Long‐term course of bronchial inflammation and pulmonary function testing in children with postinfectious bronchiolitis obliterans

Abstract Rationale Postinfectious bronchiolitis obliterans (PIBO) is a rare, chronic respiratory condition, which follows an acute insult due to a severe infection of the lower airways. Objectives The objective of this study was to investigate the long‐term course of bronchial inflammation and pulmonary function testing in children with PIBO. Methods Medical charts of 21 children with PIBO were analyzed retrospectively at the Children's University Hospital Frankfurt/Main Germany. Pulmonary function tests (PFTs) with an interval of at least 1 month were studied between 2002 and 2019. A total of 382 PFTs were analyzed retrospectively and per year, the two best PFTs, in total 217, were evaluated. Additionally, 56 sputum analysis were assessed and the sputum neutrophils were evaluated. Results The evaluation of the 217 PFTs showed a decrease in FEV1 with a loss of 1.07% and a loss in z score of −0.075 per year. FEV1/FVC decreased by 1.44 per year. FVC remained stable, showing a nonsignificant increase by 0.006 in z score per year. However, FEV1 and FVC in L increased significantly with FEV1 0.032 L per cm and FVC 0.048 L/cm in height. Sputum neutrophils showed a significant increase of 2.12% per year. Conclusion Our results demonstrated that in patients with PIBO pulmonary function decreased significantly showing persistent obstruction over an average follow‐up period of 8 years. However, persistent lung growth was revealed. In addition, pulmonary inflammation persisted clearly showing an increasing amount of neutrophils in induced sputum. Patients did not present with a general susceptibility to respiratory infections.