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Bronchial responsiveness and symptoms in 5-6 year old children: a comparison of a direct and indirect challenge
N M Wilson1, P Bridge, M Silverman
1Department of Paediatrics and Neonatal Medicine, Royal Postgraduate Medical School, Hammersmith Hospital, London, UK.
Insights
Neither direct (methacholine) nor indirect (hypertonic saline) bronchial challenges could distinguish wheeze severity or patterns in young children. Bronchial responsiveness may not be a reliable marker for airway inflammation in this age group.
Area of Science:
- Pediatric Pulmonology
- Respiratory Medicine
- Allergy and Immunology
Background:
- Bronchial responsiveness correlates with asthma severity and airway inflammation.
- A clear distinction between normal and abnormal bronchial responsiveness is lacking in population studies.
- A reliable marker for airway inflammation is needed due to the variable outcomes of childhood wheeze.
Purpose of the Study:
- To compare direct (methacholine) and indirect (hypertonic saline) airway challenges in children aged 5-6 years with a history of wheeze.
- To determine if symptom patterns or wheeze severity could be distinguished by either challenge test.
- To assess the utility of bronchial responsiveness as a marker for airway inflammation in early childhood wheeze.
Main Methods:
- Forty children with diverse wheeze symptoms were monitored for six months, with symptom patterns and severity graded.
- Children underwent separate direct (methacholine) and indirect (hypertonic saline) bronchial challenges.
- Airway response was measured using respiratory resistance (Rrs6) and transcutaneous oxygen (PTCO2); atopic status was assessed via IgE and skin prick tests.
Main Results:
- Both methacholine and hypertonic saline challenges yielded similar results when assessed by Rrs6 or PTCO2.
- No significant differences in response were observed between different symptom patterns or severity grades for either challenge.
- There was no correlation found between the challenge test responses and the atopic status of the children.
Conclusions:
- Neither direct nor indirect bronchial challenge tests effectively distinguished between past or present wheeze or clinical severity in the studied children.
- The findings suggest that wheezy children of this age may not exhibit detectable airway inflammation, or that bronchial responsiveness is not a suitable marker for it.
- Further research is needed to identify reliable markers of airway inflammation in early childhood wheeze.
Background:
The level of bronchial responsiveness in those with definite asthma correlates with disease severity and markers of airway inflammation. However, in population studies no clear distinction between normal and abnormal is found. Since the outcome of wheeze in early childhood is very variable, a marker of underlying airway inflammation would be of practical value. A stimulus acting indirectly may be more appropriate than one acting directly on smooth muscle. In this study the airway response to a direct (methacholine) and indirect (hypertonic saline) challenge have been compared in 5-6 year old children with past or present wheeze to see if symptom patterns or severity could be distinguished by either test.
Methods:
Forty children with a wide spectrum of wheeze were monitored for a six month period after which their pattern and severity of symptoms were graded. Hypertonic saline and methacholine challenges were then performed on separate days. The response was assessed by both respiratory resistance (Rrs6) and transcutaneous oxygen (PTCO2). Atopic status was determined by IgE and skin prick tests.
Results:
The results of both challenges were similar whether assessed by Rrs6 or PTCO2. There was no difference in the response to either methacholine or saline between different symptom patterns or severity grades, nor was there any correlation with either test to atopic status.
Conclusions:
Neither an indirect nor a direct challenge distinguished between past or present wheeze or degree of clinical severity in this group of children. Either wheezy children of this age do not have airway inflammation or bronchial responsiveness is not a marker for it.