Photoplethysmographic signal waveform index for detection of increased arterial stiffness.

The aim of this research was to assess the validity of the photoplethysmographic (PPG) waveform index PPGAI for the estimation of increased arterial stiffness. For this purpose, PPG signals were recorded from 24 healthy subjects and from 20 type II diabetes patients. The recorded PPG signals were processed with the analysis algorithm developed and the waveform index PPGAI similar to the augmentation index (AIx) was calculated.

Estimation of removed uremic toxin indoxyl sulphate during hemodialysis by using optical data of the spent dialysate.

The aim of this study was to explore the possibility to determine the amount of total removed Indoxyl Sulphate (TR_IS) during dialysis session, an optical method utilizing absorbance and fluorescence spectral data of the spent dialysate was used. Eight uremic patients from Linköping, Sweden and 10 from Tallinn, Estonia, were studied during dialysis treatments. Dialysate samples were taken during each treatment and analyzed at a laboratory.

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.

Relationship between approximate entropy and visual inspection of irregularity in the EEG signal, a comparison with spectral entropy.

Background: Several measures have been developed to quantify the change in EEG from wakefulness to deep anaesthesia. Measures of signal complexity or entropy have been popular and even applied in commercial monitors. These measures quantify different features of the signal, however, and may therefore behave in an incomparable way when calculated for standardized EEG patterns.

Adjustment of adaptive sum comb filter for PPG signals.

AC component of photoplethysmography signal carries important information for diagnostics. Registered signal may be affected by noises, which are sharing the same bandwidth. Adaptive comb filter is used for the AC component extraction.

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.

A new method for evaluating the performance of depth-of-hypnosis indices - the D-value.

An alternative statistic, the D-value, is presented for the evaluation of the performance of EEG-based depth-of-hypnosis measures against the Observers' Assessment of Alertness/Sedation scale. The measures considered here are spectral entropy, approximate entropy, Lempel-Ziv complexity and Higuchi fractal dimension. The study is based on recordings from 45 patients, divided into three groups of 15 recordings each.

Comparison of the properties of EEG spindles in sleep and propofol anesthesia.

Electroencephalogram spindle patterns corresponding to two different phenomena-natural sleep and propofol anesthesia-are compared. The spindles are extracted from 5 overnight sleep recordings and 10 recordings of deep propofol anesthesia. Mean frequency, angle of the trend in instant frequency as well as 3 nonlinear parameters-spectral entropy, approximate entropy, and Higuchi fractal dimension- are calculated to characterize the spindle waveforms.

Behavior 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).

Comparison of entropy and complexity measures for the assessment of depth of sedation.

Entropy and complexity of the electroencephalogram (EEG) have recently been proposed as measures of depth of anesthesia and sedation. Using surrogate data of predefined spectrum and probability distribution we show that the various algorithms used for the calculation of entropy and complexity actually measure different properties of the signal. The tested methods, Shannon entropy (ShEn), spectral entropy, approximate entropy (ApEn), Lempel-Ziv complexity (LZC), and Higuchi fractal dimension (HFD) are then applied to the EEG signal recorded during sedation in the intensive care unit (ICU).

Effects of 7 Hz-modulated 450 MHz electromagnetic radiation on human performance in visual memory tasks.

Purpose: The aim was to examine low-level 7 Hz-modulated 450 MHz radiation effects on human performance in visually presented neuropsychological tasks associated with attention and short-term memory.

Materials And Methods: A homogeneous group of 100 subjects (37 female, 63 male) were randomly assigned to either the exposed (10-20 min, 0.158 mW cm(-2)) or the sham-exposed group.