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Cotton induced bronchoconstriction detected by a forced random noise oscillator.

Sepulveda MJ; Hankinson JL; Castellan RM; Cocke JB
Br J Ind Med 1984 Nov; 41(4):480-486
Cotton dust induced bronchoconstriction by a forced random noise oscillator was examined among humans. Fifty eight healthy subjects were exposed for 6 hours to cotton dust at a concentration of 1 milligram per cubic meter. Comparisons were exposed to air. Respiratory resistance was measured by a forced random noise system. A random pressure bandwidth of 2 to 45 Hertz (Hz) was introduced into each subject's mouth by means of a loudspeaker mounted in an enclosure. The loudspeaker was driven by a random noise generator (oscillator) and the corresponding pressure flow at the mouth was measured over 32 seconds of quiet tidal breathing. Spirometric tests were also administered. Airway resistance was also examined in 20 subjects by body plethysmography. Exposure to cotton dust caused significant increase in Thevenin or effective resistance at low noise frequencies, 5 to 9Hz, and significant decreases in maximal expiratory volumes and flows. No significant changes in average resistance at high noise frequencies, 20 to 24Hz, occurred. No changes in airway resistance were detected by body plethysmography. Non response to the spirometric tests, comparison exposure, was correlated with increases in effective airway resistance at both low and high noise frequencies. The authors conclude that experimental measurements of effective airway resistance by the forced random noise method can reliably indicate bronchoconstriction due to cotton dust exposure. Response to low frequency noise probably reflects increases in flow resistance in peripheral airways, while response to high frequency noise indicates changes in the central airway. However, assessing airway resistance by evaluation of random noise impedance parameters should be considered an adjunct to standard methods such as spirometry.
NIOSH-Author; Industrial-dusts; Aerosol-particles; Airborne-fibers; Physiological-response; Respiratory-irritants; Occupational-respiratory-disease; Quantitative-analysis; Occupational-medicine; Analytical-methods; Clinical-tests;
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British Journal of Industrial Medicine
Page last reviewed: November 6, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division