Chapter 11: the infant and toddler with wheezing

Area of Science:

• Pediatrics
• Pulmonology
• Immunology

Background:

• Recurrent wheezing affects a significant portion of young children, often triggered by viral infections or bacterial colonization.
• Wheezing phenotypes in early childhood include transient early wheezers, nonatopic wheezers, and atopic wheezers, each with distinct clinical trajectories.
• Understanding these phenotypes is crucial for predicting long-term respiratory health and guiding interventions.

Purpose of the Study:

• To characterize the different phenotypes of recurrent wheezing in infants and toddlers.
• To investigate the association between wheezing phenotypes, lung function, and bronchial hyperreactivity.
• To explore the long-term outcomes of early childhood wheezing.

Main Methods:

• Classification of wheezing phenotypes based on age of onset, duration, and associated factors.
• Assessment of lung function in children with different wheezing phenotypes.
• Evaluation of bronchial hyperreactivity using methacholine challenge tests.

Main Results:

• Transient early wheezers (60%) show reduced lung function by age 6, despite symptom resolution.
• "Nonatopic wheezers" (20%) have persistent but less frequent symptoms and slightly reduced lung function without bronchial hyperreactivity.
• "Atopic wheezers" (20%) present with normal infancy lung function but develop reduced lung function and bronchial hyperreactivity by age 6.

Conclusions:

• Early childhood wheezing is heterogeneous, with distinct phenotypes having different prognoses.
• Atopic wheezing is associated with the development of reduced lung function and bronchial hyperreactivity.
• Long-term respiratory health in children with recurrent wheezing depends on the underlying phenotype.