right arm (RA) brachial artery (BA) using a blood pressure cuff inflator. This procedure is usually done for the assessment of endothelial dysfunction which is a risk factor for developing CVD. In this study, signals of the infrared (IR) and red (R) LEDs of the PPG sensor were analyzed. These signals were preprocessed, normalized and slow varying component of the signal (DC values) and the pulsatile component (AC values) were extracted and evaluated for peak response during the reactive hyperemia after the release of blood flow blockage. PPG data of five healthy young female individuals (mean age 32.0 ± 1.6 years) were compared to that of five aged female individuals (mean age 64.0 ± 2.9 years). Results show that the IR PPG signals behave similarly to that of the R PPG signals (AC and DC) for both study groups. The young healthy subjects peak AC-IR and peak AC-R are significantly smaller than that of the aged subjects, (4.0 ± 2.4 versus 9.3 ± 5.0, p-value 0.06) and (2.0 ± 1.3 versus 5.4 ± 2.5, p-value 0.03), respectively. Nevertheless, the peak DC-R for the young subjects is significantly higher than that of the aged subjects (23.4 ± 8.3 versus 11.8 ± 6.3, p-value 0.04). The time to reach the peak points is not significantly different between the groups, which confirms our previous study. Since this optical technique is non-invasive and low-cost, it could be ultimately performed in routine clinical setting for the screening of endothelial dysfunction disorders.