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Assessment of bronchodilator response in children with asthma. Dutch CNSLD Study Group
H J Waalkens1, P J Merkus, E E van Essen-Zandvliet
1Dept of Paediatrics, Beatrix Children Clinic, University Hospital Groningen, The Netherlands.
Insights
This study explored how to best measure bronchodilator response (BDR) in children with asthma. The findings suggest expressing BDR as a percentage of predicted FEV1 may be most reliable for assessing airway reversibility.
Area of Science:
- Pediatric Pulmonology
- Respiratory Medicine
- Asthma Research
Background:
- Bronchodilator response (BDR) in forced expiratory volume in one second (FEV1) assesses airway obstruction reversibility.
- Current methods for expressing BDR lack consensus, especially for pediatric populations.
- The relationship between BDR and bronchial hyperresponsiveness (BHR) in children remains unclear.
Purpose of the Study:
- To evaluate different methods of expressing BDR in children with asthma.
- To investigate the relationship between BDR and non-specific bronchial hyperresponsiveness (BHR) in pediatric asthma.
- To provide recommendations for BDR assessment in children.
Main Methods:
- 116 children (7-16 years) with stable asthma underwent spirometry and BDR testing post-salbutamol inhalation.
- Bronchodilator response was calculated using four different metrics: absolute change, percentage of predicted FEV1, percentage of initial FEV1, and percentage of FEV1 deficit.
- Histamine challenge was used to assess non-specific bronchial hyperresponsiveness (BHR).
Main Results:
- Bronchodilator response expressed as delta FEV1%pred showed less correlation with age and stature compared to other metrics.
- delta FEV1%init and delta FEV1%pred were not significantly related to age and stature.
- delta FEV1%(pred-init) correlated with stature, and delta FEV1(l) correlated with both age and stature.
- BDR, particularly when expressed as delta FEV1%pred, showed a weak relationship with BHR.
Conclusions:
- Expressing bronchodilator response as a percentage of predicted FEV1 (delta FEV1%pred) appears more robust for pediatric asthma assessment.
- The choice of BDR expression impacts its relationship with patient characteristics and bronchial hyperresponsiveness.
- Further research is needed to standardize BDR measurement in children with asthma.
Abstract:
The bronchodilator response (BDR) in forced expiratory volume in one second (FEV1) is routinely assessed to estimate the reversibility of airways obstruction. However, there is no consensus on how the BDR should be expressed, and recommendations applying to children are lacking. Similarly, the relationship between BDR and nonspecific bronchial hyperresponsiveness to histamine (BHR) has not been elucidated. These questions were addressed in 116 children, 7-16 yrs of age, with stable asthma after withdrawal of all pulmonary maintenance medication. Inclusion criteria were an initial FEV1 between 55-90% predicted, and/or FEV1/forced vital capacity (FVC) between 50-75%, as well as a fall in FEV1 of 20% or more when challenged with up to 150 micrograms histamine. The change in FEV1 (delta FEV1) 20 min after inhalation of 800 micrograms salbutamol was expressed in four ways: as an absolute difference (delta FEV1(l)), as a percentage of predicted FEV1 (delta FEV1%pred) or initial FEV1 (delta FEV1%init), and as a percentage of the deficit in FEV1 (delta FEV1%(pred-init)). delta FEV1%init and delta FEV1%pred were not related to age and stature of the children; delta FEV1%(pred-init) was related to stature, whilst delta FEV1(l) was related to both age and stature. All indices correlated with initial FEV1. However, this is an artefact introduced by relating change to initial value, rather than to the mean of initial and final value. In fact, BDR, expressed as delta FEV1%pred, was only slightly greater in children with the lowest initial airway calibre (p = 0.08), unlike delta FEV1%init. BDR was weakly related to BHR.(ABSTRACT TRUNCATED AT 250 WORDS)