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[Circadian variations of bronchoconstriction in asthmatic children]
A Battistini1, G Pisi, G Padula
1Centro di Fisiopatologia Respiratoria Infantile, Università di Parma, Italia.
Insights
Asthmatic children exhibit significant daily lung function changes, masking typical circadian rhythms. Rapid variations in bronchial tone can obscure the expected morning bronchoconstriction pattern.
Area of Science:
- Pediatric Pulmonology
- Circadian Biology
- Respiratory Medicine
Background:
- Asthma is characterized by variable airway obstruction.
- Circadian rhythms are known to influence respiratory function.
Purpose of the Study:
- To quantify daily variations in spirometry for asthmatic children.
- To assess if these variations mask underlying circadian patterns.
Main Methods:
- Evaluated spirometry, including forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC).
- Compared measurements taken at different times of day and on consecutive mornings in 31 asthmatic children.
- Analyzed significant modifications (>10%) in FEV1 and FVC.
Main Results:
- Mean FEV1 and FVC values were similar across different times of day and consecutive mornings.
- High variability was observed in individual patient measurements.
- A significant percentage of patients showed >10% changes in FEV1 or FVC throughout the day.
Conclusions:
- Daily spirometric variations in asthmatic children are substantial.
- These rapid changes can obscure the typical circadian rhythm of airway patency.
- Bronchial tone variability plays a key role in daily lung function fluctuations.
Abstract:
In order to determine the magnitude of circadian variations in bronchoconstriction, we examined modifications of the spirometry observed during the 24-hr in a group of asthmatic (31 males, mean age = 8 years, 6 months). Particular attention was paid to the forced expiratory volume in 1 sec. (FEV1) and the forced vital capacity (FVC). We were thus able to compare in single patients 43 spirometry pairs between morning (between 8 and 10 am) and early afternoon (between 1 and 4 pm), 46 pairs between morning and evening (between 6 and 10 pm) and 54 between 2 consecutive mornings. The results of this study, substantially similar for the FEV1 and the FVC, show that the mean values obtained at different hours during the day and in two consecutive mornings were almost superimposable. On the other hand, the mean values and the standard deviations of the differences between two determinations in single patients are high. The percentage of patients who present significant modifications (greater than 10%) of FEV1 or of FVC at different hours of the day is also quite high. Moreover these variations seem directly related to the baseline spirometric value. Although the literature frequently outlines the existence of a circadian rhythm in the modifications or airways patency (maximum bronchoconstriction in the morning and minimum in the evening), in the asthmatic, however, the fast variations in the bronchial tone can be such as to mask this cyclic rhythm.(ABSTRACT TRUNCATED AT 250 WORDS)