Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Spectral Analysis”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,171 records · Page 65Linked to original sources
PubMed1990

Clinical application of spectral analysis of bowel sounds in intestinal obstruction.

The bowel sounds of 21 patients with mechanical obstruction of the intestine were studied. A computer analysis of bowel sounds was performed using a signal processor. Bowel sounds of patients were classified into 3 types (Types I, II, and III) based on the histograms, although these were not distinguishable on auscultation. The lower, peak, and upper frequencies were 173 +/- 25 Hz, 273 +/- 64 Hz, and 667 +/- 58 Hz, respectively, in Type I; 309 +/- 121 Hz, 632 +/- 94 Hz, and 878 +/- 116 Hz, respectively, in Type II; and 330 +/- 120 Hz, 612 +/- 86 Hz, and 766 +/- 82 Hz, respectively, in Type III. High frequency sounds above 900 Hz were recorded in Types I and II but not in Type III. The ratio of the operated patients was 0, 23, and 100 percent in Types I, II, and III, respectively. The intervals between the times of admission and operation were 4.3 days and 1.2 days in Types II and III, respectively. Thus, it appears that the methods described by the authors could provide a very objective assessment of the severity and help determine the treatment (conservative or operative) of each patient.

Adult↗
PubMedDate not supplied

Modeling of the heart's ventricular conduction system using fractal geometry: spectral analysis of the QRS complex.

Many biological systems having one or more characteristics that remain constant over a wide range of scales may be considered self-similar or fractal. Geometrical and functional overview of the ventricular conduction system of the heart reveals that it shares structures common to a tree with repeatedly bifurcating "branches," decreasing in length with each generation. This system may further simplify by assuming that the bifurcating and decreasing process is the same at any generation, that is, the shortening factor and the angle of bifurcation are the same for each generation. Under these assumptions, the conduction system can be described as a fractal tree. A model of the heart's ventricles which consists of muscle cells and a fractal conduction system is described. The model is activated and the dipole potential generated by adjacent activated and resting cells is calculated to obtain a QRS complex. Analysis of the frequency spectrum of the QRS complex reveals that the simulated waveforms show an enhancement in the high frequency components as generations are added to the conduction system. It was also found that the QRS complex shows a form of an inverse power law, which was predicted by the fractal depolarization hypothesis, with a highly correlated straight line for a log-power versus log frequency plot with a slope of approximately -4. Similar results were obtained using real QRS data from healthy subjects.

Computer Simulation↗
PubMed1984

Spectral analysis of Doppler flow velocity signals: assessment of objectives, methods, and interpretation.

The objective of this paper is to review the theoretical basis and clinical application of electrical impedance plethysmography in the noninvasive evaluation of peripheral arterial and venous disease. Theoretical, experimental and clinical studies have not demonstrated a direct relationship between electrical impedance changes and limb volume changes. Potential sources of error have also been identified. This has led to the development of clinical tests based on impedance plethysmography for the detection of peripheral arterial disease, venous insufficiency and venous outflow obstruction. Impedance plethysmography, using the method of venous occlusion, is presently the most commonly employed noninvasive method for the detection of deep venous thrombosis.

Carotid Artery Diseases↗
PubMed1990

Spectral analysis and acoustic transmission of mitral and aortic valve closure sounds in dogs. Part 2. Effects of neuromuscular blockade, sternotomy and pacemaker control, and a two-week recovery period.

The paper describes the effects of neuromuscular blockade, sternotomy and atrio-ventricular pacing, and a two-week recovery period on the spectra and acoustic transmission of mitral M1 and aortic A2 sound components in dogs. Results indicate that neuromuscular blockade does not affect the attenuation properties of the heart/thorax acoustic system even if it modifies the intensity of M1 and the phase of the transfer function. The immediate effect of sternotomy and cardiac pacing is an important increase in the attenuation of the heart/thorax acoustic system. This increased attenuation is different for both sounds (20 dB for M1 and 11 dB for A2) and disappears after a two-week recovery period. However, the resulting controlled dog model shows slightly different acoustic characteristics than those of the normal animal model.

Animals↗