Influence of the rheological properties of airway mucus on cough sound generation.
OBJECTIVE
There have been several reports regarding the role of airway mucus in cough sound generation, but the properties of the mucus that influence cough sound generation remain unclear. The aim of this study was to elucidate the influence of the rheological properties of airway mucus on cough sound generation.


METHODS
The acoustic properties of voluntary cough sounds from 15 patients with chronic productive cough and nine controls with dry cough were analyzed by dividing the energy envelope of the sounds into three phases and computing the root mean square values and the duration of each phase as a proportion of the total cough duration. The rheological properties of the airway mucus (yield value, ciliary transportability and spinability) were also measured. Differences between productive and dry cough sounds, and correlations between the acoustic properties of cough sounds and the rheological properties of the airway mucus, were analyzed.


RESULTS
The acoustic properties of productive and dry cough sounds differed significantly (P < 0.05). The acoustic properties of second phase cough sounds correlated significantly with the yield value and ciliary transportability of the airway mucus (P < 0.05).


CONCLUSIONS
The rheological properties of the airway mucus influenced cough sound generation.
Hashimoto
Yasushi
Y
Department of Respiratory Medicine, Tokyo Metropolitan Hiro-o General Hospital, Tokyo, Japan. ciu74880@rio.odn.ne.jp
Murata
Akira
A
Mikami
Masashi
M
Nakamura
Seiichi
S
Yamanaka
Eiichi
E
Kudoh
Shoji
S
D000328:Adult; D000402:Airway Obstruction / Q000209:etiology / Q000503:physiopathology*; D016022:Case-Control Studies; D002908:Chronic Disease; D003371:Cough / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009079:Mucociliary Clearance; D009093:Mucus / Q000378:metabolism*; D011336:Probability; D011446:Prospective Studies; D012016:Reference Values; D012137:Respiratory System; D012212:Rheology; D012307:Risk Factors; D012720:Severity of Illness Index; D013016:Sound; D013018:Sound Spectrography; D018709:Statistics, Nonparametric