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Symptom-pattern phenotype and pulmonary function in preschool wheezers
Samatha Sonnappa1, Cristina M Bastardo, Angela Wade
1Portex Unit, Respiratory Medicine and Physiology, UCL Institute of Child Health, London, United Kingdom.
Insights
Children with multiple-trigger wheeze show abnormal lung function, unlike those with episodic wheeze. Conductive airways ventilation inhomogeneity (S(cond)) is the most sensitive measure for detecting these pulmonary function abnormalities in young children.
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.
Background:
Pulmonary function in preschool wheezing phenotypes based on wheeze onset and duration and atopic status has been extensively described but has not been studied in symptom-pattern phenotypes of episodic (viral) and multiple-trigger wheeze.
Objective:
We investigated whether multiple-trigger wheezers were more likely to have abnormal pulmonary function and increased fraction of exhaled nitric oxide (FeNO) than episodic (viral) wheezers and whether multiple-breath wash-out was more sensitive at detecting abnormal pulmonary function than specific airways resistance (sR(aw)) in preschool wheezers.
Methods:
FeNO, multiple-breath wash-out indices (lung clearance index [LCI] and conductive airways ventilation inhomogeneity [S(cond)]) and sR(aw) were measured in healthy children and those with recurrent wheeze aged 4 to 6 years. Subgroup analysis was performed according to current symptom-pattern (multiple-trigger vs episodic [viral]), atopic status (atopic vs nonatopic), and wheeze status (currently symptomatic vs asymptomatic).
Results:
Seventy-two control subjects and 62 wheezers were tested. Multiple-trigger wheezers were associated with an average increase of 11% (95% CI, 7% to 18%; P < .001) in LCI, 211% (95% CI, 70% to 470%; P < .001) in S(cond), and 15% (95% CI, 3% to 28%; P = .01) in sR(aw) compared with episodic (viral) wheezers. Pulmonary function in episodic (viral) wheezers did not differ significantly from control subjects. The presence of current atopy or wheeze was associated with higher FeNO (P = .05) but did not influence pulmonary function significantly. On average, LCI was abnormal in 39% (95% CI, 32% to 45%), S(cond) was abnormal in 68% (95% CI, 61% to 74%), and sR(aw) was abnormal in 26% (95% CI, 16% to 35%) of multiple-trigger wheezers.
Conclusions:
Multiple-trigger wheeze is associated with pulmonary function abnormalities independent of atopic and current wheeze status. S(cond) is the most sensitive indicator of abnormal pulmonary function in preschool wheezers.
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