Related Experiment Videos
Airway response to exercise and methacholine in children with respiratory symptoms
J B Clough1, S A Hutchinson, J D Williams
1University of Southampton, Department of Immunopharmacology, Medicine 1, Southampton General Hospital.
Insights
Atopic children with respiratory symptoms showed increased airway responsiveness to both methacholine and exercise challenges. However, these two stimuli were not significantly correlated in children with symptoms, suggesting different underlying airway dysfunctions.
Area of Science:
- Pediatric Pulmonology
- Respiratory Medicine
- Allergy and Immunology
Background:
- Children with respiratory symptoms may exhibit varying airway reactivity.
- Atopy is a known risk factor for respiratory conditions.
- Understanding airway dysfunction is crucial for diagnosing and managing asthma.
Purpose of the Study:
- To compare airway responsiveness to methacholine and exercise challenges in children with respiratory symptoms.
- To investigate the correlation between methacholine and exercise responsiveness in atopic versus non-atopic children.
- To assess the association of these stimuli with asthma diagnosis.
Main Methods:
- Recruited 30 atopic and 30 non-atopic children aged 7-8 years with current respiratory symptoms.
- Administered methacholine provocation tests, measuring the dose causing a 20% fall in forced expiratory volume in one second (PD20).
- Conducted exercise challenge tests, assessing the percentage fall in forced expiratory volume in one second (FEV1).
Main Results:
- No significant correlation was found between methacholine and exercise responsiveness in the overall group.
- Atopic children demonstrated significantly higher responsiveness to both stimuli compared to non-atopic children.
- High odds ratios linked atopy (13.5) and asthma diagnosis (21.0) to increased responsiveness; the odds ratio for both methacholine and exercise challenge was 1.5.
Conclusions:
- Increased bronchial responsiveness to methacholine and exercise are associated with asthma but may reflect distinct airway dysfunctions.
- Atopy is a strong predictor of heightened airway responsiveness in symptomatic children.
- The complex association between stimuli suggests they capture different facets of airway dysfunction in pediatric respiratory illness.
Abstract:
Thirty atopic and 30 non-atopic subjects were identified from a population of 7-8 year old children with current respiratory symptoms. The response of the airways to exercise and provocation by methacholine were compared. In these children, who had symptoms but were not necessarily asthmatic, there was no significant correlation between the two stimuli. The atopic children were, however, significantly more responsive than the non-atopic children to both. For the whole group, odds ratios derived for atopy and for an increased response to methacholine (expressed as a PD20--the dose that caused the forced expiratory volume in one second (FEV1) to fall by 20%--of less than 6.4 mumol/l), a positive exercise test (greater than 15% fall in FEV1), and the presence of asthma were 13.5, 3.3, and 21.0, respectively; that for positive response to methacholine and positive exercise challenge was 1.5. Thus though increased bronchial responsiveness to methacholine and exercise challenge are both associated with a diagnosis of asthma, the association between the two stimuli is complex, and supports the view that they reflect entirely different components of airways dysfunction.