Longitudinal Assessment of Pulmonary Function and Bronchodilator
Responses in Pediatric Patients with Post-Infectious Bronchiolitis
Abstract Objective: We aimed to further assess the evolution of
pulmonary function and bronchodilator response in the Chinese case
series with post-infectious bronchiolitis obliterans (PIBO).
Methods: Twelve children with PIBO, aged 59-110 months, were
retrospectively studied between 2011 and 2019. According to the ATS/ERS
recommendations, forced vital capacity (FVC), forced expiratory volume
in 1 s (FEV1), FEV1/FVC and maximal midexpiratory flow velocity
25%-75% (MMEF25%-75%) were collected at each pulmonary function
tests (PFTs), as well as bronchodilator responses were evaluated.
Spirometric parameters were monitored over time, and generalized linear
mixed models were used to analyze longitudinal panel data. Results: The
median baseline PFT values for FVC, FEV1, FEV1/FVC ratio and MMEF25%
-75% were 41.6%, 39.75%, 90.7% and 22.2% respectively. At the
initial PFTs, 10 (83.3%) patients demonstrated a significant
bronchodilator response. FVC and FEV1 increased by a mean of
8.212%/year and 5.007%/year, and FEV1/FVC ratio with an average
decrease of 3.537%/year. MMEF25-75% showed an average increase of
1.583% per year. Over all, FEV1 and MMEF25%-75% showed different
degrees of improvement after inhaled bronchodilators at each PFT
sessions for ten patients, and FEV1 was with significant
(>12%) β2-bronchodilation in 53% of PFT sessions.
Conclusions: Pediatric patients with PIBO showed an obstructive defect
of pulmonary function. The FVC, FEV1 and MMEF25%-75% improved as they
grew old, while FEV1/FVC ratio decreased. It may be due to the
development of lung parenchyma more than airway growth. Airway
obstruction of some patients improved with the use of β2 agonists.