RT Journal Article
SR Electronic
T1 Cough threshold in patients with chronic obstructive pulmonary disease
JF Thorax
JO Thorax
FD BMJ Publishing Group Ltd and British Thoracic Society
SP 62
OP 64
DO 10.1136/thx.54.1.62
VO 54
IS 1
A1 C H Wong
A1 A H Morice
YR 1999
UL http://thorax.bmj.com/content/54/1/62.abstract
AB BACKGROUND Cough is an important symptom of patients with chronic obstructive pulmonary disease (COPD). The cough threshold to citric acid and capsaicin in patients with COPD and in normal volunteers was measured, as well as bronchial hyperresponsiveness to methacholine.METHODS Nineteen patients with COPD and 22 controls were recruited. Subjects underwent a methacholine bronchoprovocation test and a cough challenge to citric acid and capsaicin.RESULTS The log citric acid cough threshold D2 (concentration causing two coughs) was significantly lower in patients with COPD (mean 2.17 versus 2.56, mean difference (95% CI) 0.39 (0.04 to 0.74), p = 0.02) but not for capsaicin cough D2 (0.66 versus 0.8, p = 0.41). Sixteen patients with COPD had bronchial hyperresponsiveness which was correlated with baseline FEV1 (r= 0.6, p = 0.01, 95% CI 0.15 to 0.84).CONCLUSIONS Patients with COPD have a lower cough threshold to citric acid, possibly due to a differential effect of cigarette smoke on citric acid sensitive cough receptors.