Airway hyperresponsiveness and cough-receptor sensitivity in children with recurrent cough.
In children, recurrent cough is a common presenting symptom that may represent asthma. We tested the hypotheses that children with recurrent cough have increased cough-receptor sensitivity (CRS) or airway hyperresponsiveness (AHR). Skin prick testing, the capsaicin CRS test, and hypertonic saline (HS) challenge were performed in 44 children (median age: 8.9 yr) with recurrent dry cough (> or = 2 episodes of cough, each lasting > or = 2 wk, within a period of 12 mo) and 44 controls. Measures of CRS were the concentration of capsaicin required to stimulate > or = 2 coughs (Cth) and > or = 5 coughs (C5). During the coughing period, Cth (mean log: 0.62 [95% CI: 0.43 to 0.81]) and C5 (mean log: 1.15 [95% CI: 0.86 to 1.44]) of the subjects without AHR were significantly lower (p = 0.0026, 0.027, respectively) than Cth (mean log: 1.27 [95% CI: 0.88 to 1.66]) and C5 (mean log: 1.79 [95% CI: 1.21 to 2.37]) of the subjects with AHR and those of the controls (p = 0.0002 and 0.0001). During the cough-free period, there was no difference in CRS among the groups. In subjects who demonstrated AHR, the provocation dose causing a > or = 15% fall in FEV1 (PD15) during the cough period was significantly lower (p = 0.005) than that during the cough-free period. We conclude that AHR or increased CRS is present during the coughing phase in children with recurrent cough.
Chang
A B
AB
Department of Thoracic Medicine, University of Melbourne, and Centre for Adolescent Health, Royal Children's Hospital, Australia.
Phelan
P D
PD
Sawyer
S M
SM
Robertson
C F
CF
D000293:Adolescent; D016535:Bronchial Hyperreactivity / Q000175:diagnosis / Q000503:physiopathology*; D002211:Capsaicin; D002648:Child; D003371:Cough / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008465:Mechanoreceptors / Q000503:physiopathology*; D012008:Recurrence; D012462:Saline Solution, Hypertonic
D012462:Saline Solution, Hypertonic; D002211:Capsaicin