Stanislaw Pietraszek

The relationship between clinical measurements and gait analysis data in children with cerebral palsy

Spasticity is a common impairment that interferes with motor function (particularly gait pattern) in children with cerebral palsy (CP). Gait analysis and clinical measurements are equally important in evaluating and treating gait disorders in children with CP. This study aimed to explore the relationship between the spasticity of lower extremity muscles and deviations from the normal gait pattern in children with CP. Thirty-six children with spastic CP (18 with spastic hemiplegia [HS] and 18 with spastic diplegia [DS]), ranging in age from 7 to 12 years, participated in the study. The children were classified as level I (n=24) or level II (n=12) according to the Gross Motor Function Classification System. Spasticity levels were evaluated with the Dynamic Evaluation of Range of Motion (DAROM) using the accelerometer-based system, and gait patterns were evaluated with a three dimensional gait analysis using the Zebris system (Isny, Germany). The Gillette Gait Index (GGI) was calculated from the gait data. The results show that gait pathology in children with CP does not depend on the static and dynamic contractures of hip and knee flexors. Although significant correlations were observed for a few clinical measures with the gait data (GGI), the correlation coefficients were low. Only the spasticity of rectus femoris showed a fair to moderate correlation with GGI. In conclusion, the results indicate the independence of the clinical evaluation and gait pattern and support the view that both factors provide important information about the functional problems of children with CP.

The wireless system for EGG signal acquisition

The paper provides a case study on the wireless circuit for the purpose of the EGG (Electrogastrography) signal acquisition. The authors present an amplifier based on the ADS1298, wireless communication module (Bluetooth) and the microprocessor unit which have been recently built. The system is currently under examination but the outcome is very promising because the amplifier input is fed with the pure signal, i.e. no high/low pass filter is applied, that is a novelty. The system presented in this paper could be helpful in diagnosis gastric disorders in noninvasive way. It could determine patients with unexplained nausea, vomiting and other dyspeptic symptoms. The unit is under clinical trials tests and preliminary evaluation indicates acceptance by medical staff. Additional advantages are the relatively low cost of manufacture and the possibility of application remotely (pervasive computing).

The Use of Continuous Wavelet Transform Based on the Fast Fourier Transform in the Analysis of Multi-channel Electrogastrography Recordings

This paper presents the analysis of multi-channel electrogastrographic (EGG) signals using the continuous wavelet transform based on the fast Fourier transform (CWTFT). The EGG analysis was based on the determination of the several signal parameters such as dominant frequency (DF), dominant power (DP) and index of normogastria (NI). The use of continuous wavelet transform (CWT) allows for better visible localization of the frequency components in the analyzed signals, than commonly used short-time Fourier transform (STFT). Such an analysis is possible by means of a variable width window, which corresponds to the scale time of observation (analysis). Wavelet analysis allows using long time windows when we need more precise low-frequency information, and shorter when we need high frequency information. Since the classic CWT transform requires considerable computing power and time, especially while applying it to the analysis of long signals, the authors used the CWT analysis based on the fast Fourier transform (FFT). The CWT was obtained using properties of the circular convolution to improve the speed of calculation. This method allows to obtain results for relatively long records of EGG in a fairly short time, much faster than using the classical methods based on running spectrum analysis (RSA). In this study authors indicate the possibility of a parametric analysis of EGG signals using continuous wavelet transform which is the completely new solution. The results obtained with the described method are shown in the example of an analysis of four-channel EGG recordings, performed for a non-caloric meal.

The simultaneous recording and analysis both EGG and HRV signals

This paper presents a method for synchronous recording and analyzing both the electrogastrographic signal (EGG) and the heart rate variability signal (HRV). The electrogastrographic examination can be considered as a noninvasive method for an investigation of a stomach slow wave propagation. The four channel signal are non-invasively captured by the appropriately placed electrodes on the surface of the stomach. The EGG and electrocardiographic (ECG) signals, recorded simultaneously by means of the same electrodes and an amplifier, are separated by the proper digital filtration. In our work the EGG and ECG analysis is limited to calculation the most frequently used parameters: the dominant frequency of the EGG (DF), and LF/HF ratio of the HRV power spectrum for the ECG. In this way it is possible to examine mutual interaction among EGG and HRV. This paper also depicts the preliminary results of a comparison of the some EGG and the HRV parameters e.g. dominant power distribution (DPD) and balance of low frequency and high frequency of HRV power spectrum.

Comparative study of acceleration transducers for biomedical applications

The results of comparative studies of the metrological parameters of acceleration transducers constructed in Institute of Electronics, Silesian University of Technology is presented in this article. The construction of the transducers is based on commercially available monolithic accelerometers and optimized for biomedical applications. The parameters determined during the tests are similar to the parameters of the monolithic accelerometers declared by their manufacturers. It proofs that both the mechanical and the electronic construction of the transducers are correct.

Essential tremor – assessment of tremor accelerometric parameters' symmetry and the relationship between hand dominance and severity of tremor

BACKGROUND AND PURPOSE Essential tremor (ET) is likely the most common movement disorder. The aim of the study was to carry out spectral analysis of the essential tremor recorded by an accelerometer and assess the symmetry of tremor parameters between the two hands. MATERIAL AND METHODS We examined 39 patients with ET diagnosed clinically using the criteria of the Movement Disorder Society. The control group consisted of 52 healthy persons. A biaxial accelerometer mounted at the dorsal side of the hand was used. Spectral analysis was performed. Tremor intensity, frequency of spectral peaks, centre frequency, standard deviation of the centre frequency, and harmonic index were measured. The side-to-side symmetry of these parameters was analysed. The relationship of hand dominance and severity of tremor was also analysed. RESULTS There was significant side-to-side asymmetry of intensity in ET. The intensity in the more affected hand was over two times higher than that in the less affected one. The tremor was more severe in the nondominant hand in 62% of patients. In spite of significant difference in tremor intensity between the two sides, tremor frequency was similar in both hands. The standard deviation of centre frequency was significantly lower and the harmonic index was significantly higher in the more trembling hand. CONCLUSIONS Accelerometric registration revealed that asymmetry of intensity and symmetry of frequency are characteristic features of ET. The remaining two coefficients reflecting the rhythmicity and regularity of tremor also differed considerably between the hands.

Hybrid QRS detection circuit based on dynamic reconfigurable field programmable analog array.

Abstract In many medical applications it is important to detect the QRS complex in the electrocardiogram (ECG) waveform with possibly low time delay. Traditional software detectors of the QRS complex implement algorithms usually based on cascades of digital filters introduce delays up to parts of a second. Hardware QRS detectors fulfill the low delay requirements, but have worse adaptive features for the changing ECG shape. In this paper a new approach to QRS detection is presented. The proposed detector is based on a Field Programmable Analog Array (FPAA). The most interesting feature of the FPAA is the dynamic reconfigurability. This solution makes it possible to modify the parameters of particular blocks of the detector or even the whole structure during runtime, without any changes in hardware and disturbance of the system functionality. The prototype QRS detector was built using AN221E04 circuit from the Anadigm company. The reconfiguration data are calculated by the AD7020 microcontroller and downloaded to the FPAA after each QRS detection.

The noise influence on determination dominant frequencies of EGG signal

Electrogastrographic examination (EGG) can be considered as a noninvasive method for an investigation of a stomach slow wave propagation This paper presents a method for determining dominant frequencies. It also shows details of influence of a noise on dominant frequencies determination. The EGG signal is noninvasively captured by appropriately placed electrodes on the surface of the stomach. The typical range of frequency for EGG signal is from 0.015Hz to 0.15Hz. One of EGG signal analyzing method is based on a determination of dominant harmonic frequencies contained in the chosen segments of EGG signal. The dominant frequencies are used for calculation base parameters of the EGG signal.

Pressure and Output Flow Estimation of Pneumatically Controlled Ventricular Assist Device (VAD) with the help of Both Acceleration and Gyro Sensors

The Polish ventricular assist device (VAD) POLVAD is a pulsatile pump designated to both short and mid term, single and/or double chamber circulatory system assistance during cardiac surgery treatment. Also, it can be applied as temporary assistance of critical heart failure up to its energetic recovery or homodynamic sufficiency (before or post operation stages) or as a temporary bridge to heart transplantation. The important parameters necessary to know during such described assistance are both value and shape of blood pressure and flow. These parameters are strongly dependent on shape of circulatory system input blood pressure curve as well as on set of physiological system parameters. Direct measurement of pressure and flow curves inside VAD is possible but unfortunately it is connected with additional risk for patient and require some construction changes or improvements of VAD itself. One of the possible solution allowing to satisfactory estimation of pressure and flow curve shape concerns application of sensors detecting movement of assistance chamber flexible elements. Therefore the application of monolithic acceleration and gyro sensors estimating both displacement and rotation of chamber construction elements caused by blood pressure changes seem to be reasonable and justified.

Heart Rate Analysis in the EGG Examination

This paper presents a novel method for synchronous recording and analyzing both the electrogastrographic signal (EGG) and the heart rate variability signal (HRV). The four channel signals are non-invasively captured by six electrodes placed on the surface of the stomach. The EGG and electrocardiographic (ECG) signals, recorded simultaneously using the same electrodes and an amplifier, are separated by digital filtration. In our work the EGG and ECG analysis is limited to the calculation the most frequently used parameters: the dominant frequency (DF), dominant power (DP) of the power spectrum for the EGG, and LF/HF ratio of the HRV power spectrum for the ECG signals.