Chest
Volume 123, Issue 3, March 2003, Pages 685-688
Journal home page for Chest

Clinical Investigations
Cough
Cough Reflex Sensitivity in Cigarette Smokersa

https://doi.org/10.1378/chest.123.3.685Get rights and content

Study objectives

To evaluate cough reflex sensitivity in a population of young, healthy, male cigarette smokers.

Design

Cross-sectional comparison.

Setting

Academic medical center.

Participants

Twenty healthy, male current-smokers (mean [± SEM] age, 32.2 ± 1.2 years).

Measurements

Subjects underwent baseline spirometry followed by capsaicin cough challenge testing, which involved the inhalation of capsaicin in ascending, doubling concentrations until the concentrations inducing two or more coughs (C2) and those inducing five or more coughs (C5) were reached. The data were compared to those from a group of 50 healthy, male nonsmokers who had undergone identical cough challenge testing.

Results

The two groups did not differ in terms of age or baseline pulmonary function. Cough sensitivity was significantly diminished in the current-smokers compared to control subjects. The mean (± SEM) log C2 values in smokers and nonsmokers were 1.26 ± 0.13 and 0.81 ± 0.08, respectively (p = 0.004). The mean log C5 values in smokers and nonsmokers were 2.03 ± 0.10 and 1.20 ± 0.08, respectively (p < 0.000001).

Conclusions

Cough reflex sensitivity is significantly diminished in young, healthy, male current-smokers compared to a similar population of nonsmokers. The mechanism of cough suppression in smokers remains speculative but may involve long-term tobacco smoke-induced desensitization of the cough receptors within the airway epithelium.

Section snippets

Subjects

Twenty healthy, asymptomatic, male, current-smokers were recruited for the study, which was approved by the Institutional Review Board of Albert Einstein Hospital/Montefiore Medical Center. The amount and duration of cigarette smoking required for study entry was arbitrarily defined as at least five cigarettes daily for 1 year. Subjects had no history of pulmonary disease (including asthma or previous history of chronic cough) or recent (ie, within 4 weeks) symptoms suggestive of respiratory

Results

The induction of five or more coughs was achieved in all subjects and nonsmoking control subjects. Subjects and control subjects did not differ in terms of age and baseline pulmonary function (Table 1). The mean (± SEM) log C2 and log C5 values for subjects and control subjects are displayed in Figure 1. Cough reflex sensitivity was significantly diminished in current-smokers relative to nonsmokers.

Discussion

This study has demonstrated that asymptomatic current cigarette smokers have a significantly diminished cough reflex relative to that of healthy nonsmokers. The inhibition of cough sensitivity due to long-term exposure to tobacco smoke contrasts with the previously documented enhancement of bronchial reactivity caused by cigarette smoking.1112 These observations are an excellent illustration of the concept that cough and bronchoconstriction are separate entities that are controlled by distinct

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