Symptom-pattern phenotype and pulmonary function in preschool wheezers.

Area of Science:

• Pediatric Pulmonology
• Respiratory Medicine
• Allergy and Immunology

Background:

• Preschool wheezing phenotypes are typically categorized by onset, duration, and atopic status.
• Previous research has not focused on symptom-pattern phenotypes like episodic (viral) and multiple-trigger wheeze.
• Understanding these distinct wheeze patterns is crucial for accurate diagnosis and management.

Purpose of the Study:

• To determine if multiple-trigger wheezers exhibit more pulmonary function abnormalities and higher fraction of exhaled nitric oxide (FeNO) than episodic (viral) wheezers.
• To compare the sensitivity of multiple-breath wash-out techniques versus specific airways resistance (sR(aw)) in detecting lung function deficits in preschool wheezers.
• To investigate the impact of atopy and current wheeze status on these measures.

Main Methods:

• Pulmonary function tests including FeNO, multiple-breath wash-out (lung clearance index [LCI], conductive airways ventilation inhomogeneity [S(cond)]), and sR(aw) were performed on healthy children and those with recurrent wheeze (ages 4-6).
• Participants were sub-grouped based on symptom pattern (multiple-trigger vs. episodic [viral]), atopic status, and current wheeze symptoms.
• Statistical analyses compared measures between groups and assessed the sensitivity of different pulmonary function tests.

Main Results:

• Multiple-trigger wheezers showed significantly increased LCI (11%), S(cond) (211%), and sR(aw) (15%) compared to episodic (viral) wheezers.
• Episodic (viral) wheezers' pulmonary function did not differ significantly from healthy controls.
• Higher FeNO was observed in those with current atopy or wheeze, but this did not significantly impact pulmonary function.
• Abnormalities were detected in LCI (39%), S(cond) (68%), and sR(aw) (26%) among multiple-trigger wheezers.

Conclusions:

• Multiple-trigger wheeze is linked to pulmonary function abnormalities, irrespective of atopic status or current wheeze.
• Conductive airways ventilation inhomogeneity (S(cond)) emerged as the most sensitive indicator of abnormal pulmonary function in preschool wheezers.
• These findings highlight the distinct physiological impact of different wheeze phenotypes in young children.