Airway hypersensitivity is routinely evaluated by measuring the concentration (PC20) of inhaled methacholine or histamine that causes a 20% fall in forced expiratory volume in 1 second (FEV1). It has been suggested that a percentage fall in forced vital capacity (FVC) measured at the PC20 dose of inhaled agonist (deltaFVC) is a potentially useful clinical measure in patients who have asthma bec...

BACKGROUND It is desirable to prescribe the minimal effective dose of inhaled steroids to control asthma. To ensure that inflammation is suppressed whilst using the lowest possible dose, a sensitive and specific method for assessing airway inflammation is needed. METHODS The usefulness of exhaled nitric oxide (NO), sputum eosinophils, and methacholine airway responsiveness (PC20) for monitori...

BACKGROUND Cough in the patients with cough variant asthma is triggered by bronchoconstriction, which responds to bronchodilator therapy. Following airway narrowing induced by inhaled methacholine, deep inspiration (DI) causes dilation of the airways in both asthmatic and non-asthmatic subjects. The aim of the present study was to investigate the relationship between bronchodilator effect of DI...

Exhaled nitric oxide (NO) is elevated in asthmatics, and varies with disease severity. We postulated that a respiratory virus infection increases exhaled NO levels in asthma, and examined the relationship between the virus-induced changes in exhaled NO and in airway hyperresponsiveness to histamine. In a parallel study, seven patients underwent experimental rhinovirus 16 (RV16) inoculation at d...

Two methods of interpreting histamine inhalation dose-response curves were compared in 27 normal and 41 asthmatic subjects. The histamine provocation concentration producing a 20% fall (PC20) in forced expiratory volume in one second (FEV1) was calculated on the basis of the lowest FEV1 after inhalation of saline and the lowest value after inhalation of histamine. The histamine threshold was de...

BACKGROUND Eosinophils in induced sputum and exhaled nitric oxide (NO) are currently used as non-invasive markers in the assessment of airway inflammation in asthma. As both sputum eosinophils (%) and exhaled NO are raised in asthmatic subjects not receiving inhaled steroids and decreased following corticosteroid therapy, a relationship between them is plausible. METHODS Exhaled NO was measur...

chronic cough is a common problem in patients visiting physicians and its prevalence in different populations range from 3 to 40%. postnasal drip, asthma and gastroesophageal reflux are the known cause of chronic cough. although diagnosis of asthma is usually made by clinical signs and spirometeric results, methacholine challenge test is a good diagnostic test in patients who show normal physic...

We welcome the comments of Dr. Lipworth regarding the comparison between exhaled nitric oxide (NO) and methacholine reactivity in separating doses of inhaled steroid. Our study looked at the short-term effects of administering doses, increased weekly, of inhaled beclomethasone on exhaled NO and PC20 methacholine, in a small number of asthmatic subjects. First, there are important differences in...

Bronchial hyperresponsiveness (BHR) in smokers is believed to be a consequence of airway wall inflammation. We have examined the effects of treatment with nonsteroidal anti-inflammatory drugs (NSAID) on BHR to inhaled histamine, measured as the provocative concentration reducing forced expiratory volume in one second (FEV1) by 20% (PC20), in middle-aged male cigarette smokers in two separate do...

BACKGROUND Recent in vitro and in vivo studies in animals have suggested that ambient oxygen tension may influence airway responsiveness to bronchoconstrictor stimuli. These observations may have relevance to the management of acute exacerbations of asthma. The present studies were designed to examine the influence of inspired oxygen tension (Fio2 1.0, 0.21, 0.15) on methacholine-induced bronch...