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Peak expiratory flow variation and bronchial hyperresponsiveness in asthmatic children during periods of antigen
E A Valletta1, A Comis, G Del Col
1Pediatric Clinic, University of Verona, Italy.
Insights
A prolonged stay in a mite-free, high-altitude environment improved peak expiratory flow rate (PEF) variation and reduced bronchial hyperresponsiveness (BHR) in children with asthma. Returning home worsened these asthma indicators.
Area of Science:
- Pediatric Pulmonology
- Allergy and Immunology
- Environmental Medicine
Background:
- Asthma management in children often involves allergen avoidance.
- High-altitude environments may offer reduced allergen exposure.
- Peak expiratory flow rate (PEF) variation and bronchial hyperresponsiveness (BHR) are key asthma indicators.
Purpose of the Study:
- To evaluate the impact of a high-altitude, mite-free environment on PEF variation and BHR in children with asthma.
- To assess the reversibility of these effects upon return to a sea-level, home environment.
Main Methods:
- 12 children with mild-to-moderate asthma and house-dust mite allergy participated.
- PEF was measured daily for 3 months at high altitude and 10 days post-return.
- Bronchial hyperresponsiveness (BHR) to methacholine (PC20) was assessed monthly and post-return.
Main Results:
- A significant decrease in mean %PEF variation and an increase in PC20 were observed during high-altitude stay.
- Upon returning home, both %PEF variation and PC20 significantly worsened.
- A significant negative correlation (r = -0.63, P = 0.001) was found between PC20 and mean %PEF variation.
Conclusions:
- Prolonged high-altitude, mite-free residence demonstrates a beneficial effect on PEF variability and BHR in asthmatic children.
- Asthma control, indicated by PEF variability and BHR, can be negatively impacted by returning to a high-allergen environment.
- These findings support allergen avoidance strategies in asthma management, particularly in pediatric populations.
Abstract:
Changes of diurnal variation of peak expiratory flow rate (%PEF variation) and their relationship with bronchial hyperresponsiveness (BHR) to methacholine (PC20) were evaluated in 12 children with mild-to-moderate asthma and house-dust mite allergy, during successive periods of stay in a mite-free environment at high altitude (1756 m) and at their home at sea level. The children remained at the high altitude from October until the end of December; then they spent a 3-week period at home and returned to high altitude residence in January. PEF was measured daily, in the morning and in the evening, during the 3 months' stay at high altitude and them for 10 days after the return in January. PC20 was assessed in 8/12 children, once a month from October to December, and at the return in January. Mean absolute PEF values did not change significantly throughout the study. From October to December, patients showed a significant decrease of mean %PEF variation (P = 0.04), while PC20 showed an increase (P = 0.05). After the 3 weeks at home, both %PEF variation (P = 0.03) and PC20 (P = 0.05) significantly worsened. The correlation between PC20 values and mean %PEF variation in the 2 days before and after each methacholine test was r = -0.63 (P = 0.001). Our data suggest that there is a beneficial effect of a prolonged stay in a mite-free environment, on both PEF variability and BHR, also in asthmatic children with good pulmonary function. PEF variability and bronchial responsiveness to methacholine were significantly correlated also for small changes of the two variables.