Related Experiment Videos
Specific approach on dose-response curves to inhaled carbachol assessed by the interruption technique in children
C W Sommer1, U Frey, M H Schönli
1Department of Paediatrics, University of Berne, Switzerland.
Insights
This study introduces a new method, the variance-based provocation dose (PDvb), to better assess bronchial reactivity in children. PDvb effectively differentiates between healthy and asthmatic children using carbachol challenge tests.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
- Allergy and Immunology
Background:
- Bronchial hyperresponsiveness is a key feature of asthma in children.
- Accurate assessment of bronchial reactivity is crucial for diagnosis and management.
- Existing provocation dose thresholds may lack precision in differentiating between healthy and asthmatic children.
Purpose of the Study:
- To evaluate significant thresholds for bronchial challenge tests in children.
- To compare traditional provocation dose (PD) metrics with a novel variance-based provocation dose (PDvb).
- To identify the most reliable threshold for assessing bronchial reactivity in pediatric populations.
Main Methods:
- Carbachol bronchial challenge tests were conducted on 20 asthmatic and 20 healthy children.
- Respiratory resistance (Rint) was measured using whole body plethysmography and the interruption technique.
- Provocation doses (PD50, PD65, PD75, PD100) and a new variance-based provocation dose (PDvb) were calculated and compared.
Main Results:
- Traditional PD thresholds (PD50, PD65, PD75, PD100) were computed using 4th power polynomial function analysis.
- The variance-based provocation dose (PDvb) was defined as a threshold definitively above baseline Rint variation.
- PDvb demonstrated superior ability in differentiating between healthy and asthmatic children (p < 0.002).
Conclusions:
- The variance-based provocation dose (PDvb) offers a statistically robust and practically advantageous threshold for bronchial reactivity assessment.
- PDvb provides a more precise measure for distinguishing asthmatic children from healthy controls compared to traditional PD values.
- This novel approach enhances the diagnostic utility of bronchial challenge tests in pediatric asthma.
Abstract:
To determine significant thresholds obtained by bronchial challenge tests in children for assessment of bronchial reactivity, changes of respiratory resistance (Rint) induced by inhaled carbachol were evaluated in 20 asthmatic children (10 boys and 10 girls, mean age 9.1 +/- 2.8 y, range 5 to 15 y) and 20 healthy control children (10 boys and 10 girls, mean age 12.1 +/- 2.6 y, range 8 to 16 y). Baseline lung function was assessed by whole body plethysmography. The carbachol challenge test was performed by the interruption technique. The objectives were to search for the most predictable provocation dose (PD) according to statistical and practical considerations. The statistical argument is given by the condition that the target PD must definitively be out of the measurement error of baseline values. From the practical point of view, the object is to provoke the subjects the least amount possible. As thresholds of bronchial reactivity, the provocation doses inducing a 50%, 65%, 75%, or 100% increase in baseline Rint (PD50, PD65, PD75, PD100) were computed by a 4th power polynomial function analysis including data points of the entire dose-response curve. In comparison, a new threshold, the "variance based" provocation dose (PDvb), was defined as threshold to be definitively above the range of the baseline Rint variation before initiating challenge [PDvb > mean + 2 SD range of Rint(0)]. Although the PD50, PD65, PD75, and PD100 can be adequately computed by the 4th power function from the whole dose-response curve, comparison between the different provocation thresholds revealed that PDvb gives the best values to differentiate between healthy and asthmatic children (p < 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)