Evaluating bronchodilator response in pediatric patients with post-infectious bronchiolitis obliterans: use of different criteria for identifying airway reversibility

Abstract

Objective: Post-infectious bronchiolitis obliterans (PIBO) is a clinical entity that has been classified as constrictive, fixed obstruction of the lumen by fibrotic tissue. However, recent studies using impulse oscillometry have reported bronchodilator responses in PIBO patients. The objective of this study was to evaluate bronchodilator responses in pediatric PIBO patients, comparing different criteria to define the response. Methods: We evaluated pediatric patients diagnosed with PIBO and treated at one of two pediatric pulmonology outpatient clinics in the city of Porto Alegre, Brazil. Spirometric parameters were measured in accordance with international recommendations. Results: We included a total of 72 pediatric PIBO patients. The mean pre- and post-bronchodilator values were clearly lower than the reference values for all parameters, especially FEF25-75%. There were post-bronchodilator improvements. When measured as mean percent increases, FEV1 and FEF25-75%, improved by 11% and 20%, respectively. However, when the absolute values were calculated, the mean FEV1 and FEF25-75% both increased by only 0.1 L. We found that age at viral aggression, a family history of asthma, and allergy had no significant effects on bronchodilator responses. Conclusions: Pediatric patients with PIBO have peripheral airway obstruction that is responsive to treatment but is not completely reversible with a bronchodilator. The concept of PIBO as fixed, irreversible obstruction does not seem to apply to this population. Our data suggest that airway obstruction is variable in PIBO patients, a finding that could have major clinical implications.

Post‐infectious bronchiolitis obliterans

“…During childhood some patients show a bronchodilator response in FEV1 nearly 12%, but the RV diminishes by less than 200 mL. Patients with a significant bronchodilator response (>12% in FEV1 and >200 mL in RV) are few but are important to identify because in these patients bronchodilators can help improve lung function …”

Clinical, functional, and cytological evaluation of sputum in postinfectious bronchiolitis obliterans: a possible overlap with asthma?

“…(12,13) Those studies have shown severe and permanent impairment of lung function, though air trapping slowly decreased with patient growth. (1,12,13) There were no significant correlations between sputum cellularity and the clinical, functional, and CT variables studied. The lack of statistical correlation between the variables in the present study was probably due to the small sample size; the low prevalence of the disease represents an analytical challenge.…”

“…The inflammatory process is secondary to infectious bronchiolitis, which can be caused by viruses, atypical germs (especially Mycoplasma pneumoniae), and other bacteria. (1,2) Although the clinical manifestations of PIBO can vary widely, its main characteristic is that patients with the condition present with signs and symptoms of a severe and persistent lower airway obstruction. (2) The objective of the present study was to evaluate the clinical presentation, pulmonary function, CT findings, and sputum cellularity in patients with PIBO, as well as to correlate sputum cell pattern with spirometry and other imaging findings, clinical manifestations, and atopy.…”

Variation in spirometry parameters in children with and without recurrent respiratory problems

“…According to a report by Global Initiative For Asthma (GINA 2018) FEV 1 and FEV 1 /FVC are markers of expiratory airflow obstruction 29 . In a study conducted on 72 children with bronchiolitis obliterans, it was found that the baseline spirometric parameters were all below the reference parameters for all variables 30 . In our study since the FVC was also below 80%, it leads us to think that there was some degree of restrictive pathology involved.…”