It was previously shown that unexplained chronic cough is associated with asymptomatic gastroesophageal reflux. The aim of this study was to determine if distal esophageal acid is important in the pathogenesis of this cough. In 22 patients with cough and reflux as determined by 24-h ambulatory esophageal pH monitoring, distal esophageal acid perfusion was performed in a double-blind controlled fashion. Patients received both 0.1 N HCl and 0.9% saline for 15 min, in random order. Cough was recorded with a microphone and then computer analyzed. In 12 matched control subjects, 24-h ambulatory esophageal pH monitoring and distal esophageal acid perfusion studies were also performed. In patients, there was a significant increase in cough frequency, median (range): 36.5 (6 to 111) versus 8.3 (0 to 46)/15 min, p < 0.001, and amplitude, geometric mean (range): 85.2 (78.1 to 92.3) versus 73.1 (0.0 to 87.1) dB, p < 0.01, with HCl compared with saline. During HCl infusion, compared with control subjects, patients had more cough episodes, 36.5 (6 to 111) versus 0.0 (0 to 11)/15 min, p < 0.0001, with greater amplitude, 85.2 (78.1 to 92.3) versus 0.0 (0.0 to 79.6) dB, p < 0.001, but there was no difference in cough duration. We subsequently investigated whether inhibition of the induced cough was possible. In seven patients repeat esophageal acid perfusion was performed 15 min after the esophageal instillation of 4 ml of 4% lignocaine.(ABSTRACT TRUNCATED AT 250 WORDS)

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Chronic cough persisting for two months or more that remains unexplained after extensive investigations is a common clinical problem. The purpose of this study was to determine whether such cough is associated with otherwise asymptomatic gastro-oesophageal reflux. Thirteen patients with chronic persistent cough that was unexplained after a standard diagnostic assessment were identified. All were non-smokers. The mean (SE) duration of cough was 17-8 (8 0) months. Ten had never had reflux symptoms and three had had mild symptoms only after the onset of the cough. All the patients completed standardised cough diary cards for eight weeks and underwent 24 hour ambulatory oesophageal pH monitoring. A reflux episode was defined as a fall in oesophageal pH to below 4.0. Nine control subjects were matched for age, lung function, and body mass index. The patients experienced significantly more episodes of reflux per 24 hours than the controls (115-8 (SE 31-7) versus 4-7 (1-4) and longer reflux episodes (15-5 (5-8) versus 1-7 (0-5) minutes), and the oesophageal pH was below 4 0 considerably longer (84 5 (20 2) versus 3-8 (1P3) minutes). Cough occurred simultaneously with 13% (2-2%) of reflux episodes and within five minutes in another 35% (5-8%) of episodes, whereas gastro-oesophageal reflux occurred simultaneously with 78% (5-

Occupational type exposure tests in two female hairdressers with occupational asthma gave, in one, an immediate asthmatic reaction to the mixing of a bleach containing potassium persulphate with hydrogen peroxide and also immediate skin test reactions to sodium and potassium persulphate, and in the other a non-immediate asthmatic reaction and negative skin tests to the persulphate preparations and also immediate skin and bronchial reactions to an extract of henna.

A comparison was made between the eflFects of prior inhalation of sodium cromoglycate or beclomethasone dipropionate on immediate, late and dual asthmatic reactions to provocation challenge tests with a range of allergcnii. Whereas sodium cromoglycate inhibited immediate and dual asthmatic reactions, beclomethasone dipropionate had no elTect on immediate asthmatic reactions, but consistently inhibited late asthmatic reactions.