The prevalence of bronchial hyperreactivity to inhaled methacholine and of a clinical history of symptoms of asthma was determined in a birth cohort of9 year old New Zealand children. A history of current or previous recurrent wheezing was obtained in 220 of 815 children. Of 800 who had spirometric tests, 27 (3.4%) had resting airflow obstruction (FEV,/FVC < 75%). Methacholine challenge was und...

A new inhalation synchronised dosimeter triggered by low inspiratory flow rates has been assessed. The methacholine challenge test using dosimeter nebulisation with controlled tidal breathing was compared with continuous nebulisation using De Vilbiss No 40 nebulisers with deep inhalations in 11 asthmatic subjects. Within subject PD20 FEV1 values were lower with the dosimeter method than with th...

The prevalence of bronchial hyperreactivity to inhaled methacholine and of a clinical history of symptoms of asthma was determined in a birth cohort of9 year old New Zealand children. A history of current or previous recurrent wheezing was obtained in 220 of 815 children. Of 800 who had spirometric tests, 27 (3.4%) had resting airflow obstruction (FEV,/FVC < 75%). Methacholine challenge was und...

We examined the relationship between lung function changes and ambient acid aerosol episodes in children attending a residential summer camp. Young females (112) performed daily spirometry, and 96 were assessed on one occasion for airway hyperresponsiveness using a methacholine bronchoprovocation test. Air quality measurements were performed on site and four distinct acid aerosol episodes were ...

In normal subjects in vivo the dose-response curve to inhaled nonsensitizing stimuli reaches a plateau at mild degrees of airway narrowing. We investigated whether the limitation of the response is due to non-optimal smooth muscle activation, by administering high doses of histamine and methacholine together. In fifteen normal subjects a complete dose-response curve to methacholine was recorded...

The relative contributions of large and small airways to hyperresponsiveness in asthma have yet to be fully assessed. This study used a mouse model of chronic allergic airways disease to induce inflammation and remodelling and determine whether in vivo hyperresponsiveness to methacholine is consistent with in vitro reactivity of trachea and small airways. Balb/C mice were sensitised (days 0, 14...

Exercise-induced bronchoconstriction (EIB) has a high prevalence in elite athletes, particularly endurance athletes, winter athletes and swimmers. Recent studies have shown that a clinical diagnosis of EIB has only a moderate sensitivity and specificity for EIB. This finding in conjunction with a recent ruling by the IOC-medical commission that all athletes competing in initially the 2003 Winte...

The effect of histamine or methacholine inhalational challenge on breathing patterns and oxygen saturation was investigated in ten stable asthmatic patients. We used the respiratory inductive plethysmograph to record respiratory timing and minute ventilation along with an ear oximeter to measure oxygen saturation (SaO2). As FEV1 fell during the challenge procedure, SaO2 also fell (average 3 per...