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Development of forced random noise system for the measurement of respiratory impedance. Final Report.

Viola-JO; Hankinson-JL; Sepulveda-MJ; Castellan-RM; Cocke-JB
NIOSH 1983 Dec; :1-161
Part one of the study called for the design and analysis of a respiratory measurement system employing forced random noise. Respiratory impedance of a human was determined by the administration of a noninvasive test in which random oscillations were superimposed on the respiratory cycle. Spectral analysis was applied to the forcing pressure and resultant flow to arrive at a measure of impedance which is a function of frequency. The measuring system consisted of a random noise source, speaker enclosure, and a portable computer. To isolate physiological (ZL) and respiratory (Zrsp) impedance from measured data, the impedance contributions of the system were determined. With this system, ZL could be determined in less than five minutes with Zrsp isolation taking twice the time. The magnitude and phase of Zrsp for a normal healthy adult were comparable to the results obtained by other studies. In part two of the study lung function responses to inhaled cotton dust were evaluated in a group of 58 healthy subjects by spirometry (MEFV curves) and forced random noise impedance parameters. The data indicate that measures of the Thevenin resistance (real part of impedance) by the forced random noise method are reliable indicators of cotton induced bronchoconstriction. However, measurement variability suggests that these are more appropriate for group studies and should remain adjuncts to standard tests of lung function such as spirometry.
NIOSH-Author; Respiratory-system-disorders; Respiration-rate; Respirable-dust; Cotton-mill-workers; Lung-irritants; Pulmonary-function-tests; Pulmonary-congestion
Publication Date
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NTIS Accession No.
NTIS Price
NIOSH Division
Priority Area
Asthma and Chronic Obstructive Pulmonary Disease; Disease and Injury; Respiratory-system-disorders
Source Name
Division of Respiratory Disease Studies, NIOSH, Morgantown, West Virginia, 161 pages, 38 references
Page last reviewed: April 12, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division