Research

Perception of urge-to-cough and dyspnea in healthy smokers with decreased cough reflex sensitivity

Masashi Kanezaki¹ , Satoru Ebihara¹ , Etsuhiro Nikkuni¹ , Peijun Gui¹ , Chihiro Suda¹ , Takae Ebihara² , Miyako Yamasaki² and Masahiro Kohzuki¹

¹  Department of Internal Medicine and Rehabilitation Science, Tohoku University Graduate School of Medicine, Seiryo-machi 1-1, Aoba-ku, Sendai 980-8574, Japan

²  Department of Geriatrics and Gerontology, Institute of Development, Aging and Cancer, Tohoku University, Seiryo-machi 4-1, Aoba-ku, Sendai 980-8575, Japan

author email corresponding author email

Cough 2010, 6:1doi:10.1186/1745-9974-6-1

Published:	5 February 2010

Abstract

Background

Although cigarette smoking has been implicated as an important risk factor for the development of respiratory symptoms, the perceptional aspects of two symptoms in smokers have not been fully elucidated. Therefore, we simultaneously evaluated the cough reflex sensitivity, the cognition of urge-to-cough and perception of dyspnea in both healthy smokers and non-smokers.

Methods

Fourteen male healthy never-smokers and 14 age-matched male healthy current-smokers were recruited via public postings. The cough reflex sensitivity and the urge-to-cough were evaluated by the inhalation of citric acid. The perception of dyspnea was evaluated by Borg scores during applications of external inspiratory resistive loads.

Results

The cough reflex threshold to citric acid, as expressed by the lowest concentration of citric acid that elicited two or more coughs (C₂) and the lowest concentration of citric acid that elicited five or more coughs (C₅) in smokers was significantly higher than in non-smokers. The urge-to-cough log-log slope in smokers was significantly milder than that of non-smokers. There were no significant differences in the urge-to-cough threshold between non-smokers and smokers. There were no significant differences in perceptions of dyspnea between non-smokers and smokers.

Conclusions

The study showed that decreased cough reflex sensitivity in healthy smokers was accompanied by a decreased cognition of urge-to-cough whereas it was not accompanied by the alternation of perception of dyspnea. Physicians should pay attention to the perceptual alterations of cough in smokers.