[Capsaicin-induced cough. Tachyphylaxis and the effect of anaesthesia on the pharynx]

We examined the reproducibility of capsaicin-induced cough thresholds and the influence of pharynx anaesthesia used to treat the cough. We performed cough threshold tests on ten patients with bronchial asthma and ten patients with chronic cough. The lowest level of capsaicin-induced cough threshold was defined as ten coughs. Tachyphylaxis in cough thresholds was examined three times at intervals of 30 minutes and 120 minutes after the initial test. We measured cough thresholds before and after pharynx anaesthesia with xylocainbiscus. There was no change in cough thresholds among the three times; nor was them any change in the thresholds before and after pharynx anaesthesia. But in five patients with acute pharyngitis, the cough thresholds after pharynx anaesthesia were greater than before. It was suggested that cough threshold tests had reproducibility 30 minutes and 120 minutes after indicating that tachyphylaxis did not exist. Furthermore it was suggested that pharynx anaesthesia influenced the cough threshold in patients with acute inflammation of the pharynx, but anesthesia had no influence on cough thresholds in patients without acute inflammation of the pharynx.