Abstract: Objective To summarize the clinical features and risk factors of children with post-infectious bronchiolitis obliterans (PBO), who were treated with invasive mechanical ventilation because of severe pneumonia, and to provide clinical reference for early diagnosis, early treatment and improvement of prognosis of pediatric patients with PBO. Methods The pediatric patients treated with invasive mechanical ventilation because of severe pneumonia, who were hospitalized in PICU of Tianjin Children’ s Hospital from October 2010 to December 2015 were included in this study. The pediatric patients who were diagnosed with PBO were used as the observation group. The general characteristics, clinical presentation, treatment time, treatment results, distribution of pathogens and relevant laboratory examination results were analyzed by using SAS 9.3 statistical software. Results A total of 73 pediatric patients were included in this study, including 49 male and 24 female, and their mean age was 8 months (P25-P75: 4-12), the minimum age was 1 month and the maximum age was 36 months. They were divided into PBO group (n=30) and control group (n=43). It was found that wheezing (27 cases, 90.0% ), persistent cough (22 cases, 73.3%) and exercise intolerance (22 cases, 73.3%) were the main clinical symptoms in PBO group. Results of physical examination showed wheeze (24 cases, 80.0% ) and crackles (21 cases, 70.0% ). Mosaic perfusion (25 cases, 83.3%) was the most prominent sign in lung CT scan. More than 2/3 of the pediatric patients were found moderate and severe pulmonary dysfunction. Pathogen detection rate was 50% in PBO group, and virus was prevalent (respiratory syncytial virus 4 cases, influenza virus 1 case, measles virus 2 cases and adenovirus 4 cases). The results of Logistic multivariate regression analysis showed that the risk factors included using corticosteroids at the beginning of disease (OR=8.515, 95%CI: 1.948- 37.224), prolonged mechanical ventilation (OR=1.116, 95%CI: 1.031-1.327) and postponing clinic time (OR=1.114, 95%CI:1.010- 1.227). Conclusion Once the severe pneumonia children, with the risk factors of using corticosteroids at the beginning of disease, prolonged invasive mechanical ventilation and postponing clinic time, are found the wheezing, persistent cough and exercise intolerance, and persisting wheeze and/or crackles, the PBO relevant examination should be executed as soon as possible to diagnosis and treatment.

Key words: bronchiolitis obliterans, pneumonia, risk factors, child, post-infectious bronchiolitis obliterans, invasive mechanical ventilation, clinical features