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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(More)
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(More)
The ability of two easy-to-calculate nonlinear parameters, the Higuchi fractal dimension (HDf) and spectral entropy, to follow the depth of sedation in the intensive care unit is assessed. For comparison, the relative beta ratio is calculated. The results are evaluated using clinical assessment of the Ramsay score. The results show that the HD/sub f/(More)
A novel algorithm for the detection and tracking of rhythmic patterns in the EEG signal is presented. The algorithm includes the following steps: 1) linear filtering using symmetric impulse response, 2) calculation of the first intrinsic mode of the filter output and 3) calculation of instantaneous frequency and amplitude using the Hilbert transform. The(More)
In this paper 5 methods for the assessment of signal entropy are compared in their capability to follow the changes in the EEG signal during transition from continuous EEG to burst suppression in deep anesthesia. To study the sensitivity of the measures to phase information in the signal, phase randomization as well as amplitude adjusted surrogates are also(More)
AIM To elucidate relation between prolongation of corrected maximal QT intervals and QT dispersion (QTcmax, QTcD) and presence and severity of arterial hypertension, as well as other factors determining high cardiovascular risk in female population of Tallinn aged 56 - 66 years. MATERIAL AND METHODS A sample of female citizens of Tallinn (n=123, age 56 -(More)
Transesophageal atrial stimulation (TAS) is widely used in evaluation and treatment of supraventricular arrhythmias. It can yield important information in most situations, where invasive atrial stimulation is usually done, but is safe, rapid, inexpensive and can often be performed in an outpatient setting. However, in clinical practice TAS pacing usually(More)
Aim of the study was to investigate relationship between arterial hypertension (AH), left ventricular myocardial mass (LVMM), and levels of N-terminal pro-B type natriuretic peptide (pro-NT BNP) in a population of women inhabitants of Tallinn aged 56-65 years. Of 163 women aged 50-59 years who had participated in epidemiological study in 2000 in 132(More)
In order to reduce pacing current threshold in transesophageal stimulation, a novel multichannel transesophageal pacemaker and multichannel esophageal lead has been developed. Three different approaches to reduce pacing current threshold were clinically studied. Precise positioning of the pacing dipole allowed reduction of pacing current threshold on(More)
We present a content-centric software architecture of home monitoring solution designed to support universal semantically described context information and formal reasoning for automated profile generation and data aggregation. At the core of each data processing node in the system is a semantic RDF-based datastore to which a peripheral agent cloud is(More)
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