Land Assembly for Housing Developments

The ability to identify premature arterial stiffening is of considerable value in the prevention of cardiovascular diseases. The “ageing index” (AGI), which is calculated from the second derivative photoplethysmographic (SDPPG) waveform, has been used as one method for arterial stiffness estimation and the evaluation of cardiovascular ageing. In this study, the new SDPPG analysis algorithm is proposed with optimal filtering and signal normalization in time. The filter parameters were optimized in order to achieve the minimal standard deviation of AGI, which gives more effective differentiation between the levels of arterial stiffness. As a result, the optimal low-pass filter edge frequency of 6 Hz and transitionband of 1 Hz were found, which facilitates AGI calculation with a standard deviation of 0.06. The study was carried out on 21 healthy subjects and 20 diabetes patients. The linear relationship (r=0.91) between each subject’s age and AGI was found, and a linear model with regression line was constructed. For diabetes patients, the mean AGI value difference from the proposed model yAGI was found to be 0.359. The difference was found between healthy and diabetes patients groups with significance level of P<0.0005

Using the nonlinear control of anaesthesia-induced hypersensitivity of EEG at burst suppression level to test the effects of radiofrequency radiation on brain function

Background In this study, investigating the effects of mobile phone radiation on test animals, eleven pigs were anaesthetised to the level where burst-suppression pattern appears in the electroencephalogram (EEG). At this level of anaesthesia both human subjects and animals show high sensitivity to external stimuli which produce EEG bursts during suppression. The burst-suppression phenomenon represents a nonlinear control system, where low-amplitude EEG abruptly switches to very high amplitude bursts. This switching can be triggered by very minor stimuli and the phenomenon has been described as hypersensitivity. To test if also radio frequency (RF) stimulation can trigger this nonlinear control, the animals were exposed to pulse modulated signal of a GSM mobile phone at 890 MHz. In the first phase of the experiment electromagnetic field (EMF) stimulation was randomly switched on and off and the relation between EEG bursts and EMF stimulation onsets and endpoints were studied. In the second phase a continuous RF stimulation at 31 W/kg was applied for 10 minutes. The ECG, the EEG, and the subcutaneous temperature were recorded. Results No correlation between the exposure and the EEG burst occurrences was observed in phase I measurements. No significant changes were observed in the EEG activity of the pigs during phase II measurements although several EEG signal analysis methods were applied. The temperature measured subcutaneously from the pigs' head increased by 1.6°C and the heart rate by 14.2 bpm on the average during the 10 min exposure periods. Conclusion The hypothesis that RF radiation would produce sensory stimulation of somatosensory, auditory or visual system or directly affect the brain so as to produce EEG bursts during suppression was not confirmed.BioMed Central Open acces

EEG Patterns and Regularity Properties during Propofol Induced Anesthesia/Sedation

The purpose of this thesis is to study properties of the EEG signal recorded during anesthesia or sedation. The main emphasis was put on the regularity/complexity analysis of the EEG during gradually deepening sedation and the EEG patterns of burst-suppression level anesthesia. Additionally, time-frequency analysis was applied to selected EEG patterns during burst-suppression level anesthesia. The EEG signals underlying this work have mainly been recorded during propofol anesthesia/sedation, however, for the comparison purposes also sevoflurane recordings have been used. For most of the cases the EEG was recorded using the conventional skin electrodes, however for one case EEG recorded with depth electrodes from the subthalamic region of the brain was used.Regularity/complexity properties of the signals have been analyzed using several entropy based measures (Shannon entropy, spectral entropy, and approximate entropy), a coarse-grained complexity measure (Lempel-Ziv complexity), and a fractal dimension estimator (Higuchi fractal dimension). The main idea of the regularity/complexity analysis was to study the ability of the different measures to follow the anesthetic depth. In addition, the influence of the frequency content of the EEG signal, as well as co-administration of the commonly used opiate remifentanil, on the efficiency of the mentioned measures as depth-of-sedation indicators was studied. The time-frequency analysis was conducted by using quadratic time-frequency distributions (Wigner-Ville distribution, Choi-Williams distribution, and optimal distributions) in order to investigate the instantaneous frequency of the spindles during propofol induced anesthesia as well as during normal physiological sleep.The results show that, although the applied regularity/complexity measures do not depend directly on the power spectrum of the signal (with the exception of spectral entropy), they are highly sensitive to the frequency content of the EEG. Higuchi fractal dimension almost always outperformed other measures when their ability to differentiate between different levels of sedation was tested. Remifentanil was found to significantly deteriorate the ability of the tested measures to follow the depth of sedation.The time-frequency analysis of the spindle patterns shows that the angle of the trend of its instantaneous frequency is generally small. However, occasionally spindles can show either increasing or decreasing trend in the instantaneous frequency. The analysis also reveals that the spindles during propofol anesthesia have slightly higher average frequency than that of the spindles during physiological sleep

Digitaalne signaali- ja pilditöötlus : harjutused

Kopeerimine ja printimine keelatudhttp://www.ester.ee/record=b2244506*es

Photoplethysmographic signal processing using adaptive sum comb filter for pulse delay measurement

Abstract. Pulse transit time, which correlates with blood pressure, is measured between the electrocardiogram R-wave peak and 50 % raising front level of a photoplethysmographic (PPG) signal. Registered PPG signal bandwidth may be shared by noise and therefore the signal raising front is undetectable. Electrocardiogram reference adaptive sum comb filter was used to extract the harmonic components of the PPG signal and suppress the noises between them. Averaging effect of the filter on the PPG signal was studied and adjustments were made. The influence of the comb filtered PPG signal on the measurement of pulse transit time was analysed. Key words: photoplethysmography, electrocardiography, pulse transit time, adaptive comb filter. 1

Behaviour of entropy/complexity measures of the electroencephalogram during propofol-induced sedation: dose-dependent effects of remifentanil

Background: Several new measures based on the regularity of the electroencephalogram signal for the assessment of depth of anesthesia/sedation have been proposed recently. in this study we analyze the influence of remifentanil and electroencephalogram frequency content of the performance of a set of such measures. Methods: Forty-five patients with American Society of Anesthesiologists physical status I were randomly allocated to one of three groups according to the received dose of predicted effect compartment-controlled remifentanil (0, 2, and 4 ng/ml). All 45 patients received stepwise increased effect site concentration-controlled dose of propofol. At every step of propofol increase, the Observer's Assessment of Alertness/Sedation score was assessed. The following measures were calulated from the electroencephalographic signal: spectral entropy, approximate entropy, Higuchi fractal dimension, Lempel-Ziv complexity, relative beta ratio, and SyncFastSlow measure. Results: The behavior of the electroencephalogram-based measures is highly sensitive to the frequency content of the signal and the dose of remifentanil. The prediction probability with respect to the Observer's Assessment of Alertness/Sedation score of the most discriminative measure, the Higuchi fractal dimension, dropped from 0.90 (electroencephalographic frequency band 6-47 Hz, no remifentanil) to 0.55 when the frequency band was changed to 0.5-19 Hz and to 0.83 when remifentanil concentration was increased to 4 ng/ml. The coeffect of remifentanil on electroencephalographic regularity is bimodal depending on the frequency band of the signal. Conclusions: Cutting off high frequencies from the electroencephalogram and increased remifentanil concentration deteriorate the performance of the electroencephalogram-based entropy/complexity measures as indicators of the depth of propofol sedation

New Photoplethysmographic Signal Analysis Algorithm for Arterial Stiffness Estimation

The ability to identify premature arterial stiffening is of considerable value in the prevention of cardiovascular diseases. The "ageing index" (AGI), which is calculated from the second derivative photoplethysmographic (SDPPG) waveform, has been used as one method for arterial stiffness estimation and the evaluation of cardiovascular ageing. In this study, the new SDPPG analysis algorithm is proposed with optimal filtering and signal normalization in time. The filter parameters were optimized in order to achieve the minimal standard deviation of AGI, which gives more effective differentiation between the levels of arterial stiffness. As a result, the optimal low-pass filter edge frequency of 6 Hz and transitionband of 1 Hz were found, which facilitates AGI calculation with a standard deviation of 0.06. The study was carried out on 21 healthy subjects and 20 diabetes patients. The linear relationship (r = 0.91) between each subjects age and AGI was found, and a linear model with regression line was constructed. For diabetes patients, the mean AGI value difference from the proposed model y(AGI) was found to be 0.359. The difference was found between healthy and diabetes patients groups with significance level of P andlt; 0.0005.Funding Agencies|Estonian Science Foundation|7506|Estonian Targeted Financing Project|SF0140027s07|European Union through the European Regional Development Fund||</p