20 research outputs found
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Improved reliability of impedance cardiography by new signal processing techniques
The authors used the impedance cardiogram (ICG), the phonocardiogram (PCG), and the electrocardiogram (ECG) to determine stroke volume and systolic time intervals. Comparisons between a fully automated PC/AT-based signal processing system and a computer-assisted visual detection processing system revealed comparable means, standard errors, correlations (Spearman r), and reliability (Chronbach's alpha ) coefficients on all relevant parameters. Other analyses confirmed the utility of using Q onset to mark the beginning of ventricular systole, the B point of the ICG to denote the aortic opening, and end diastole as the reference for determining the amplitude of dZ/dt/sub mzx/.<
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New signal processing techniques for improved reliability of impedance cardiography
Different techniques have been developed for parameter extraction and segmentation of the impedance cardiogram for improved reliability and precision of beat-to-beat determination of systolic time intervals, stroke volume, and related cardiac indices. The solutions presented improve on previous techniques by: (1) substantially reducing jitter in the localization of events within the cardiac cycle; (2) providing exact determination of signal amplitudes even in the presence of artifacts and interference signals; and (3) eliminating the influence of respiratory signal modulation on parameter extraction.<
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Influence Of Signal Fidelity On Impedance Cardiographically Derived Values At Resting And Accelerated Heart Rates
Retinal periphlebitis in ulcerative colitis.
A man presented with unilateral visual blurring associated with bilateral retinal periphlebitis which was felt to be a complication of his biopsy-proven active ulcerative colitis. Retinal periphlebitis has been associated rarely with some forms of colitis but we can find no report of its occurrence in association with ulcerative colitis although other ocular inflammatory disorders are well recognized