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At least 415 records · Page 23Linked to original sources
PubMed1991

[Spectrum analysis of gastrointestinal potentials from the body surface].

Spectral analysis was employed to assess the electric activity of the stomach and intestine from the body surface. Equipment including a microcomputer and a specially designed program were used. Examinations of 134 normal subjects and patients with various gastrointestinal conditions have demonstrated a sufficient accuracy of the method in the detection of gastrointestinal dyskinesia and in assessment of gastrointestinal function, as well as in presentation of individual elements of regular gastrointestinal activity.

Action Potentials↗
PubMed1990

EEG changes measured by spectrum analysis under hyperbaric conditions.

The EEG activity was followed during simulated diving to 20 m depth. Altogether 49 EEG records of 5 min length were taken in 5 divers breathing compressed air in a close system. No significant changes of the EEG could be found during either compression or decompression if only conventional indicators, such as the amplitude of theta activity, were tested. However, a complex "normality ratio," based on multivariate analysis of a normal material, was capable of showing significant impairment of the brain activity during the decompression. The indicator has been designed to reflect the abnormality level rather than the short-lasting EEG changes, the latter being mostly dependent on the alertness fluctuations. The EEG changes associated with alertness fluctuations were assessed separately by means of a specific "alertness indicator" and a prominent alertness increase was found during both compression and decompression phases of the diving experiment.

Adult↗
PubMed1989

[Spectrum analysis of the EEG in children and adolescents with epilepsy: general characteristics and pathophysiological interpretation of the data].

Spectral EEG analysis (fast Fourier transform) was performed in 48 patients with epilepsy, 4 patients after one epileptic seizure, 12 sibs of epileptic patients, 18 children with febrile convulsions, 18 patients with vasoautonomic dystonia, and 23 normal children. Means, standard deviations, standard errors of the means were calculated for the spectra. A distinct EEG type was found characteristic of the epileptic patients: power increase by the factor of 5 to 10 as compared to normals, predominantly in theta band. This EEG type was shared by epileptic patients and their sibs. Both had peculiar patterns on hyperventilation.

Adolescent↗
PubMed1989

[Possibilities of the diagnosis and the evaluation of epilepsy risk based on the data of EEG spectrum analysis in children and adolescents].

Using spectral analysis data of the previous study a trial was undertaken to develop criteria for diagnosis and risk assessment of epilepsy. To the spectral parameters++, differentiating groups of epilepsy and normals, the diagnostic weights from 1 to 10 were attributed, according to the probability "p" from 0.01 to 0.001 using "t" criterion. Sums of the weights formed "epilepsy indexes" (EL) for each normal and patient. From these EI confidence intervals for p less than 0.034 and less than 0.003 were obtained. The criteria were checked on a mixed group of patients differing by the degree of epileptic charge. Positive EI were found only in the patients with high risk of epilepsy (febrile convulsions and epileptic siblings) and in patients with actual epileptic seizures, corresponding in the latter mostly to p less than 0.003.

Adolescent↗
PubMedDate not supplied

EMG interference pattern power spectrum analysis in neuro-muscular disorders.

One hundred sixty six subjects, who had clinically proven Neuromuscular (NM) diagnoses and 37 normal controls, had their biceps muscle EMGs, recorded in sustained isometric maximum voluntary contraction (MVC). The EMG signals were repeatedly transformed into power spectra (PS). The PS were then analysed by various statistical methods. The statistical analyses showed an overall significant difference in power between the sexes but only in the Dysschwannian Neuropathy group and no differences due to age; a very highly significant fatigue trend that manifests, to a different extent, in all frequency bands; the groups were significantly different from one another in both total power and in band-specific power, and to differ in their responses to fatigue. These analyses showed that based on PS alone discriminant analysis can separate the cases into only two significantly different groups: normal controls could not be separated from neuropathies, but both were significantly different from Myasthenia Gravis and myopathies. The statistical analysis highlighted as important the use of separate PS frequency bands and the use of a fatigue paradigm for separating the various NM disorders--showing Group-by-Fatigue; Group-by-Band and Group-by-Band-by-Fatigue interactions to be highly significant. All the above mentioned significant features, though, resulted in a low predictive (diagnostic) value by discriminant analysis and even worse by clustering techniques.

Adult↗
PubMedDate not supplied

[Continuous spectrum analysis during anesthesia and the recovery period in infants under 1 year of age].

Continuous spectral EEG activity monitoring has been used in adults as a monitor of brain activity during anesthesia. It has not been used in infants. We studied 22 infants less than 7 months old undergoing minor surgery. Halothane alone or minimal Halothane anesthesia associated with caudal epidural anesthesia were used. Life-Scan analysis, in spite of wide individual variations, allowed us to detect infraclinical hypoxia episodes, it provided informations about operative confort, depth of anesthesia and added in the post-operative period an objective criteria to clinical evaluation of pain. A wide use of such a monitoring is warranted in infants.

Age Factors↗
PubMedDate not supplied

[Spectrum analysis of the electroencephalographic signal using the Life-Scan method during the early months of life].

EEG activity in infants is difficult to assess because of the fast development of brain activity during the first months of life. EEG spectral activity monitoring seems to be easier than non processed EEG analysis. We studied processed EEG aspects in infants less than one year old. As in previous studies, we found an early lack of dominant frequency with slow activity alone with subsequent wanderning of the dominant frequency from slow towards faster frequencies.

Electroencephalography↗
PubMed1987

[Continuous emission Doppler study with spectrum analysis in the evaluation of aortic stenosis in adults. Apropos of 30 cases].

The value of continuous wave doppler with spectral analysis for the evaluation of aortic stenosis in adults being controverted, we analyzed prospectively the results obtained in 30 consecutive elderly patients (mean age 63 years) investigated by invasive and non-invasive methods. In 24 patients who underwent both ultrasonic and catheter examinations, the correlation between mean gradients measured by catheterization and calculated separately by doppler was 0.80. For a semi-quantitative evaluation of the aortic valve area, we suggest to use an additional severity index R calculated from doppler data (R = mean gradient/maximal instantaneous gradient) which correlated well (r = -0.68) with the aortic valve area. In our experience, this index makes it possible to separate patients with a less than 0.75 cm2 aortic valve area, as calculated from Gorlin's formula (R greater than 0.65) from patients with a more than 0.75 cm2 aortic valve area (R less than 0.65), irrespective of the associated cardiac index. It is concluded that the doppler ultrasound method provides a highly satisfactory evaluation of transaortic gradient, as well as a semi-quantitative evaluation of the stenotic aortic ostium in the majority of elderly patients with aortic stenosis.

Adult↗
PubMedDate not supplied

[Frequency spectrum analysis of the electrical activity of the brain in the rat as affected by ketamine].

The effect of ketamine (80 mg/kg, intraperitoneally) on the frequency composition of electrograms of the visual and somatosensory regions of the cerebral cortex, hippocampus and medial nuclei of the hypothalamus was studied in chronic experiments on rats. An increase of the power of 4 Hz fluctuations and a decrease of 6 Hz fluctuations were noted in all structures. Ten min. after the drug injection the effect of 4 Hz rhythm enhancement was sharply suppressed (except the visual cortex). A combined administration of 5-hydroxytryptophan (30 mg/kg) and alpha-methyl-dihydroxyphenylalanine (100 mg/kg) resulted in the occurrence on the visual cortex of the effects similar to those produced by ketamine.

5-Hydroxytryptophan↗