Results 241 to 250 of about 1,026,837 (287)
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Characteristics of a simple measure of respiratory impedance
Respiration Physiology, 1987The ratio of mouth pressure developed 0.1 sec after occlusion at end-expiration (P0.1) to average inspiratory flow rate (VT/TI) has been proposed as 'effective inspiratory impedance', Imeff. We have studied a simple mathematical model of lung mechanics, consisting of an effective resistance, an effective compliance and a single pressure generator, to ...
W E, Fordyce, R M, Whetstone
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Modeling of respiratory system impedances in dogs
Journal of Applied Physiology, 1987Mechanical impedances between 4 and 64 Hz of the respiratory system in dogs have been reported (A.C. Jackson et al. J. Appl. Physiol. 57: 34–39, 1984) previously by this laboratory. It was observed that resistance (the real part of impedance) decreased slightly with frequency between 4 and 22 Hz then increased considerably with frequency above 22 Hz ...
A C, Jackson, K R, Lutchen
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Effect of body posture on respiratory impedance
Journal of Applied Physiology, 1988The effects of posture on the mechanics of the respiratory system are not well known, particularly in terms of total respiratory resistance. We have measured respiratory impedance (Zrs) by the forced random noise excitation technique in the sitting and the supine position in 24 healthy subjects. Spirometry and lung volumes (He-dilution technique) were
D, Navajas +4 more
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Within-breath measurement of respiratory impedance
Physiological Measurement, 1993The measurement of the complex respiratory impedance at a high temporal resolution is described. The measurement of impedance is correlated with the breathing cycle using electrical transthoracic impedance. This allows the determination of the complex impedance at any fixed point in the respiratory cycle, which results in lower variability in the ...
W J, van der Putten +2 more
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Serum Impedance in Children with Recurrent Respiratory Infections
2022The role of disturbed immunoglobulin content during recurrent respiratory tract infections (RTI) might escape recognition in practical children's diagnostics. This study aims to investigate the potential changes in serum impedance caused by a constellation of decreases in the immunoglobulin IgA, IgG, and IgM content in RTI.
Gerard Pasternak +4 more
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Low-frequency respiratory mechanical impedance in the rat [PDF]
Journal of Applied Physiology, 1987 modified forced oscillatory technique was used to determine the respiratory mechanical impedances in anesthetized, paralyzed rats between 0.25 and 10 Hz. From the total respiratory (Zrs) and pulmonary impedance (ZL), measured with pseudorandom oscillations applied at the airway opening before and after thoracotomy, respectively, the chest wall ...
Hantos Zoltán +3 more
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A calibrator for measurements of respiratory impedance
Measurement Science and Technology, 1995We describe a simple device that may be employed as a compact and quick calibrator for measurements of respiratory impedance. The real and imaginary parts of the complex impedance of the calibrator are computed as a function of frequency from the theory of sound propagation along a cylindrical duct; a table is set up for the usual operational range 0 ...
L Basano, P Ottonello
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Active impedance of respiratory system in anesthetized cats
Journal of Applied Physiology, 1982We have assessed the validity of the method of Siafakas et al. (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 51: 10913;121, 1981) for determining active elastance (E'rs) and flow resistance (R'rs) of the respiratory system. In six cats anesthetized with pentobarbital sodium we have measured flow, volume, and tracheal occlusion pressure ...
W A, Zin, L D, Pengelly, J, Milic-Emili
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Influence of signal processing on estimation of respiratory impedance
Journal of Applied Physiology, 1993Respiratory impedance was estimated between 4 and 30 Hz by spectral analysis of the mouth flow and pressure signals measured in spontaneously breathing subjects when applying a pseudorandom pressure excitation at the mouth. The signals were submitted to antialiasing low-pass filtering followed by digital preprocessing before the calculation of spectra
H, Lorino +3 more
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Instrumentation for Measuring Respiratory Impedance by Forced Oscillations
IEEE Transactions on Biomedical Engineering, 1977Recent reports have suggested that the frequency dependence of the respiratory impedance may provide a sensitive method for characterizing early changes in pulmonary mechanics. A modification of the forced-oscillation technique provides an experimental method for obtaining the necessary data. A loudspeaker was used to provide the pressure oscillations,
R L, Pimmel +5 more
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